Cocrystallization of 1-Pyrenemethylamine/CD-MOF Composite Using THF as a Cosolvent

Abstract

The techniques used for encapsulating a hydrophilic molecule into a cyclodextrin-based metal–organic framework (CD-MOF) can be divided into either an adsorption method or a cocrystallization method. However, neither of these methods can be applied directly to water-insoluble hydrophobic molecules. In this study, it was found that tetrahydrofuran (THF) can be used as a suitable cosolvent for dissolving hydrophobic 1-pyrenemethylamine (PMA) in water during the cocrystallization of CD-MOF. PMA-loaded CD-MOF (PMA/CD-MOF) was crystallized in an aqueous solution of PMA containing THF via methanol vapor diffusion. PMA/CD-MOF crystal growth was achieved without methanol vapor diffusion, by a novel method in which the volatilization of THF led to a solubility change for γ-cyclodextrin (γ-CD) leading to crystallization.