In this study, the optical properties and excited-state dynamics of the unique self-assembled donor-acceptor (DA) merocyanine dye stacks from dimer up to octamer, prepared via dipole-dipole interactions, are reported in terms of coherent exciton dynamics and formation of an excimer-like state. Our findings are based on the steady-state absorption/emission, time-resolved fluorescence, and transient absorption (anisotropy) measurements, including wavepacket analysis and quantum mechanical calculations. Coherent exciton of torsional motions-restricted dye stacks rapidly localizes into the weakly emissive excimer-like state, by shortening the inter-moiety distance and changing the bond-length alternation pattern. The inner merocyanine moiety, having two neighboring units, has a reversed resonance character (non-polar (N) < zwitterionic (Z)) compared with the outer moiety (N > Z) in the ground state. This difference has led to two conclusions: (1) tetramers and octamers exhibit different features of excimer-like state than the dimer, and (2) octamers exhibit slower localization dynamics due to the enhanced homogeneity (six inner-moieties) compared with tetramers (two inner moieties).

在这项研究中，通过相干激子动力学和形成，报道了通过偶极-偶极相互作用制备的独特的自组装供体-受体（DA）的花色素从二聚物到八聚物的光学性质和激发态动力学。准分子状的状态。我们的发现基于稳态吸收/发射，时间分辨荧光和瞬态吸收（各向异性）测量，包括波包分析和量子力学计算。通过缩短分子间距离并改变键长交替模式，受扭转运动限制的染料堆栈的相干激子迅速定位为弱发射态的准分子状态。具有两个相邻单元的内部花青素部分具有相反的共振特性（非极性（N）< 两性离子（Z）与基态的外部部分（N> Z）进行比较。这种差异导致了两个结论：（1）四聚体和八聚体与二聚体相比表现出与准分子类似的状态特征；（2）与四聚体相比，八聚体由于均一性增强（六个内部部分）而显示出较慢的定位动力学。两个内部部分）。