Large Guest Molecules Selectively Forming sII- or sH-Type Hydrates: Chameleon-Like Behavior

Abstract

Over the past decades, extensive research on large guest molecules (LGMs) has shown that a given LGM exclusively forms only a single type of clathrate hydrate (sI, sII, or sH). This study challenges this prevailing understanding by revealing that certain LGMs can selectively form sII- or sH-type hydrates depending on the environment. This study presents various experimental evidence demonstrating that cyclohexylamine and cyclohexanol exhibit chameleon-like behavior, forming sII or sH hydrates when mixed with sII or sH formers, respectively. This intriguing structural modification induced by coguest inclusion is expected to broaden the scope of physicochemical investigations into hydrate materials. Furthermore, this study also suggests that shifting from the traditional approach, which has predominantly focused on single LGMs, could potentially drive breakthroughs in the development and application of sustainable hydrate-based technologies.