Spectral characterization of thiophene acylhydrazides.

The spectroscopic properties of a series of new thiophene acylhydrazides were examined. Extremely low fluorescence quantum yields were observed for all these compounds including the hydrazide parent compound and their acylhydrazide homologous polymers. The heteroatoms concomitant with the thiophene sulfurs were responsible for decreasing the singlet-triplet energy level resulting in increased intersystem crossing and low fluorescence emission for the studied compounds. Intramolecular triplet self-quenching from the acylhydrazide bond ultimately deactivates the triplet state by non-emissive means.