Title of Invention

COLORIMETRIC ARTIFICIAL NOSE HAVING AN ARRAY OF DYES AND METHOD FOR ARTIFICIAL OLFACTION

Abstract

The present invention involves an artificial nose (10) having an array (12) comprising at least a first dye and a second dye in combination and having a distinct spectral response to an analyte. In one embodiment the first and second dyes are from the group comprising porphyrin, chlorine, chlorophyll, phthalocyanine, or salen. In a further embodiment, the first and second dyes are metalloporphyrins. The present invention is particularly useful in detecting metal ligating vapors. Further, the array (12) of the present invention can be connected to a wavelength sensitive light detecting device.

Full Text

FORM 2 THE PATENT ACT 1970 (39 OF 1970) & The Patents Rules, 2003 PROVISIONAL/COMPLETE SPECIFICTION (See section 10 and rule 13) 1. TITLE OF THE INVENTION "Colorimetric Artificial Nose Having an Array of Dyes and Method for Artificial Olfaction" 2. APPLICANTNAME : The Board of Trustees of the University of Illinois (a) NATIONALITY: A trust constituted under the laws of United States of America (b) 352 Henry Administration Building,506 south wright Street, Urbana, Illinois 61801, USA 3. PREAMBLE TO THE DESCRIPTION PROVISIONAL The following specification describes the invention COMPLETE The following specification particularly describes;the invention and the manner in which it is to be performed. 4." DESCRIPTION (Description shall start from the next page) 5. CLAIMS (not applicable for provisional specification. Claims should start with the permeable "I/We Claim on separate page) 6. DATE AND SIGNATURE (to be given at the end of last page of specification) 7. ABSTRACT OF THE INVENTION (to be given along with complete specification on separate page) Note :- *Repeat boxes in case of more than one entry. To be signed by the applicant(s) or by authorized registered patent agent. *Name of the applicant should be given in full, family name in the beginning. *Complete address of the applicant should be given stating the postal index no./code, state and country. Strike out the column which is/are not applicable. COLORIMETRIC ARTIFICIAL NOSE HAVING AN ARRAY OF DYES AND METHOD FOR ARTIFICIAL OLFACTION FIELD OF THE INVENTION The present invention relates to methods and apparatus for artificial olfaction, e.g., artificial noses, for the detection of odorants by a visual display. BACKGROUND OF THE INVENTION There is a great need for olfactory or vapor-selective detectors (i.e., "artificial noses") in a wide variety of applications. For example, there is a need for artificial "ncrses"that"can detect low levels-of.odorants .and/or where odorants may be harmful to humans, animals or plants. Artificial noses that can detect many different chemicals are desirable for personal dosimeters in order to detect the type and amount of odorants exposed to a human, the presence of chemical poisons or toxins, the spoilage in foods, the presence of flavorings, or the presence of vapor emitting items, such as plant materials, fruits and vegetables, e.g., at customs portals. Conventional artificial noses have severe limitations and disadvantages and are not considered generally useful for such purposes. Limitations and disadvantages of conventional artificial noses include their need for extensive signal transduction hardware, and their inability to selectively target metal-coordinating vapors and toxins. In addition, artificial noses-which incorporate mass sensitive signal transduction or polar polymers as sensor elements are susceptible to interference by water vapor. This limitation is significant in that it can cause variable response of the detector with changes ambient humidity. See F. L. Dickert, 0. Hayden. Zenkel, M. E. Anal. Chem. 71, 1338 (1999). Initial work in the field of artificial noses was conducted by Wilkens and Hatman -in 1964, though the bulk of research done in this area has been carried out since the early 1980"s. See, e.g., W. F. Wilkens, A. D. Hatman. Ann. NY Acad. Sci., 116, 60S (1964); K. Pursaud, G. H. Dodd. Nature, 299, 352-355 (1982); and J. W. Gardner, P. N. Bartlett. Sensors and ActuatorsB, 18-19, 211-220 (1994). Vapor-selective detectors or "artificial noses" are typically based upon the production of an interpretable signal or display upon exposure to a vapor emitting substance or odorant (hereinafter sometimes referred to as an "analyte"). More specifically, typical artificial noses are based upon selective chemical binding or an interface between a detecting compound of the artificial nose and an analyte or odorant, and then transforming that chemical binding into a signal or display, i.e., signal transduction. Polymer arrays having a single dye have been used for artificial noses. That is, a series of chemically-diverse polymers or polymer blends are chosen so that their composite response distinguishes a given odorant or analyte from others. Examples of polymer array vapor detectors, including conductive polymer and conductive polymer/carbon black composites, are discussed in: M. S. Freund, N. S. Lewis, Proc. Natl. Acad. Sci. USA 92, 2652-2656 (1995); B. J. Doleman, R. D. Sanner, E. J. Severin, R. H. Grubbs, N. S. Lewis, Anal. Chem. 70, 2560-2564 (1998); T. A. Dickinson, J. White, J. S. Kauer, D. R. Walt, Nature 382, 697-700 (1996)(polymer array with optical detection); A. E. Hoyt, A. J. Ricco, H. C. Yang, R. M. Crooks, J. Am. Chem. Soc. 117,8672 (1995); and J. W. Grate, M. H. Abrahamn, Sensors and Actuators B 3, 85-111 (1991). Other interface materials include functionalized self-assembled monolayers (SAM), metal oxides, and dendrimers. Signal transduction is commonly achieved with mass sensitive piezoelectric substrates, surface acoustic wave (SAW) transducers, or conductive materials. Optical transducers (based on absorbance or luminescence) have also been examined. Examples of metal oxide, SAM, and dendrimer-based detectors are discussed in J. W. Gardner, H. V. Shurmer, P. Corcoran, Sensors and Actuators B 4, 117-121 (1991); J. W. Gardner, H. V. Shurmer, T. T. Tan, Sensors and Actuators B 6, 71-75 (1992); and R. M. Crooks, A. J. Ricco, Ace. Chem. Res. 31,219-227 (1998). These devices also use a single dye. Techniques have also been developed using a metalloporphyrin for optical detection of a specific, single gas such as oxygen or ammonia, and for vapor cleTe^fiorrbiTclTemically interactive-layer-s-on-quar-tz crystal microbalances. See_A._ E. Baron, J. D. S. Danielson, M. Gouterman, J. R. Wan, J. B. Callis, Rev. Sci. lustrum. 64, 3394-3402 (1993); J. Kavandi, etal., Rev. Sci. Instrum. 61, 3340-3347 (1990); W. Lee, et al., J. Mater. Chem. 3, 1031-1035 (1993); A. A. Vaughan, M. G. Baron, R. Narayanaswamyy, Anal Comm. 33, 393-396 (1996); J. A. J. Brunink, et aL Anal. Chim. Acta 325, 53-64 (1996); C. Di Natale, et al., Sensors 2 and Actuators B 44, 521-526 (1997); and C. Di Natale, et al., Mat. Sci. Eng. C 5, 209-215 (1998). However, these techniques either require extensive signal transduction hardware, or, as noted above, are limited to the detection of a specific, single gas. They are also subject to water vapor interference problems, as discussed previously. While typical systems to date have demonstrated some success in chemical vapor detection and differentiation, these systems have focused on the detection of non-metal binding or non-metal ligating solvent vapors, such as arenes, halocarbons and ketones. Detection of metal-ligating vapors (such as amines, thiols, and phosphines) has been much less explored. Further, while some single porphyrin based sensors have been used for detection of a single strong acid, there is a need for sensor devices that will detect a wide variety of vapors. To summarize, there are a number of limitations and drawbacks to typical artificial noses and single porphyrin based sensors. As noted above typical artificial noses are not designed for metal binding and metal ligating vapors, such as amines, thiols, and phosphines. Further, typical artificial noses require extensive signal transduction hardware, and are subject to interference from water vapor. As noted above, single porphyrin based sensors have been used for detection of a single strong acid, but cannot detect a wide variety of vapors. Thus, there is a need for new artificial noses and methods that overcome these and other limitations of prior artificial noses and single porphyrin based sensors and methods. SUMMARY OF THE INVENTION The present invention comprises an array of dyes including at least a first dye and a second dye which in combination provide a spectral response distinct to an analyte or odorant. The dyes of the present invention produce a response in the spectrum range of about 200 nanometers to 2,000 nanometers, which includes the visible spectrum