物理化学学报

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间位/对位共轭拓扑调控顺式/反式四硼发色团的单重态与三重态光物理性质

尚英建1,2, 于长江1,3, 程超1, 孙启可1, 许新胜1, 魏亚雄1, 许洋洋1, 赵学峰2, 焦莉娟1, 郝二红1, 缪伟2   

  1. 1 安徽师范大学化学与分子科学学院、物理与电子信息学院, 功能分子固体教育部重点实验室, 安徽 芜湖 241002;
    2 安徽医科大学第一附属医院核医学科, 安徽 合肥 230022;
    3 安徽美佳新材料有限公司博士后科研工作站, 安徽 芜湖 241200
  • 收稿日期:2026-06-23 修回日期:2026-07-31
  • 通讯作者: 于长江, 魏亚雄, 许洋洋, 郝二红, 缪伟 E-mail:yuchj@ahnu.edu.cn;Davidl@ustc.edu.cn;ahnuxyy@ahnu.edu.cn;haoehong@ahnu.edu.cn;mwei1992@fy.ahmu.edu.cn

Meta/para conjugation topology regulates singlet and triplet photophysics in cis/trans tetra-boron chromophores

Yingjian Shang1,2, Changjiang Yu1,3, Chao Cheng1, Qike Sun1, Xinsheng Xu1, Yaxiong Wei1, Yangyang Xu1, Xuefeng Zhao2, Lijuan Jiao1, Erhong Hao1, Wei Miao2   

  1. 1 Key Laboratory of Functional Molecular Solids of Ministry of Education, College of Chemistry and Molecular Science, School of Physics and Electronic Information, Anhui Normal University, Wuhu 241002, Anhui Province, China;
    2 Department of Nuclear Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China;
    3 Post-Doctoral Research Station, Anhui MeiJia New Materials Co. Ltd., Wuhu 241200, Anhui Province, China
  • Received:2026-06-23 Revised:2026-07-31
  • Contact: Changjiang Yu, Yaxiong Wei, Yangyang Xu, Erhong Hao, Wei Miao E-mail:yuchj@ahnu.edu.cn;Davidl@ustc.edu.cn;ahnuxyy@ahnu.edu.cn;haoehong@ahnu.edu.cn;mwei1992@fy.ahmu.edu.cn

摘要: 调控单重态辐射衰减与三重态布居的竞争关系,是无重原子有机发色团物理化学领域的核心研究问题。本文报道了两对含四硼的顺式/反式结构异构体,系统研究了分子构型以及由有效连接方式决定的间位/对位共轭拓扑对激发态行为的调控作用。间位顺式异构体通过中心亚苯基连接单元形成间位连接的交叉共轭路径,分子整体构型相对平面,固态下呈交叉堆积排列,因此在溶液与凝聚态中均表现出强荧光发射。与之相反,反式异构体为对位连接的线性共轭路径,具有更窄的光学/电化学带隙,吸收与发射光谱红移,荧光量子产率更低,非辐射衰减过程显著增强。纳秒瞬态吸收光谱结果显示,对位反式异构体存在长寿命三重态特征信号,寿命最长可达79.1 μs;而相同测试条件下,间位顺式异构体未观测到明显的长寿命瞬态吸收信号。进一步研究发现,对位反式异构体具备高效的单线态氧生成能力,可作为可见光光敏剂应用于三组分自由基光聚合体系。晶体结构解析、稳态光谱、瞬态吸收、电化学测试、活性氧检测及理论计算的结果共同佐证了一种拓扑辅助的激发态调控机制:在共轭拓扑、分子构型、窄化激发态带隙与非辐射衰减动力学的协同作用下,间位顺式分子骨架更有利于单重态的辐射弛豫,而对位反式骨架更有利于实现长寿命三重态的有效布居。本工作证实,有效共轭拓扑可作为调控无重原子含硼发色团单重态与三重态光功能的重要分子参数。

关键词: 四硼发色团, 结构异构, 共轭拓扑, 激发态动力学, 光聚合

Abstract: Regulating the competition between radiative singlet-state decay and triplet-state population is a central issue in the physical chemistry of heavy-atom-free organic chromophores. Herein, we report two pairs of tetra-boron-containing cis/trans structural isomers, and investigate how configurational geometry and effective connectivity-dependent meta/para conjugation topology regulate their excited-state behaviors. The m-Cis isomers possess a meta-connected cross-conjugated pathway through the central phenylene linker, together with relatively planar molecular geometries and cross-packed solid-state arrangements, giving intense fluorescence in solution and in the condensed state. In contrast, the p-Trans isomers feature a para-connected, more linearly conjugated pathway, narrowed optical/electrochemical gaps, red-shifted absorption and emission, lower fluorescence quantum yields, and enhanced nonradiative decay. Nanosecond transient absorption spectroscopy reveals long-lived triplet-state signatures for the p-Trans isomers with lifetimes up to 79.1 μs, whereas the m-Cis isomers show no obvious long-lived transient absorption under the same conditions. The p-Trans isomers further exhibit efficient singlet oxygen generation and serve as visible-light sensitizers in three-component free-radical photopolymerization systems. Combined crystallographic, steady-state spectroscopic, transient absorption, electrochemical, ROS-detection, and theoretical results support a topology-assisted excited-state regulation mechanism, in which the m-Cis framework favors radiative singlet-state relaxation, while the p-Trans framework favors access to long-lived triplet states through the interplay of conjugation topology, molecular geometry, narrowed excited-state gaps, and nonradiative decay kinetics. This work highlights effective conjugation topology as a useful molecular parameter for tuning singlet and triplet photofunctions in heavy-atom-free boron-containing chromophores.

Key words: Tetra-boron chromophores, Structural isomerism, Conjugation topology, Excited-state dynamics, Photopolymerization