Filtern
Dokumenttyp
Sprache
- Englisch (2)
Referierte Publikation
- ja (2)
Schlagworte
- ADT (1)
- Electron diffraction (1)
- In situ (1)
- Mechanochemistry (1)
- Metal phosphonate (1)
- Polymorphism caffeine (1)
The use of Automated electron Diffraction Tomography (ADT) is presented as a novel approach for crystallization studies at the nanometer scale for nonequilibrium phases. Here, ADT was applied to elucidate the structural identity of the recently reported hexagonal morphology of caffeine crystals, which grow only on specific surfaces. Caffeine was crystallized from solution on a specially treated TEM carbon grid. The analysis of ADT data revealed that the lattice parameters of these hexagons match those of the high temperature α-form of caffeine. Furthermore, it was observed that in this hexagonal morphology, the α-form remained stable for a prolonged period of time. The stabilization of hexagons can be interpreted in terms of enhanced interactions with the supporting surfaces.
The crystal structures and syntheses of four different copper(II) phenylphosphonates, the monophenylphosphonates α-, β-, and γ-Cu(O3PC6H5)·H2O (α-CuPhPmH (1) β-CuPhPmH (2) and γ-CuPhPmH (3)), and the diphosphonate Cu(HO3PC6H5)2·H2O (CuPhP2mH (4)), are presented. The compounds were synthesized from solution at room temperature, at elevated temperature, under hydrothermal conditions, and mechanochemical conditions. The structures of α-CuPhPmH (1) and CuPhP2mH (4) were solved from powder X-ray diffraction data. The structure of β-CuPhPmH (2) was solved by single crystal X-ray analysis. The structures were validated by extended X-ray absorption fine structure (EXAFS) and DTA analyses. Disorder of the crystal structure was elucidated by electron diffraction. The relationship between the compounds and their reaction pathways were investigated by in situ synchrotron measurements.