Sarkar Abani, Behera Kanhu Charan, Ravikanth Mangalampalli
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Dalton Trans. 2024 Jul 9;53(27):11543-11555. doi: 10.1039/d4dt01356e.
Two novel covalently linked triads containing one 3-pyrrolyl BODIPY unit and two BODIPY units were synthesized over a sequence of steps using -(-formylphenyl)-3-pyrrolyl BODIPY as a key precursor. Both triads were thoroughly characterized and studied by using HRMS, 1D and 2D NMR spectroscopy, X-ray crystallography, absorption, steady-state and time-resolved fluorescence, cyclic voltammetry, and DFT/TD-DFT techniques. X-ray structural analysis of these triads revealed that the dipyrrin units of both -BODIPY and 3-pyrrolyl BODIPY were oriented in the same plane whereas the dipyrrin unit of the α-BODIPY unit was oriented almost perpendicular to that of the 3-pyrrolyl BODIPY unit. Both triads showed two well-separated absorption bands corresponding to BODIPY and 3-pyrrolyl BODIPY units in the 510-675 nm region. In these triads, the BODIPY unit absorbs in the higher energy region and acts as an energy donor whereas the 3-pyrrolyl BODIPY unit absorbs in the lower energy region and acts as an energy acceptor. Steady-state and time-resolved fluorescence studies of these triads indicated the possibility of intramolecular singlet-singlet energy transfer with almost 98% efficiency from the BODIPY units to the 3-pyrrolyl BODIPY unit upon selective excitation of the BODIPY unit in both triads. DFT and TD-DFT investigations corroborated the experimental findings.
以 -(-甲酰基苯基)-3-吡咯基BODIPY为关键前体，通过一系列步骤合成了两种新型的共价连接三联体，其中包含一个3-吡咯基BODIPY单元和两个BODIPY单元。使用高分辨质谱（HRMS）、一维和二维核磁共振光谱、X射线晶体学、吸收光谱、稳态和时间分辨荧光光谱、循环伏安法以及密度泛函理论/含时密度泛函理论（DFT/TD-DFT）技术对这两种三联体进行了全面表征和研究。这些三联体的X射线结构分析表明，-BODIPY和3-吡咯基BODIPY的二吡咯单元位于同一平面，而α-BODIPY单元的二吡咯单元几乎垂直于3-吡咯基BODIPY单元的二吡咯单元。两种三联体在510 - 675 nm区域均显示出对应于BODIPY和3-吡咯基BODIPY单元的两个明显分开的吸收带。在这些三联体中，BODIPY单元在较高能量区域吸收并作为能量供体，而3-吡咯基BODIPY单元在较低能量区域吸收并作为能量受体。对这些三联体的稳态和时间分辨荧光研究表明，在选择性激发两种三联体中的BODIPY单元时，分子内单重态-单重态能量转移的可能性很高，效率几乎达到98%，从BODIPY单元转移到3-吡咯基BODIPY单元。DFT和TD-DFT研究证实了实验结果。
