Applications of metal compounds and cholesteric liquid crystals for chemical sensing

APPLICATIONS OF METAL COMPOUNDS AND CHOLESTERIC LIQUID CRYSTALS FOR CHEMICAL SENSING LAURA SUTARLIE NATIONAL UNIVERSITY OF SINGAPORE 2012 APPLICATIONS OF METAL COMPOUNDS AND CHOLESTERIC LIQUID CRYSTALS FOR CHEMICAL SENSING LAURA SUTARLIE (B. Eng., ITB) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMICAL AND BIOMOLECULAR ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2012 ACKNOWLEDGEMENTS First of all, I would like to express my sincere gratitude to my supervisor Dr. Yang Kun-Lin. He has challenged my way of thinking and provided valuable advice and guidance for my research. I have learnt many things about research and various skills from him. In my PhD study, I am grateful for the graduate student research scholarship from National University of Singapore (NUS) with support from ASEAN University Network/ Southeast Asia Engineering Education Development Network (AUN/SEED-net). Moreover, I am thankful to all members of Dr. Yang’s group for sharing their knowledge and creating enjoyable lab atmosphere. In addition, I highly appreciate all suggestions and comments from everyone in the Monday group meeting. I also would like to thank all lab officers who have kindly assisted me in various matters, especially Mr. Boey Kok Hong, Ms. Lee Chai Keng, Ms. Alyssa Tay, and Mr. Ng Kim Poi from workshop. Furthermore, I would like to express my deepest gratitude to my parents and my brother for their continuous prayer, support, and encouragement. I am grateful as well for all the support and encouragement from my housemates and all of my friends in NUS and outside campus. The last but not the least, I would like to thank Jesus God for His grace and blessings. He is the help, the strength, and the hope that keeps me on. i TABLE OF CONTENTS ACKNOWLEDGEMENTS…………………………………………………… TABLE OF CONTENTS……………………………………………………… SUMMARY…………………………………………………………………… LIST OF FIGURES ……………………………………………………………. LIST OF TABLES …………………………………………………………… . LIST OF SCHEMES …………………………………………………………… NOMENCLATURES…………………………………………………… .…… i ii vi viii xiii xiv xv CHAPTER 1. INTRODUCTION ………………………………………… … 1.1. Applications of metal compounds for chemical sensing …………………. 1.2. Applications of cholesteric liquid crystals (CLCs) for chemical sensing …. 1.3. Objectives ………………………………………………………………… 1 CHAPTER 2. LITERATURE REVIEW ……… …………………………… . 2.1. Chemical sensors for VOCs ……………………………………………… 2.1.1. Electrochemical sensors …………………………………………… 2.1.2. Mass sensors ……………………………………………………… . 2.1.3. Optical sensors ……………………………………………………… 2.1.4. Recent advances in VOCs sensors ………………………………… 2.1.4.1. Arrays with multiple sensing elements ……………………. 2.1.4.2. Microfluidic devices ………………………………………. 2.2. Interactions between molecular receptors and target analytes …………… 2.2.1. Hydrogen bonds …………………………………………………… 2.2.2. Electron pair donor acceptor and metal-ligand interactions ……… . 2.3. Metal compounds and their applications for VOCs sensing ………………. 2.3.1. Metal compounds as molecular receptors for VOCs sensing ………. 2.3.2. Chemical sensitive layers with metal compounds as molecular receptors ……………………………………………………………. 2.4. Cholesteric liquid crystals (CLCs) and their applications for VOCs sensing 2.4.1. Optical properties of CLCs………………………………………… 2.4.2. CLC based VOCs sensors ………………………………………… . 7 10 11 13 13 14 16 17 19 20 20 CHAPTER 3. COLORIMETRIC RESPONSES OF TRANSPARENT POLYMERS DOPED WITH METAL PHTHALOCYANINE FOR DETECTING VAPOROUS AMINES………….…….……………………… . 3.1. Introduction………………………………………………………………… 23 25 25 28 29 29 ii 3.2. Experimental methods …………………………………………………… . 3.2.1. Materials ……………………………………………………………. 3.2.2. Preparation of polymer …………………………………………… . 3.2.3. UV-Vis and FTIR spectroscopy ……………………………………. 3.3. Results and discussion …………………………………………………… 3.3.1. Screening candidate MPcs for detecting amines …………………… 3.3.2. Selectivity for hexylamine …………………………………………. 3.3.3. FePc-doped polymers……………………………………………… 3.4. Conclusions………………………………………………………………… 32 32 33 33 34 34 35 38 44 CHAPTER 4. COLORIMETRIC RESPONSES OF COPPER IONS TO AMMONIA VAPOR: DISPERSION AND SURFACE LIGANDS EFFECTS 4.1. Introduction ……………………………………………………………… . 4.2. Experimental methods …………………………………………………… . 4.2.1. Materials ……………………………………………………………. 4.2.2. Preparation of polymer …………………………………………… . 4.2.3. Detection of ammonia vapor ……………………………………… 4.2.4. Leaching Cu2+ from silica gel ….………………………………… . 4.3. Results and discussion …………………………………………………… 4.3.1. Colorimetric responses of Cu2+ to ammonia vapor… …… .……… 4.3.2. Effect of anions on colorimetric response of Cu2+………………… 4.3.3. Surface ligands effect……………………………………………… 4.3.4. Surface acidity effect……………………………………………… . 4.4. Conclusions………………………………………………………………… 45 45 48 48 49 49 50 50 50 53 54 60 61 CHAPTER 5. POLYMER STABILIZED CHOLESTERIC LIQUID CRYSTAL ARRAYS FOR DETECTING VAPOROUS AMINES…………… 5.1. Introduction ……………………………………………………………… . 5.2. Experimental methods …………………………………………………… . 5.2.1. Materials ……………………………………………………………. 5.2.2. Preparation of PSCLC cells and PSCLC thin films………………… 5.2.3. Vapor detection…………….……………………………………… 5.2.4. Vis spectroscopy…………… ….………………………………… . 5.3. Results and discussion …………………………………………………… 5.3.1. Dependence of PSCLC colors on temperature…………… .………. 5.3.2. Colorimetric responses of PSCLCs to amine vapors……………… 5.3.3. Specificity of PSCLCs… ………………………………………… . 5.3.4. Correlations between molecular weights and detection limits of PSCLCs to aliphatic primary amine………………………………… 63 64 66 66 66 67 68 69 69 72 73 76 iii 5.3.5. Response time and reversibility of PSCLCs………………………… 5.4. Conclusions………………………………………………………………… 79 81 CHAPTER 6. CHOLESTERIC LIQUID CRYSTALS DOPED WITH DODECYLAMINE FOR DETECTING ALDEHYDE VAPORS ……………. 6.1. Introduction ……………………………………………………………… . 6.2. Experimental methods …………………………………………………… . 6.2.1. Materials ……………………………………………………………. 6.2.2. Preparation of thin films of PDMS………………………….………. 6.2.3. Preparation of CLCs and CLCs doped with dodecylamine…………. 6.2.4. Exposure of CLC thin films to vapor analytes……………………… 6.2.5. UV-Vis spectroscopy……………………………………………… . 6.2.6. Fourier transform infrared (FTIR) spectroscopy……………………. 6.3. Results and discussion …………………………………………………… 6.3.1. Effect of glass on CLCs doped with dodecylamine………………… 6.3.2. Effect of dopant concentrations…………………………………… . 6.3.3. Colorimetric responses of CLCs to pentyl aldehyde vapor… …… . 6.3.4. Response time and reversibility…………………………………… . 6.3.5. Detection limit and sensitivity………………………………….