Crystal Structure, Photophysical Study, Hirshfeld Surface Analysis, and Nonlinear Optical Properties of a New Hydroxyphenylamino Meldrum's Acid Derivative

The structural, photophysical, and vibrational properties of a new hydroxyphenylamino Meldrum's acid derivative, 3-((2-hydroxyphenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione (HMD), were studied. The comparison of experimental and theoretical vibrational spectra can help understand basic vibration patterns and provides a better interpretation of IR spectra. The UV-Vis spectrum of HMD was computed using density functional theory (DFT)/B3LYP/6-311 G(d,p) basis set in the gas state, and the maximum wavelength was in accord with the experimental data. The molecular electrostatic potential (MEP) and Hirshfeld surface analysis confirmed O(1)-H(1A)center dot center dot center dot O(2) intermolecular hydrogen bonds in the HMD molecule. The natural bond orbital (NBO) analysis provided delocalizing interactions between pi ->pi* orbitals and n ->sigma*/pi* charge transfer transitions. Finally, the thermal gravimetric (TG)/differential scanning calorimeter (DSC) and the non-linear optical (NLO) properties of HMD were also reported.