Systematic Structure−Property Investigations and Ion-Sensing Studies of Pyridine-Derivatized Donor/Acceptor Tetrakis(arylethynyl)benzenes

Abstract

Nine structural isomers of a tetrakis(arylethynyl)benzene chromophore functionalized with dibutylaniline and pyridine units as respective donors and acceptors have been synthesized and their steady-state spectroscopic parameters investigated. The effects of small structural variations on the electronic absorption and emission spectra have been explored in evaluation of their potential as optical materials components. These structural variations have predictable consequences and thus allow fine-tuning of the optoelectronic properties for specialized applications. Strong solvatochromism is also displayed. Their response to protonation and metal ion complexation caused dynamic shifts in the emission spectra, providing evidence for a stepwise intramolecular charge-transfer switching phenomenon manifested by either hypsochromic or bathochromic shifts in the fluorescence lambda max. These shifts are believed to correlate strongly to the relative energies of the fluorophore's HOMO and LUMO levels. The complete array of compounds represents an interesting set of candidates for fluorescent sensing device components.