…… 6.4. Conclusions………………………………………………………………… 83 83 86 86 86 87 88 89 89 90 90 92 94 96 98 100 CHAPTER 7. MONITORING SPATIAL DISTRIBUTION OF ETHANOL IN MICROFLUIDIC CHANNELS BY USING A THIN LAYER OF CHOLESTERIC LIQUID CRYSTALS………… .……………… 7.1. Introduction ……………………………………………………………… . 7.2. Experimental methods …………………………………………………… . 7.2.1. Materials ……………………………………………………………. 7.2.2. Preparation of PDMS and thin films of PDMS………………… .… 7.2.3. Preparation of CLCs …………………………………… .………… 7.2.4. Preparation of microfluidic devices with embedded PDCLCs or embedded CLCs…………………………………………………… 7.2.5. Ethanol detection inside microfluidic channels…………………… . 7.2.6. Visible spectrometry……………………………… .………………. 7.2.7. Detection of ethanol produced from fermentation………………… 7.3. Results and discussion …………………………………………………… 7.3.1. Ethanol detection in microfluidic channels with embedded PDCLCs 7.3.2. Reversibility of colorimetric responses in PDCLCs………………… 7.3.3. Ethanol detection in microfluidic channels with embedded CLCs…. 7.3.4. Reversibility of colorimetric responses to ethanol in CLCs………… 7.3.5. Detection of ethanol from fermentation in microfluidic channels… 7.4. Conclusions………………………………………………………………… 101 101 104 104 105 105 105 107 107 108 108 108 111 112 113 114 116 iv CHAPTER 8. CONCLUSIONS AND RECOMMENDATIONS………….… . 8.1. Conclusions…………………………………………… ………………… 8.2. Recommendations………………………………………………………… 117 117 121 REFERENCES…………………………………………………………………. LIST OF PUBLICATIONS…………………………………………………… 125 142 v SUMMARY Chemical sensing of volatile organic compounds (VOCs) has attracted much attention. However, challenges such as how to produce low-cost, portable VOC sensors with good sensory performance remain. Motivated by these challenges, in this thesis we developed VOCs sensors from two potential materials. The first one is metal compounds because they can be used as molecular receptors for VOCs based on metal-ligand interactions. Firstly, metal phthalocyanines were employed for colorimetric detection of amines vapor. To develop portable amines sensors, metal phthalocyanines were added as dopants in free-standing transparent polymers. Secondly, metal compounds are often immobilized on surfaces having ligand groups to construct chemical sensitive layers. However, the effects of surface ligands on the metal compounds are still unclear. To obtain a better understanding on the effects of surface ligands, we studied the colorimetric responses of Cu2+ immobilized on various surfaces to ammonia. The second material exploited here is cholesteric liquid crystals (CLCs) which are colorful to the naked eyes and can show colorimetric responses to VOCs. Nevertheless, development of useful VOCs sensors based on CLCs face challenges such as limited portability, small temperature range, and selectivity of CLCs that remains unclear. Firstly, to improve portability of CLCs, polymer stabilized cholesteric liquid crystals (PSCLCs) were developed. PSCLCs were made into an array of PSCLCs with different polymer concentration to expand the working vi temperature range. Their colorimetric responses to amines vapor were studied and their selectivity to any particular VOCs was investigated. Furthermore, to improve the selectivity of CLCs, we incorporated suitable molecular receptors as dopants in CLCs. We demonstrated addition of dodecylamine as a dopant in CLCs for aldehyde vapor detection. The colorimetric responses of the CLCs doped with dodecylamine to aldehyde vapor were studied in term of their selectivity, sensitivity, and reusability. Finally, because our results show that CLCs give colorimetric responses with fast response time, reusability, and detection limit at low VOCs concentration, we explored the possibility of utilizing CLCs to develop integrated VOCs sensors with microfluidic channels. Here, a thin layer of CLCs or polymer dispersed cholesteric liquid crystals (PDCLCs) was embedded to microfluidic channels for monitoring ethanol inside the channels. Furthermore, we also demonstrated their utilization for monitoring ethanol production from fermentation in microfluidic channels. Overall, the VOCs sensors based on metal compounds and CLCs developed in this thesis show colorimetric responses to VOCs without complex instrumentation. They are suitable to be used as portable and low-cost sensors. vii LIST OF FIGURES Figure 2.1. Figure 2.2. Figure 3.1. Figure 3.2. Figure 3.3. Figure 3.4. Figure 3.5. Figure 3.6. Figure 3.7 Figure 3.8. Orientational and positional order of solid, liquid crystal, and liquid……………………………………………………………. 12 Molecular arrangement of CLC molecules forming helical pattern………………………………………………………… . 26 Molecular structure of metal phthalocyanine (MPc). M = H+, Cu2+, Ni2+, Pb2+, Zn2+, Fe2+. . 32 Photographs of various metal phthalocyanines in toluene solution (50 µM) showing colorimetric responses (a) before and (b) after the addition of mmol hexylamine…………………… 34 FTIR spectra of dodecylamine (dotted line) and mixture of FePc and dodecylamine with a 1:1 molar ratio (solid line)…… 35 FePc solution in toluene (5 µM) and its colorimetric responses (a) before and (b) after the addition of 10 mM of hexane, heptanol, DMMP, DIPEA, DIPA, hexylamine, and EDA (from left to right)…………………………………………………… . 36 Absorbance of FePc solution (50 µM in toluene) at 663 nm when aliquots of hexylamine (solid circle) and EDA (hollow circle) were added to the FePc solution ……………………… . 37 Images of several FePc-doped (0.03 wt%) transparent polymers before (first column) and after (second column) being exposed to 11,600 ppmv of hexylamine vapor. These polymers are (a) PVA (b) NOA65 (c) PDMS……………………… … .… … 38 Time resolved UV/Vis absorption spectra of three FePc doped (0.03 wt%) polymers upon exposure to 11,600 ppmv hexylamine vapor. (a) PVA (b) NOA65 (c) PDMS………….…. 