Study of the thermal decomposition of tetrapyrazino[2,3-b]indoloporphyrazine films

Abstract

Phthalocyanines are attractive due to their technological applications in the field of organic solar cells, sensors, optical data storage, and sensitizers for photodynamic therapy.1 Their physicochemical properties can be readily adjusted by suitable substitution. Introduction of two nitrogen atoms into the equivalence of the 1,4-positions of the phthalocyanine benzene units leads to tetrapyrazinoporphyrazines. Tetrapyrazino[2,3-b]indoloporphyrazines have been synthesized by substituting an indole group at the 2,3 position of the pyrazine. These molecules behave as push-pull intramolecular charge-transfer chromophoric systems in which the indole ring works as a donor group and the pyrazine ring as an acceptor group.2 In this work, tetrapyrazino[2,3-b]indoloporphyrazine films have been prepared by vacuum thermal evaporation and Langmuir-Blodgett (LB) techniques. The spectroscopic properties of the tetrapyrazino[2,3-b]indoloporphyrazine films have been investigated using various spectroscopic techniques. FT-IR, NMR and X-ray photoelectron spectroscopy (XPS) have been used to analyze the structural compositions of the films, and ultraviolet photoelectron spectroscopy (UPS) has been performed to compare the valence electronic states of the thermally evaporated and LB films. UV-vis spectroscopy has been used to compare the electronic transitions of the films.