B- and Al-Doped Porous 2D Covalent Organic Frameworks as Nanocarriers for Biguanides and Metformin Drugs.

Nanostructures such as nanosheets, nanotubes, nanocages, and fullerenes have been extensively studied as potential candidates in various fields since the advancement of nanoscience. Herein, the interaction between biguanides (BGN) and metformin (MET) on the modified covalent organic framework (COF), COF-B, and COF-Al was investigated using density functional theory at the ωB97XD/6-311+G (d, p) level of computation to explore a new drug delivery system. The electronic properties evaluation reveals that the studied surfaces are suited for the delivery of both drug molecules. The calculated adsorption energies and basis set superposition errors (BSSE) ranged between -21.20 and -65.86 kJ/mol. The negative values obtained are an indication of excellent interaction between the drug molecules and the COF surfaces. Moreover, BGN is better adsorbed on COF-B with E ads of -65.86 kJ/mol, while MET is better adsorbed on COF-Al with E ads = -47.30 kJ/mol. The analysis of the quantum theory of atom in molecules (QTAIM) explained the nature and strength of intermolecular interaction existing between the drug molecules BGN and MET with the adsorbing surfaces. The analysis of noncovalent interaction (NCI) shows a weak hydrogen-bond interaction. Other properties such as quantum chemical descriptors and natural bond orbital (NBO) analysis also agree with the potential of COF surfaces as drug delivery systems. The electron localization function (ELF) is discussed, and it confirms the transitions occurring in the NBO analysis of the complexes. In conclusion, COF-B and COF-Al are suitable candidates for the effective delivery of BGN and MET.