Photophysical and two-photon absorption properties of protonation-induced tribranched chromophore having 1,3,5-triazine core and pyrrole end-groups

• DOI: 10.1016/j.synthmet.2011.01.030
• Publication Date: 2011-03-07T23:21:35Z
• Authors: Li Liu; Zhiqiang Zhou; Jieping Shi; Zeyu Liu; Changgui Lu; Weijiang He; Jing Ma; Yiping Cui; Guo-Yuan Lu
• Keywords: 01 natural sciences; 0104 chemical sciences

Abstract The octupolar chromophore TA with a 1,3,5-triazine core and pyrrole electron-donating end-groups was prepared via Knoevenagel coupling. Its photophysical and two-photon absorption (TPA) properties upon the protonation with CF 3 COOH were investigated by absorption, fluorescence, NMR spectroscopy and TPA cross-section determination. The UV–vis spectroscopic study shows that the absorption band is shifted from 401 nm to 471 nm with the color change from pale-yellow to red upon CF 3 COOH addition. The fluorescence spectra shows that the emission band is red-shifted from 490 nm to 553 nm accompanied by the distinct emission quench effect caused by the protonation. NMR spectropic study demonstrates the protonation of triazine upon CF 3 COOH addition, and the protonated molecule retain the C 3h symmetry. In addition, the theoretical calculations of the absorption spectra of neutral and protonated TA demonstrate an obvious red-shift of λ max in the absorption after protonation. TPA cross-section of TA measured by nonlinear transmission (NLT) exhibits the obvious TPA cross-section enhancement effect upon protonation, provides a simple way to enhance the TPA cross-section of molecules and makes it attractive for application involving the proton-controlled optical sensor.