TD-DFT calculations of visible spectra and structural studies of carbendazim inclusion complex with cucurbit[7]uril

•HF/6-31G and B3LYP/6-31G methods were applied to study the binding of CBZ with CB[7].•Two models of the CBZ/CB[7] complex were proposed.•TD-DFT calculation indicates that charge transfer was occurred from CBZ to CB[7].

The binding of the carbendazim (CBZ) with cucurbit[7]uril (CB[7]) was investigated theoretically using HF/6-31G and B3LYP/6-31G methods. Two modes of complexation were considered for studying such complex. In A complex the benzimidazole group of the guest was introduced into CB[7] cavity, while in B complex the carbamate group was included in the CB[7] cavity. Energetic analysis indicates that the formed complexes are stable and both host and guest were little deformed after complexation. Electronic properties given by TD-DFT calculation clearly demonstrate that a charge transfer was occurred between CBZ and CB[7] molecules.