39 Colorimetric responses of NOA65 and PDMS, either doped with FePc (0.03 wt%) or without FePc, after being (a) stored in clean air, (b) exposed to 11,600 ppmv hexylamine vapor, (c) exposed to 15,000 ppmv EDA vapor………………… … …… 40 viii Collings, P.J., 2002. Liquid Crystals: Nature's Delicate Phase of Matter. Princeton University Press. Comes, M., Marcos, M.D., MartinezManez, R., Sancenon, F., Soto, J., Villaescusa, L.A., Amoros, P. and Beltran, D., 2004. Chromogenic Discrimination of Primary Aliphatic Amines in Water with Mesoporous Silica. Advanced Materials, 16, 1783 1786. Cotton, F.A., Wilkinson, G., Murillo, C.A. and Bochmann, M., 1999. Advanced Inorganic Chemistry. John Wiley and Sons. Crawford, G.P. and Zumer, S., 1996. Liquid Crystals in Complex Geometries: Formed by Polymer and Porous Networks. Taylor & Francis. Crissey, J.T., Fergason, J.L. and Bettenha. J.M, 1965. Cutaneous thermography with liquid crystals. Journal of Investigative Dermatology, 45, 329333. Crooks, R.M. and Ricco, A.J., 1998. New organic materials suitable for use in chemical sensor arrays. Accounts of Chemical Research, 31, 219227. Crooks, R.M., Yang, H.C., Mcellistrem, L.J., Thomas, R.C. and Ricco, A.J., 1997. Interactions between selfassembled monolayers and an organophosphonate Detailed study using surface acoustic wavebased mass analysis, polarization modulation FTIR spectroscopy and ellipsometry. Faraday Discussions, 107, 285305. D'amico, A., Di Natale, C., Paolesse, R., Macagnano, A. and Mantini, A., 2000. Metalloporphyrins as basic material for volatile sensitive sensors. Sensors and Actuators BChemical, 65, 209215. Dale, B.W., 1969. Effect of axial ligands upon electronic absorption spectrum of phthalocyanineiron (II). Transactions of the Faraday Society, 65, 331339. Davidsson, R., Genin, F., Bengtsson, M., Laurell, T. and Emneus, J., 2004a. Microfluidic biosensing systems Part I. Development and optimisation of enzymatic chemiluminescent mubiosensors based on silicon microchips. Lab on a Chip, 4, 481 487. Davidsson, R., Johansson, B., Passoth, V., Bengtsson, M., Laurell, T. and Emneus, J., 2004b. Microfluidic biosensing systems Part II. Monitoring the dynamic production of glucose and ethanol from microchipimmobilised yeast cells using enzymatic chemiluminescent mubiosensors. Lab on a Chip, 4, 488494. De La Torre, G., Nicolau, M. and Torres, T., 2001. Phthalocyanines: synthesis, suparmolecular organization, and physical properties. In H.S. Nalwa (ed.) Supramolecular Photosensitive and Electroactive Materials. Academic Press. De Silva, A.P., Gunaratne, H.Q.N. and Gunnlaugsson, T., 1998. Fluorescent PET (photoinduced electron transfer) reagents for thiols. Tetrahedron Letters, 39, 5077 5080. 127 Degennes, P.G., 1974. The Physics of Liquid Crystals. Oxford University Press. Demus, D., 1990. Types and classification of liquid crystals. In B. Bahadur (ed.) Liquid Crystals: Applications and Uses. World Scientific. Di Natale, C., Paolesse, R., Macagnano, A., Mantini, A., Goletti, C. and D'amico, A., 1998. Characterization and design of porphyrinsbased broad selectivity chemical sensors for electronic nose applications. Sensors and Actuators BChemical, 52, 162 168. Di Natale, C., Paolesse, R., Macagnano, A., Troitsky, V.I., Berzina, T.S. and D'amico, A., 1999. Pattern recognition approach to the study of the interactions between metalloporphyrin LangmuirBlodgett films and volatile organic compounds. Analytica Chimica Acta, 384, 249259. Dickert, F.L., Bruckdorfer, T., Feigl, H., Haunschild, A., Kuschow, V., Obermeier, E., Bulst, W.E., Knauer, U. and Mages, G., 1993. Supramolecular detection of solvent vapors with QMB and SAW devices. Sensors and Actuators BChemical, 13, 297 301. Dickert, F.L., Haunschild, A. and Hofmann, P., 1992. Molecular recognition of organic solvents and ammonia: Shapes and donor properties as sensors effects. Sensors and Actuators BChemical, 6, 25 28. Dickert, F.L., Haunschild, A. and Hofmann, P., 1994. Cholesteric liquid crystals for solvent vapor detection elimination of crosssensitivity by band shapeanalysis and patternrecognition. Fresenius Journal of Analytical Chemistry, 350, 577581. Dickinson, T.A. and Walt, D.R., 2003. Optical electronic noses. In T.C. Pearce (ed.) Handbook of Machine Olfaction: Electronic Nose Technology. Wiley VCH. Dubey, M., Bernasek, S.L. and Schwartz, J., 2007. Highly sensitive nitric oxide detection using XRay Photoelectron Spectroscopy. Journal of the American Chemical Society, 129, 6980 6981. Dunbar, A.D.F., Brittle, S., Richardson, T.H., Hutchinson, J. and Hunter, C.A., 2010. Detection of volatile organic compounds using porphyrin derivatives. Journal of Physical Chemistry B, 114, 1169711702. Edel, J.B., Fortt, R., Demello, J.C. and Demello, A.J., 2002. Microfluidic routes to the controlled production of nanoparticles. Chemical Communications, 11361137. Edmonds, T.E., 1988. Chemical Sensors. Blackie and Son. ElAli, J., Sorger, P.K. and Jensen, K.F., 2006. Cells on chips. Nature, 442, 403411. Emsley, J., 1980. Very strong hydrogenbonding. Chemical Society Reviews, 9, 91 124. 128 Ennulat, R.D., 1971. Selective light reflection by plane textures. Molecular Crystals and Liquid Crystals, 13, 337341. Epstein, J.R. and Walt, D.R., 2003. Fluorescencebased fibre optic arrays: A universal platform for sensing. Chemical Society Reviews, 32, 203214. Fergason, J.L., 1964. Liquid Crystals. Scientific American, 211, 7785. Fergason, J.L., 1966. Cholesteric structure. I. Optical properties. Molecular Crystals, 1, 293307. Fergason, J.L., 1968. Liquid crystals in nondestructive testing. Applied Optics, 7, 17291733. FernandezSanchez, J.F., Nezel, T., Steiger, R. and SpichigerKeller, U.E., 2006. Novel optical NO2selective sensor based on phthalocyaninatoiron(II) incorporated into a nanostructured matrix. Sensors and Actuators BChemical, 113, 630638. Funke, M., Buchenauer, A., Mokwa, W., Kluge, S., Hein, L., Muller, C., Kensy, F. and Buchs, J., 2010. Bioprocess control in microscale: scalable fermentations in disposable and userfriendly microfluidic systems. Microbial Cell Factories, 9, 8699. Georghiou, P.E., Harlick, L., Winsor, L. and Snow, D., 1983. Temperature dependence of the modified pararosaniline method for the determination of formaldehyde in air. Analytical Chemistry, 55, 567570. Getino, J., Ares, L., Robla, J.I., Horrillo, M.C., Sayago, I., Fernandez, M.J., Rodrigo, J. and Gutierrez, J., 1999. Environmental applications of gas sensor arrays: Combustion atmospheres and contaminated soils. Sensors and Actuators BChemical, 59, 249254. Gomes, M.T.S.R., Verissimo, M.I.S. and Oliveira, J.A.B.P., 1999. Detection of volatile amines using a quartz crystal with gold electrodes. Sensors and Actuators B Chemical, 57, 261 267. Gotz, S. and Karst, U., 2007. Recent developments in optical detection methods for microchip separations. Analytical and Bioanalytical Chemistry, 387, 183192. Gouterman, M., 1961. Spectra of porphyrins. Journal of Molecular Spectroscopy, 6, 138163. Grate, J.W., 2000. Acoustic wave microsensor arrays for vapor sensing. Chemical Reviews, 100, 26272647. Grate, J.W., 2008. Hydrogenbond acidic polymers for chemical vapor sensing. Chemical Reviews, 108, 726745. 