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

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) thin films were grown on quartz substrates and then postcoordinated with different cations (Fe or FeCl) in InTCPP(H) (named InTCPP(Fe) and InTCPP(FeCl)). The third-order NLO results reveal the Fe and FeCl coordinated InTCPP thin films have substantially enhanced NLO performance. Moreover, InTCPP(FeCl) thin films cause symmetry breaking of microstructures, resulting in a 3-fold increase in the nonlinear absorption coefficient (up to 6.35 × 10 m/W) compared to InTCPP(Fe). 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.