Li Yu, Zhang Zi-Yu, Gao Feng-Wei, Su Zhong-Min
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China; Chongqing Research Institute, Changchun University of Science and Technology, No.618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City 401135, China.
School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, 7989 Weixing Road, Changchun 130012, China; Chongqing Research Institute, Changchun University of Science and Technology, No.618 Liangjiang Avenue, Longxing Town, Yubei District, Chongqing City 401135, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Dec 15;343:126509. doi: 10.1016/j.saa.2025.126509. Epub 2025 May 31.
Through-space charge transfer (TSCT) mechanism has emerged as key strategies for the creating of hybrid localized and charge transfer (HLCT) emitters. We present a systematic study of U-shaped molecules incorporating benzofuran (BDF) as electron acceptors and carbazole as the bridge-connected donor (carbazole, phenoxazine, and dihydrophenazine, Cz/PXZ/DHPZ), named BDF-Cz-Cz, BDF-Cz-PXZ, BDF-Cz-DHPZ, BDFCN-Cz-Cz, BDFCN-Cz-PXZ, and BDFCN-Cz-DHPZ. The photophysical properties of these molecules were systematically analyzed based on density functional theory (DFT) and time-dependent DFT (TD-DFT). By adjusting the donor-acceptor strength, theproportionof charge transfer (CT) between the donor and acceptor through space versus through bonds can be altered, enabling the switching between through-bond charge transfer (TBCT) and TSCT. Strong donors and acceptors possess a significant driving force, and analysis of the weak interactions within the molecule revealed that BDFCN-Cz-DHPZ possesses TSCT character. Significantly, PXZ-based and DHPZ-based molecules exhibit the high-lying reverse intersystem crossing (hRISC) process from the triplet excited state (T, n ≥ 2) to the singlet excited state (S), with fast reverse intersystem crossing rate (k) values (in the order of 10 to10 s) and high fluorescence radiative rates (k) values (in the order of 10 s). Therefore, U-shaped molecules are promising candidates for efficient HLCT molecules. This innovative design strategy offers new ideas and avenues for regulating and optimizing the performance of TBCT-HLCT and TSCT-HLCT emitters.
空间电荷转移（TSCT）机制已成为构建杂化局域和电荷转移（HLCT）发光体的关键策略。我们对以苯并呋喃（BDF）为电子受体、咔唑为桥连供体（咔唑、吩恶嗪和二氢吩恶嗪，Cz/PXZ/DHPZ）的U形分子进行了系统研究，这些分子分别命名为BDF-Cz-Cz、BDF-Cz-PXZ、BDF-Cz-DHPZ、BDFCN-Cz-Cz、BDFCN-Cz-PXZ和BDFCN-Cz-DHPZ。基于密度泛函理论（DFT）和含时DFT（TD-DFT）对这些分子的光物理性质进行了系统分析。通过调节供体-受体强度，可以改变供体和受体之间通过空间与通过化学键的电荷转移（CT）比例，从而实现通过化学键的电荷转移（TBCT）和TSCT之间的切换。强供体和受体具有显著的驱动力，对分子内弱相互作用的分析表明BDFCN-Cz-DHPZ具有TSCT特性。值得注意的是，基于PXZ和基于DHPZ的分子表现出从三重激发态（T，n≥2）到单重激发态（S）的高位反向系间窜越（hRISC）过程，具有快速的反向系间窜越速率（k）值（约为10至10 s）和高荧光辐射速率（k）值（约为10 s）。因此，U形分子是高效HLCT分子的有前途的候选者。这种创新的设计策略为调节和优化TBCT-HLCT和TSCT-HLCT发光体的性能提供了新的思路和途径。
