Supramolecular Assembly of Conjugated Polymers under Vibrational Strong Coupling

Abstract

Strong coupling plays a significant role in influencing chemical reactions and tuning material properties by modifying the energy landscapes of the systems. Here we study the effect of vibrational strong coupling (VSC) on supramolecular organization. For this purpose, a rigid-rod conjugated polymer known to form gels was strongly coupled together with its solvent in a microfluidic IR Fabry-Perot cavity. Absorption and fluorescence studies indicate a large modification of the self-assembly under such cooperative VSC. Electron microscopy confirms that in this case, the supramolecular morphology is totally different from that observed in the absence of strong coupling. In addition, the self-assembly kinetics are altered and depend on the solvent vibration under VSC. The results are compared to kinetic isotope effects on the self-assembly to help clarify the role of different parameters under strong coupling. These findings indicate that VSC is a valuable new tool for controlling supramolecular assemblies with broad implications for the molecular and material sciences.

Vibrational Coupling of Water from Weak to Ultrastrong Coupling Regime via Cavity Mode Tuning

“…Those cavity mode modification can induce the chemical bonding state, spatial anisotropy, and chemical reactivity of molecules. The control of cavity modes leads to the ground-state modification of chemical reactivity, self-assembly of molecules, , and ionic conductivity or even proton coupled electron transfer reaction via coherent interaction . This study specifically posed the importance of the cavity modes for the modification of chemical bonding of water molecules via vibrational strong coupling, which can be used as a principle for designing ground-state chemistry.…”

“…11−16 This concept can also be applied to the vibrational states of molecules; placing molecules in a microscale cavity induces the vibro-polaritonic states, 17−27 which leads to modification of the ground-state thermochemical reactivity via vacuum vibrational coupling. 28−39 This vacuum vibrational strong coupling is also used to modify Raman scattering, 40,41 vibro-polaritonic infrared (IR) emissions, 42 the self-assembly of molecules, 43,44 ferromagnetism, 45 and even the superconductivity of materials. 46 Recently, we also investigated the use of vacuum vibrational coupling to modify the proton conductivity of aqueous electrolyte solutions.…”

“…In contrast, in the case of the strong coupling regime, the photon can mediate hybridization of the electromagnetic field to achieve energy splitting of polaritonic states. ,, As a result, observed Rabi splitting frequency is larger value than sum of photon loss rate and dephasing rate. Recently, polaritonic states have been used to transform ground-state molecular properties via formation of a vacuum strong coupling state. − This concept can also be applied to the vibrational states of molecules; placing molecules in a microscale cavity induces the vibro-polaritonic states, − which leads to modification of the ground-state thermochemical reactivity via vacuum vibrational coupling. − This vacuum vibrational strong coupling is also used to modify Raman scattering, , vibro-polaritonic infrared (IR) emissions, the self-assembly of molecules, , ferromagnetism, and even the superconductivity of materials . Recently, we also investigated the use of vacuum vibrational coupling to modify the proton conductivity of aqueous electrolyte solutions .…”

Chemistry under Vibrational Strong Coupling

“…116 There is normally sufficient material even in a microcavity to measure the NMR 85 or mass 63 spectrum of the products. In the cases of supramolecular assembly 100 and crystallization 90 under strong coupling, microscope images can be used to monitor the changes in the morphology and crystal structure, respectively. It is important to follow such an analysis in the tuned area of the cavity to see the changes under strong coupling.…”

“…49,61−63,76,77,85−88 The possibility of coupling the reactants indirectly through their overlap with the vibrational modes of surrounding molecules (such as the matrix or the solvent), the so-called cooperative strong coupling, opens up new possibilities to modify material properties when direct c o u p l i n g i s n o t p o s s i b l e, a s e x p l a i n e d f u r t h e r down. 62,65,72,88,96,100 Many theoretical groups are working in this field to understand why VSC leads to such large changes in experimental observations, and not surprisingly, symmetry is a fundamental factor. This Perspective introduces fundamental concepts before highlighting the recent advancements of VSC to alter the chemical reactivity and molecular processes.…”