Unveiling the nature of interactions in the supramolecular complex of Cucurbit [7-8] uril with ascorbic acid, dopamine and uric acid for biosensing applications: a computational study

The selectivity and sensitivity in the detection of ascorbic acid, dopamine and uric acid is an open problem in the field of biosensing. The host-guest interactions of Cucurbit[n]uril ( n =7, 8) as host and ascorbic acid (AA), dopamine (DA) and uric acid (UA) as the guest molecules has been studied using density functional theory with dispersion corrections. The energetic and thermodynamic results indicates that UA forms the most stable structure with CB7 and CB8 in gas phase. In aqueous phase, CB7 favours complexation with AA while CB8 favours DA. The non-covalent interactions that binds the supramolecular complexes are analyzed by molecular electrostatic potentials, non-covalent interactions-reduced density gradient and natural bond orbital analysis. Local energy decomposition (LED) analysis based on the non-perturbative natural orbital local domain (DLPNO)-CCSD(T) calculations is carried out for quantifying the intermolecular forces which stabilizes the complexes. The results indicate that the electrostatic interactions, van der Waals forces, intermolecular charge transfer interactions and intermolecular hydrogen bonding are responsible for the stabilization of the complexes. The study may be useful in designing Cucurbituril-based sensing device for these analytes.