CEQUINOR   05415
CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
artículos
Título:
Supramolecular self-assembly of a new multi-conformational Schiff base through hydrogen bonds: Crystal structure, spectroscopic and theoretical investigation.
Autor/es:
MARIANA ROCHA; OSCAR E. PIRO; DIEGO M. GIL; GUSTAVO A. ECHEVERRIA; SONIA ULIC ; ALEJANDRO DI SANTO; FABIO CUKIERNIK
Revista:
JOURNAL OF MOLECULAR STRUCTURE
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2017 vol. 1133 p. 24 - 36
ISSN:
0022-2860
Resumen:
The compound 4-(4-dimethylaminobenzylidene)aminoacetophenone was synthesized by condensation of 4-aminoacetophenone and 4-(dimethylamino) benzaldehyde in ethanol. This compound was characterized by CG-MS, infrared, Raman, UVeVis, 1H and 13C NMR spectroscopy. The crystal structure was solved by single-crystal X-ray diffraction methods. The crystallographic data reveals that there are four independent molecules per asymmetric unit, that mainly differ from one another in rotations around the s-bond of the azomethine N-atom with the phenyl ring. A detailed analysis of the intermolecular interactions in the four conformers of the compound has been performed using Hirshfeld surfaces andtheir associated two-dimensional fingerprint plots. The optimized geometrical parameters and calculated spectroscopic features obtained by quantum chemical calculations at B3LYP method show a very good agreement with the experimental data. Moreover, Natural Bond Orbital (NBO) analysis confirms the strong hyper-conjugative LP N(n1)/ s* C(n9)eH interaction between the lone pair located in the N atom of the azomethine group and the CeH bond. Liquid crystalline properties of the Schiff base were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and Powder Xraydiffraction techniques. Mesomorphic behaviour was observed in this unsymmetrical azomethine.Based on POM and DSC measurements, the hexatic Smetic B phase was detected.