129 Grate, J.W. and Abraham, M.H., 1991. Solubility interactions and the design of chemically selective sorbent coatings for chemical sensors and arrays. Sensors and Actuators BChemical, 3, 85111. Grate, J.W., Patrash, S.J., Kaganove, S.N. and Wise, B.M., 1999. Hydrogen bond acidic polymers for surface acoustic wave vapor sensors and arrays. Analytical Chemistry, 71, 10331040. Grundler, P., 2007. Chemical Sensors: an Introduction for Scientists and Engineers. Springer. Guilbault, G.G., Billedea, S.M. and Lopezrom, A., 1972. Gasphase reactions of monomethylamine, dimethylamine, and trimethylamine with various metalssalts. Use of piezoelectric cyrstals in a vacuumsystem. Analytica Chimica Acta, 58, 421427. Gulino, A., Gupta, T., Altman, M., Lo Schiavo, S., Mineo, P.G., Fragala, I.L., Evmenenko, G., Dutta, P. and Van Der Boom, M.E., 2008. Selective monitoring of parts per million levels of CO by covalently immobilized metal complexes on glass. Chemical Communications, 25, 29002902. Gulino, A., Lupo, F., Condorelli, G.G., Mineo, P. and Fragala, I., 2007. Viable synthetic route for a luminescent porphyrin monolayer covalently assembled on a molecularly engineered Si (100) surface. Chemistry of Materials., 19, 5102 5109. Hathaway, B.J. and Tomlinson, A.A.G., 1970. Copper (II) ammonia complexes. Coordination Chemistry Reviews, 5, 143. Hauser, T.R. and Cummins, R.L., 1964. Increasing sensitivity of 3methyl2 benzothiazolone hydrazone test for analysis of aliphatic aldehydes in air. Analytical Chemistry, 36, 679681. Hidayat, A., Hibbert, D.B. and Alexander, P.W., 1997. Amperometric detection of amines using cobalt electrodes after separation by ion moderated partition chromatohraphy. Talanta, 44, 239 248. Hierlemann, A., Bodenhofer, K., Fluck, M., Schurig, V. and Gopel, W., 1997. Selective detection of nitrogen and oxygen containing volatile organic compounds: use of metalmodified polysiloxanes as sensor coatings. Analytica Chimica Acta, 346, 327339. Hierlemann, A., Ricco, A.J., Bodenhofer, K. and Gopel, W., 1999. Effective use of molecular recognition in gas sensing: results from acoustic wave and in situ FTIR measurements. Analytical Chemistry, 71, 30223035. Hulanicki, A., Glab, S. and Ingman, F., 1991. Chemical sensors definitions and classification. Pure and Applied Chemistry, 63, 12471250. Hunt, H.C. and Wilkinson, J.S., 2008. Optofluidic integration for microanalysis. Microfluidics and Nanofluidics, 4, 5379. 130 Imawan, C., Solzbacher, F., Steffes, H. and Obermeier, E., 2000. Gassensing characteristics of modifiedMoO3 thin films using Tioverlayers for NH3 gas sensors. Sensors and Actuators BChemical, 64, 193197. Inouye, K., Ichimura, K., Kaneko, K. and Ishikawa, T., 1976. Effect of copper (II) in formation of gammaFeOOH. Corrosion Science, 16, 507517. Irving, H. and Williams, R.J.P., 1948. Order of stability of metal complexes. Nature, 162, 746747. Jahnisch, K., Hessel, V., Lowe, H. and Baerns, M., 2004. Chemistry in microstructured reactors. Angewandte ChemieInternational Edition, 43, 406446. James, D., Scott, S.M., Ali, Z. and O'hare, W.T., 2005. Chemical sensors for electronic nose systems. Microchimica Acta, 149, 1 17. Janzen, M.C., Ponder, J.B., Bailey, D.P., Ingison, C.K. and Suslick, K.S., 2006. Colorimetric sensor arrays for volatile organic compounds. Analytical Chemistry, 78, 35913600. Joesten, M.D. and Schaad, L.J., 1974. Hydrogen Bonding: Marcell Dekker. Johnson, S.R., Sutter, J.M., Engelhardt, H.L., Jurs, P.C., White, J., Kauer, J.S., Dickinson, T.A. and Walt, D.R., 1997. Identification of multiple analytes using an optical sensor array and pattern recognition neural networks. Analytical Chemistry, 69, 46414648. Jones, J.G. and Twigg, M.V., 1969. Axial ligand exchange reactions of ferrous phthalocyanine. Exchange of imidazole for dimethyl sulfoxide. Inorganic Chemistry, 8, 21202123. Jones, J.G. and Twigg, M.V., 1974. Binding of nitrogenous bases to iron(II) phthalocyanine in dimethylsulfoxide. Inorganica Chimica Acta, 10, 103108. Kahn, F.J., 1973. Orientation of liquidcrystals by surface coupling agents. Applied Physics Letters, 22, 386388. Kelker, H. and Hatz, R., 1980. Handbook of Liquid Crystals. Verlag Chemie GmbH. Kepley, L.J., Crooks, R.M. and Ricco, A.J., 1992. Selective surface acoustic wave based organophosphonate chemical sensor employing a selfassembled composite monolayer a new paradigm for sensor design. Analytical Chemistry, 64, 31913193. Khan, S.A. and Jensen, K.F., 2007. Microfluidic synthesis of titania shells on colloidal silica. Advanced Materials, 19, 25562560. 131 Kirchner, N., Zedler, L., Mayerhofer, T.G. and Mohr, G.J., 2006. Functional liquid crystal films selectively recognize amine vapours and simultaneously change their color. Chemical Communications, 14, 1512 1514. Kollman, P.A. and Allen, L.C., 1972. Theory of hydrogenbond. Chemical Reviews, 72, 283303. Koster, S. and Verpoorte, E., 2007. A decade of microfluidic analysis coupled with electrospray mass spectrometry: an overview. Lab on a Chip, 7, 13941412. KressRogers, E., 1997. Biosensors and electronic noses for practical applications. In E. KressRogers (ed.) Handbook of Biosensors and Electronic Noses, Medicine, Food, and the Environment. CRC Press. Krupa, S.V., 2003. Effects of atmospheric ammonia (NH3) on terrestrial vegetation: a review. Environmental Pollution, 124, 179221. Kukla, A.L., Shirshov, Y.M. and Piletsky, S.A., 1996. Ammonia sensors based on sensitive polyaniline films. Sensors and Actuators BChemical, 37, 135140. Kuswandi, B., Nuriman, Huskens, J. and Verboom, W., 2007. Optical sensing systems for microfluidic devices: A review. Analytica Chimica Acta, 601, 141155. Labianca, D.A., 1990. The chemical basis of the breathalyzer a critical analysis. Journal of Chemical Education, 67, 259261. Lahdesmaki, I., Lewenstam, A. and Ivaska, A., 1996. A polypyrrolebased amperometric ammonia sensor. Talanta, 43, 125134. Lange, U., Roznyatouskaya, N.V. and Mirsky, V.M., 2008. Conducting polymers in chemical sensors and arrays. Analytica Chimica Acta, 614, 126. Lau, K.T., Edwards, S. and Diamond, D., 2004. Solidstate ammonia sensor based on Berthelot's reaction. Sensors and Actuators BChemical, 98, 1217. Layer, R.W., 1963. Chemistry of imines. Chemical Reviews, 63, 489510. Leder, L.B., 1971. Rotatory sense and pitch of cholesteric liquid crystals. Journal of Chemical Physics, 55, 26492657. Lee, D.S., Jung, J.K., Lim, J.W., Huh, J.S. and Lee, D.D., 2001. Recognition of volatile organic compounds using SnO2 sensor array and pattern recognition analysis. Sensors and Actuators BChemical, 77, 228236. Lee, D.S., Kim, Y.T., Huh, J.S. and Lee, D.D., 2002. Fabrication and characteristics of SnO2 gas sensor array for volatile organic compounds recognition. Thin Solid Films, 416, 271278. 