Spectral and luminescent properties of triareno-substituted tetraazachlorins

Spectral and luminescent properties of recently synthesized compounds of a class of hydroporphyrazines, triarenotetraazachlorins, in polyvinylbutyral films have been studied. Fluorescence lifetimes have been measured in film and in solution. Fluorescence quantum yields have been estimated. It is found that annelation of aromatic rings to the pyrrole rings of the tetraazachlorin macrocycle enhances fluorescence. Quantum-chemical optimization of the geometrical structures of the free-base 1,2-trinaphthotetraazachlorins has been carried out using the AM1 method. The two isomers were shown to be highly non-planar. Spectral hole burning in absorption bands of both this compound and free-base 2,3-trinaphthotetraazachlorin in polyvinylbutyral films at 5 K in the wavelength region of titanium-sapphire laser radiation is possible and is ascribed to NH-photoisomerization. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 376–386, May–June, 2009.