Experimental and Density Functional Theoretical Studies on the Spectra of <i>N</i>, <i>N'</i>-di[3-hydroxy-4-(2-benzothiazole)phenyl]urea

Abstract

The experimental infrared (IR), nuclear magnetic resonance (NMR), and ultraviolet (UV) spectra, and density functional theory (DFT) calculations of the novel compoundN,N′-di[3-hydroxy-4-(2-benzothiazole) phenyl]urea (4-DHBTU) are presented. Compared with the UV spectra of the 2-(4-amino-2-hydroxyphenyl) benzothiazole (4-AHBT) monomer, the experimental spectra of 4-DHBTU, a dimer of 4-AHBT, show dual-wavelength absorption with significantly enhanced absorption intensity and an obvious red shift of the maximum absorption peak. Analysis of the experimental spectra and the DFT calculations shows that the structures ofcis-C11 andtrans-C11 are the two most stable conformers, and that the main reason for the different UV spectral properties of the dimer and monomer is the coexistence ofcis-C11,trans-C11,cis-C22, and trans-C22 in the 4-DHBTU sample. In addition, the DFT calculations indicate that a hydrogen-bonding interaction between 4-DHBTU and the dimethyl sulfoxide (DMSO) solvent leads to a large1H NMR chemical shift for atoms 15H and 16H in 4-DHBTU.