of light. It has now been discovered that an array of two or more dyes responds to a given ligating species with a unique color pattern spectrally and in a time dependent manner. Thus, dyes in the array of the present invention are _c.ap.able_oLchan.ging-co4or in-a-distinGt-nianner-when-exposed-to-any-one analyte or odorant. The pattern of colors manifested by the multiple dyes is indicative of a specific or given analyte. In other words, the pattern of dye colors observed is indicative of a particular vapor or liquid species. In a preferred embodiment, the dyes of the array are porphyrins In another 3 preferred embodiment, the porphyrin dyes are metalloporphyrins. In a further preferred embodiment, the array will comprise ten to fifty distinct metalloporphyrins in combination. Metalloporphyrins are preferable dyes in the present invention because they can coordinate metal-ligating vapors through open axial coordination sites, and they produce large spectral shifts upon binding of or interaction with metal-ligating vapors. In addition, porphyrins, metalloporphyrins, and many dyes show significant color changes upon changes in the polarity of their environment; this so-called solvatochromic effect will give net color changes even in the absence of direct bonding between the vapor molecules and the metal ions. Thus, metalloporphyrins produce intense and distinctive changes in coloration upon ligand binding with metal ligating vapors. The present invention provides a means for the detection or differentiation and quantitative measurement of a wide range of ligand vapors, such as amines, alcohols, and thiols. Further, the color data obtained using the arrays of the present innovation may be used to give a qualitative fingerprint of an analyte, or may be quantitatively analyzed to allow for automated pattern recognition and/or determination of analyte concentration. Because porphyrins also exhibit wavelength and intensity changes in their absorption bands with varying solvent polarity, weakly ligating vapors (e.g., arenes, halocarbons, or ketones) are also differentiable. Diversity within the metalloporphyrin array may be obtained by variation of the parent porphyrin, the porphyrin metal center, or the peripheral porphyrin substituents. The parent porphyrin is also referred to as a free base ("FB") porphyrin, which has two central nitrogen atoms protonated (i.e., hydrogen cations bonded to two of the central pyrrole nitrogen atoms). A preferred parent porphyrin is depicted in FIG. 2A, with the substitution of a two hydrogen ion for the metal ion (depicted as "M") in the center of the porphyrin. In FIG. 2 A, TTP stands for 5,10,15,20-tetraphenylporphyrinate(-2). In accordance with the present invention, colorimetric difference maps can be generated by subtracting unexposed and exposed metallopoq:>hyrin array images (obtained, for example, with a common flatbed scanner or inexpensive video or charge coupled device ("CCD") detector) with image analysis software. This eliminates the need for extensive and expensive signal transduction hardware associateaLwith-prev-ious-techniques4e.g.,-piezoelectr-ic-or-seniiconductor-sensors).-^ By simply differencing images of the array before and after exposure to analytes, the 4 present invention provides unique color change signatures for the analytes, for both qualitative recognition and quantitative analysis. Sensor plates which incorporate vapor sensitive combinations of dyes comprise an embodiment of the present invention which is economical, disposable, and can be utilized to provide qualitative and/or quantitative identification of an analyte. In accordance with the present invention, a catalog of arrays and the resultant visual pattern for each analyte can be coded and placed in a look-up table or bopk for future reference. Thus, the present invention includes a method of detecting an analyte comprising the steps of forming an array of at least a first dye and a second dye, subjecting the array to an analyte, inspecting the first and second dyes for a spectral response, and comparing the spectral response with a catalog of analyte spectral responses to identify the analyte. Because sensing is based upon either covalent interaction (i.e., ligation) or non-covalent solvation interactions between the analyte and the porphyrin array, a broad spectrum of chemical species is differentiable. While long response times (e.g., about 45 minutes) are observed at low analyte concentrations of about 1 ppm with large reverse phase silica gel plates, use of impermeable solid supports (such as polymer- or glass-based micro-array plates) or of small (e.g., about 1 square cm.) substantially increases the low-level response to about 5 minutes. Tli us, it is an object of the present invention to provide methods and devices for artificial olfaction, vapor-selective detectors or artificial noses for a wide variety of applications. It is another object of the present invention to provide methods of detection and artificial noses that can detect low levels of odorants and/or where odorants may be harmful to living human, animal or plant cells. It is also an object of the present invention to provide methods of olfactory detection and artificial noses that can detect and quantify many different chemicals for dosimeters that can detect chemical poisons or toxins, that can detect spoilage in foods, that can detect flavorings and additives, and that can detect plant materials, e.g., fruits and vegetables. Another object of the present invention is to provide lor the detection of analytes using data analysis/pattern recognition techniques, including automated techniques. BRIEF DESCRIPTION OF THE DRAWINGS The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawing(s) will be provided by the Patent and Trademark Office upon request and payment of the necessajy fee. Figure 1 illustrates an embodiment of the optical sensing plate of the present invention using a first elution in the y axis and a second elution in the x axis of the plate. In this embodiment the first elution P.-OH/liexane and the second elution is R-SH/hexanc. Figure 2A illustrates an embodiment of the invention using mctalloporphyrins as the sensing dyes. Figure 2B illustrates an embodiment of the invention using metalloporphyrins as the sensing dyes. Figure 3A illustrates a vapor exposure apparatus for demonstration of the present invention. Figure 3B illustrates a vapor exposure apparatus for demonstration of the present invention. Figure 4 illustrates the color change profile in a metalloporphyrin array of Figure 2 when used in the vapor exposure apparatus of Figure 3 A to detect n-butylaminc. Metalloporphyrins were immobilized on reverse phase silica gel plates. Figure 5 illustrates a comparison of color changes at saturation for a wide range of analytes. Each analytc was delivered to the array as a nitrogen stream saturated with the analyte vapor at 20°C. DMF stands for dimethylformamide; THF stands for tctrahydrofuran. Figure 6 illustrates two component saturation responses of mixtures of 2-mcthylnyridine and trimethylphosphite. Vapor mixtures were obtained by mixing two analyte-saturated N2 streams at variable flow ratios. Figure 7 illustrates a comparison of Zn(TPP) spectral shifts upon exposure to cthanol and pyridine (py) in methylene chloride solution (A) and on the reverse phase support (B). Figure 8 illustrates another embodiment of the present invention, and more particularly, an small aaay comprising microwclls built into a wearable detector which also contains a portable light source and a light detector, such as a charge-coupled device (CCD) or photodiode array. Figure 9 illustrates another embodiment of the present invention, and more particularly, a microwcll porphyrin array wellplate constructed from polydimethylsiloxane (PDMS). Figure 10 illustrates another embodiment of the present invention, and more particularly, a rnicroplatc containing machined teflon posts, upon which the porphyrin array is immobilized in a polymer matrix (polystyrcnc/dibutylphthalale). Figure 11 illustrates another embodiment of the present invention, showing a microplate of Ihc type shown in Figure 10, consisting of a minimized array of four metalloporphyrins. showing the color profile changes for n-octylamine, dodecanethiol, and tri-n-butylphosphine, each at 1.8 ppm. Figure 12 illustrates the immunity of the present invention to interference from water vapor. Figure 13 illustrates tlie .synthesis of siloxyl-substituted bis-pocket porphyrins in accordance with the present invention. Figures 14a, 14b, and 14c illustrate differences in Kc, for various porphyrins. Figure 15 illustrates molecular models of Zn(Si$PP) (left column) and Zn(SigPP) (right column). