Influence of axial substitution on the optical limiting properties of indium porphyrins

Abstract

Optical limiting properties in CH2Cl2 solution of a series of axially substituted InTPP (indium tetraphenyl-porphyrin) and axially substituted InTTP (indium tetra-p-tolyl-porphyrin) are investigated using a 532 nm laser with a pulse duration of 5 ns. The axial substitutions include -Cl, -SCN, -SPh and -SPh(p-Me). The optical limiting measurements reveal that the optical limiting properties of the indium porphyrins are greatly influenced by the axially attached functional groups. A limiting threshold of 0.18 J/cm2 is achieved for TTPInSCN, which is the best optical limiting material in this report. Z-scan experiments are also conducted and confirm that the good optical limiting performance of these indium porphyrins is due to the large value of σex/σg.