title: Hydrogen bond strengthening of cis-trans glyoxal dimers in electronic excited states: a theoretical study.
abstract: The second-order approximate coupled-cluster (CC2) method was performed to investigate the excited state hydrogen-bonding properties of Glyoxal (C2H2O2, Gl) dimers. Since the strengthening and weakening of hydrogen bonds can be investigated by monitoring the vibrational absorption spectra of some hydrogen-bonded groups in different electronic states, the infrared spectra of the hydrogen-bonded Gl-Gl complexes in both of the ground state and the S1 electronically excited state are calculated using the MP2/CC2 methods respectively. We demonstrated that the intermolecular hydrogen bond C=O⋯H-C between two glyoxal molecules is significantly strengthened in the electronically excited S1 state upon photoexcitation of the hydrogen-bonded Gl-Gl complexes.
authors: Department of Chemistry, University of Isfahan, 81746-7344 Isfahan, Iran.
authors: Hamidreza
authors: H
authors: Poorabdollah
authors: Department of Chemistry, University of Isfahan, 81746-7344 Isfahan, Iran. Electronic address: r.omidyan@sci.ui.ac.ir.
authors: Reza
authors: R
authors: Omidyan
authors: Quantum Chemistry Group, Department of Chemistry, Faculty of Sciences, Arak University, Arak 38156-8-8349, Iran.
authors: Mohammad
authors: M
authors: Solimannejad
authors: Department of Chemistry, University of Isfahan, 81746-7344 Isfahan, Iran.
authors: Gholamhasan
authors: G
authors: Azimi
mesh_terms: D019281:Dimerization; D004583:Electrons; D006037:Glyoxal / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008962:Models, Theoretical; D008968:Molecular Conformation; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D013816:Thermodynamics; D014732:Vibration
chemical_list: D006037:Glyoxal
keywords: Excited state; Glyoxal; MP2 and CC2 methods; Red shift