MOLECULAR DESIGN, CHARACTERIZATION, AND APPLICATION OF MULTI-INFORMATION DYES FOR MULTIDIMENSIONAL OPTICAL CHEMICAL SENSING - MOLECULAR DESIGN CONCEPTS OF THE DYES AND THEIR FUNDAMENTAL SPECTRAL CHARACTERISTICS

The molecular design of multi-functional dyes, called 'multi-informati on dyes' (MIDs), and their application to several methods of optical c hemical sensing were proposed. The concepts for the molecular design o f the dyes were as follows: (1) the introduction of multiple (both pos itive and negative) charges on both ends of the large conjugated pi-el ectron system of the dye molecule, so that the dye interacts with many chemical species or environments; (2) the introduction of different s ubstitution (electron-donating or electron-accepting) groups in the co njugated pi-electron system of the dye molecule, so that the dye has a different pK(a) and solvatochromic property; and (3) the introduction of an immobilization site in the dye molecule, so that the dye can be easily prepared as a sensing probe. Based on these concepts, sixteen kinds of dyes were synthesized, all being of the merocyanine type. The basic color-change characteristics of the MIDs were evaluated with a homogeneous system and a solvent extraction two-phase system. Some of these dyes (e.g., KD-M5) offered two-dimensional sensing information f or sensing the water content in organic solvents, in which the absorba nce maximum wavelength (lambda(max)) shift and absorbance change were both utilized as the detecting signals. From these results, the MIDs d eveloped in this study have several possibilities for analytical appli cations in optical chemical sensing such as pH sensing, ion sensing, n eutral molecule sensing, and water content-sensing in organic solvents . (C) 1998 Elsevier Science B.V. All rights reserved.