132 Lei, L., Mattos, I.L. and Chen, Y., 2008. Microfluidic devices for optical determination of ethanol concentration. Microelectronic Engineering, 85, 13181320. Lewis, P.R., Manginell, R.P., Adkins, D.R., Kottenstette, R.J., Wheeler, D.R., Sokolowski, S.S., Trudell, D.E., Byrnes, J.E., Okandan, M., Bauer, J.M., Manley, R.G. and FryeMason, G.C., 2006. Recent advancements in the gasphase MicroChemLab. IEEE Sensors Journal, 6, 784795. Li, H.F. and Lin, J.M., 2009. Applications of microfluidic systems in environmental analysis. Analytical and Bioanalytical Chemistry, 393, 555567. Linstead, R.P. and Robertson, J.M., 1936. The stereochemistry of metallic phthalocyanines. Journal of the Chemical Society, 17361738. Liu, C.J., Lin, J.T., Wang, S.H., Jiang, J.C. and Lin, L.G., 2005. Chromogenic calixarene sensors for amine detection. Sensors and Actuators BChemical, 108, 521 527. Lombardi, D. and Dittrich, P.S., 2010. Advances in microfluidics for drug discovery. Expert Opinion on Drug Discovery, 5, 10811094. Loughran, M. and Diamod, D., 2000. Monitoring of volatile bases in fish sample headspace using an acidochromic dye. Food Chemistry, 69, 97 103. Lu, X., Li, M., Yang, C., Zhang, L., Li, Y., Jiang, L., Li, H., Jiang, L., Liu, C. and Hu, W., 2006. Electron transport through a selfassembled monolayer of thiolend functionalized tetraphenylporphines and metal tetraphenylporphines. Langmuir, 22, 3035 3039. Luan, L., Evans, R.D., Jokerst, N.M. and Fair, R.B., 2008. Integrated optical sensor in a digital microfluidic platform. IEEE Sensors Journal, 8, 628635. Lundstroem, I., Shivaraman, S., Svensson, C. and Lundkvist, L., 1975. Hydrogen sensitive MOS fieldeffect transistor. Applied Physics Letters, 26, 5557. Lundstrom, I., Ederth, T., Kariis, H., Sundgren, H., Spetz, A. and Winquist, F., 1995. Recent developments in fieldeffect gas sensors. Sensors and Actuators BChemical, 23, 127133. Lundstrom, I., Spetz, A., Winquist, F., Ackelid, U. and Sundgren, H., 1990. Catalytic metals and fieldeffect devices a useful combination. Sensors and Actuators B Chemical, 1, 1520. Maekawa, T., Suzuki, K., Takada, T., Kobayashi, T. and Egashira, M., 2001. Odor identification using a SnO2based sensor array. Sensors and Actuators BChemical, 80, 5158. 133 Malins, C., Doyle, A., Maccraith, B.D., Kvasnik, F., Landl, M., Simon, P., Kalvoda, L., Lukas, R., Pufler, K. and Babusik, I., 1999. Personal ammonia sensor for industrial environments. Journal of Environmental Monitoring, 1, 417422. Masterton, W.L., Bolocofsky. D and Lee, T.P., 1971. Ionic radii form scaled particle theory of salt effect. Journal of Physical Chemistry, 75, 28092815. Mattos, I.L., Sartini, R.P., Zagatto, E.A.G., Reis, B.F. and Gine, M.F., 1998. Spectrophotometric flow injection determination of ethanol in distilled spirits and wines involving permeation through a silicon tubular membrane. Analytical Sciences, 14, 10051008. Mccallien, D.W.J., Burn, P.L. and Anderson, H.L., 1997. Chelation of diamine ligands to zinc porphyrin monolayers amidelinked glass. Journal of the Chemical Society, Perkin Transactions 1, 17, 2581 2586. Mckeown, N.B., 1998. Phthalocyanine materials: Synthesis, structure and function. Cambridge University Press. Miessler, G.L. and Tarr, D.A., 1999. Inorganic chemistry. Prentice Hall. Miksch, R.R., Anthon, D.W., Fanning, L.Z., Hollowell, C.D., Revzan, K. and Glanville, J., 1981. Modified pararosaniline method for the determination of formaldehyde in air. Analytical Chemistry, 53, 21182123. Mogensen, K.B., Klank, H. and Kutter, J.P., 2004. Recent developments in detection for microfluidic systems. Electrophoresis, 25, 34983512. Mogensen, K.B. and Kutter, J.P., 2009. Optical detection in microfluidic systems. Electrophoresis, 30, S92S100. Mohr, G.J., 2005. Covalent bond formation as an analytical tool to optically detect neutral and anionic analytes. Sensors and Actuators BChemical, 107, 213. Mohr, G.J., 2006. New chromogenic and fluorogenic reagents and sensors for neutral and ionic analytes based on covalent bond formation a review of recent developments. Analytical and Bioanalytical Chemistry, 386, 12011214. Mohr, G.J., Demuth, C. and SpichigerKeller, U.E., 1998. Application of chromogenic and fluorogenic reactands in the optical sensing of dissolved aliphatic amines. Analytical Chemistry, 70, 3868 3873. Mohr, J., Wenzel, M., Lehmann, F. and Czerney, P., 2002. A chromoreactand for optical sensing of amphetamines. Analytical Bioanalytical Chemistry, 374, 399 402. Montague, T.J. and Macneil, A.R., 1980. Mass ammonia inhalation. Chest, 77, 496 498. 134 Moralesbahnik, A., Czolk, R. and Ache, H.J., 1994. An optochemical ammonia sensorbased on immobilized metalloporphyrins. Sensors and Actuators BChemical, 19, 493496. Moseley, P.T. and Williams, D.E., 1990. A selective ammonia sensor. Sensors and Actuators BChemical, 1, 113115. Mucha, M., 2003. Polymer as an important component of blends and composites with liquid crystals. Progress in Polymer Science, 28, 837873. Murphy, R.A. and Davis, J.C., 1968. A proton magnetic resonance study of hydrogen bonding in aliphatic secondary amines. Journal of Physical Chemistry, 72, 3111 3116. Nanto, H. and Stetter, J.R., 2003. Introduction to chemosensors. In T.C. Pearce (ed.) Handbook of Machine Olfaction: Electronic Nose Technology. Wiley VCH. Nebel, G.J., 1981. Determination of total aliphaticaldehydes in auto exhaust by a modified 3methyl2benzothiazolinone hydrazone method. Analytical Chemistry, 53, 17081709. Nieuwenhuizen, M.S. and Harteveld, J.L.N., 1994. Development of a surfaceacoustic wave gas sensor for organophosphorus nerve agents employing lanthanide compounds as the chemical interface. Talanta, 41, 461472. Nieuwenhuizen, M.S. and Harteveld, J.L.N., 1997. Studies on a surface acoustic wave (SAW) dosimeter sensor for organophosphorous nerve agents. Sensors and Actuators BChemical, 40, 167173. Nieuwenhuizen, M.S. and Nederlof, A.J., 1988. Surface acousticwave gas sensor for nitrogendioxide using phthalocyanines as chemical interfaces effects of nitric oxide, halogen gases, and prolonged heattreatment. Analytical Chemistry, 60, 236 240. Novak, T.J., Poziomek, E.J. and Mackay, R.A., 1972. Use of anisotropic materials as chemical detectors. Analytical Letters, 5, 187 192. Nunes, P.S., Mortensen, N.A., Kutter, J.P. and Mogensen, K.B., 2008. Photonic crystal resonator integrated in a microfluidic system. Optics Letters, 33, 16231625. Nyholm, L., 2005. Electrochemical techniques for labonachip applications. Analyst, 130, 599605. Oberg, K.I., Hodyss, R. and Beauchamp, J.L., 2006. Simple optical sensor for amine vapors based on dyed silica microspheres. Sensors and Actuators BChemical, 115, 7985. 