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Production of The Sensor Plate of the Present Invention A sensor plate 10 fabricated in accordance with the present invention is shown in Figure 1. Sensorplate 10 comprises a two-dimensionally spatially resolved array 12 of various sensing elements or dyes 14 capable of changing color upon interaction (e.g., binding, pi-pi complcxation, or polarity induced shifts in color). As shown in Figure 1, a library of such dyes 14 can be given spatial resolution by two-dimensional chromatography or by direct deposition, including, but not limited to, ink-jet printing, micropipette spotting, screen printing, or stamping.. In Figure 1, metalloporphyrin mixture 6 is placed at origin 7. Next, the metalloporphyrin mixture 6 is elutcd through a silica gel or reversed-phase silica gel 5 in sensor plate 10, and the mctalloporphyrins are spatially resolved from each other and immobilized in silica gel 5 as depicted by the oval and circular shapes 4 as shown in Figure 1. Sensor plate 10 can be made from any suitable material or materials, including but not limited to, chromatography plates, paper, filter papers, porous membranes, or properly machined polymers, glasses, or metals. Figure 1 also illustrates an embodiment of the optical sensing plate of the present invention using a first elution 8 in tlie y axis and a second elution 9 in the x axis of sensor plate 10. In this embodiment, tlie first elution 8 is R-OH/hexane and die second elution 9 is R-- — SH/hcxane. The order of the first and second elulions can be reversed. The first and second clutions are used to spatially resolve the metalloporphyrin mixture 6 in silica gel 5. As shown in Figure 1, the upper left hand quadrant 3 is characterized by inetalloporphyrins that are "hard" selective, i.e., having a metal center having a high chemical hardness, i.e., a high charge density. As shown in Figure 1, the lower right hand quadrant 2 is characterized by inetalloporphyrins that are "soft" selective, i.e., having a metal center having a low chemical hardness, i.e., a low charge density. In accordance with the present invention, the array can be a spatially resolved collection of dyes, and more particularly a spatially resolved combinatorial family of dyes. In accordance with the present invention, a porphyrin - metalloporphyrin sensor plate was prepared and then used to detect various odorants. More specifically, solutions of various metalated tetraphenylporphyrins in either methylene chloride or chlorobenzene were spotted in 1 HL aliquots onto two carbon ("C2", i.e, ethyl-capped) reverse phase silica thin layer" chromatography plates (Product No. 4809-800, by Whatman, Inc., Clifton, New Jersey) to yield the sensor array 16 seen in"Figure 2B. As shown in Figure 2B and summarized in Table 1 below, the dyes have the following colors (the exact colors depend, among other things, upon"scanner settings). Table 1 (Summarizing Colors of Dves in Figure 2B1 Sn4t-Green """:"V Co" - Red Cr5* - Deep Green Mn3* — Green Fe1* - Dark Red Co2* - Red J> Cu2* -Red Ru2* - Light Yellow Zn2* — Greenish Red Ag2" - Red 2H4 (Free Base "FB")- Red A metalloporphyrin 15, sometimes referred to as MfTPP), of the present invention is depicted in Figure 2A. Figure 2A also depicts various metals of the metalloporphyrins 15 of the present invention, and corresponding metal ion charge to radius ratio (i.e., Z/r Ratio) in reciprocal angstroms. The Z/r Ratio should preferably span a wide range in order to target a wide range of metal ligating analytes. These metalloporphyrins have excellent chemical stability on the solid support and most have well-studied solution ligation chemistry. Reverse phase silica was chosen as a non-interacting dispersion medium for the metalloporphyrin array 16 depicted in Figure 2B, as well as a suitable surface for diffuse reflectance spectral measurements. More importantly, the reverse phase silica presents a hydrophobic interface, which virtually eliminates interference from ambient water vapor. After spotting, sensor plates 18 like the one depicted in Figure 2B were dried under vacuum at 50"C for 1 hour prior to use. Thus, immobilization of the metalloporphyrins on a reverse phase silica support is obtained. While ten (10) different metalloporphyrins arc shown in Figure 2A, those of skill in the art will recognize that many other metalloporphyrins are useful in accordance wit".i the present invention. Those of skill in the art will further recognize that in accordance with the broad teachings of the present invention, any dyes capable of changing color upon interacting with an analyte, both containing and not containing metal ions, are useful in the array of the present invention. Colorimetric Analysis Using the Sensor Plate For the detection and analysis of odorants in accordance with the present invention, one needs to monitor the absorbance of the sensor plate at one or more wavelengths in a spatially resolved fashion. This can be accomplished with an imaging spectrophotometer, a simple flatbed scanner (e.g. a Hewlett Packard Scanjet 3c), or an inexpensive video or CCD camera. Figure 3 A illustrates a vapor exposure apparatus 19 of the present invention. Figure 3B illustrates top and side views of bottom piece 21 and a top view of top piece 21" of a vapor exposure flow cell 20 of the present invention. In an embodiment of the present invention for purposes of demonstration, each sensor plate 18 was placed inside of a stainless steel flow cell 20 equipped with a quartz window 22 as shown in Figures 3A and 3B. Scanning of the sensorplate - "" 18 was done on a commercially available flatbed scanner 24 (Hewlett Packard Scanjet 3c) at 200 dpi resolution, in full color mode. Following an initial scan, a control run with a first pure nitrogen flow stream 26 was performed. The array 16 of plate 18 was then exposed to a second nitrogen flow stream 28 saturated with a liquid analyte 30 of interest. As shownin Figure 3A, the nitrogen flow stream 28 saturated with liquid analyte 30 results in a saturated vapor 32. Saturated vapor 32, containing the analyte 30 of interest were generated by flowing nitrogen flow stream 28 at 0.47 L/min. through the neat liquid analyte 30 in a water-jacketed, glass fritted bubbler 34. Vapor pressures were controlled by regulating the bubbler 34 temperature. As shown in Figure 3B, vapor channels 23 permit vapor flow to sensor plate 18. . Example 1 Scanning at different time intervals and subtracting the red, green and blue ("RGB") values of the new images from those of the original scan yields a color change profile. Tliis is shown for n-bulylamine in Figure 4, in which color change profiles of the mctalloporphyrin sensor array 16 as a function of exposure time to »-buty)aminc vapor. Subtraction of the initial scan from a scan after 5 min. of N, exposure was used as a control, giving a black response, as shown. 9.3% >/-butylamine in Nj was then passed over the array and scans made after exposure for 30 s, 5 min., and 15 min. The red, green and blue ("RGB") mode images were subtracted (absolute value) to produce the color change profiles illustrated. Virtually all porphyrins are saturated after 30 seconds of exposure, yielding a color fingerprint unique for each class of analytes, which is illustrated in Figure 4. More specifically, subtraction of the initial scan 40 from a scan after 5 min. of N, exposure was used as a control, giving a black response, as shown in Figure 4. A nitrogen flow stream containing 0.093% ;i-butylamine was then passed over the array 16 and scans 42,44, and 46 were made after exposure for 30 seconds, 5 minutes, and 15 minutes, respectively. The RGB mode images were subtracted (absolute value) using Adobe Photoshop™ (which comprises standard image analyzing software), with contrast enhancement by expanding"the pixel range (a 32 value range was expanded to 256 each for the R, G,and B values). Subtraction of exposed and unexposed images gives color change patterns that vary in hue and intensity. • Because differentiation is provided by an array of detectors, the system has parallels the mammalian olfactory system. As shown in Figure 4 and summarized in Table 2 below, the dyes have the following colors in scans 42,44, and 46. Table 2 (Summarizing Colors of Dyes in Figure 4. Scans 42. 