Coordination-Induced Symmetry Breaking on Metal-Porphyrinic Framework Thin Films for Enhanced Nonlinear Optical Limiting.

Tian, Yi-Bo; Li, Qiao-Hong; Wang, Zirui; Gu, Zhi-Gang; Zhang, Jian · Nano Lett · 2023

basic_science · Level V

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Abstract

Structural asymmetry affecting the nonlinear optics (NLO) of metal-organic frameworks (MOFs) is very important in fundamentals and applications but is still a challenge. Herein we develop a series of indium-porphyrinic framework (InTCPP) thin films and provide the first study on the coordination-induced symmetry breaking on their third-order NLO. The continuous and oriented InTCPP(H<sub>2</sub>) thin films were grown on quartz substrates and then postcoordinated with different cations (Fe<sup>2+</sup> or Fe<sup>3+</sup>Cl<sup>-</sup>) in InTCPP(H<sub>2</sub>) (named InTCPP(Fe<sup>2+</sup>) and InTCPP(Fe<sup>3+</sup>Cl<sup>-</sup>)). The third-order NLO results reveal the Fe<sup>2+</sup> and Fe<sup>3+</sup>Cl<sup>-</sup> coordinated InTCPP thin films have substantially enhanced NLO performance. Moreover, InTCPP(Fe<sup>3+</sup>Cl<sup>-</sup>) thin films cause symmetry breaking of microstructures, resulting in a 3-fold increase in the nonlinear absorption coefficient (up to 6.35 × 10<sup>-6</sup> m/W) compared to InTCPP(Fe<sup>2+</sup>). This work not only develops a series of nonlinear optical MOF thin films but also provides new insight into symmetry breaking on MOFs for nonlinear optoelectronic applications.