Hydrogen bond cooperativity effects in cyclic and ladder cyanamide oligomers using density functional theory method

• Published in: Journal of molecular liquids Vol. 186; pp. 131 - 141
• Main Authors: Kharat, Bhagwat, Deshmukh, Vinayak, Chaudhari, Ajay
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2013
• Subjects: Cyanamide oligomer; Hydrogen bond cooperativity; Nonlinear optical property; Nonlinear optical property; Hydrogen bond cooperativity; Cyanamide oligomer
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2013.07.001

The hydrogen bond cooperativity effects in cyclic and ladder oligomers of cyanamide are studied using density functional theory (DFT) method. Among different levels of theory used here, the geometrical parameters for cyanamide monomer at B3LYP/aug-cc-pvdz level are in excellent agreement with the experimental determinations. Cyclic oligomers are found to be more stable than the ladder, and the hydrogen bonds in the former are stronger than those in the latter. The hydrogen bond cooperativity effects are discussed in terms of the strength of hydrogen bonds, energy per hydrogen bond, excess energy, inter- and intra-molecular distances and vibrational frequencies. The positive and negative hydrogen bond cooperativity effects are found for the cyclic and ladder oligomers, respectively. We also report hyperpolarizabilities for these oligomers. •Positive and negative hydrogen bond co-operativity effects for cyclic and ladder cynamide oligomers respectively.•Cyclic structures are more stable than the ladder.•Large change in second hyperpolarizability (γ) value with number of monomeric units for cyclic and ladder structures.