Gas-phase conformational and intramolecular π-π interaction studies on some pyrazolo[3,4-d]pyrimidine derivatives

► Conformational flexibility has been carried out on trimethylene linker compounds. ► B3LYP, B97D and MO6-2X methods are employed for PES scan, optimization and refinement ► MO6-2X method is best suited for the estimation of π-π interaction energies. ► B97D method may overestimate the dispersion energy. ► π-π Interaction energy has been estimated to be of the order of 5 kcal/mol.