Miyashita Tsumugi, He Sheng, Jaimes Paulina, Kaledin Alexey L, Fumanal Maria, Lian Tianquan, Lee Tang Ming
Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah 84112, USA.
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
J Chem Phys. 2024 Sep 7;161(9). doi: 10.1063/5.0223478.
Polyyne bridges have attracted extensive interest as molecular wires due to their shallow distance dependence during charge transfer. Here, we investigate whether triplet energy transfer from cadmium selenide (CdSe) quantum dots (QDs) to anthracene acceptors benefits from the high conductance associated with polyyne bridges, especially from the potential cumulene character in their excited states. Introducing π-electron rich oligoyne bridges between the surface-bound anthracene-based transmitter ligands, we explore the triplet energy transfer rate between the CdSe QDs and anthracene core. Our femtosecond transient absorption results reveal that a rate constant damping coefficient of β is 0.118 ± 0.011 Å-1, attributed to a through-bond coupling mechanism facilitated by conjugation among the anthracene core, the oligoyne bridges, and the COO⊖ anchoring group. In addition, oligoyne bridges lower the T1 energy level of the anthracene-based transmitters, enabling efficient triplet energy transfer from trapped excitons in CdSe QDs. Density-functional theory calculations suggest a slight cumulene character in these oligoyne bridges during triplet energy transfer, with diminished bond length alternation. This work demonstrates the potential of oligoyne bridges in mediating long-distance energy transfer.
由于聚炔桥在电荷转移过程中对距离的依赖性较弱，因此作为分子导线受到了广泛关注。在此，我们研究了从硒化镉（CdSe）量子点（QDs）到蒽受体的三线态能量转移是否受益于与聚炔桥相关的高电导率，特别是其激发态中潜在的累积烯特性。通过在表面结合的基于蒽的发射体配体之间引入富含π电子的低聚炔桥，我们探索了CdSe量子点与蒽核之间的三线态能量转移速率。我们的飞秒瞬态吸收结果表明，速率常数阻尼系数β为0.118±0.011 Å-1，这归因于蒽核、低聚炔桥和COO⊖锚定基团之间共轭促进的键间耦合机制。此外，低聚炔桥降低了基于蒽的发射体的T1能级，使得能够从CdSe量子点中捕获的激子进行有效的三线态能量转移。密度泛函理论计算表明，在三线态能量转移过程中，这些低聚炔桥具有轻微的累积烯特性，键长交替减小。这项工作证明了低聚炔桥在介导长距离能量转移方面的潜力。
