S. Salunke-Gawali, Omkar Pawar, M. Nikalje
Jan 6, 2014
Citations
0
Influential Citations
28
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract Four analogues of 2-bromo-3-( n -alkylamino)-1,4-napthoquinone (where n -alkyl is methyl in L-1Br, ethyl in L-2Br, propyl in L-3Br and butyl in L-4Br) are synthesized and characterized. A reaction mechanism is proposed for the formation of L-1Br to L-4Br from the starting material 2,3-dibromo-1,4-naphthoquinone. The ν N H frequency in the FT-IR spectra is affected by the intramolecular hydrogen bonding in L-1Br to L-4Br and is observed ∼3267 cm −1 in L-2Br. A shift of ∼25 cm −1 is observed in the ν C Br frequency in all the compounds as compared to 2,3-dibromo-1,4-naphthoquinone (627 cm −1 ). A broad charge transfer band is observed between 400 and 600 nm in the UV–Vis spectra, which imparts red colour to all the compounds. Molecular structures of L-2Br and L-3Br were studied by single crystal X-ray diffraction studies. Molecules of L-2Br crystallize in Pca2 1 , whereas the molecule L-3Br crystallizes in the P-1 space group. Molecules of L-2Br forms a polymeric chain through N H⋯O interaction and forms beautiful butterfly like arrangement of molecules when viewed down the ‘ a ’ axis. Ladder like polymeric chain of molecules is observed in L-3Br via C H⋯O and N H⋯O interactions. Every alternating neighbouring chains of L-3Br, show π–π stacking interactions between the quinonoid rings of the molecules, however this interaction is not observed in L-2Br.