RESUMO
The linear and nonlinear optical properties of the heteroaromatic push-pull-push two-photon absorbing dye N-methyl-2,5-bis[1-(N-methylpyrid-4-yl)ethen-2-yl]-pyrrole ditriflate (PEPEP) are reported. The determination of the two-photon absorption (TPA) cross-section spectrum has been performed with different techniques: femtosecond TPA-white light continuum probe experiments, two-photon-induced fluorescence, and open aperture Z-scan measurements using both nanosecond and femtosecond laser pulses. The measured TPA cross sections and their wavelength dispersion show a marked dependence on the parameters of the laser pulses and on the measurement technique employed. These properties are discussed in terms of the different microscopic mechanisms that can contribute to the multiphoton absorption processes, with different weight depending on the measurement conditions and on the photophysical parameters of the dye.
RESUMO
In this work we present an investigation of the non-linear optical (NLO) properties of two octupolar chromophores: [Zn(4,4'-bis(dibutylaminostyryl)-[2,2']-bipyridine)(3)](2+) and [Zn(4,4'-bis((E)-2-(N-(TEG)pyrrol-2-yl)vinyl)-[2,2']-bipyridine)(3)](2+) with Zn(ii) as the coordination center, using two-photon emission technique (TPE) in fs-pulse temporal regime. Compared to the free ligands, our results do not show a net increase in the two-photon absorption (TPA) cross-section for the octupolar complexes, once normalized to the ligand unit. This is in partial disagreement with a previous theoretical study investigating the first molecule where a significant increase of the TPA cross-section was predicted (X. J. Liu, et al., J. Chem. Phys., 2004, 120, 11 493).
RESUMO
This paper presents the synthesis and two photon-induced absorption (TPA) properties of a functionalized distyrylbenzene (DSB) 1 containing a tetra-azacyclododecane (cyclen) receptor for Zn(II). The influence of Zn(II) on one- and two-photon absorption characteristics of 1 has been investigated in dimethyl sulfoxide. The experiments show that the TPA action spectrum of uncomplexed 1, at 750 nm employing nanosecond-long excitation pulses, is 5 times more intense than that of the complexed form. This moderate contrast between the bound and unbound species confirms, however, the potential of this design scheme for the development of molecular structures with enhanced sensitivity and contrast to be used as Zn(II) sensors through TPA-induced fluorescence microscopy.
