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Exciton Isolation in Cross Pentacene Architecture
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-09-02 , DOI: 10.1021/jacs.0c06016
M P Lijina 1 , Alfy Benny 1 , Remya Ramakrishnan 1 , Nanditha G Nair 1 , Mahesh Hariharan 1
Affiliation  

Null aggregates are elusive, emergent class of molecular assembly categorized as spectroscopically uncoupled molecules. Orthogonally stacked chromophoric arrays are considered as a highlighted architecture for null aggregates. Herein, we unveil the null exciton character in a series of crystalline Greek cross (+) assembly of 6,13-bisaryl substituted pentacene derivatives. Quantum chemical computations suggest that synergistic perpendicular orientation and significant inter-chromophoric separations realize, negligible long-range Coulombic and short-range charge transfer mediated couplings in the null aggregate. The Greek cross (+) orientation of pentacene dimers exhibit a selectively higher electron transfer coupling with near-zero hole transfer coupling and thereby contribute to the lowering of charge transfer mediated coupling even at shorter inter-chromophoric distances. Additional investigations on the nature of excitonic states of pentacene dimers proved that any deviation from 90° cross-stacked orientation results in the emergence of delocalized Frenkel/mixed Frenkel-CT character and the consequent loss of null exciton/monomer-like properties. The retention of exciton isolation even at short range coupling regime reassures the universality of null excitonic character in perpendicularly cross-stacked pentacene systems. The null-excitonic character was experimentally verified by the observation of similar spectral characteristics in the crystalline and monomeric solution state for 6,13-bisaryl substituted pentacene derivatives. Partitioned influence of aryl and pentacene fragments on interchromophoric noncovalent interactions and photophysical properties respectively resulted in the emergence of pentacene centric Kasha's ideal null exciton, providing novel in-sights towards the design strategies for cross-stacked chromophoric assemblies. Identifying Greek cross-stacked architecture mediated null excitons with charge filtering phenomenon for the first time in the ever-versatile pentacene chromophoric systems can offer an extensive ground for the engineering of functional materials with advanced optoelectronic properties.

中文翻译:

交叉并五苯结构中的激子隔离

空聚集体是难以捉摸的、新兴的分子组装类,被归类为光谱非耦合分子。正交堆叠的发色团阵列被认为是无效聚合的突出架构。在此,我们揭示了 6,13-​​双芳基取代并五苯衍生物的一系列结晶希腊十字 (+) 组装中的零激子特征。量子化学计算表明协同垂直取向和显着的发色团间分离实现了可忽略的长程库仑和短程电荷转移介导的空聚集体中的耦合。并五苯二聚体的希腊十字 (+) 取向表现出选择性更高的电子转移耦合和接近零的空穴转移耦合,从而有助于降低电荷转移介导的耦合,即使在较短的发色团间距离下也是如此。对并五苯二聚体激子态性质的其他研究证明,任何偏离 90° 交叉堆叠方向的偏差都会导致离域 Frenkel/混合 Frenkel-CT 特征的出现,以及随之而来的空激子/单体样特性的丧失。即使在短程耦合状态下激子隔离的保留也保证了垂直交叉堆叠并五苯系统中零激子特性的普遍性。通过观察 6,13-​​双芳基取代并五苯衍生物在结晶和单体溶液状态下的类似光谱特征,实验验证了零激子特性。芳基和并五苯片段分别对发色团间非共价相互作用和光物理性质的影响导致并五苯中心 Kasha 理想零激子的出现,为交叉堆叠发色团组件的设计策略提供了新的见解。在用途广泛的并五苯发色系统中首次识别具有电荷过滤现象的希腊交叉堆叠结构介导的零激子可以为具有先进光电特性的功能材料的工程提供广泛的基础。13-双芳基取代的并五苯衍生物。芳基和并五苯片段分别对发色团间非共价相互作用和光物理性质的影响导致并五苯中心 Kasha 理想零激子的出现,为交叉堆叠发色团组件的设计策略提供了新的见解。在用途广泛的并五苯发色系统中首次识别具有电荷过滤现象的希腊交叉堆叠结构介导的零激子可以为具有先进光电特性的功能材料的工程提供广泛的基础。13-双芳基取代的并五苯衍生物。芳基和并五苯片段分别对发色团间非共价相互作用和光物理性质的影响导致并五苯中心 Kasha 理想零激子的出现,为交叉堆叠发色团组件的设计策略提供了新的见解。在用途广泛的并五苯发色系统中首次识别具有电荷过滤现象的希腊交叉堆叠结构介导的零激子可以为具有先进光电特性的功能材料的工程提供广泛的基础。芳基和并五苯片段分别对发色团间非共价相互作用和光物理性质的影响导致并五苯中心 Kasha 理想零激子的出现,为交叉堆叠发色团组件的设计策略提供了新的见解。在用途广泛的并五苯发色系统中首次识别具有电荷过滤现象的希腊交叉堆叠结构介导的零激子可以为具有先进光电特性的功能材料的工程提供广泛的基础。芳基和并五苯片段分别对发色团间非共价相互作用和光物理性质的影响导致并五苯中心 Kasha 理想零激子的出现,为交叉堆叠发色团组件的设计策略提供了新的见解。在用途广泛的并五苯发色系统中首次识别具有电荷过滤现象的希腊交叉堆叠结构介导的零激子可以为具有先进光电特性的功能材料的工程提供广泛的基础。
更新日期:2020-09-02
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