44. and 46^ Sn4* - No Change Co1* - Green Cr3* - Green Mn5"- No Change Fe^~Rcd - - - - - - Co2" -- Faint-Green Cu2* - No Change Ru2* — No Change Zn2" - Light Green Ag2" - No Change 2H* (Free Base "FB") - Light Blue As summarized in Table 3 below, for the TTP array 16 depicted on the left-hand side of Figure 4, the dyes have the following colors. Table 3 Sn4" - Greenish Yellow Co3" - Red Cr1" -- Yellow with Dark Red Center Mn" - Greenish Yellow Fc1" -- Dark Red Co1* -- Red Cu2* - Red Ru1" -- Light Yellow Zn1" -- Red Ag2" - Red 2H* (Free Base "FB") - Red Example 2 Visible spectral shifts and absorption intensity differences occur upon ligation of the metal center, leading to readily observable color changes. As is well known to those with skill in the art, the magnitude of spectral shift correlates with the polarizability of the ligand; hence, there exists an electronic basis for analyte distinction. Using metal centers that span a range of chemical hardness and ligand binding affinity, a wide range of volatile analytes (including soft ligands, such as thiols, and harder ligandi, such as amines) are differentiable. Because porphyrins have been shown to exhibit wavelength and intensity changes in their absorption bands with varying solvent polarity, it is contemplated that the methods and apparatus of the present invention can be used to coJorimetricaJJ}" distinguish among a series of weakly Jigating solvent vapors (e.g., arenes, halocarbons, or ketones), as shown for example in Figure 5. A comparison of color changes at saturation for a wide range of analytes is shown in Figure 5. Each analyte is identified under the colored array 16 that identifies each analyte.). DMF stands for the analyte dimethylforrnamide, and THF stands for the analyte tetrahydrofuran. As shown in Figure 5 and summarized in Table 4 below, the colors of each dye in response to a particular analyte are as follows. Table 4 Analyte: DM17 SnAf - No Change Co" - Green Cr" -- No Change Mn" -- No Change Fe" - No Change Co" - No Change Cu" -- Blue • Ru" - No Change Zn" - No Change Ag" - No Change 2H" (Free Base "FB") - Blue Analyte: Ethanol Sn4" - Dark Blue Co" -- No Change Cr" -- Red Mn" -- No Change Fc" -- No Change Co2" -- No Change Cu2" -NoChange Ru" - No Change Zn" - Blue Ag2" --No Change 2H* (Free Base "FB") - No Change Analyte: Pyridine Sn" - No Change Co3" - Green Cr3*- Dark Green Mn3* - No Change Fe3* - No Change Co2" - No Change Cu2* -- No Change Ru2" - No Change Zn2* — Green Ag2* - No Change iff (Free Base "FB")-Blue Analyte: Hexylamine Sn"" - No Change Co1* - Dark Green Cr3* - Green Mn3* - No Change Fc3*-Red Co2* - No Change Cu2* -- Blue Ru2* -- No Change Zn2* - Green Ag2* - Dark Blue 2H* (Free Base "FB")-Blue Analyte: Acetonitrile Sn4* - Blue Co3* - Dark Green Cr3* - No Change Mn3* -- Yellow Fe3* - Dark Green Co2* - No Change Cu2" - Blue Ru2" - Blue (faint dot) Zn2* - Blue Ag2" - No Change 2H* (Free Base "FB") - Blue Analylc: Acetone Sn" - No Change Co3" - No Change Cr3* - Red (small dot) Mn3* — No Change Fe3* - No Change Co2* -- No Change Cu2* -- Dark Blue . Ru2" - No Change Zn2* - Dark Blue Ag2" -- No Change 2ir (Free Base "FB") - Blue Analyte: THF Sn" - Dark Blue Co3* — Green Cr3* - Red Mn3* -- Blue (small dot) Fe3" - Dark Green Co2* -- No Change Cu2" -- Blue Ru2" - No Change Zn2" - Blue Ag"* -- No Change 211"(Free Base "FB")-Blue Analyte: CH2CI2 Sn4"-Dark Blue Co1*--No Change Cr" - No Change Mn5* - Yellow and Red (small dot) Fe3* - No Change Co2* - No Change Cu2* -DarkBlue Ru2" - No Change Zn2" - No Change Ag2" ~ No Change 2H* (Free Base "FB")- Blue Analyte: CHC13 Sn4*-Dark Blue Co3* - Dark Green Cr*4-Yellow (circle) Mn3* - YeUow Fe3* - Dark Green (very faint) Co2*-No Change Cu2 Ag2* - Blue (very faint) 2H* (Free Base "FB") - Blue Analyte: PtOCjH,), Sn4* - No Change" Co3" - Yellow Cr3*-Dark Green Mn3* - No Change Fe3* - Dark Green (very faint) Co2* - Greenish Yellow Cu2* - Dark Blue (faint) -Zn-—GreenishBlue KU — INO Change Ag2* - Blue (very faint) 2I-T (Free Base "FB") - Blue Analyte: P(C,H,)3 Sn" - No Change Co3" - Yellow and Red Cr3* - Deep Red Mn3" - No Change Fe3" - Dark Green (faint) Co2* - Red (with some yellow) Cu2" - No Change Ru2" - Dark Blue Zn:* - Yellow Ag2" --No Change 2H" (Free Base "FB") - No Change Analyte: C6H„SH Sn4f — Green Co3" - No Change Cr3" - Yellow circle surrounded by greenish blue circle Mn" - Yellow lV - Dark Green Co2" - No Change Cu2" -Dark Blue (faint) Ru1" - No Change Zn2" -- Green Ag2" - Blue (very faint) 2H* (Free Base "FB") -Blue Analyte: (C3H7),S Sn""- Dark Blue (faint) Co3* — Deep Green Cr3* - Green MnM-No Change Fe^-Dark Green Co2* - Dark Green (very faint) Cu" - Dark Blue (faint) Ru2* -- Green Zn2* -- Green t Ag** - Blue (very faint) 2H* (Free Base "FB")- Blue Analyte: Benzene Sn"*-No Change Co1* - Green Cr1* - Yellow (very faint) MnJ* - Yellow (some green) FeJ*-Dark Green Co2* - No Change Cu2* - No Change Ru2* - No Change Zn2* - Dark Green Ag2* - No Change 2H* (Free Base "FB") - Blue The degree of ligand softness (roughly their polarizability) increases from left to right, top to bottom as shown in Figure 1. Each analyte is easily distinguished from the others, and there are family resemblances among chemically similar species (e.g., pyridine and n-hcxylamine). Ana1vte distinction originates both in the metal specific ligation affinities and in their specific, unique color changes upon ligation. Each analyte was delivered to the array as a nitrogen stream saturated with the analyte vapor at 20°C (to ensure complete saturation, 30 min. exposure,:: to vapor were used. Although these fingerprints were obtained by exposure to saturated vapors (thousands of ppm), unique patterns can be identified at much lower concentrations. The metalloporphyrin array 16 has been used to quantify single analytes and to identify vapor mixtures. Because the images" color channel data (i.e., RGB values) vary linearly with poiphyrin concentration, wc were able to quantify single porphyrin responses to different ."inalytcs. Color channel data were collected for individual spots and plotted, for example, as the quantity (R B - R,pJ/(R,J, where Rp„ was the red channel value for the initial silica surface and R,„the. average value for the spot. For example, Fe(TFPP)(CI) responded linearly to ocrylamine between 0 and 1.5 ppm. Other porphyrins showed linear response ranges that varied with ligand affinity (i.e., equilibrium constant). Example 3 The array of the present invention has demonstrated interpretable and reversible responses even to analyte mixtures of strong ligands, such as pyridines and phosphites, as is shown in Figure 6. Color change patterns for the mixtures are distinct from either of the neat vapors. Good reversibility was demonstrated for this analyte pair as the vapor mixtures were cycled between the neat analyte extremes, as shown in Figure 6, which shows the two component saturation responses to mixtures of 2-methylpyridin6 ("2MEPY") and trimethylphosphite ("TMP"). Vapor mixtures were obtained by mixing the analyte-saturated N2 streams at variable flow ratios. A single plate was first exposed to pure trimethylphosphite vapor in N: (Scan A), followed by increasing mole fractions of 2-methyIpyridine up to pure 2-mcthylpyridine vapor (Scan C), followed by decreasing mole fractions of 2-methylpyridinc back to pure trimethylphosphite vapor. In both directions, scans were taken at the same mole fraction trimethylphosphite and showed excellent reversibility; scans at mole fractions at 67% trimethylphosphite (x=0.67 Scans B and D) and of their difference map are shown (Scan E). Response curves for the individual porphyrins allow for quantification of the mixture composition. The colors of each dye upon exposure to the analytes TMP and 2MEPY are.shown in Figure 6 and are summarized in Tabic 5 below. Table 5 Scan A, Analyte: Neat IMP Sn4" - Dark Blue Co3f - Yellow Cr3" -- No Change Mn3" - Yellow with red center Fe3* - Dark Green Co1" - Greenish Yellow Cu2" - Dark Blue Ru2" - No Change Zn2" -- Blue Ag" -- Green (very faint) 2H" (Free Base "FB") -Reddish Blue Scan B, Analyte: TMP.x^^O.G? Sn" - Blue Co3" -- Green Cr1" -- Green (small dot) Mn" - Yellow andGrecn Fe3* — Green and Yellow Co2" - Green with red center Cu2" -Dark Blue Ru2" -- Purple (very faint) Zn2" -- Blue Ag2" - Greenish Blue 2H* (Free Base "FB") -Reddish Blue Scan C, Analyte: Neat2MEPY Sn4* - Blue Co3* - Green Cr3*--No Change Mn3* - Yellow and Green with Red center FeJ* - Red with some Yellow Co2* - Green Cu2* -DarkBlue Ru2* - Deep Blue Zn2* - Green with some Blue Ag2* — Green with some Blue 2H* (Free Base "FB") -Reddish Blue Scan D, Analyte: TMP.Xn^O.e? Sn4* - Blue Co1* - Green Cr3* -- No Change Mn1* -- Yellow and Green Fe3* - Green and Yellow Co2* - Green Cu2* - Dark Blue Ru2* - Purple (very faint) Zn2* - Blue Ag1* - Greenish Blue (very faint) 2H* (Free Base "FB") -Reddish Blue -Scan E Sn" -- No Change Co3" - No Change Cr" - No Change Mn3" - No Change Fc3t - No Change Co2" -- No Change Cu2* - Blue (very faint) Ru2* ~ Blue (small dot) Zn2" --NoChange Ag1* ~ Blue (very faint) 2H* (Free Base "TB") - Green Example 4 In an effort to understand the origin of the color changes upon vapor exposure, diffuse reflectance spectra were obtained for single porphyrin spots before and after exposure to analyte vapors. Porphyrin solutions