The Nonlinear Optical Characterization of Meso-Substituted Porphyrin Dyes

Abstract

Nine structurally related porphyrins are studied and it is shown how the material parameters that control the optical limiting depend on the molecular structure. Optical limiting measurements at 532 nm on the metal-free, zinc and lead analogues of tetraphenyl porphyrin (TPP), tetra(trimethylsilyethynyl) porphyrin (TTMSAP) and tetra(4-n-butylphenylethynyl) porphyrin (TNBBAP) reveal a strong dependence on the metal atom and peripheral substitution. A double pump/cw probe technique is used to measure the material parameters that control the optical limiting and the results give a strong insight into how the molecular structure influences the individual parameters. These measurements revealed that one of the materials TTMSAP(Pb) has a σex/σgr ratio of ∼45 at 532 nm, which is one of the largest values ever reported. Finally, broadband measurements with a picosecond white-light source show that the position and strength of the excited state absorption features also depend strongly on the porphyrin design.

Nonlinear absorption properties of 5,10-A2B2porphyrins—correlation of molecular structure with the nonlinear responses

“…Based on previous studies in which we identified {5,15-bis-(3-methoxyphenyl)-10,20-di[(trimethylsilyl)ethynyl]porphyrinato}-zinc(II) as the most promising among numerous porphyrins with varied meso substituents 14 and the literature indicated the utility of lead porphyrins with (trimethylsilyl)ethynyl (TMSethynyl) groups, 7 thus, we decided to further explore the potential of the very promising TMS-ethynyl substituent in the context of 5,10-A 2 B 2 porphyrins.…”

“…The model assumed fast ISC and high yield for the formation of the triplet states, which should be a valid approximation for macrocycles with heavy atoms in the core or on the molecular periphery. 7,31 Illustration of the model and definition of the parameters used in the fitting are presented in Fig. 5.…”

“…Good thermaland photo-stability and ease of processability are desirable as well. 7 Relevant research in this area focuses on the synthesis of new compounds, 8 materials composition, 9 and a better understanding of complex NLO responses. 7,10 Significant progress has been made in the improvement of the OL performance of porphyrins since the first observation of the OL effect in TPP in 1985.…”

“…7 Relevant research in this area focuses on the synthesis of new compounds, 8 materials composition, 9 and a better understanding of complex NLO responses. 7,10 Significant progress has been made in the improvement of the OL performance of porphyrins since the first observation of the OL effect in TPP in 1985. 5,11,12 Most studies focused on highly symmetric meso tetrasubstituted compounds and a few reports on meso and β-substituted compounds or 5,15-A 2 B 2 -type porphyrins have been published.…”

“…Likewise, the incorporation of conjugated groups at the meso positions was shown to enhance the OL action of porphyrins. (5,10,15,20-Tetra(trimethylsilylethynyl)porphyrinato)lead(II) 7 and lead, indium and thallium complexes of 5,10,15,20-tetra(triisopropylsilylethynyl)porphyrin 15 provided the best OL porphyrins up to date. The highest ratio of the excited to the ground state absorption cross-section reached values in the range of 45-48.…”