Sun Ran, Wang Ting, Ren Xiaoyu, Zhang Lijuan, Zhou Yunshan, Huang Chengcheng
State Key Laboratory of Chemical Resource Engineering, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China.
Dalton Trans. 2022 May 24;51(20):7966-7974. doi: 10.1039/d2dt00367h.
In this paper, three zinc porphyrins bearing carboxyl, amino or hydroxyl groups on the porphyrin ring, namely, 5,10,15,20-tetra(4-carboxyphenyl) zinc porphyrin (ZnTCPP), 5,10,15,20-tetra(4-hydroxyphenyl) zinc porphyrin (ZnTHPP) and 5,10,15,20-tetra(4-aminophenyl) zinc porphyrin (ZnTAPP), reacted with the doughnut-like molybdenum crown cluster [(MoO)(HO)(CHOH)H] (denoted as {Mo}), resulting in the formation of three porphyrin-polyoxometalate hybrids (denoted as hybrids 1-3), respectively, with the ratio of {Mo} to the porphyrin molecules in each compound being 1 : 3. Compared with the corresponding parent porphyrins, the fluorescence quenching efficiency of hybrid 1, hybrid 2 and hybrid 3 was found to be 51%, 58% and 66%, respectively, indicating electron/energy transfer occurring from the porphyrin moiety to the POM moiety. -Scan experimental results showed that the three porphyrins and hybrids 1-3 exhibited nonlinear reverse saturated absorption and self-defocusing properties. The molecular second hyperpolarizability () values of hybrids 1-3 (7.38 × 10, 7.26 × 10 and 4.26 × 10 (esu)) are higher than those of the corresponding porphyrins (1.18 × 10, 1.34 × 10 and 1.36 × 10 (esu)), indicating that the doughnut-like molybdenum crown cluster in the hybrids 1-3 improved the third-order optical nonlinearities of the accommodated H-aggregate of the zinc porphyrin molecules, wherein the optical nonlinearities of the porphyrin with the electron-withdrawing functional group of -COOH ( = 7.38 × 10 for hybrid 1. = 1.18 × 10 for ZnTCPP) were enhanced the most. In addition, studies on the optical limiting properties of hybrid 1 and hybrid 2 showed that the nonlinear attenuation factor (NAF) of both hybrid 1 and hybrid 2 was larger than that of their corresponding porphyrins (NAF = 5.65 for hybrid 1 1.82 for ZnTCPP) and the limiting threshold of hybrid 1 and hybrid 2 can reach 0.3 J cm and 0.32 J cm, which proved that hybrids 1 and 2 are potential optical limiting materials.
