Intersystem Crossing and Intramolecular Triplet Excitation Energy Transfer in Spiro[9,10-dihydro-9-oxoanthracene-10,2´- 5´,6´-benzindan] Investigated by DFT/MRCI Methods
S. Metz, Tobias Böhmer, Ben Raunitschke, C. Marian
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引用次数: 0
Abstract
Recent experimental studies of a spiro-linked anthracenone (A)–naphthalene (N) compound (AN) in butyronitrile solution [Dobkowski et al., J. Phys. Chem. A 2019, 123, 6978] proposed an excited-state energy dissipation pathway {1ππ*(N)+1ππ*(A)}→1nπ*(A)→3nπ*(A)→3ππ*(N). However, a detailed theoretical study employing combined density functional theory and multireference configuration interaction methods, performed in the present work, suggests that the photoexcitation decay follows a different pathway. In butyronitrile solution, the intersystem crossing (ISC) follows the well-established El-Sayed rule and involves the 3ππ*(A) state which is found to be the lowest excited triplet state localized on the anthracenone moiety. Because the Dexter triplet excitation energy transfer (TEET) to the first excited triplet state of the naphthalene subunit is forbidden in C2v symmetry, it is mandatory to go beyond the Condon approximation in modeling this process. Non-adiabatic coupling matrix elementswere computed to obtain a TEET rate different from zero. Our calculations yield time constants of 5 ps for the 1nπ*(A)→3ππ*(A) ISC and of 3 ps for the subsequent 3ππ*(A)→3ππ*(N) TEET in butyronitrile whereas the energy dissipation involving the 3nπ*(A) state as an intermediate occurs on a much longer time scale.
一种螺链蒽酮(a) -萘(N)化合物(AN)在丁腈溶液中的实验研究[Dobkowski et al., J. Phys。化学。A[2019,123, 6978]提出了一个激发态能量耗散路径{1ππ*(N)+1ππ*(A)}→1nπ*(A)→3nπ*(A)→3ππ*(N)。然而,采用密度泛函理论和多参考配置相互作用方法进行的详细理论研究表明,光激发衰变遵循不同的途径。在丁腈溶液中,系统间交叉(ISC)遵循公认的El-Sayed规则,涉及3ππ*(A)态,这是定位于蒽酮部分的最低激发态。由于在C2v对称中禁止Dexter三重态激发能转移(TEET)到萘亚基的第一激发态,因此在模拟这一过程时必须超越Condon近似。计算了非绝热耦合矩阵单元,得到了不同于零的TEET速率。我们的计算得到了丁腈中1nπ*(A)→3ππ*(A) ISC和随后的3ππ*(A)→3ππ*(N) TEET的时间常数为5 ps,而3nπ*(A)作为中间态的能量耗散发生在更长的时间尺度上。
期刊介绍:
Published since 1929, the Canadian Journal of Chemistry reports current research findings in all branches of chemistry. It includes the traditional areas of analytical, inorganic, organic, and physical-theoretical chemistry and newer interdisciplinary areas such as materials science, spectroscopy, chemical physics, and biological, medicinal and environmental chemistry. Articles describing original research are welcomed.