were spotted in 50 11L aliquots onto a plate and allowed to dry under vacuum at 50°C. Diffuse reflectance spectra of the plate were then taken using a UV-visible spectrophotometer equipped with an integrating sphere. Unique spectral shifts were observed upon analyte exposure, which correlated well with those seen from solution ligation. For example, Zn(TPP) exposure to ethanol am" pyridine gave unique shifts which were very similar to those resulting from ligand exposure in solution. Figure 7 shows a comparison of Zn(TPP) spectral shifts upon exposure to ethanol and pyridine (py) in methylene chloride solution (A) and on the reverse phase support (B). In both A and B, the bands conespond, from left to right, to Zn(TPP), Zn(TPP)(C,HjOH), and Zn(TPP)(py), respectively. Solution spectra (A) were collected using a Hitachi U-3300 spectrophotometer, Zn(TPP), C,HjOH, and py concentrations were approximately 2 uM, 170 mM, and 200 jiM, respectively. Diffuse reflectance spectra (B) were obtained with an integrating sphere attachment before exposure to analytes, after exposure to cthanol vapor in N2, and after exposure to pyridine vapor in N, for 30 min. each using the flow cell. Improvement to Low Concentration Response Color changes at levels as low as 460 ppb have been observed for octylamine vapor, albeit with slow response times due to the high surface area of the silica on the plate 18. The surface area of C2 plates is «350 mVgram. Removal of excess silica gel surrounding the porphyrin spots from the plate 18 led to substantial improvements in response time for exposures to trace levels of octylamine. Because the high surface area of the reverse phase silica surface is - — primarily responsible for the increased response time, other means of solid support or film formation can be used to improve low concentration response. Further, the present invention contemplates miniaturization of the array using small wells ~60"( These embodiments are depicted in Figures 8, 9, and 10. Figure 8 illustrates the interfacing of a microplatc 60 into an assembly consisting of a CCD 70, a microplate 72 and a light source 74. Figure 9 illustrates another embodiment of the present invention, and more particularly, a microwell porphyrin array wellplate 80 constructed from polydimethylsiloxane (l"DMS). The colors of the dyes shown in Figure 9 are summarized below in Table 6. Table 6 Sn"* -- Dark Red Co3" -- Dark Red CrJ* -- Dark Green Mn1" -- Green Fe" -- Dark Red Co2f -- Yellowish Green Cu2" -- Deep Red Ru2" - Dark Red Zn2" - Red with some Yellow Ag2t -- Red 2H+ (Free Base "FB") - Red Figure 10 demonstrates deposition of metalloporphyrin/polymer (polystyrene/ ibulylphthalate) solutions upon a plate, which includes a series of micro-machined Teflon® posts 100 having the same basic position relative to each other as shown in Figure 2A and Figure 2B. The colors for the dyes in the middle of Figure 10 are summarized in Table 7 below. Table 7 Sn"- Yellow Co" - Orange Cr3* - Yellow Mn3*-Yellow Fe3* - Orange Co1* — Orange Cu2f - Orange" Ru1*-Dark Yellow Zn2* - Orange Ag2* - Orange 2H* (Free Base "FB") - Red T The colors for the dyes on the right hand side of Figure 10 are summarized in Tabic 8 below. Table 8 -Snl-T-No-Change Co3" - Green Cr3" - Red Mn3" -- Blue Fe3*-Red To2* ~ Red, Green, Blue, and Yellow Cu2* - Green with some Blue Ru2* - Blue (very faint) Zn2f — Yellow with some Red Ag1" - Green with some Blue 2H* (Free Base "FB") - Green with some Blue Example 5 Figure 11 shows the eolorprofile changes from a microplate of the type shown in Figure 10. The microplate, consisting of a minimized array of four mctalloporphyrins, i.e., SnCri"PXCI,), Co(TPP)(Cl), Zn(TPP), Fe(TFPP)(Cl), clockwise from the upper left (where TFPP stands for 5,10,l5,20-tetrakis(pcntafluorophenyl)porphyrinate). "Hie color profile changes arc shown in Figure 11 after exposure to low levels of n-octylamiuc, dodocancthiol (C,jHuSH),and tri-w-butylphosphine (P(C4H9)3), each at 1.8 ppm, which is summarized in Table 9 below. Table 9 Dyes on Teflon® Sn - Dark Yellow Co-Red Zn-Red Fe - Orange with Red outline Dyes exposed to n-octylamine Sn-No Change Co - Green (very faint) Zn-Red Fe-Green Dyes exposed to CUHUSH Sn-Red Co - Green with some red, yellow and blue (faint) Zn - Red with some green and yellow Fe - Blue (very faint) Dyes exposed to (C4H9)3 Sn-No Change Co - Yellow with red center and some red periphery Zn - Green Fe - Yellow with some Green and Blue The low ppm levels of octylamine, an analyte of interest, were generated from temperature-regulated octylamine/dodecane solutions with the assumption of solution ideality. The dodecane acts as a diluent to lower the level of octylamine vapor pressure for the purposes of this demonstration of the invention. Example 6 Figure 12 illustrates the immunity of the present invention to interference from water vapor. The hydrophobicity of the reverse phase support greatly any possible effects from varying water vapor in the atmosphere to be tested. For instance, as shown in Figure 12, a color fingcrprint generated from exposure of the array to n-hexylamine (0.86% in N2) was identical to that for n-hexylamine spiked heavily with water vapor (1.2% H2O, 0.48% hcxylamine in N2). See scans 120, 122 and 124. The ability to easily detect species in the presence of a large water background represents a substantial advantage over mass-sensitive sensing techniques or methodologies that employ polar polymers, as part of the sensor array. The color patterns shown in Figure 12 are summarized in Table 10 below. Table 10 Scan 120 Sn4* - No Change Co3* -- Green Cr3" - Green Mn3"- No Change Fe3"-Red Co1"-No Change Cu2* -NoChange Ru2* - No Change Zn2* - Green Ag2* - No Change 2H* (Free Base "FB") - Dark Blue Scan 122 Sn"* - No Change Co3" - Green Cr" - Green Mn3" -No Change Fe^-Red Co2" - No Change Cu2" - No Change Ru2* - Green (small dot) Zn2* — Green Ag2* - No Change 2H* (Free Base "TB") - Dark Blue Scan 124 Sn4" - Bluish Circle Co3" - Bluish Circle Cr3* - Bluish Circle Mn3" - Bluish Circle Fe3* - Bluish Circle Co2" - Bluish Circle Cu2" - Bluish Circle Ru2f - Bluish Circle Zn2* -- Bluish Circle Ag2* - Bluish Circle 2H" (Free Base "FB") - Bluish Circle Additional Features of the Preferred Embodiments of the Invention Having demonstrated electronic differentiation, an important further goal is the shape-selective distinction of analytes (e.g., n-hcxylaminc vs. cyclohcxylamine). Functionalizcd metalloporphyrins that limit stcric access to the metal ion are candidates for such differentiation. For instance, we have been able to control ligation of various nitrogenous ligands to dendrimcr-metalloporphyrins and induce selectivities over a range of more than 104. As an initial attempt toward shape-selective detection, we employed the slightly-hindered letrakis(2,4,6- trimethoxypheny l)porphyrins (TTMPP) in our sensing array. With these porphyrins, fingerprints for t-butylamine and n-butylamine showed subtle distinctions, as did those for cyclohexylamine and n-hexylamine. Using more hindered metalloporphyrins, it is contemplated that the present invention can provide greater visual differentiation. Such porphyrins include those whose periphery is decorated with dendrimer, siloxyl, phenyl, t-butyl and other bulky substituents, providing sterically constrained pockets on at least one face (and preferably both) of the porphyrin. In a similar fashion, it is contemplated that the sensor plates of the present invention can be used for the detection of analytes in liquids or solutions, or solids. A device that detects an analyte in a liquid or solution or solid can be referred to as an artificial tongue. Proper choice of the metal complexes and the solid support must preclude their dissolution into the solution to be analyzed. It is preferred that the surface support repel any carrier solvent to promote the detection of trace analytes in solution; for example, for analysis of aqueous solutions, reverse phase silica has advantages as a support since it will not be wetted directly by water. Alternative sensors in accordance with the present invention may include any other dyes or metal complexes with intense absorbance in..the_ultrayiolet, visible, or.near. infrared spectra— that show a color change upon exposure to analytes. These alternative sensors include, but arc not limited to, a variety of macrocycles and non-macrocycles such as chlorins and chlorophylls, phthalocyanines and mctallophthalocyanines, salen-type compounds and their metal complexes, or other metal-containing dyes. The present invention can be used to detect a wide variety of analytes regardless of physical form of the analytes. That is, the present invention can be used to detect any vapor emitting substance, including liquid, solid, or gaseous forms, and