Low-Symmetry Phthalocyanines Bearing Carboxy-Groups: Synthesis, Spectroscopic and Quantum-Chemical Characterization.

The synthesis and characterization of A 3 B-type phthalocyanines, ZnPc1 - 4 , bearing bulky 2,6-diisopropylphenoxy-groups or chlorine atoms on isoindoline units "A" and either one or two carboxylic anchors on isoindoline unit "B" are reported. A comparison of molecular modelling with the conventional time dependent-density functional theory (TD-DFT) approach and its simplified sTD-DFT approximation provides further evidence that the latter method accurately reproduces the key trends in the spectral properties, providing colossal savings in computer time for quite large molecules. This demonstrates that it is a valuable tool for guiding the rational design of new phthalocyanines for practical applications.