Theoretical investigation on sensing of dopamine and tyramine neurotransmitters by the B9N9 nanoring

Purpose

The investigation concerns the first demonstration of employing the B₉N₉ nanoring as an active material for sensing dopamine and tyramine neurotransmitters.

Method

The calculations for optimization and vibrational frequencies of B₉N₉ ring, dopamine, and tyramine neurotransmitters have been executed by using density functional theory (DFT) available in the Gaussian09 suite. The standard functional (B3LYP) coupled with the basis set 6-311G(d, p) have been adopted for calculations. Natural bond orbital (NBO) analysis quantified charge transfer, while molecular electrostatic potential (MEP) mapping, electron localization function (ELF), reduced density gradient (RDG) analysis, and quantum theory of atoms in molecules (QTAIM) characterized intermolecular interactions.

Results

The responsiveness of B₉N₉ ring towards the considered neurotransmitters is characterized thoroughly by the optimized electronic structures, energies, electronic, and other properties using density functional theory (B3LYP/6-311G(d, p)). The interaction of dopamine and tyramine governs through formation of the N-B dative bond in the most favorable configurations. The interaction energies for the most stable configurations of dopamine@B₉N₉ and tyramine@B₉N₉ complexes are found to be −22.11 and −21.49 kcal/mol, respectively, which show a significant interaction of neurotransmitters to nanoring and elucidate the adoption of B₉N₉ ring in sensing applications for these neurotransmitters. The critical conventional electronic parameters, viz., HOMO, LUMO, Fermi energy, work function, and energy gap, are also computed, and the effect of an aqueous medium is investigated on these parameters. The ELF and RGD techniques are used to quantify the electron density distribution and explore the involved interactions. TD-DFT calculations are performed to simulate the UV-Vis spectra. Additionally, a quantum theory of atoms in molecules (QTAIM) analysis is conducted, which shows that dopamine@B₉N₉ and tyramine@B₉N₉ exhibit stronger hydrogen bond interactions, resulting in increased bond strengths.

Conclusion

B₉N₉ nanoring shows significant interaction with both neurotransmitters and results in the change in the electronic properties helping in detection of both neurotransmitters.

Graphical Abstract