Zhu Huaning, Li Yang, Chen Jun, Zhou Meng, Niu Yingli, Zhang Xinxing, Guo Qianjin, Wang Shuangqing, Yang Guoqiang, Xia Andong
Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China.
Chemphyschem. 2015 Dec 21;16(18):3893-901. doi: 10.1002/cphc.201500738. Epub 2015 Oct 23.
The excited-state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis- and trisphthalocyanines) are studied by using steady-state and femtosecond transient absorption spectral measurements, where the excited-state energy-transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis-Pc). In trisphthalocyanine (tris-Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre-associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady-state spectra also show a face-to-face conformation in bis-Pc, whereas in tris-Pc, two of the three phthalocyanine branches form a pre-associated face-to-face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure-property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems.
通过稳态和飞秒瞬态吸收光谱测量，研究了两种酞菁化合物（双酞菁和三酞菁）中的激发态弛豫动力学和发色团相互作用，其中探索了激发态能量转移机制。通过将酞菁化合物激发到其第二电子激发态并探测随后的弛豫动力学，确定了多种失活途径。瞬态吸收光谱显示了双酞菁（bis-Pc）中从激子态到准分子态然后回到基态的弛豫途径。在三酞菁（tris-Pc）中，单体和二聚体亚基被激发，激发能从单体振动热S1态转移到预缔合二聚体的激子态，随后通过准分子态弛豫到基态。理论计算和稳态光谱也显示了bis-Pc中的面对面构象，而在tris-Pc中，三个酞菁分支中的两个形成了预缔合的面对面二聚体构象，第三个作为单体单元；从分子结构的角度来看，这与瞬态吸收实验的结果一致。酞菁化合物中详细的结构-性质关系对于探索分子聚集体在天然光合作用系统能量迁移中的功能很有用。
