Selective Crystallization via Vibrational Strong Coupling

Abstract

The coupling of (photo)chemical processes to optical cavity vacuum fields is an emerging method for modulating molecular and material properties. Recent reports have shown that strong coupling of the vibrational modes of solvents to cavity vacuum fields can influence the chemical reaction kinetics of dissolved solutes. This suggests that vibrational strong coupling might also effect other important solution-based processes, such as crystallization from solution. Here we test this hither-to unexplored notion, investigating pseudopolymorphism in the crystallization from water of ZIF metal-organic frameworks inside optical microcavities. We find that ZIF-8 crystals are selectively obtained from solution inside optical microcavities, where the OH stretching vibration of water is strongly coupled to cavity vacuum fields, whereas mixtures of ZIF-8 and ZIF-L are obtained otherwise. This work suggests that cavity vacuum fields might become a tool for materials synthesis, biasing molecular self-assembly and driving macroscopic material outcomes.

Supramolecular Assembly of Conjugated Polymers under Vibrational Strong Coupling

“…Recently Hirai et al reported that VSC of the solvent could drive selective crystallization of metal-organic frameworks (MOFs), suggesting that VSC can alter molecular organization. [20] Here we demonstrate that VSC modifies supramolecular assembly and its dynamics. We study the gelation of rigid-rod conjugated polymers under strong coupling.…”

“…In the last several years, it has been shown that coupling vibrational modes in this way has a pronounced effect on chemistry and molecular properties. [3,[5][6][7][8][9][10][11][12][13][14][15][16][17]20] In this vibrational strong coupling regime (VSC), vibro-polaritonic states (VP + , VPÀ) are formed, separated by the so-called Rabi splitting energy (" h W R ) (Figure 1 a). In typical experiments, a large number N of molecules are coupled by VSC to a single optical mode which leads to the formation of N-1 dark states (DS) which are, together with VP + and VPÀ, delocalized over many molecules.…”

Mode-Specific Chemistry through Vibrational Strong Coupling (or A Wish Come True)

“…The potential of cavity modified physical and chemical properties is extraordinary. The most exciting results in this field are the reports of VSC-modified chemistry in the dark, first published by Ebbesen and co-workers and later established by several of those authors in new roles as independent investigators, , as well as by other unaffiliated researchers. , The methodologies these papers present appear to be robust. They include appropriate controls, repeated measurements, and reasonable attempts to rationalize the observations.…”

“…These challenges call attention to the advantages of nonoptical interrogation. We will highlight the use of electrochemical cycling, , mass spectrometry, nuclear magnetic resonance, and phase change processes as alternative means for monitoring cavity chemistry. One critical concern for these physical measurements, however, is the correlation between the locality of the measurement and the cavity resonance at that location.…”

Resonant Cavity Modification of Ground State Chemical Kinetics

“…Vibrational polaritons [1][2][3], quasi-particles formed by coupling molecular vibrations and radiation modes in an optical cavity, exhibit a wide range of exotic phenomena. A series of recent experiments [1][2][3][4][5][6][7][8] have demonstrated that chemical kinetics can be enhanced [4,6,8] or suppressed [1,5], molecular bonds can be selectively broken [2], and selective crystallization can be achieved [9] via the formation of vibrational polaritons. On the other hand, several studies [10,11] have also reported possible discrepancies or inconsistencies in the interpretation of experiment purporting sizable kinetic effects.…”