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The 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. [ABSTRACT FROM AUTHOR]

The present investigation focuses on the geometrical optimized parameters, IR and raman activity based on vibrational frequencies, and global reactivity descriptors of mesogens namely; para-azoxyanisole (PAA), ethyl para-azoxybenzoate (EPAB) and non-mesogen biphenyl-4-carboxylic acid (BCA) molecules via the Density functional theory (DFT) and Hartree–Fock (HF) technique accompanied with 6–31++G (d, p) basis set. The wavenumbers/frequencies obtained for utmost of the vibrational modes are in the predicted range but with minimal error. Reactivity of these molecules based on the molecular properties viz., HOMO, LUMO energies, ionization potential, electro negativity, chemical potential, electron affinity, chemical hardness, and softness has also been focused. The DFT method considers all different electronic interactions thereby give accurate results as compared to Hartree–Fock method. The azoxy bond plays an important role in chemical bond formation in liquid crystals, chemical intermediates, process control, and pharmaceuticals etc. Further, the estimated band gap values indicate the understanding of fine tuning mechanism for exploring the possible industrial applications. [ABSTRACT FROM AUTHOR]

The interaction of tyramine neurotransmitter with silver nano-particle (Ag6) cluster is explored in terms of the molecular structure, electronic properties and NBO analysis of tyramine-AgNPs bio-molecular conjugate. The adsorption mechanism of tyramine onto the Ag6 cluster has been investigated through computing of the electronic and geometrical properties in addition to the adsorption energies in various possible configurations. The magnitude of adsorption energy corresponding to the most favorable tyramine-Ag6 bio-molecular conjugate has been computed to be − 14.36 kcal/mol in the gas phase, which infers a good adsorption of tyramine with AgNPs cluster suggesting the practical applications of tyramine-AgNPs bio-molecular conjugates in bio-sensing, drug delivery, bio-imaging and other applications. Different electronic properties such as the energy gap of HOMO–LUMO, Fermi level and work function have been investigated in detail. Moreover, the effect of aqueous media on adsorption energy and electronic properties of the most favorable tyramine-AgNPs bio-molecular conjugate is investigated in order to understand the impact of the real biological situation. [ABSTRACT FROM AUTHOR]