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Updated: Aug 19, 2026
Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers
Published on: May 12, 2023
Site-specific bromination on an organic cation scaffold: a minimal-variable platform reveals structure-luminescence
Junjie Dong1, Yue Jiang1, Youcai Hu1
1Collaborative Innovation Center for Advanced Organic Chemical Materials, Co-constructed by the Province and Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, PR China. fwg@hubu.edu.cn.
Abstract:
Organic-inorganic hybrid manganese halides (OIMnHs) are promising stimuli-responsive materials due to their structural tunability and rich photophysical properties. However, current research relies largely on empirical screening of numerous organic cations, and a rational design model that decouples the multiple structural variables affecting luminescence remains scarce. Here, a site-specific chemical modification strategy on a 2-amino-3,5-dimethylpyridinium scaffold [A]2[MnCl4] is proposed to systematically decouple the effects of the anionic halide site (X-site) and the organic cation site (A-site). Through two orthogonal bromination pathways: substituting Cl- with Br- at the X-site and -CH3 with -Br at the functional group of the A-site, six Mn-based hybrid crystals are synthesized, which form a tightly interlinked comparative platform with minimal structural perturbation. Although A-site Br substitution reduces the PLQY from 32.4% (35DM-C) to approximately 5% (3BG and 5BG), it simultaneously imparts distinctive humidity-responsive behaviors. At 75% relative humidity, 3BG and 5BG undergo humidity-induced structural transformations into 3BY and 5BR, respectively, boosting PLQY dramatically (∼11-fold) to 55.0% and 52.9%. Taking advantage of the humidity response and broad spectral coverage of these materials, their potential for information encryption and high-color-rendering white-light illumination is further demonstrated, achieving a color-rendering index of 91.6. Systematic experiments and theoretical calculations reveal that local chemical modification of the organic cation regulates excited-state dynamics, enhancing radiative transitions and suppressing nonradiative pathways by tuning weak-interaction networks, which in turn governs the humidity-induced structural transformation and luminescence switching. This stepwise, interlocking research framework enables clear structure-property correlations.
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