135 Odashima, K., Yagi, K., Tohda, K. and Umezawa, Y., 1993. Potentiometric discrimination of organic amines by a liquid membrane electrode based on a lipophilic hexaester of calix[6]arene. Analytical Chemistry, 65, 1074 1083. Ohno, K., Tachikawa, K. and Manz, A., 2008. Microfluidics: applications for analytical purposes in chemistry and biochemistry. Electrophoresis, 29, 44434453. Okahata, Y., Matsuura, K., Ito, K. and Ebara, Y., 1996. Gasphase selective adsorption on functional monolayers immobilized on a highly sensitive quartzcrystal microbalance. Langmuir, 12, 10231026. Oleschuk, R.D. and Harrison, D.J., 2000. Analytical microdevices for mass spectrometry. TrACTrends in Analytical Chemistry, 19, 379388. Onclin, S., Ravoo, B.J. and Reinhoudt, D.N., 2005. Engineering silicon oxide surfaces using selfassembled monolayers. Angewandte ChemieInternational Edition, 44, 6282 6304. Oswald, P. and Pieranski, P., 2005. Nematic and Cholesteric Liquid Crystals. Taylor and Francis. Otson, R. and Fellin, P., 1988. A review of techniques for measurement of airborne aldehyde. Science of the Total Environment, 77, 95131. Ozturk, Z.Z., Zhou, R., Weimar, U., Ahsen, V., Bekaroglu, O. and Gopel, W., 1995. Soluble phthalocyanines for the detection of organic solvents: Thin film structures with quartz microbalance and capacitance transducers. Sensors and Actuators B Chemical, 26, 208 212. Pacquit, A., Lau, K.T., Mclaughlin, H., Frisby, J., Quilty, B. and Diamond, D., 2006. Development of a volatile amine sensor for the monitoring of fish spoilage. Talanta, 69, 515520. PalffyMuhoray, P., 1998. Liquid crystals new designs in cholesteric colour. Nature, 391, 745746. Paolesse, R., Di Natale, C., Dall'orto, V.C., Macagnano, A., Angelaccio, A., Motta, N., Sgarlata, A., Hurst, J., Rezzano, I., Mascini, M. and D'amico, A., 1999. Porphyrin thin films coated quartz crystal microbalances prepared by electropolymerization technique. Thin Solid Films, 354, 245250. Paolesse, R., Di Natale, C., Macagnano, A., Davide, F., Boschi, T. and D'amico, A., 1998. Selfassembled monolayers of mercaptoporphyrins as sensing material for quartz crystal microbalance chemical sensors. Sensors and Actuators BChemical, 1, 7076. Parthasarathi, R. and Subramanian, V., 2006. Characterization of hydrogen bonding: from van der Waals interactions to covalency. In S. Grabowski (ed.) Hydrogen BondingNew Insights. Springer. 136 Parthasarathi, R., Subramanian, V. and Sathyamurthy, N., 2006. Hydrogen bonding without borders: An atomsinmolecules perspective. Journal of Physical Chemistry A, 110, 33493351. Patch, G. and Hope, G.A., 1985. Preparation and properties of cholesteric liquid crystals. Journal of Chemical Education, 62, 454455. Pauling, L., 1928. The sharedelectron chemical bond. Proceedings of the National Academy of Sciences of the United States of America, 14, 359362. Peris, M. and EscuderGilabert, L., 2009. A 21st century technique for food control: Electronic noses. Analytica Chimica Acta, 638, 115. Perry, R.H. and Green, D.W., 2008. Perry's Chemical Engineers' Handbook. Mc GrawHill. Persaud, K. and Dodd, G., 1982. Analysis of discrimination mechanisms in the mammalian olfactory system using a model nose. Nature, 299, 352355. Pilloud, D.L., Moser, C.C., Reddy, K.S. and Dutton, P.L., 1998. Surfacepromoted thioether linkage between proto or hemato porphyrins and thiolsilanized quartz: Formation of selfassembled monolayers and interaction with imidazole and carbon monoxide. Langmuir, 14, 48094818. PintoIguanero, B., OlivaresPerez, A. and FuentesTapia, I., 2002. Holographic material film composed by Norland NOA 65 adhesive. Optical Materials, 20, 225 232. Poziomek, E.J., Novak, T.J. and Mackay, R.A., 1973. Use of liquid crystals as vapor detectors. Molecular Crystals Liquid Crystals, 22, 175 185. Raible, I., Burghards, M., Schlecht, U., Yasuda, A. and Vossmeyer, T., 2005. V2O5 nanofibers novel gas sensors with extremely high sensitivity and selectivity to amines. Sensors and Actuators BChemical, 106, 730 735. Rakow, N.A., Sen, A., Janzen, M.C., Ponder, J.B. and Suslick, K.S., 2005. Molecular recognition and discrimination of amines with a colorimetric array. Angewandte ChemieInternational Edition, 44, 45284532. Rakow, N.A. and Suslick, K.A., 2000. A colorimetric sensor array for odour visualization. Nature, 406, 710 713. Rella, R., Spadavecchia, J., Ciccarella, P., Siciliano, P., Vasapollo, G. and Valli, L., 2003. optochemical vapour detection using spin coated thin films of metal substituted phthalocyanines. Sensors and Actuators BChemical, 89, 89 91. 137 Rey, A.D., 1997. Theory and simulation of gas diffusion in cholesteric liquid crystal films. Molecular Crystals and Liquid Crystals Science and Technology Section A Molecular Crystals and Liquid Crystals, 293, 87109. Rock, F., Barsan, N. and Weimar, U., 2008. Electronic nose: current status and future trends. Chemical Reviews, 108, 705725. Rosepehrsson, S.L., Grate, J.W., Ballantine, D.S. and Jurs, P.C., 1988. Detection of hazardous vapors including mixtures using patternrecognition analysis of responses from surface acousticwave devices. Analytical Chemistry, 60, 28012811. Schaller, E., Bosset, J.O. and Escher, F., 1998. 'Electronic noses' and their application to food. Food Science and Technology, 31, 305316. Schapper, D., Alam, M., Szita, N., Lantz, A.E. and Gernaey, K.V., 2009. Application of microbioreactors in fermentation process development: a review. Analytical and Bioanalytical Chemistry, 395, 679695. Scheide, E.P. and Guilbault, G.G., 1972. Piezoelectric detectors for organophosphorus compounds and pesticides. Analytical Chemistry, 44, 17641768. Schierbaum, K.D., Gerlach, A., Haug, M. and Gopel, W., 1992. Selective detection of organicmolecules with polymers and supramolecular compounds application of capacitance, quartz microbalance and calorimetric transducers. Sensors and Actuators APhysical, 31, 130137. Schindler, P.W., Furst, B., Dick, R. and Wolf, P.U., 1976. Ligand properties of surface silanol groups. 