Combined experimental and theoretical investigations on 1,4-Diazabicyclo [2.2.2]octane 4-nitrophenol (DONP) crystals

1,4-Diazabicyclo[2.2.2]octane 4-nitrophenol (DONP) was synthesized by taking 1,4-Diazabicyclo[2.2.2]octane and 4-nitrophenol in a ratio of 1:2 via slow evaporation method. Density functional theory (DFT) calculations were performed by Becke-3-Lee-Yang-Par (B3LYP) level and CAM-B3LYP with the standard 6-31 G (d,p) basis set on the DONP molecule to correlate with experimental results. The structure of the DONP molecule was confirmed by H-1 NMR and C-13 NMR analyses. Vibrational frequencies and corresponding vibrational assignments have been calculated theoretically using the B3LYP and CAM-B3LYP methods and compared with experimental FT-IR and Raman spectra. The presence of p-nitrophenol was confirmed by strong absorption at 319 nm and slight absorption at 393 nm in the UV-visible absorption spectrum. From the FMOs analysis, the energy gap was calculated as 4.231 and 7.115 eV using B3LYP and CAM-B3LYP. The emission peaks at 481 and 508 nm with energy gap values of 2.57 and 2.43 eV were confirmed by fluorescence spectroscopy. The green emission of the DONP crystal was confirmed by the CIE 1931 diagram.