even when mixed with other vapor emitting substances, such solution mixtures of substances. The present invention can be used in combinatorial libraries of metalloporphyrins for shape selective detection of substrates where the substituents on the periphery of the macrocycle or the metal bound by the porphyrin are created and then physically dispersed in two dimensions by (partial) chromatographic or electropliorctic separation. Hie present invention can be used with chiral substituents on the periphery of the macrocycle for identification of chiral substrates, including but not limited to drugs, natural products, blood or bodily fluid components. The present invention can be used for analysis of biological entities based on the surface proteins, oligosacharides, antigens, etc., that interact with the metalloporphyrin array sensors of the present invention. Further, the sensors of the present invention can be used for specific • recognition of individual species of bacteria or viruses. The present invention can be used for analysis of nucleic acid sequences based on sequence specific the surface interactions with the metalloporphyrin array sensors. The sensors of the present invention can be used for specific recognition of individual sequences of nucleic acids. Substituents on the porphyrins that would be particularly useful in this regard are known DNA intercalating molecules and nucleic acid oligomers. The present invention can be used with ordinary flat bed scanners, as well as portable miniaturized detectors, such as CCD detectors with microarrays of dyes such as metalloporphyrins. The present invention can be used for improved sensitivity, "automation of partern recognition of liquids and solutions, and analysis of biological and biochemical samples. Superstructure bonded to the periphery of the porphyrin The present invention includes modified porphyrins that have a superstructure bonded to the periphery of the porphyrin. A superstructure bonded to the periphery of the porphyrin in accordance with the present invention includes any additional structural element or chemical structure built at the edge of the porphyrin and bonded thereto. The superstructures can include any structural element or chemical structure characterized in having a certain selectivity. Those of skill in the art will recognize that the superstructures of the present invention include structures tliat are shape selective, polarity selective, inantio selective, regio selective, hydrogen bonding selective, and acid-basc selective. These structures can include siloxyl-substituted substituents, nonsiloxyl-substituted substituents and nonsiloxyl-substituted substituents, including but not limited to aryl substituents, alkyl substituents, and organic, organomclallic, and inorganic functional group substituents. Superstructure Pis-Pocket Porphyrins A number of modified porphyrins have been synthesized to mimic various aspects of the enzymatic functions of heme proteins, especially oxygen binding (myoglobin and hemoglobin) and substrate oxidation (cytochrome P-450). Sec Suslick, K. S.; Reinctt, T. J. J. Chem. Ed. 1985, 62, 974; Collman, J. P.; Zhang, X.; Lee, V. J.; Uffelman, E. S.; Brauman, J. 1. Science 1993, 261, 1404; Collman, J. P.; Zhang, X. in Comprehensive Supramolecular Chemistry; Atwood,J.L.;Davics,J.E.D.; MacNicol, D. D.; Vogtel.F. Eds.; Pergamon: New York, 1996; vol. 5, pp. 1-32; Suslick, K_ S.; van Dcusen-Jcffrics, S. in Comprehensive Supramolecular Chemistry; Atwood, J. L.; Davies, J.E.D.; MacNicol,D.D.; Vogtel, F. Eds.; Pcrgamon: New York, 1996; vol. 5, pp. 141-170; Suslick, K.S. in Activation and Functionalization of Alkanes; Hill, C. L., cd.; Wiley & Sons: New York, 1989; pp. 219-241. The notable property of many heme proteins is their remarkable substrate selectivity; the development of highly regioselective synthetic catalysts, however, is still at an early stage. Discrimination of one site on a molecule from another and distinguishing among many similar molecules presents a difficult and important challenge to both industrial and biological chemistry. Sec Metalloporphyrins in Catalytic Oxidations; Sheldon, R. A. Ed. Marcel Dekker: New York, 1994). Although the axial ligation properties of simple synthetic metalloporphyrins arc well documented in literature, see Bampos, N.; Marvaud, V.; Sanders, J. K. M. Chem. Eur. J. 1998, 4, 325; Stibrany, R. T.; Vasudevan, J.; Knapp, S.; Potenza, J. A.; Emgc, T.; Schugar, H. J. J. Am. Chem. Soc. 1996,118, 3980, size and shape control of ligation to peripherally modified metalloporphyrins has been largely unexplored, with few notable exceptions, where only limited selectivitics have been obscrved._ see bhyrappa, p.vaijayantimala, G; sustick, K.S.J.Am Chem. Soc. 1999,121,262; Iinai, II.; Nakagawa, S.; Kyuno, E. J. Am. Chem. Soc. 1992, 11.4,67!9. The present invention includes the synthesis, characterization and remarkable shape-selective ligation of silylether-mctalloporphyrin scaffolds derived from (lie reaction of 5,10,15,20-tctrakis(2",6"-dihydroxyphenyl)porphyrinatozinc(II) with t-butyldimcthylsilyl chloride, whereby the two faces of the Zn(II) porphyrin were protected with six, seven, or eight siloxyl groups. This results in a set of three porphyrins of nearly similar electronics but with different stcric encumbrance around central metal atom present in the porphyrin. Ligation to Zn by classes of different sized ligands reveal shape selectivitics as large as 10". A family of siloxyl-substilutcd bis-pockct poqihyrins were prepared according to the scheme of Figure 13. The abbreviation of the porphyrins that can be made in accordance with the scheme shown in Figure 13 are as follows: Zn(TPI"), 5,10,15,20-tctraphcnylporphyriiialozmc([l); Zn((OH)6PP], 5-plienyl-10,15,20-lris(2/,6/-dihydroxyphcnyl)porphyriuatozinc(Il); Zn[(OH),lT], 5J0,15,20-lctrakis(2A6/-dihydroxyphenyl)porphyrinatozinc(n); Zn(Si,Pl"), 5(p!icnyl)-10,15,20-i iris :,6/-disilyloxyphcnyl)porphyrinatozinc(ll); Zn(Si,OHPP), 5,10,15 tris (2/,6/- silyloxyphenyl)porphyrinatozinc(II); Zn(SilPP),5,10,15,20-tetrakis(2/16/-disilyloxyphcnyl)porphyrinatozinc(lI). The synthesis of Zn[(OH)6PP], Zn(Si6PP), and Zn(Si6PP) is detailed below.. Zn[(OH)6PP] and Zn[(OH)6PP] were obtained (see Bhyrappa, P.; Vaijayanthimala, G.; Suslick, K. S. J. Am. Chein. Soc. 1999, 121, 262) from demethylation (sec Momcnteau, M.; Mispelter, J.; Loock, B.; Bisagni, H. J. Chcm. Soc. Perkin Trans. 1, 1983, 189) of corresponding free base metlioxy compounds followed by zinc(II) insertion. The metlioxy porphyrins were synthesized by acid catalysed condensation of pyrrole with respective benzaldehydes following Lindsey procedures. Sec Lindscy, J. S.; Wagner, R. W. J. Org. Chcm. 1989, 54, 828. Metalalion was done in methanol with Zn(O2CCH3)2. The t-butyldimclhylsilyl groups were incorporated into the mctalloporphyrin by stirring a DMF solution of hydroxyporphyrin complex with TBDMSiCl (i.e., t-butyldimcthylsilyl chloride) in presence of imidazole. See Corey, E. J; Vcnkateswarlu, A. J. Am. Chem. Soc. 1972, 94, 6190. The octa (Zn(Si.PP)), hepta (Zn(Si,OHPP)), and liexa (Zn(Si4PP)) silylether porphyrins were obtained from Zn[(OH),PP] and Zn[(OH)5PP], respectively. The compounds were purified by silica gel column chromatography and fully cliaracterized-b.y_UV-=.Visiblc,-lH=NMR>.HPLC,.and.MALDI-TOF-MS. The size and shape sclectivitics of the binding sites of these bis-pocket Zn silylether porphyrins were probed using the axial ligation of various nitrogenous bases of different-shapes and sizes in toluene at 25°C. Zn(II) porphyrins were chosen because, in solution, they generally bind only a single axial ligand. Successive addition of ligand to the porphyrin solutions caused a red-shift of the Soret band typical of coordination to zinc porphyrin complexes. There is no evidence from the electronic spectra of these porphyrins for significant distortions of the electronic structure of the porphyrin. The binding constants (K,) and binding composition (always 1:1) were evaluated using standard procedures. See Collman, J. P.; Brauman, J. I.; Doxsce, K. M.; Halbcrt, T. R.; Hayes, S. E.; Suslick, K.. S. J. Am. Chem. Soc. 1978, 100,2761; Suslick, K.. S.; Fox, M. M.; Rcinert, T. J. Am. Chem. Soc. 1984,106,4522. The K values of the silylether porphyrins with nitrogenous bases of different classes arc compared with the stcrically undemanding Zn(TPP) in Figures 14a, 14b, and 14c. It is worth noting the parallel between shape selectivity in these equilibrium measurements and prior kinetically-controlled epoxidation and hydroxylation. Sec Collman, J. P.; Zhang, X. in Comprehensive Supramolecular Chemistry; Atwood, J. L.; Davies, J. E. D.; MacNicol, D. D.; Vogtcl, F. Eds.; Pcrgamon: New York, 1996; vol. 5, pp. 1-32; Suslick, K. S.; van Deusen-Jcffries, S. in Comprehensive Supramolecular Chemistry; Atwood, J. L.; Davies, J. E. D.; MacNicol, D. D.; Vogtel, F. Eds.; Pergamon: New York, 1996; vol. 5, pp. 141-170; Suslick, K. S. in Activation and Functionalization of AJJcanes; Hill, C. L, ed.; Wiley & Sons: New York, 1989; pp. 219-241; Bhyrappa, P.; Young, J.K.; Moore, I.S.; Suslick, K.S. J. Am. Chem. Soc, 1996,118,5708-5711. Suslick, K. S.; Cook, B. R. J. Chem. Soc, Chem. Comm. 1987,200-202; Cook, B. R.; Reinert, T. J.; Suslick, K. S. J. Am. Chem. Soc. 1986,108,7281-7286; Suslick, K. S.; Cook, B. R.; Fox, M. M. J. Chem. Soc, Chem. Commun. 