Investigating tautomeric polymorphism in crystalline anthranilic acid using terahertz spectroscopy and solid-state density functional theory

Sean P. Delaney, Ewelina M. Witko, Tiffany M. Smith, Timothy Michael Korter

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Terahertz spectroscopy is sensitive to the interactions between molecules in the solid-state and recently has emerged as a new analytical tool for investigating polymorphism. Here, this technique is applied for the first time to the phenomenon of tautomeric polymorphism where the crystal structures of anthranilic acid (2-aminobenzoic acid) have been investigated. Three polymorphs of anthranilic acid (denoted Forms I, II and III) were studied using terahertz spectroscopy and the vibrational modes and relative polymorph stabilities analyzed using solid-state density functional theory calculations augmented with London dispersion force corrections. Form I consists of both neutral and zwitterionic molecules and was found to be the most stable polymorph as compared to Forms II and III (both containing only neutral molecules). The simulations suggest that a balance between steric interactions and electrostatic forces is responsible for the favoring of the mixed neutral/zwitterion solid over the all neutral or all zwitterion crystalline arrangements.

Original languageEnglish (US)
Pages (from-to)8051-8057
Number of pages7
JournalJournal of Physical Chemistry A
Volume116
Issue number30
DOIs
StatePublished - Aug 2 2012

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Terahertz spectroscopy
polymorphism
Polymorphism
Density functional theory
zwitterions
density functional theory
Crystalline materials
solid state
acids
spectroscopy
molecules
Molecules
vibration mode
interactions
Electrostatic force
electrostatics
crystal structure
Crystal structure
anthranilic acid
simulation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Investigating tautomeric polymorphism in crystalline anthranilic acid using terahertz spectroscopy and solid-state density functional theory. / Delaney, Sean P.; Witko, Ewelina M.; Smith, Tiffany M.; Korter, Timothy Michael.

In: Journal of Physical Chemistry A, Vol. 116, No. 30, 02.08.2012, p. 8051-8057.

Research output: Contribution to journalArticle

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