Crystallographic and conformational analysis of two novel trans-azo benzene compounds


KARABIYIK H., Petek H., OCAK İSKELELİ N., Albayrak C.

STRUCTURAL CHEMISTRY, vol.20, no.5, pp.903-910, 2009 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 20 Issue: 5
  • Publication Date: 2009
  • Doi Number: 10.1007/s11224-009-9490-4
  • Journal Name: STRUCTURAL CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.903-910
  • Keywords: Azo benzene, DFT/B3LYP, Conformational analysis, Crystal structure, MOLECULAR-ORBITAL METHODS, RAY CRYSTAL-STRUCTURE, PEDAL MOTION, DENSITY, ISOMERIZATION, AZOBENZENE
  • Dokuz Eylül University Affiliated: Yes

Abstract

The molecular and crystal structure of (E)-2-Acetyl-4-(2-bromophenyldiazenyl)phenol (1) and (E)-2-Methyl-4-(o-tolyldiazenyl)phenol (2) were characterized and determined by single crystal X-ray diffraction method besides spectroscopic means. The periodic organization of 1 is stabilized by C-H center dot center dot center dot O type weak H-bond and Br center dot center dot center dot O type weak halogen bonding and thus, a two dimensional puckered network is established almost parallel to 10((1) over bar) the plane. Molecules of 2 are linked into C(7) chains generated by translation along the [1 0 1] direction with the aid of O-H center dot center dot center dot N type H-bonds, and these chains are strengthened by C-H center dot center dot center dot pi interactions involving o-tolylphenol ring. Quantum chemical studies at B3LYP/6-311 ++G(d,p) level reveal that potential barrier of the compounds around Ar-N torsions is of double minimum character unless it is defected by the presence of o-substituent groups in the vicinity of the azo bridge. The results from crystallographic and quantum chemical studies suggest that azo benzene compounds may adapt non-planar geometry apart from the most stable planar conformation, which is located on the secondary minima of double potential barrier regarding rotational motion around Ar-N bonds.