198*5,580-582. The selectivity for equilibrated ligation appears to be substantially larger than for irreversible oxidations of similarly shaped substrates. The binding constants of silylether porphyrins are remarkably sensitive to the shape and size of the substrates relative to ZnfTPP). See Figures 14a, 14b, and 14c. The binding constants of different amines could be controlled over a range of 10" to 10" relative to Zn(TPP). It is believed that these selectivities originate from strong steric repulsions created by the methyl groups of the /-butyldimethylsiloxyl substituents. The steric congestion caused by these bulky silylether groups is pronounced even for linear amines and small cyclic amines (e.g., azctidine and pyrrolidine). There are very large differences in K^ for porphyrins having tliree versus four silylether groups on each face (e.g., hexa- vs. octa- silylether porphyrins), as expected based on obvious steric arguments (see Figures 14a, 14b, and 14c). Even between the hexa- over licpta- silylether porphyrins, however, there are still substantial differences in binding behavior. It is believed that this is probably due to doming of the macrocycle in the hexa- and hepta- silylether porphyrins, which lessens the steric constraint relative to the octasilylether porphyrin. Such doming will be especially important in porphyrins whose two faces are not identical. The free hydroxy functionality of the hcpta-silylether may play a role in binding of bi-functionalizcd ligands (e.g., free amino acids); for the simple amines presented here, however, we have no evidence of any special effects. These silylether porphyrins showed remarkable selectivities for normal, linear amines over their cyclic analogues. For a series of linear amines (n-propylaminc through n-decylamine), K were very similar for each of the silylether porphyrins. In comparison, the relative K., for linear versus cyclic primary amines (Figure 14a, n-butylamine vs. cyclohexylaminc) were significantly difTerent: K/ K ranges from 1 to 23 to 115 to >200 for ZnfTPP), Zn(Si6PP), Zn(Si2OHPP), and Zn(Si6PP). respectively. The ability to discriminate between linear and cyclic compounds is thus established. A series of cyclic 2° amines (Figure 14b) demonstrate the remarkable size and shape selectivitics of this family of bis-pocket porphyrins. Whereas the binding constants to Zn(TPP) with those amines are virtually similar. In contrast, the K,, values for silylcther porphyrins strongly depend on the ring size and its peripheral substituents. The effect of these shape-selective binding sites is clear, even for compact aromatic ligands with non-ortho methyl substituents (Figure I4c). The molecular structures of these silylether porphyrins explains their ligation selectivity. The x-ray single crystal structure of Zn(Si6PP) has been solved in the triclinic P1 bar space group. See Single crystal x-ray structure of Zn(Si6PP) shown in Figure 15. As shown in Figure 15, Zn(Si6PP) (energy minimized molecular model) and Zn(Si,PP) (single crystal x-ray structure) have dramatically different binding pockets. In the octasilylether porphyrin, the top access on both faces of the porphyrin is very tightly controlled by the siloxyl pocket. In contrast, the metal center of the hexasilylether porphyrin is considerably more exposed for ligation. Figure 15 illustrates molecular models of Zn(Si6PP) (left column) and Zn(Si6PP) (right .- column).- The pairs of images from top to bottom are cylinder side-views, side-views, and top-views, respectively; space filling shown at 70% van dcr Waals radii; with the porphyrin carbon atoms shown in purple, oxygen ntoms in red; silicon atoms in green, and Zn in dark red. The x-ray single crystal structure of Zn(Si6PP) is shown; for Zn(Si6PP), an energy-minimized structure was obtained using Cerius 2 from MSI. In summary, a series of bis-pocket siloxyl metalloporphyrin complexes were prepared with stcrically restrictive binding pockets on both faces of the macrocycle. Ligation to Zn by various nitrogenous bases of different sizes and shapes were investigated. Shape sclcctivilies as large as 10" were found, compared to unhindered metalloporphyrins. Fine-tuning of ligation properties of these porphyrins was also possible using pockets of varying stcric demands. The shape selectivitics shown here rival or surpass those of any biological system. Examples of Synthesis of Superstnictured Porphyrins and Metalloporphyrins Synthesis of 5-phenyl-l0,15,20-tris(2/6/-dihydroxy-phenyl)-porphyriuatoziuc(II), Zn|(OH)6PP): The free base 5-phenyl-10,15,20-tris(2/6/-dimethoxyphenyl)-porphyrin was synthesized by Lewis acid catalyzed condensation of 2,6-dimethoxybezaldehydc and bcnzaldehyde with pyrrole (3:1:4 mole ratio) following the Lindsey procedure. See Lindsey, J. S.; Wagner, R. W. J. Org. Chem. 1989, 54, 828. The mixture of products thus formed was purified by silica gel column chromatography (if necessary, using CH2CI2 as eluant). The isolated yield of the desired product was found to be 7%{wrt pyrrole used). The corresponding hydroxyporphyrins were obtained by dcmcthylation with pyridine hydrochloride. Sec Momenteau, M.; Mispelter, J.; Loock, B.; Bisagni, E. J. Chem. Soc. Perkin Trans. 1,1983,189. After typical work-up known to those skilled in the art, the crude compound was purified by silica gel column chromatography using cthylacetatc as eluant The first fraction was Zn[(OH) solvent was removed. The yield of the product was 90% (based on starting hydroxyporphiyin). 1HNMR of H2[(OH)6PP]inacctonc-d6(ppm): 8.96-8.79(m,8H,b-pyrroleH),8.24(m,2H,o-H S-Phcnyl), 8.07 and 8.02(2s, 6H, -OH), 7.83(m, 3H, mp-H 5-Phenyl), 7.50(t, 3H, />-H hydroxyphenyl), 6.90(d, 6H, m-li hydroxyplicnyl), -2.69(s, 2H, imino-H). Elemental analysis, calcd.for C44H30O6N4.H2O:C = 72.5, II = 4.4 andN = 7.7%. Found C = 72.7, H= 4.4 and N = 7.4%. The compound showed molecular ion peak at 711 (m/z calcd. for €44^00^4= 710) in FAB-MS. The Zn derivative was obtain by stirring methanol solution of H2[(OH)6PP] with excess Zn(O2CCH3)2H2O for 1hour.methanol was evaporated to dryness and the residue was dissolved in cthylacetatc, washed with water, and the organic layer passed through anhyd. Na2S04- The concentrated cthylacetatc solution was passed through a silica gel column and the first band was collected as the desired product The yield of the product was nearly quantitative. 1H NMR of Zn(OH)6PPinncctonc-d6(ppm): 8.95-8.79(m, 8H, b-pyrrole H), 8.22(m, 2H, o-H 5-Phenyl), 7.79(m, 311, mp-H 5-Phenyl), 7.75 and 7.65(2s, 6H, -OH), 7.48(t, 3H, p-H hydroxyplienyl), 6.88(d, 6H, m-U hydroxyphenyl). Elemental analysis, calcd. for ZnC44H28O6N4.H2O: C = 66.7, H = 3.8, N = 7.1 and Zn = 8.3%. Found C = 66.4, II = 3.8, N = 6.7 and Zn = 8.2%. The compound showed molecular ton peak at 774 (m/z calcd. for ZnC44H28O6N4 = 773) in FAB-MS. Synthesis of 5-plicnyl-10,15,20-tris(2",6"-disilyloxyphcnyl) porpliyriiatozinc(U),Zn(Si6PP): The hcxasilylcthcr porphyrin was synthesized by stirring a DMF solution of 5-phenyl- 10,15,20-tris(2 /,6^-dihydroxyphenyl)-porpliyrinatozinc(II) (100 mg, 0.13 mmol) with t- butyldimethyll silylchloride(1.18 g, 7.8 mmol) in presence of imidazole (1.2 g, 17.9 mmol)at 60°C for 24 h under nitrogen. After this period the reaction mixture was washed with water and extracted in CHCI3. The organic layer was dried over anhyd. Na2S04- The crude reaction mixture was loaded on a short silica gel column and eluted with mixture of CHCl3/petether(l:l, v/v) to get rid of unrcactcd starting material and lower silylatcd products. The desired compound 5 was further purified by running another silica gel column chromatography using mixture of CHCl3/pctether (1:3, v/v) as eluant. The yield of the product was 60% based on starting hydroxyporphyrin. 