The aims this work to investigate the effects of (n=1, 2, 3) H+ ions functionalizing on the surface of B12N12 nanocage to detect and adsorb 5-Flucytosine (5-FC) drug using density functional theory at the WB97XD/6-31G(d, p) level of theory using Gaussian 09 software. The calculated results indicate that the adsorption of 5-FC drug on the surface of pristine and nH+ functionalized B12N12 nanocage is exothermic, and adsorption process in the presence of nH+ functionalized is more favorable than the pristine model. The thermodynamic results demonstrate that the adsorption of 5-FC on the surface of nH+ functionalized B12N12 nanocage in both the gaseous phase and in the presence of water or ethanol is spontaneous. The gap energy value of nH+ functionalized of B12N12 nanocage is more than the original value and so the conductivity of the system is lower than the pristine model. The AIM and RDG results confirm that the interaction between 5-FC with B12N12 is noncovalent type. The nonlinear optical (NLO) results show that the polarizability (α) and hyperpolarizability (β) of all adsorption models is in range (202.30 to 214.34 a.u.) and (42.18 to 603.98 a.u.) respectively, the NLO and TD-DFT results demonstrate that the optical properties of nanocage in the presence of 5-FC drug and nH+ functionalized change significantly. These results can be useful for making carrier, delivery, and detection of drugs in the biological system.
