Relationship between chemical structures and optical limiting properties of penta-azadentate porphyrinlike metal complexes

The optical limiting performances of nine asymmetric pentaazadentate porphyrin-like metal complexes {[(R- APPC)M]Cln} have been measured at 532 nm with nanosecond pulses. In a fl38 geometry, with sample transmission of 0.51 approximately 0.80 in a 2 mm cell, the limiting thresholds for these complexes were 1.4 approximately 150.0 mJ/cm2. The throughputs of these complexes were limited to 0.31 approximately 1.42 J/cm2 for incident fluences as high as 3.5 J/cm2. The limiting throughput was strongly influenced by the nature of the ligand and metal ions. Lower bounds for the ratio of triplet excited-state to ground state absorption cross sections have been estimated at 2.3 approximately 5.7. The lower limiting thresholds, lower limiting throughputs, as well as the ease of modification of the ligands and variation of the metal ions, make these complexes promising candidates for optical power limiters.