1H NMR in chJoroform-d (ppm): 8.94-8.S2(m, 8H, b-pyrrolc H), 8.20(m, 2H, o-H 5-Phenyl), 7.74(m, 3H, m.pj,-H 5-Phcnyl), 7.49(t, 3H, p-H hydroxyphenyl), 6.91 (t, 6H, m -H 10 hydroxyphenyl), -0.02 and -34(2s, 54 H, (-butyl H), -0.43, -0.78 and -1.01(3s, 36 H, metlryl H). Elemental analysis, calcd. for ZnC80H112O6N4Si6: C = 65.8, H = 7.7, N = 3.8, Si = 11.5 and Zn = 4.5%. Found C = 65.5, H = 7.7, N = 3.8, Si = 11.2 and Zn = 4.4%. The low resolution MALDI-TOF mass spectrum showed molecular ion peak at 1457 (m/z calcd. for ZnC8oHii206N4Si6=1458). Synthesis of 5,10,15-tris(2/,6 (disilyoxyphcnyl)-ZO-(2-hydroxy-6"- silyloxyp!icnyl)porpliyrinato7.itic(Tr), [Zn(Si7OITPP), and 5,l0,15,20-tctrakis(2"6"-(lisilyloxyplicnyl)(poiphyrinatozinc(II), (Zn(Si8PP)I: "The synthesis of precursor porphyrin 5,10,15,20-tctrakis-(2",6"- 20 dihydroxyphcnyl)porphyrin and its Zn derivative was accomplished as reported earlier. Sec Bhyrappa, P.; Vaijayanlhimala, G.; Suslick, K. S. J. Am. Chcm. Soc. 1999, 121, 262. The hepta-and octa- silylether porphyrins were synthesized by stirring DMF solution of 5,10,15,20- tctrakisp/,6"-dihydroxyphcnyl)poq>hyrinatozinc(ri)(100mg, 0.12 mmol) with t-butyldimcthyl silylchloridc (1.45 g, 9.6 mmol) in presence of imidazole (1.50 g, 22.1 mmol) at 60°C for 24 h 25 under nitrogen. After usual work-up the mixture of crude products were loaded on a silica gel column and clutcd with mixture of CHCI3 / pel. clhcr (1:1, v/v) to remove unrcactcd starting ma".cnnl and lower silylatcd products. The major product isolated from this column is a mixture of hepta- and octa- silylatcd porphyrins. The mixture thus obtained was further purified by another silica gel column chromatography using mixture of CHCI3 / pet. ether (1:3, v/v) as 30 eluant. The first two bands were isolated as octa- and hepta- silylether porphyrin at 45% and 30% yield, respectively. Both the compounds were characterized by UV-Visible, 1H NMR and MALDI-TOF spectroscopic techniques. The homogeneity of the sample was verified by HPLC. For Zn(Si7OHPP), 1H NMR in chloroform-d(ppm): 8.91(m,8H,b-pyrrole H),7.50(m, 4H, p-H), 7.01-6.81(m, 8H, m-H), 0.11 to-.03(12s, 105 u, /-butyl and methyl H). Elemental analysis, calcd. for ZnC86H126O8N4Si7: C=64.3, H = 7.8, N = 3.5, Si = 12.3 and Zn = 4.1 %. Found C = 63.6, H = 8.1, N = 3.5, Si = 12.1 and Zn = 3.9%. The low resolution MALDI-TOF mass spectrum showed molecular ion peak at 1604 (m/z calcd. for ZnC86H126O8N4Si7 = 1604). For Zn(SigPP), 1H NMR in chloroformed (ppm): 8.89(s, 8H. b-pyrrole H), 7.49(t, 4H, p-H), 6.92(d, 8H, w-H), 0.09(s, 72 H, /-butyl H), -1.01(s, 48 H, methyl H). Elemental analysis, calcd.for ZnC92H14oO8N4Si8:C=64:2,H = 8.1,N = 3.3,Si=13.1 and Zn = 3.8%.Found C = 63.5, H = 8.4, N = 3.3, Si = 12.8 and Zn = 4.0%. The low resolution MALDI-TOF mass spectrum showed molecular ion peak at 1719 (m/z calcd. for ZnC92H140O8N4Si8 = 1718). Many modifications and variations may be made in the techniques and structures described and illustrated herein without departing from the spirit and scope of the present invention. Accordingly, the techniques and structures described and illustrated herein should be understood to be illustrative only and not limiting upon the scope of the present invention. CLAIMS We Claim: 1. An artificial nose comprising an array, the array comprising at least a first dye and a second dye deposited directly onto a single support in a predetermined pattern combination, the combination of the dyes in the array having a distinct and direct spectral absorbance or reflectance response to distinct analytes, wherein the first dye and the second dye are selected from the group consisting of porphyrin, chlorin, chlorophyll, phtahalocyanine, and salen and their metal complexes. 2. The artificial nose of Claim 1 wherein the first dye and the second dye are porphyrins. 3. The artificial nose of Claim 1 wherein the first dye and the second dye are from the group comprising porphyrin, chlorin, chlorophyll, phthalocyanine, or salen. 4. The artificial nose of Claim 1 wherein the first dye and the second dye are metalloporphyrins. 5. The artificial nose of Claim 4 wherein the first and second metalloporphyrins are from the group of metalloporphyrins depicted in Figure 2 A. 6. The artificial nose of Claim 4 wherein the first dye and second dye are metalloporphyrins having a metal ion selected from the group consisting of Sn4+, Co3+, Cr3+, Mn3+, Fe3+, Co2+, Cu2+, Ru2+, Zn2+, and Ag2+. 7. The artificial nose of Claim 1 wherein the array is part of a sensor plate. 8. The artificial nose of Claim 1 wherein the array is connected to a visual display device. 9. The artificial nose of Claim 8 wherein the visual display device comprises a scanner. 10. The artificial nose of Claim 8 wherein the visual display device comprises a charge-coupled device. 11. The artificial nose of Claim 1 wherein the array is a spatially resolved collection of dyes. 12. The artificial nose of Claim 11 wherein the spatially resolved collection of dyes is a spatially resolved combinatorial family of dyes. 13. A method for detecting an analyte comprising the steps of: forming an array of at least a first dye and a second dye deposited directly onto a single support in a predetermined pattern combination, the combination of dyes in the array having a distinct and direct spectral absorbance or reflectance response to distinct analytes, wherein the first dye and the second dye are selected from the group consisting of porphyrin, chlorin, chlorophyll, phtahalocyanine, and salen and their metal complexes, subjecting the array to an analyte, inspecting the array for a distinct and direct spectral absorbance or reflectance response, and correlating the distinct and direct spectral absorbance or reflectance response to the presence of the analyte. 14. - The method of Claim 13 wherein the first dye and the second dye are porphyrins. 15. The method of Claim 13 wherein the first dye and the second dye are from the group comprising porphyrin, chlorin, chlorophyll, phthalocyanine, and salen. 16. The method of Claim 13 wherein the first dye and the second dye are metalloporphyrins. 17. The method of Claim 16 wherein the first and the second metalloporphyrins dyes are from the group of metalloporphyrins depicted in Figure 2A. 18. The method of Claim 16 wherein the first and the second dye are metalloporphyrins having a metal ion selected from the group consisting of Sn4+, Co3+, Cr3+, Mn3+, Fe3+, Co2+, Cu2+, Ru2+, Zn2+, and Ag2+. 19. The method of Claim 13 having the step of placing the array on a sensor plate. 20. The method of Claim 13 having the step of connecting the array to a visual display or detection device. 21. The method of Claim 20 wherein the visual display device comprises a scanner. 22. The method of Claim 20 wherein the visual display device comprises a charge-coupled device. 23. The method of Claim 13 wherein the array is a spatially resolved collection of dyes. 24. The method of Claim 23 wherein the spatially resolved collection of dyes is a spatially resolved combinatorial family of dyes. 25. The method of Claim 13 having the further step of comparing the spectral response with a catalog of analyte spectral responses to identify the analyte. 26. An artificial tongue comprising an array, the array comprising at least a first dye and a second dye deposited directly onto a single support in a predetermined pattern combination, the combination of dyes in the array having a distinct and direct spectral absorbance or reflectance response to distinct analytes in solution or liquid analytes, or analytes in a solid or solid analytes, wherein the first dye and the second dye are selected from the group consisting of porphyrin, chlorin, chlorophyll, phtahalocyanine, and salen and their metal complexes. 27. The artificial tongue of Claim 26 wherein the first dye and the second dye are porphyrins. 28. The artificial tongue of Claim 26 wherein the first dye and the second dye are from the group comprising porphyrin, chlorin, chlorophyll, phthalocyanine or salen. 29. The artificial tongue of Claim 26 wherein the first dye and the second dye are metalloporphyrins. 30. The artificial tongue of Claim 29 wherein the first and second metalloporphyrins are from the group of metalloporphyrins depicted in Figure 2 A. 31. The artificial tongue of Claim 29 wherein the first dye and second dye are metalloporphyrins having a metal ion selected from the group consisting of Sn4+, Co3+, Cr3+, Mn3+, Fe3+, Co2+, Cu2+, Ru2+, Zn2+, and Ag2+. 32. The artificial tongue of Claim 26 wherein the array is part of a sensor plate. 33. The artificial tongue of Claim 26 wherein the array is connected to a visual display device. 34. The artificial tongue of Claim 33 wherein the visual display device comprises a scanner. 35. The artificial tongue of Claim 33 wherein the visual display device comprises a charge-coupled device. 36. The artificial tongue of Claim 26 wherein the array is a spatially resolved collection of dyes. 37. The artificial tongue of Claim 36 wherein the spatially resolved collection of dyes is a spatially resolved combinatorial family of dyes. Date: July 21, 2005 AHMAD HIRANI Patent Agent of the Applicant.

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