Several substituted oligophenylenevinylenes were synthesized using the Wittig−Horner−Emmons reaction to produce the trans isomers. Optical properties of these compounds were evaluated using absorption and steady-state fluorescence spectroscopy. Fluorescence quantum yields, Φf, decrease with increasing solvent polarity and approach unity in nonpolar solvents in the case of substituted trans,trans-1,4-bis[2-(2‘,5‘-difluoro)phenylethenyl]benzenes and trans,trans-1,4-bis[2-(2‘,5‘-dialkoxy)phenylethenyl)-2,3,5,6-tetrafluorobenzenes. The compounds show a strong solvatochromic shift as a function of solvent polarity, yielding a slope of −13 300 cm- 1 according to the Lippert−Mataga equation and indicating the emission of an additional charge-transfer species. A two-state reaction model was confirmed for trans,trans-1,4-bis[2-(2‘,5‘-dialkoxy)phenylethenyl)-2,3,5,6-tetrafluorobenzene (6d) in different solvents by time-correlated single-photon counting using global analysis. A dependence of the kinetic data on solvent polarity was found (global fitted decay times in picoseconds for τ1 and τ2:  381/1281 in n-hexane; 101/1590 in toluene; 27/2974 in acetonitrile). Investigations of the solid state showed liquid crystalline behavior for 6d and for trans,trans-1,4-bis[2-(2‘,5‘-difluoro)phenylethenyl]-2,5-diheptyloxybenzene (3b). This was confirmed by polarization microscopy and thermal analysis. Both the long alkoxy chains and fluorine substitution are responsible for the formation of mesophases. Photoluminescence studies of 3b and 6d in the solid state indicated an intense emission that was yellow for 3b.

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The properties and reactivity of a series of iodonium salts with different anions were compared. The nucleophilicity of the anions in such compounds can be characterized by their melting points and NMR spectra. When using Quinaldine Red as indicator and CH3CN as solvent, the acid release rate of the iodonium salts correlated very well with their polymerization results in acid-sensitive epoxides.

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The fluorescence probes trans,trans-1,4-bis[2-(2‘,5‘-dimethoxy)phenylethenyl)-2,3,5,6-tetrafluorobenzene (1) and trans,trans-1,4-bis[2-(3‘,4‘,5‘-trimethoxy)phenylethenyl)-2,3,5,6-tetrafluorobenzene (2) show solvatochromic behavior yielding slopes in the Lippert−Mataga equation of −13 300 and −13 700 cm-1, respectively. 1 sensitively probes progress in both photoinduced radical and cationic cross-linking. Both 1 and 2 show minor tendencies for trans − cis photoisomerization. Substituted stilbenes such as trans-2-(2‘,5‘-dimethoxyphenyl)ethenyl-2,3,4,5,6-pentafluorobenzene (1r) and trans-2-(3‘,4‘,5‘-trimethoxyphenyl)ethenyl-2,3,4,5,6-pentafluorobenzene (2r) are less solvatochromic in fluorescence but evidence enhanced tendency toward photoisomerization.

Several new iodonium salts containing weakly coordinating anions were synthesized and characterized. Upon UV irradiation, the rates of photoacid generation in acetonitrile and their preliminary activity in the photopolymerization of epoxy silicones were compared. Studies showed these salts to be excellent photoacid generators. The anions [(C 6F5)3B-C3H3N2-B(C6F5)3] -, B(C6F5)4 -, and Ga(C6F5)4were more active and the compounds made from them more soluble in most solvents. The [(C6F5)3B-C6F4-B(C6F5)3] 2anion was less active, and the compounds made from them were less soluble than compounds made from the three aforementioned anions. Compounds containing hexabromocarborane anion were quite similar to compounds containing SbF6in both photoactivity and solubility.

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