Optical limiting and singlet oxygen generation properties of phosphorus triazatetrabenzcorroles

Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole-pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined.