中科院福建物质结构研究所张健团队开发了用于增强非线性光学限幅的互穿金属-卟啉框架。相关研究成果发表在2021年9月20日出版的《美国化学会杂志》。

金属-有机框架（MOF）中的结构互穿对其性质和功能有显著影响。然而，到目前为止，还没有关于MOF在三阶非线性光学（NLO）上的相互穿透机理的研究报道。

该文中，研究人员报告了两种3D卟啉MOFs，一种是2倍互穿 [Zn2(TPyP)(AC)2] (ZnTPyP-1) 和一种非互穿[Zn3(TPyP)(H2O)2(C2O4)2] (ZnTPyP-2)，其由5,10,15,20-四（4-吡啶基）卟啉（TPyP（H2））和Zn（NO3）2（AC=醋酸盐，C2O4=草酸）构成。ZnTPyP-1具有巨大的非线性吸收系数（3.61×10⁶cm/GW）和较大的三阶磁化率（7.73×10^–7esu），具有优异的光限幅（OL）性能，远优于ZnTPyP-2和其它报道的OL材料。将相应的MOFs纳米片分散到聚二甲基硅氧烷（PDMS）基质中以形成用于实际应用的高度透明柔性MOFs/PDMS玻璃。

此外，在ZnTPyP-1体系中，研究人员还讨论了通过调节PDMS基质中MOFs的浓度和金属卟啉的类型来优化OL响应。理论计算证实，互穿框架中卟啉基团丰富的π-π相互作用增加了电子的离域/转移，提高了OL性能。

该研究为通过构建互穿结构来提高光致发光性能开辟了一条新途径，并为制备非线性光学应用透明柔性MOF复合材料提供了一条新途径。

附：英文原文

Title: Interpenetrated Metal-Porphyrinic Framework for Enhanced Nonlinear Optical Limiting

Author: De-Jing Li, Qiao-hong Li, Zi-Rui Wang, Zhi-Zhou Ma, Zhi-Gang Gu, Jian Zhang

Issue&Volume: September 20, 2021

Abstract: Structural interpenetration in metal–organic frameworks (MOFs) significantly impacts on their properties and functionalities. However, understanding the interpenetration on third-order nonlinear optics (NLO) of MOFs have not been reported to date. Herein, we report two 3D porphyrinic MOFs, a 2-fold interpenetrated [Zn2(TPyP)(AC)2] (ZnTPyP-1) and a noninterpenetrated [Zn3(TPyP)(H2O)2(C2O4)2] (ZnTPyP-2), constructed from 5,10,15,20-tetra(4-pyridyl)porphyrin (TPyP(H2)) and Zn(NO3)2 (AC = acetate, C2O4 = oxalate). ZnTPyP-1 achieves excellent optical limiting (OL) performance with a giant nonlinear absorption coefficient (3.61 × 106 cm/GW) and large third-order susceptibility (7.73 × 10–7 esu), which is much better than ZnTPyP-2 and other reported OL materials. The corresponding MOFs nanosheets are dispersed into a polydimethylsiloxane (PDMS) matrix to form highly transparent and flexible MOFs/PDMS glasses for practical OL application. In addition, the OL response optimized by adjusting the MOFs concentration in the PDMS matrix and the type of metalloporphyrin are discussed in the ZnTPyP-1 system. The theoretical calculation confirmed that the abundant π–π interaction from porphyrinic groups in the interpenetrated framework increased the electron delocalization/transfer and boosted the OL performance. This study opens a new avenue to enhance OL performance by the construction of interpenetrated structures and provides a new approach for the preparation of transparent and flexible MOF composites in nonlinear optical applications.

DOI: 10.1021/jacs.1c07803

Source: https://pubs.acs.org/doi/10.1021/jacs.1c07803