Facile synthesis, X-ray diffraction studies, photophysical properties and DFT-D based conformational analysis of octa and dodecacyanomethoxycalix[4]resorcinarenes

Abstract This paper reports the synthesis of two new supramolecules, Phenyl(octacyanomethoxy)calix[4]resorcinarene (3a) and 4-Cyanomethoxyphenyl(octacyanomethoxy)calix[4]resorcinarene (3b) by alkylating the hydroxyl groups present in Phenylcalix[4]resorcinarene and 4-Hydroxyphenylcalix[4]resorcinarene respectively. Full O-alkylation was done at room temperature by simple stirring. The X-ray diffraction studies, were done to get the crystal-packing arrangements of alkylated resorcinarene derivatives. Absorption and emission spectra of the compounds were recorded in different organic solvents and both exhibited negative solvatochromism with the polarity of solvents. Molecular geometry optimization, vibrational wave numbers and frontier molecular orbitals were calculated by dispersion corrected DFT-D method using hybrid density functional ωB97X-D and the split-valence double-zeta basis set 6-31G(d). DFT-D studies revealed that the synthesised supramolecules existed in two different conformers, chair (C2h) and Boat (C2V). Boat (C2v) conformer had more stability than the chair (C2h) conformer. HOMO-LUMO energies were calculated to explain the kinetic stability of the compounds, found that Phenyl(octacyanomethoxy)calix [4]resorcinarene has more kinetic stability.