Manipulating the Self-Assembly of Phenyleneethynylenes under Vibrational Strong Coupling

Abstract

The chemical and physical properties of molecules and materials are known to be modified significantly under vibrational strong coupling (VSC). In order to gain insight into the effects of VSC on − interactions involved in molecular self-assembly, themselves sensitive to vacuum electromagnetic field fluctuations, the aggregation of two structural isomers (linear and V-shaped) of phenyleneethynylene under cooperative coupling was investigated. By coupling the aromatic C=C stretching band, the assembly of one of the molecules results in the formation of spheres as opposed to flakes under normal conditions. As a consequence, the electronic absorption and emission spectra of the self-assembled structures are also modified significantly. The VSC induced changes depend not only on the type of vibration that is coupled but also on the symmetry of the phenyleneethynylene isomer. These results confirm that VSC can be used to drive molecular assemblies to new structural minima and thereby provide a new tool for supramolecular chemistry.

Influence of Vibrational Strong Coupling on an Ordered Liquid Crystal

“…Modulations in intermolecular interactions, ground state potential landscape, and other molecular parameters inside the resonant cavity are the driving force for polariton chemistry. 56−58 Other than reaction rate modification, direct manifestation of such cavity effects has recently been reported by several groups, including altered self-assembly structures of conjugated polymers 59,60 and modified ion conductivity under vibrational strong coupling. 61 It is beyond the scope of this paper to discuss quantitatively the origin of modified orientational factors inside the cavity.…”

Solvent Dependence on Cooperative Vibrational Strong Coupling and Cavity Catalysis**

“…reported that the cooperative VSC of the solvent could also decelerate a chemical reaction by coupling the solvent vibrational band [37] . Cooperative VSC has also been shown to be efficient in modifying super‐conductivity, ferromagnetism, supramolecular assembly, selective crystallization processes, etc [38–42] …”

Solvent Polarity under Vibrational Strong Coupling

“…Under these conditions, a system is said to enter the vibrational strong coupling (VSC) regime, ,, which leads to the formation of two vibro-polaritonic bands (P+ and P−) and dark states (DS) as shown in Figure A. This exotic interaction is mediated by EM fluctuations and therefore occurs even in the dark. , Over the past decade, it has been shown that VSC modifies a variety of chemical properties, such as reaction kinetics, − chemo- and stereoselectivity, ionic conductivity, the rate of vibrational energy transfer, − selective crystallization, or self-assembly. , The detailed mechanism at work is, however, still elusive, and more experimental results and theoretical analysis are needed.…”

“…In a microscopic perspective of solvation (microsolvation), local interactions such as hydrogen bonding or dispersion interactions can also potentially be modified under strong coupling. Accordingly, solvation-sensitive systems, such as self-assembly, , enzyme-catalyzed reactions, , and proton transfers, , have been shown or predicted to be impacted by VSC.…”

“…Inspired by recent reports on the effect of solvent coupling, ,,, we set out to study solvent properties under VSC by using Reichardt’s dye (RD), which is a solvent polarity probe. , RD exhibits an exceptionally strong negative solvatochromism, which allows one to detect subtle differences in polarity and solvent properties. − To measure the change in polarity, we used the E T (30) polarity parameter, which is defined as the molar electronic transition energy of RD E normalT ( 30 ) = 0.25em h c N normalA λ max where h , c , and N A are Planck’s constant, the speed of light, and Avogadro’s constant, respectively. λ max is the absorption maximum of the polarity-sensitive intramolecular charge transfer (CT) band.…”