Simultaneous exhibition of positive and negative cooperativity by purely C-HMIDLINE HORIZONTAL ELLIPSISO H-bonded (1,3-cyclohexanedione)(n) (n=2-6) clusters: A density functional theoretical investigation

摘要

Investigation of cooperative effect exhibited by purely C-HMIDLINE HORIZONTAL ELLIPSISO hydrogen bonded (H-bonded) networks in linear and cyclic clusters of 1,3-cyclohexanedione (up to hexamer) has been carried out using density functional theoretical calculations. Linear clusters were found to show anti-cooperative behavior, while the cyclic clusters showed positive cooperativity. In all the studied clusters, the carbonyl groups were found to form bifurcated H-bonds with two or three C-H groups. The extent of cooperativity has been found to show monotonic behavior for both linear and cyclic clusters, both in terms of H-bond strength and binding energies. Natural bond orbital analysis and atoms in molecule calculations were found to corroborate the obtained results.