Density functional investigations on 2-naphthalenecarbonitrile dimerization within cucurbit[8]uril cavitand.

Dimerization of 2-naphthalenecarbonitrile (2-NpCN) mediated by cucurbit[8]uril (CB[8]) has been investigated employing the density functional theory. Different structures of 2-NpCN dimers were generated by combining monomers in anti-head-to-head (A), anti-head-to-tail (B) and syn-head-to-tail (C) fashion. All these dimeric structures possess rigid cube-like architecture. On confinement within the CB[8] dimer A turns out to be the lowest energy structure. Calculated (1)H NMR spectra revealed that the 2-NpCN dimer exhibits large shielding for aromatic protons consistent with the experiment. The protons attached to cubane moiety on the other hand, led to down-field signals. Dimerization mediated with CB[8] cavitand is further accompanied by the frequency up-shift (blue shift) of methylene stretching vibration in its infrared spectra.