Adsorption of metformin on graphitic carbon nitride functionalized with metals of group 1–3 (Li, Na, K, Be, Mg, Ca, B, Al, and Ga), DFT calculations.

[Display omitted] • The [M/g-C 3 N 4 ]⁺ complexes have been seen as interesting adsorbents of metformin. • M/g-C 3 N 4 , M: Li, Na, K have values of 39.29–19.13 kcal/mol favorable for drug delivery. • NBO shows donor orbitals belong to the nitrogen atoms of metformin. Metformin is one of the important anti-diabetic drugs. DFT calculations have been performed to study properties of adsorption of metformin onto [M/g-C 3 N 4 ]^+,+2,+3 , where M: Li, Na, K, Be, Mg, Ca, B, Al, and Ga. Optimized structures of all systems were calculated using the ONIOM computational method. The results were used to calculate the absorption energy (E ads) with the PBE0-D3(BJ)/def2-TZVP method. The adsorption energy values for the most stable configurations are 19.1–131.6 kcal/mol. By adsorption of metformin on [M/g-C 3 N 4 ]^+,+2,+3 surfaces, the ionization potential values of [M/g-C 3 N 4 ]⁺ , M: Li, Na and K are low, which means that the stability of M: Li, Na and K systems are higher than the other systems (groups 2 and 3). The [M/g-C 3 N 4 ]⁺ complexes have been seen as interesting adsorbents of metformin molecule. [ABSTRACT FROM AUTHOR]