Solvent effect on the nonlinear absorption of 5,10-A2B2meso substituted porphyrins

Abstract

The effect of the solvent on the nonlinear absorptive properties of two series of 5,10-A 2 B 2 porphyrins was investigated with an open Z-scan technique in ns time regime. The recorded responses, which varied between compounds and solvents, were fitted with a four-level model where one-photon excited state absorption is followed by a two-photon process arising from the higher excited states. For most of the compounds the positive nonlinear absorption was stronger in toluene than in DMF and chloroform. This 10 was attributed to enhanced two-photon absorption in toluene. For DMF and chloroform the solvent effects were most likely compound specific. It was demonstrated that high saturation intensity of two-photon absorption shifts the RSA/SA turnover into higher fluence range, which is desirable for optical limiting applications. This saturation intensity of two-photon absorption varied between compounds and solvents. Additionally, nonlinear scattering contributed strongly to the open Z-scan responses for many compounds 15 in chlorobenzene and chloroform/chlorobenzene solutions. This was associated with the photodegradation of chlorobenzene.

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation

“…Other metalated meso 5,10-A 2 B 2 substituted porphyrins ( 572a – e , Chart ) were investigated with the open Z -scan technique at 532 nm in the ns regime. , As it can be seen from Figure , most of the compounds exhibited a transmission drop with increasing input fluence as expected for OL active materials. All recorded responses were successfully fitted with a four-level model with simultaneous TPA arising from the higher excited states.…”

Studying the intersystem crossing rate and triplet quantum yield of meso-substituted porphyrins by means of pulse train fluorescence technique

“…Very fast excited state absorption and high singlet to triplet conversion rates [10][11][12] make porphyrins a unique class of compounds for this application [13][14][15]. Besides OPL, the ISC features of porphyrins are also important for other applications such as photodynamic therapy (PDT) [1,16], dye sensitized solar cells [17] and photon up-conversion devices [18].…”

Nitro- and Amino-­Porphyrins: Important Intermediates for Novel Porphyrin Derivatives Formation

“…5 Por outro lado, temse dado cada vez mais ênfase na síntese e caracterização físico-química de porfirinas assimétricas, para as mais variadas aplicações. Estas aplicações estão voltadas principalmente para as áreas da fotônica, da ciência dos materiais e da fotomedicina, necessitando assim, de derivados assimetricamente substituídos, contendo apenas um tipo de grupo funcional específico para determinada função e aplicações tais como: macrociclos contendo propriedades anfifílicas como fotossensibilizadores, 6 com propriedades do tipo donnor-acceptor para aplicações na área de conversão de energia, 7 na química supramolecular, 8 como novos materiais para óptica não-linear 9 ou ainda como modelos quirais para aplicações em catálise assimétrica. …”