Garain Swadhin, Wagalgave Sopan M, Kongasseri Anju Ajayan, Garain Bidhan Chandra, Ansari Shagufi Naz, Sardar Gopa, Kabra Dinesh, Pati Swapan K, George Subi J
New Chemistry Unit and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India.
Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India.
J Am Chem Soc. 2022 Jun 22;144(24):10854-10861. doi: 10.1021/jacs.2c02678. Epub 2022 Jun 9.
The burgeoning noncovalent interactions between π-acidic aromatic surfaces and anions have been recently shown to have unique functional relevance in anion transport, ion sensing, and organocatalysis. Despite its potential to instigate charge-transfer (CT) states, modulation of the emission features by toggling between the excited states using anion-π interactions is not yet explored. On the other hand, excited states with CT characteristics play an important role in the ambient triplet harvesting of organic chromophores. In this context, herein we propose an anion-π-based molecular design for the introduction of emissive singlet and triplet CT excited states, thereby expanding the functional scope of these weak supramolecular interactions. In the present study, we investigate the anion-π-induced emission from the singlet (CT) and triplet (CT) CT states of a dibromo dicationic pyromellitic diimide derivative. Remarkably, we accomplish dual room temperature phosphorescence emission from the anion-π-mediated CT state along with the locally excited triplet state (LE) in solution phase using an organic-inorganic supramolecular scaffolding strategy. Comprehensive steady-state and time-resolved spectroscopy along with theoretical calculations provide detailed insights into the excited-state manifolds of phosphor. We envisage that the present study will expedite new molecular designs based on weak intermolecular interactions for the excited-state engineering of organic chromophores to facilitate ambient triplet harvesting and CT emission.
最近研究表明，π-酸性芳香表面与阴离子之间迅速发展的非共价相互作用在阴离子传输、离子传感和有机催化方面具有独特的功能相关性。尽管其有可能引发电荷转移（CT）态，但尚未探索通过利用阴离子-π相互作用在激发态之间切换来调节发射特性。另一方面，具有CT特征的激发态在有机发色团的环境三线态捕获中起着重要作用。在此背景下，我们在此提出一种基于阴离子-π的分子设计，用于引入发射性单重态和三重态CT激发态，从而扩大这些弱超分子相互作用的功能范围。在本研究中，我们研究了二溴二价均苯四甲酸二酰亚胺衍生物的单重态（CT）和三重态（CT）CT态的阴离子-π诱导发射。值得注意的是，我们使用有机-无机超分子支架策略在溶液相中实现了从阴离子-π介导的CT态以及局部激发三重态（LE）的双室温磷光发射。综合稳态和时间分辨光谱以及理论计算为磷光体的激发态流形提供了详细的见解。我们设想，本研究将加快基于弱分子间相互作用的新分子设计，用于有机发色团的激发态工程，以促进环境三线态捕获和CT发射。
