A decade ago, Aprahamian and coworkers first reported their initial accidental discovery of a series of BF2-coordinated azo dyes which photoisomerize at much longer (lower energy) wavelengths than conventional azo dyes. Shortly thereafter they published a second paper using electron donating groups on only the phenyl moiety to tune the spectroscopic and photophysical properties of these dyes before returning to their intended hydrazone chemistry. These BF2-azo dyes’ longer wavelength absorbance would make them ideal for many applications where conventional azo dyes are limited by their shorter wavelength higher energy absorbance spectra (leading to biomedical incompatibility, competitive absorbance, and photodegradation). At Hope College, in the Gillmore undergraduate organic photochemistry research group, we began preparing analogs of Aprahamian’s dyes with polymerizable “handles” in an attempt to incorporate the dyes into photomechanical polymer systems. Unfortunately, we soon discovered that there was yet too much unknown about these dyes for such an ambitious project. However, we did demonstrate methods to functionalize the quinoline as well as the phenyl moiety, and had preliminary indication of similar effects upon substituting either moiety. The Gillmore group has undertaken an ACS PRF funded project to capitalize on these preliminary results to better understand these dyes. Substitutions on the quinoline moiety have the potential to allow even greater spectroscopic tuning of these dyes. In this poster we present our fledgling efforts toward developing both even more electron rich analogs of the dyes, with electron donating groups (EDG) on both the quinoline and the phenyl moieties, and also push-pull systems in which there are electron withdrawing groups (EWG) on the quinoline and EDG on the phenyl (potentially increasing effective conjugation length and single bond character of the azo bond). Effects of substitution at the 4- and 6-positions of the quinoline will also be described.

Exploring quinoline-functionalized long-wavelength BF2-coordinated azo dyes

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