Investigation of x-ray single crystal structure and the spectroscopic properties of nitrogen containing aromatic ring compounds

In this study, (E)-4-(4-(dimethylamino)benzylidenamino)-2isopropyl-5-methylphenol which has C19H24N2O formula, and 2-isopropyl-5-methyl-4-((5-methylfuran-2-yl)methyleneamino) phenol compound which has C16H20N2O formula, have been synthesized and characterized by single crystal XRD and spectroscopic methods (FT-IR, NMR, UV-Vis). Further, the molecular geometry, vibration spectra and assignments, 1H and 13CNMR chemical shifts, electronic absorption spectra, Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO) analysis of this compound have studied as theoretically by the B3LYP/6-311++G(d,p) level and compared with experimental results. The single crystal XRD result has shown that C19H24N2O ligand crystallizes in the monoclinic crystal system with space group P21/n, unit cell parameters a= 9.79 (9), b= 9.97 (9) and c= 17.72 (17) Å, and the angle β= 99.85 (4)°, and molecular formula C19H24N2O. C—H stretching vibrational frequencies for aromatic C—H bonds have been seen at 2875, 2960, 2978, 2995, and 3068 cm-1 and C=C stretching bands have been seen at 1481,1525, 1552 and 1591 cm-1. MEP results of the C19H24N2O has shown negative potantial region on O1 and N1 on the ring with -0.032 e−2 and -0.040 e−2, respectively. The most positive potential (positively charged region) is shown in blue and it has been observed on the hydrogens with 0,0054 e−2. The single crystal XRD result has shown that C16H20N2O ligand crystallizes in the monoclinic crystal system with space group P21/c, unit cell parameters a= 10.119(11), b= 10.165(6) and c= 14.838(14) Å, and the angle β= 99.22(4)°, and molecular formula C16H20N2O. FT-IR spectra have shown that (C—H) stretching band in aliphatic rings at 1619 cm-1, stretching band of imine (C=N) group at 1619 cm-1, C=C stretching band of furan ring at 1504 cm-1, (C—O—C) tension band at 1015 cm-1. The UV-Vis spectrum of C16H20N2O has shown thatthe transition observed at 250 nm was similar to the π-π* transitions of phenyl and furan rings at 300 nm. The gap between Homo and Lumo of the C16H20N2O compound is 5.85 eV. Similarly, This gap for HOMO+1 and LUMO-1 is 3.88 eV.