| Abstract
| - The synthesis, characterization, and various photophysical properties of axially substituted tetrapyrazinotetraazaporphyrinatotitanium(IV) oxide (Pyz4TAPTiO) (1), tetrapyrazinotetraazaporphyrinatovanadium(IV) oxide(Pyz4TAPVO) (2), tetrapyrazinotetraazaporphyrinatozirconium(IV) dihydroxide [Pyz4TAPZr(OH)2] (3) arereported. Nonlinear optical (NLO) properties of Pyz4TAPs 1−3 have been evaluated at 532 nm with nanosecondpulses for optical limiting (OL). It is found that the introduction of nitrogen atoms in the condensed rings ofthe tetrapyrrolic macrocycles together with the presence of axial substituents lead to an improvement of theexcited-state absorption properties in comparison to phthalocyanines (Pcs). In the linear optical regime Pyz4TAPs 1−3 display a blue shift (about 50−60 nm) of the main UV−vis absorption bands with respect to Pcsand exhibit orange-red fluorescence, which can be observed with the eye in the case of 1. Frontier electronicorbitals of a Pyz4TAP could be depicted from available experimental data and the results of density functionaltheory (DFT) calculations. In the solid state, Pyz4TAPTiO (1) displays photoconducting properties.
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