We report a solvent-assisted increase in the emission of a cationic perylene diimide derivative, which is water-soluble in nature. Favorably, all the emission-assisting solvents used in all the experiments are water-miscible such as ethanol, tetrahydrofuran (THF), or dimethyl sulfoxide (DMSO). The preliminary assumption of associated fluorescent assembly of perylene stacks (via spectroscopic analysis) has been further explored with dynamic light scattering (DLS), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and time-correlated single photon counting (TCSPC) techniques. Spectroscopically observed drastic enhancement in the emission intensity seems to be born out of a major change in the assembly pattern of the interacting hydrophobic surfaces of perylene derivatives. These changes further have a macroscopic impact on the DLS or powder XRD outcomes. Furthermore, molecular dynamics simulations have been performed to interpret the nature of aggregation of perylene oligomers in water and in an ethanol/water binary mixture. The aggregation propensity (H-type dimer) of the dye molecules is found to decrease with increase in the ethanol concentration. It has been revealed that in water, the association of perylene-based oligomers is entropic in nature. In contrast, the association is driven via enthalpy in ethanol. Moreover, if we extend the oligomer size, the enthalpic stabilization for this unfamiliar supramolecular assembly of perylene moiety seems to be enhanced greatly. These results along with the calculated molar extinction coefficient of monomer and dimer provide the molecular rationale behind the observed solvent-assisted increase of emission intensity.

中文翻译：

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水中阳离子Per二酰亚胺超分子组装的溶剂辅助增强发射：从实验和仿真的角度

我们报告了在自然界中水溶性的阳离子per二酰亚胺衍生物的发射过程中溶剂辅助的增加。有利地，在所有实验中使用的所有发射辅助溶剂都是可与水混溶的，例如乙醇，四氢呋喃（THF）或二甲基亚砜（DMSO）。通过动态光散射（DLS），核磁共振（NMR），X射线衍射（XRD）和与时间相关的单光子计数（光谱学），进一步探索了ylene堆叠体相关荧光组装的初步假设（通过光谱分析）。 TCSPC）技术。光谱观察到的发射强度的急剧增强似乎是由于per衍生物相互作用的疏水表面的组装模式的重大变化而产生的。这些变化进一步对DLS或粉末XRD结果产生了宏观影响。此外，已经进行了分子动力学模拟以解释per低聚物在水中和在乙醇/水二元混合物中的聚集性质。发现染料分子的聚集倾向（H型二聚体）随着乙醇浓度的增加而降低。已经发现，在水中，per基低聚物的缔合本质上是熵的。相反，缔合是通过乙醇中的焓驱动的。而且，如果我们扩展低聚物的尺寸，这种陌生的per部分的超分子组装的焓稳定性似乎会大大增强。