Woon Kai Lin, Mustapa Siti Aisyah Syaerah, Mohd Jamel Nor Shafiq, Lee Vannajan Sanghiran, Zakaria Muhammad Zhafran, Ariffin Azhar
Low Dimensional Material Research Centre, Department of Physics, University Malaya, Kuala Lumpur, Malaysia.
Department of Chemistry, Faculty of Science, University Malaya, Kuala Lumpur, Malaysia.
Chemphyschem. 2020 Nov 17;21(22):2620-2626. doi: 10.1002/cphc.202000612. Epub 2020 Oct 30.
Material designs that use donor and acceptor units are often found in organic optoelectronic devices. Molecular level insight into the interactions between donors and acceptors are crucial for understanding how such interactions can modify the optical properties of the organic optoelectronic materials. In this paper, tris(4-(tert-butyl)phenyl)amine (pTPA) was synthesized as a donor in order to compare with unmodified triphenylamine (TPA) in a donor-acceptor system by having 2,4,6-triphenyl-1,3,5-triazine (TRZ) as an acceptor. Dimerization of donors and acceptors occurred in solvent when the concentration of solute is high. At 0 K, using a polarizable continuum model, the nitrogen atom of TPA is found to stack on top of the center of triazine of TRZ, whereas such alignment is offset in pTPA and TRZ. We attributed such alignment in TPA-TRZ as the result of attractive interactions between partial localization of 2p electrons at the nitrogen atom of TPA and the π deficiency of triazine in TPA-TRZ. By taking into account random motions of the solvent effect at 300 K in quantum molecular dynamics and classical molecular dynamics simulations to interpret the marked difference in emission spectra between TPA-TRZ and pTPA-TRZ, it was revealed that the attractive interaction between pTPA and TRZ in toluene is weaker than TPA and TRZ. Because of the weaker attractive interaction between pTPA and TRZ in toluene, the dimers adopted numerous ground state conformations resulting in broad emission bands superimposed with multiple small Gaussian peaks. This is in contrast to TPA-TRZ which has only one dominant dimer conformation. This study demonstrates that the strength of intermolecular interactions between donors and acceptors should be taken into consideration in designing supramolecular structures.
在有机光电器件中，经常会用到包含供体和受体单元的材料设计。从分子层面深入了解供体与受体之间的相互作用，对于理解这种相互作用如何改变有机光电子材料的光学性质至关重要。在本文中，合成了三（4-叔丁基苯基）胺（pTPA）作为供体，以便在供体-受体体系中与未修饰的三苯胺（TPA）进行比较，其中以2,4,6-三苯基-1,3,5-三嗪（TRZ）作为受体。当溶质浓度较高时，供体和受体在溶剂中会发生二聚化。在0 K时，使用极化连续介质模型发现，TPA的氮原子堆叠在TRZ三嗪中心的上方，而在pTPA和TRZ中这种排列是偏移的。我们将TPA-TRZ中的这种排列归因于TPA氮原子处2p电子的部分局域化与TPA-TRZ中三嗪的π缺电子之间的吸引相互作用。通过在量子分子动力学和经典分子动力学模拟中考虑300 K时溶剂效应的随机运动，以解释TPA-TRZ和pTPA-TRZ发射光谱的显著差异，结果表明甲苯中pTPA与TRZ之间的吸引相互作用比TPA与TRZ之间的弱。由于甲苯中pTPA与TRZ之间的吸引相互作用较弱，二聚体采用了多种基态构象，导致发射带变宽并叠加有多个小高斯峰。这与TPA-TRZ形成对比，TPA-TRZ只有一种主要的二聚体构象。这项研究表明，在设计超分子结构时应考虑供体与受体之间分子间相互作用的强度。
