Yamaguchi Kaho, Yamawaki Kazuma, Kimura Takuya, Kuwabara Junpei, Yasuda Takeshi, Nishimura Yoshinobu, Kanbara Takaki
Tsukuba Research Center for Energy Materials Science (TREMS), Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan.
Research Center for Functional Materials, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
Dalton Trans. 2018 Mar 28;47(12):4087-4092. doi: 10.1039/c8dt00314a. Epub 2018 Feb 16.
The cationic Pt complexes with amide groups have been found to show dimer emission through hydrogen bonding interactions with counter anions even at low concentration. In order to investigate further details of dimer emission, we prepared three Pt complexes, Pt·B(CF), Pt·Cl, and Pt·PF, whose counter anions possess different strengths of a hydrogen bonding acceptor. Hydrogen bonding interactions in the ground state and excited-state dynamics of the Pt complexes were evaluated by NMR analysis, temperature dependence, and kinetics of dimer emission. These studies revealed that the hydrogen bonding interaction in the ground state is essential for dimer emission, but too strong hydrogen bonding prevents dimer emission due to the inhibition of a stacked dimer formation in the excited state. Owing to this trade-off, the Pt complex with a moderate hydrogen bonding acceptor, PF, most effectively shows dimer emission. In general, a strong supramolecular interaction efficiently provides a desired assembled structure showing multi-molecular emission. We revealed a unique phenomenon that a moderate interaction is beneficial to effective multi-molecular emission.
已发现带有酰胺基团的阳离子铂配合物即使在低浓度下也能通过与抗衡阴离子的氢键相互作用表现出二聚体发射。为了进一步研究二聚体发射的细节，我们制备了三种铂配合物，Pt·B(CF)、Pt·Cl和Pt·PF，其抗衡阴离子具有不同强度的氢键受体。通过核磁共振分析、温度依赖性和二聚体发射动力学评估了铂配合物基态和激发态动力学中的氢键相互作用。这些研究表明，基态中的氢键相互作用对于二聚体发射至关重要，但过强的氢键会由于抑制激发态中堆叠二聚体的形成而阻止二聚体发射。由于这种权衡，具有适度氢键受体PF的铂配合物最有效地表现出二聚体发射。一般来说，强超分子相互作用有效地提供了显示多分子发射的所需组装结构。我们揭示了一种独特的现象，即适度的相互作用有利于有效的多分子发射。
