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From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Cocrystal dissociation and molecular demixing in the solid state.
Mark D Eddleston1, Gareth O Lloyd, William Jones
1Department of Chemistry, University of Cambridge, Cambridge, UK. mde32@cam.ac.uk
Chemical Communications (Cambridge, England)
|July 12, 2012
Summary
Heating a caffeine and theophylline cocrystal causes it to dissociate into separate caffeine and theophylline crystals. This solid-solid transition is likely driven by increased entropy and observed using transmission electron microscopy.
Area of Science:
- Crystallization science
- Materials science
- Chemical engineering
Background:
- Cocrystals are crystalline compounds composed of two or more different molecules held together by non-covalent interactions.
- Understanding cocrystal behavior under different conditions is crucial for their application in pharmaceuticals and materials science.
- Theophylline and caffeine are common pharmaceutical compounds with potential for cocrystal formation.
Purpose of the Study:
- To investigate the thermal behavior of a novel caffeine-theophylline cocrystal.
- To elucidate the mechanism of cocrystal dissociation and subsequent recrystallization.
- To characterize the morphology and composition of the resulting solid phases.
Main Methods:
- Synthesis and characterization of a caffeine-theophylline cocrystal.
- Differential scanning calorimetry (DSC) to study thermal transitions.
- Transmission electron microscopy (TEM) for morphological and compositional analysis.
Main Results:
- The caffeine-theophylline cocrystal undergoes a solid-solid transition upon heating.
- Dissociation of the cocrystal leads to spontaneous demixing and recrystallization of individual caffeine and theophylline phases.
- Transmission electron microscopy confirmed the formation of distinct caffeine and theophylline crystals with specific morphologies.
Conclusions:
- The observed solid-solid transition in the caffeine-theophylline cocrystal is likely entropy-driven.
- Cocrystal dissociation and recrystallization represent a significant solid-state transformation.
- This study provides insights into the stability and phase behavior of pharmaceutical cocrystals.
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