Structural Modeling, Spectroscopic Signature and NBO Analysis of Octopamine and Its Radical

AbstractThe present communication deals with theoretical vibrational spectroscopic signature (IR and Raman) of octopamine molecule and its radical. All theoretical calculations for octopamine and its radical are performed at DFT/B3LYP/6‐31++G (d, p) level. Besides, the vibrational frequencies of these two structures has been compared. Most of the vibrational frequencies agree well with experimental ones. It has been documented how the geometrical characteristics and vibrational frequencies of octopamine are affected when hydrogen is removed from the oxygen atom's site. The HOMO‐LUMO energy gap in the case of neutral form of octopamine is computed to be 5.42 eV while for deprotonated octopamine this gap has been increased by 0.78 eV. The NBO analysis is also performed to ensure stability of radical of octopamine. The magnitude of occupancy at bonding orbitals within the 0.997–0.885e, and 0.996–0.885e range in octopamine and octopamine, respectively, is calculated.