Direct Optical Mapping of Hydrogen Bond Energies and the Emergence of a Nanourea-Stabilized Glassy Crystal Phase

Abstract

The ubiquitous hydrogen bond, a cornerstone of supramolecular chemistry, underpins diverse processes from catalysis mechanisms to rational artificial photosynthesis. The imperative optical determination of hydrogen bond strength during phase transition represents a critical frontier in contemporary scientific inquiry. This study introduces an innovative optical approach that leverages the dielectric properties of a surrounding medium to address this critical gap. Here, urea is utilized in a water−acetonitrile (co-solvent) system as a prototypical example to demonstrate a topology morphological unit of urea in a perturbed solvent system. We illustrate, quantify, and validate the H-bond-mediated topological unit configurations that emerge during phase transitions using complementray techniques, including MD simulations, Mueller matrix polarimetry, spectroscopy, and microscopy. Going a step further, by exploiting the system’s dielectric constant and applying a theoretical framework, we demonstrate the formation of a nanourea-enriched glassy crystal phase at an interface dynamically defined by two limiting dielectric bounds of the same hydrogen-bonded nanourea system. The design strategy described herein can emerge as a facile fabrication route for dynamical meta-materials.