1. Surface complexformation with Fe 3+ , Cu 2+ , Cd 2+ , and Pb 2+ . Journal of Colloid and Interface Science, 55, 469475. Schultz, J.S. and Taylor, R.F., 1996. Introduction to chemical and biological sensors. In R.F. Taylor and J.S. Schultz (eds.) Handbook of Chemical and Biological Sensors. Institute of Physics Publishing. Schwarz, M.A. and Hauser, P.C., 2001. Recent developments in detection methods for microfabricated analytical devices. Lab on a Chip, 1, 16. SchweizerBerberich, P.M., Vaihinger, S. and Gopel, W., 1994. Characterization of food freshness with sensor arrays. Sensors and Actuators BChemical, 18, 282 290. Sekula, J., Everaert, J., Bohets, H., Vissers, B., Pietraszkiewicz, M., Piestraszkiewicz, O., Du Prez, F., Vanhoutte, K., Prus, P. and Nagels, L.J., 2006. coated wire potentiometric detection for capillary electrophoresis studied using organic amines, drugs, and biogenic amines. Analytical Chemistry, 78, 3772 3779. Selawry, O.S., Neubauer, H.W., Selawry, H.S. and Hoffmeis.Fs, 1966. Cholesteric thermography in tumors of head and neck. American Journal of Surgery, 112, 537 541. 138 Shah, R.S. and Abbott, N.L., 2001. Principles for measurement of chemical exposure based on recognitiondriven anchoring transitions in liquid crystals. Science, 293, 1296 1299. Smith, R.M. and Martell, A.E., 1975. Critical Stability Constants. Vol. 2. Plenum Press. Smith, R.M. and Martell, A.E., 1976. Critical Stability Constants. Vol. 4. Plenum Press. Smith, R.M. and Martell, A.E., 1977. Critical Stability Constants. Vol. 3. Plenum Press. Snow, A. and Barger, W.R., 1989. Phthalocyanine films in chemical sensor. In C.C. Leznoff and A.B.P. Lever (eds.) Phthalocyanine Properties and Applications. VCH. Song, Y.J., Hormes, J. and Kumar, C., 2008. Microfluidic synthesis of nanomaterials. Small, 4, 698711. Spadavecchia, J., Ciccarella, G., Rella, R., Capone, S. and Siciliano, P., 2003. Metallophthalocyanines thin films in array configuration for electronic optical nose applications. Sensors and Actuators BChemical, 96, 489497. Spadavecchia, J., Ciccarella, G., Stomeo, T., Rella, R., Capone, S. and Siciliano, P., 2004a. variation in the optical sensing responses toward vapors of a porphyrin phthalocyanine hybrid thin film. Chemistry of Materials, 16, 2083 2090. Spadavecchia, J., Ciccarella, G., Vasapollo, G., Siciliano, P. and Rella, R., 2004b. UVVis absorption optosensing materials based on metallophthalocyanines thin films. Sensors and Actuators BChemical, 100, 135138. Spencer, J.N., Wolbach, W.S., Hovick, J.W., Ansel, L. and Modarress, K.J., 1985. Hydrogenbonding by alcohols and amines. Journal of Solution Chemistry, 14, 805 814. Sun, L., Kepley, L.J. and Crooks, R.M., 1992. Molecularinteractions between organized, surfaceconfined monolayers and vaporphase probe molecules Hydrogenbonding interactions. Langmuir, 8, 21012103. Sun, Y. and Ong, K.Y., 2005. Detection Technologies for Chemical Warfare Agents and Toxic Vapors. CRC Press. Suslick, K.S., 2004. An optoelectronic nose: "Seeing" smells by means of colorimetric sensor arrays. MRS Bulletin, 29, 720725. Suslick, K.S., Rakow, N.A. and Sen, A., 2004. Colorimetric sensor arrays for molecular recognition. Tetrahedron, 60, 1113311138. 139 Szita, N., Boccazzi, P., Zhang, Z.Y., Boyle, P., Sinskey, A.J. and Jensen, K.F., 2005. Development of a multiplexed microbioreactor system for highthroughput bioprocessing. Lab on a Chip, 5, 819826. Tao, S.Q., Fanguy, J.C. and Sarma, T.V.S., 2008. A fiberoptic sensor for monitoring trace ammonia in hightemperature gas samples with a CuCl2doped porous silica optical fiber as a transducer. IEEE Sensors Journal, 8, 20002007. Thomas, R.C., Yang, H.C., Dirubio, C.R., Ricco, A.J. and Crooks, R.M., 1996. Chemically sensitive surface acoustic wave devices employing a selfassembled composite monolayer film: Molecular specificity and effects due to selfassembled monolayer adsorption time and gold surface morphology. Langmuir, 12, 22392246. Timmer, B., Olthuis, W. and Van Den Berg, A., 2005. Ammonia sensors and their applications a review. Sensors and Actuators BChemical, 107, 666677. Tomchenko, A.A., Harmer, G.P., Marquis, B.T. and Allen, J.W., 2003. Semiconducting metal oxide sensor array for the selective detection of combustion gases. Sensors and Actuators BChemical, 93, 126134. Trevani, L.N., Roberts, J.C. and Tremaine, P.R., 2001. Copper(II)ammonia complexation equilibria in aqueous solutions at temperatures from 30 to 250 °C by visible spectroscopy. Journal of Solution Chemistry, 30, 585622. Ulman, A., 1996. Formation and structure of selfassembled monolayers. Chemical Reviews, 96, 1533 1554. Vairavamurthy, A., Roberts, J.M. and Newman, L., 1992. Methods for determination of lowmolecularweight carbonylcompounds in the atmosphere. Atmospheric Environment Part AGeneral Topics, 26, 19651993. Vandaveer, W.R., PasasFarmer, S.A., Fischer, D.J., Frankenfeld, C.N. and Lunte, S.M., 2004. Recent developments in electrochemical detection for microchip capillary electrophoresis. Electrophoresis, 25, 35283549. Virji, S., Huang, J.X., Kaner, R.B. and Weiller, B.H., 2004. Polyaniline nanofiber gas sensors: Examination of response mechanisms. Nano Letters, 4, 491496. Wang, C., He, X.W. and Chen, L.X., 2002. A piezoelectric quartz crystal sensor array self assembled calixarene bilayers for detection of volatile organic amine in gas. Talanta, 57, 1181 1188. Wang, J., LutheySchulten, Z.A. and Suslick, K.S., 2003. Is the olfactory receptor a metalloprotein? Proceedings of the National Academy of Sciences United States of America, 100, 3035 3039. Watts, P. and Haswell, S.J., 2005. The application of microreactors for small scale organic synthesis. Chemical Engineering and Technology, 28, 290301. 140 White, J., Kauer, J.S., Dickinson, T.A. and Walt, D.R., 1996. Rapid analyte recognition in a device based on optical sensors and the olfactory system. Analytical Chemistry, 68, 21912202. Williams, R.J.P., 1956. The propertis of metalloporphyrins. Chemical Reviews, 56, 299328. Wilson, A.D. and Baietto, M., 2009. Applications and advances in electronicnose technologies. Sensors, 9, 50995148. Winterbottom, D.A., Narayanaswamy, R. and Raimundo, I.M., 2003. Cholesteric liquid crystals for detection of organic vapours. Sensors and Actuators BChemical, 90, 52 57. Wohltjen, H. and Dessy, R., 1979. Surface acousticwave probe for chemical analysis. 