Strongly Coupled Excitonic States in H-Aggregated Single Crystalline Nanoparticles of 2,5-Bis(4-methoxybenzylidene) Cyclopentanone

Abstract

This paper reports that extremely strongly coupled excitonic states were formed in H-aggregated monocrystalline nanosheets and semicrystalline nanowires of coplanar organic molecules of 2,5-bis(4-methoxybenzylidene) cyclopentanone, due to the highly regular face-to-face stacking of molecular excitons. It was demonstrated that the spectral absorption and fluorescence emission behaviors are dependent on the routes of molecular aggregation and the ordered degree of molecular arrangement in aggregated nanoparticles. In particular, the H-type aggregation of molecules through a highly ordered molecular arrangement in the monocrystalline nanosheets led to the formation of a new exciton coupling state with an energy band higher than that in normal semi-/noncrystalline H-aggregation. A strong symmetric absorption at higher energy bands was thus observed in the solution of nanosheets. Furthermore, the strongly coupled excitonic state may hold all the oscillator strength, leading to the extinction of the original intramolecular electronic transitions of individual molecules and the appearance of new strong absorption and fluorescence emissions at high-energy bands. These results show a perspective that the ability to control the molecular structure and its arrangement in aggregates holds promise for creating novel optical properties in molecular materials.

Self-Assembly of Hierarchical Microstructures and Their Ring Patterns in Evaporating Droplets

“…The changes in the absorption of self-assembled products are associated with the formation of parallel-oriented chromophores (H-aggregates) resulting from the strong p-stacking interactions in the self-assembled products. [18,31] In addition, the H-aggregate formation in the selfassembled products also results in the enhanced B p-p à bands at longer wavenumber. [31] The self-assembled morphology has also an obvious effect on the UV absorption spectra of the products.…”

“…[18,31] In addition, the H-aggregate formation in the selfassembled products also results in the enhanced B p-p à bands at longer wavenumber. [31] The self-assembled morphology has also an obvious effect on the UV absorption spectra of the products. The hierarchical microstructures composed ring patterns exhibits a larger blue-shift at lower wavenumber compared to that of branching dendrites, which is due to more regular H-structure in the urchin-like microspheres.…”

Спектральные Свойства Индотрикарбоцианинового Красителя В Процессе Самоорганизации Его H-=sup=-*-=/Sup=-- И J-Агрегатов

“…H-агрегаты характеризуются полосой поглощения, которая гипсохромно смещена относительно максимума мономеров [15,56]. В большинстве случаев агрегаты этого типа не обладают флуоресценцией [15,56], хотя существуют и исключения [57][58][59]. Как правило, H-полоса в поглощении по своей полуширине примерно такая же, как полоса мономеров [15,32,48].…”

Tuning the Surface Electrochemistry by Strained Epitaxial Pt Thin Film Model Electrodes Prepared by Pulsed Laser Deposition

“…In recent years it has been demonstrated that strain on metal surfaces can have a significant impact on the adsorbate's binding energies and on the activation energy barrier for adsorption processes . In this regard, core–shell nanoparticles (NPs), where an outer monolayer (ML) of Pt is supported on another metal or on Pt‐alloy NPs have been designed. The strain in these systems is generated due to the difference in lattice constant between the outer ML and the core of the NP.…”