Determination of Structural and Vibrational Spectroscopic Properties of 4-Amino-2, 2, 6, 6-tetramethylpiperidine using FT-IR and FT-Raman Experimental Techniques and Quantum Chemical Calculations

In this work, the molecular conformation and vibrational analysis of 4-Amino-2, 2, 6, 6-tetramethylpiperidine (abbreviated as ATMP) were presented for the ground state using experimental techniques (FT-IR and FT-Raman) and the spectra were interpreted with the aid of normal coordinate analysis based on ab initio Hartree−Fock (HF) and density functional theory (DFT/B3LYP) methods with 6-311+G (d, p) basis set level. The statistical thermodynamic functions (heat capacity, entropy change, enthalpy change and free energy change) were obtained. The polarizability, first hyperpolarizability, anisotropy polarizability invariant has been computed using quantum chemical calculations. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of the experimental and theoretical spectra values provides important information about the ability of the computational method to describe the vibrational modes. UV-VIS spectral analyses of ATMP have been researched by theoretical calculations. In order to understand electronic transitions of the compound, TD-DFT calculations on electronic absorption spectra in gas phase and solvent (DMSO and Chloroform) were performed. The calculated frontier orbital energies, excitation energies (E), absorption wavelengths (λ), os cillator strengths (ƒ) and life span(τ) for gas phase and solvent (DMSO and Chloroform) are also illustrated.