1. Introduction and instrument description. Analytical Chemistry, 51, 1458 1464. Xu, H., Bi, X.Y., Ngo, X.M. and Yang, K.L., 2009. Principles of detecting vaporous thiols using liquid crystals and metal ion microarrays. Analyst, 134, 911915. Xue, C.Y. and Yang, K.L., 2008. Darktobright optical responses of liquid crystals supported on solid surfaces decorated with proteins. Langmuir, 24, 563567. Yang, K.L., Cadwell, K. and Abbott, N.L., 2004. Mechanistic study of the anchoring behavior of liquid crystals supported on metal salts and their orientational responses to dimethyl methylphosphonate. Journal of Physical Chemistry B, 108, 2018020186. Yang, K.L., Cadwell, K. and Abbott, N.L., 2005. Use of selfassembled monolayers, metal ions and smectic liquid crystals to detect organophosphonates. Sensors and Actuators BChemical, 104, 5056. Yaws, C.L., 1997. Handbook of Chemical Compound Data for Process Safety. Gulf Publisher. Zhang, Z., Hu, R. and Liu, Z., 2000. Formation of a porphyrin monolayer film by axial ligation of protoporphyrin IX zinc to an aminoterminated silanized glass surface. Langmuir, 16, 1158 1162. Zhou, R., Josse, F., Gopel, W., Ozturk, Z.Z. and Bekaroglu, O., 1996. Phthalocyanines as sensitive materials for chemical sensors. Applied Organometallic Chemistry, 10, 557 577. Zhu, L., Meier, D., Boger, Z., Montgomery, C., Semancik, S. and Devoe, D.L., 2007. Integrated microfluidic gas sensor for detection of volatile organic compounds in water. Sensors and Actuators BChemical, 121, 679688. 141 LIST OF PUBLICATIONS Sutarlie, L. and Yang, K.L., 2008. Colorimetric responses of transparent polymers doped with metal phthalocyanine for detecting vaporous amines. Sensors and Actuators BChemical, 134, 1000 – 1004. Sutarlie, L., Qin, H., and Yang, K.L., 2010. Polymer stabilized cholesteric liquid crystal arrays for detecting vaporous amines. Analyst, 135, 1691 – 1696. Sutarlie, L., Lim, J. Y., and Yang, K.L., 2011. Cholesteric liquid crystals doped with dodecylamine for detecting aldehyde vapors. Analytical Chemistry, 83, 5253 5258. Sutarlie, L. and Yang, K.L., 2011. Monitoring spatial distribution of ethanol in microfluidic channels by using a thin layer of cholesteric liquid crystal. Lab on a Chip, 11, 40934098. 142 [...]... thesis. Below, an overview of how to use metal compounds and cholesteric liquid crystals (CLCs) for developing VOCs sensors is provided. Furthermore, a more detailed review of VOCs sensors, metal compounds and CLCs applications for chemical sensing is presented in Chapter 2. 1.1 Applications of metal compounds for chemical sensing In the development of VOCs sensors, molecular receptors which bind specifically to ... (CLCs) for developing VOCs sensors. In this chapter, we provide literature review on chemical sensors for VOCs, utilization of metal compounds as molecular receptors, and utilization of CLCs for VOCs sensing. 2.1 Chemical sensors for VOCs Chemical sensors have many civil and military applications such as pollution control and environmental safety monitoring. Chemical sensors are defined by IUPAC as devices that transform chemical information ... P’ T tilt angle of CLC layers wavelength light angle of incidence binding constant effective refractive index of cholesteric liquid crystals pitch of cholesteric liquid crystals effective pitch of cholesteric liquid crystals temperature xv CHAPTER 1 INTRODUCTION Volatile organic compounds (VOCs) such as alcohols, organoamines, and aldehydes appear in many chemical products and are widely ... The strength of metal ligand interactions depend on the nature of metal ions and ligands. Ligands with strong interactions create large energy level splitting of metal ions d orbitals and force electron pairing in the d orbitals of metal ions. These ligands are called strongfield ligands. In contrast, ligands with weak interactions are weaker in forcing electron ... VOCs are considered as hazardous chemicals for health and environment and it is important to detect and monitor VOCs. Because of its importance, chemical sensing of VOCs has attracted much attention and many chemical sensors for VOCs have been developed. The chemical sensors for VOCs are often fabricated as combination of chemical sensitive layers containing ... performance of metal compounds as molecular receptors for binding with VOCs. 1.2. Applications of cholesteric liquid crystals (CLCs) for chemical sensing Chemical sensors for VOCs also can be developed by using cholesteric liquid crystals (CLCs). CLC molecules arrange in layers with orientational order of each subsequent layer rotates a small angle and forms a helical pattern (Collings, 2002, Oswald and Pieranski, 2005). The distance to create 360° rotation or one helical pattern is called a ... (Lombardi and Dittrich, 2010), chemistry and biochemistry analytical purposes (Ohno et al., 2008, Li and Lin, 2009, Arora et al., 2010). In these applications, it is important to detect and monitor of the chemicals and biochemicals inside the microfluidic devices. In order to perform the detection and monitoring of chemicals in microfluidic devices, the microfluidic ... and they offer a wide range of metal ligand interaction strength. These metal compounds can be utilized as molecular receptors and developed as arrays of multiple sensing elements for VOCs sensing. Recent studies have demonstrated the utilization of metalloporphyrins spotted on reverse phase silica gel plates as colorimetric arrays for VOCs detection (Rakow and Suslick, ... molecular orientation of liquid crystals. Liquid crystal is a phase of matter between solid and liquid. Liquid crystals molecules do not have positional order but still maintain orientational order such as shown by the director line (n) in Figure 2.1 (Collings, 2002). Figure 2.1. Orientational and positional order of solid, liquid crystal, and liquid Based on ... interactions occur in metal ligand interactions during formation of complexes as metal ions having unoccupied orbitals accept electron pairs from ligands (molecules having at least one free electron pair). In metal ligand interactions, overlapped orbitals of metal ions and ligands re hybridize and electrons transfer change the electronic energy levels within the hybrid orbitals (Miessler and Tarr, 1999). . APPLICATIONS OF METAL COMPOUNDS AND CHOLESTERIC LIQUID CRYSTALS FOR CHEMICAL SENSING  LAURASUTARLIE NATIONALUNIVERSITY OF SINGAPORE 2012 APPLICATIONS OF METAL COMPOUNDS AND CHOLESTERIC LIQUID CRYSTALS FOR CHEMICAL. ………………………………………… … 1 1.1. Applications of metal compounds for chemical sensing …………………. 1 1.2. Applications of cholesteric liquid crystals (CLCs) for chemical sensing …. 3 1.3. Objectives. ligands affectthe 3 performance of metal compounds asmolecularreceptors for bindingwithVOCs. 1.2. Applications of cholesteric liquid crystals (CLCs) for chemic al sensing Chemical sensors for VOCsalsocanbedevelopedby

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