Guanidine‐Templated Manganese Halides Single Crystals toward Efficient Mechanoluminescence and Photoluminescence by Supramolecular Interactions Modulation

Abstract Interaction between organic molecule and inorganic frameworks can significantly change the photophysical properties of organic metal‐halides hybrid materials. Here, a family of guanidine‐based manganese‐halides is synthesized via supramolecular interactions modulation by adjusting conjugated degree and the number of hydrogen‐bonding donors in the guanidine‐based templates cations, which further endows intriguing optoelectrical properties. Single‐crystalline mono‐gua (gua = (C(NH 2 ) 3 + )) and bigua‐functional group (bigua = (C(NH 2 ) 2 NHC(NH 2 ) 2 ) 2+ )‐based manganese‐halides are prepared and efficient phosphorescence as well as strong mechanoluminescence (ML) are achieved by modulating the hydrogen‐bonding interaction and CH⋯π interaction with the manganese‐halides. The stronger weak interaction between the metal‐halides and organic ligands greatly reduces the molecular vibration and rotation of [MnBr 4 ] 2− and suppresses the non‐radiative transition under mechanical stimuli, which is favorable for ML. Based on this unique character of ML, a pressure sensor can be made as is demonstrated in this article by fabricating a highly uniform wafer‐sized (gua) 2 MnBr 4 film. Furthermore, arc discharge is observed for the first time in the organic manganese halides during cooling‐induced shrinkage of crystals in the (gua) 2 MnBr 4 system with highly symmetric and conjugated gua‐ligands.