Computationally-assisted approach to the vibrational spectra of molecular crystals: Study of hydrogen-bonding and pseudo-polymorphism
authors Nolasco, MM; Amado, AM; Ribeiro-Claro, PJA
nationality International
journal CHEMPHYSCHEM
author keywords ab initio calculations; crystals; IR spectroscopy; noncovalent interactions; polymorphism; Raman spectroscopy
keywords ANHYDROUS THEOPHYLLINE; RAMAN-SPECTROSCOPY; CAFFEINE HYDRATE; SOLID-STATE; X-RAY; THEOBROMINE; METHYLXANTHINES; STABILITY; BEHAVIOR; DEHYDRATION
abstract A new computationally-assisted methodology (PiMM), which accounts for the effects of intermolecular interactions in the crystal, is applied to the complete assignment of the Roman and infrared vibrational spectra of room temperature forms of crystalline caffeine, theobromine, and theophylline. The vibrational shifts due to crystal packing interactions are evaluated from ob initio calculations for a set of suitable molecular pairs, using the B3LYP/6-31G* approach. The proposed methodology provides on answer to the current demand for a reliable assignment of the vibrational spectra of these methyl-xanthines, and clarifies several misleading assignments. The most relevant intermolecular interactions in each system and their effect on the vibrational spectra are considered and discussed. Based on these results, significant insights are obtained for the structure of caffeine in the anhydrous form (stable at room temperature), for which no X-ray structure has been reported. A possible structure based on C-(8)-H center dot center dot center dot N-(9) and C-(1,C-3)-H center dot center dot center dot O intermolecular interactions is suggested.
publisher WILEY-V C H VERLAG GMBH
issn 1439-4235
year published 2006
volume 7
issue 10
beginning page 2150
ending page 2161
digital object identifier (doi) 10.1002/cphc.200600308
web of science category Chemistry, Physical; Physics, Atomic, Molecular & Chemical
subject category Chemistry; Physics
unique article identifier WOS:000241464700018
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journal analysis (jcr 2019):
journal impact factor 3.144
5 year journal impact factor 2.86
category normalized journal impact factor percentile 64.678
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