Structural and spectroscopic study on N-2-fluorobenzoyl-N′-4-methoxyphenylthiourea

The structure of N-2-fluorobenzoyl-N′-4-methoxyphenylthiourea (C15H13N2OFS, Mr = 288.34) (FBMPT) derived from X-ray diffraction of a single crystal has been presented. The crystals of FBMPT are in the triclinic, space group: P1¯, a = 8.413(5), b = 9.532(5), c = 9.927(6) Å, α = 66.24(2), β = 85.40(2), γ = 72.27(2)°, V = 693.2(7) Å3, Z = 2. FTIR, NMR, UV absorbance and fluorescence spectroscopy methods have been employed to study the structure of FBMPT. All of the experimental results have proven that there are intra-molecular hydrogen bond interactions. Theoretical calculations of bond parameters, harmonic vibration frequencies, nuclear magnetic resonance and vertical excitation energies are in good agreement with experimental results. The absorbance and fluorescence spectra of FBMPT have been investigated in several organic solvents. Both absorbance and fluorescence spectra exhibit a slight solvent dependence. Dual fluorescence has also been observed in polar solvent, consistent with excited state proton transfer or twisted intra-molecular charge transfer (TICT) emission. The solvent ethanol quenches fluorescence band, which is associated with intermolecular hydrogen bond interaction between FBMPT and ethanol.