title: 3-Phenylpyridinium hydrogen squarate: experimental and computational study of a nonlinear optical material.
abstract: The detailed investigation of an organic nonlinear optical (NLO) squarate salt of 3-phenylpyridinium hydrogen squarate (1), C11H10N+·C4HO4(-), was reported in this study. The XRD data indicates that the crystal structure of the title compound is in the triclinic P-1 space group. In the asymmetric unit, the 3-phenylpyridine molecule is protonated by one hydrogen atom donation of squaric acid molecule, forming the salt (1). The X-ray analysis shows that the crystal packing has hydrogen bonding ring pattern of D2(2)(10) (α-dimer) through NH···O interactions. The structural and vibrational properties of the compound were also studied by computational methods of ab initio at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) levels of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 are presented and compared with the experimental results. Non-linear optical properties (NLO) of the title compound together with the molecular electrostatic potential (MEP), electronic absorption spectrum, frontier molecular orbitals (FMOs) and conformational flexibility were also studied at the 2 level and the results were reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.
authors.affiliation: Department of Physics, Faculty of Arts and Sciences, Ondokuzmayıs University, Kurupelit, 55139 Samsun, Turkey.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Korkmaz
authors.affiliation: Department of Physics, Faculty of Arts and Sciences, Ondokuzmayıs University, Kurupelit, 55139 Samsun, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Bulut
authors.affiliation: Department of Chemistry, Faculty of Engineering, Ondokuzmayıs University, Kurupelit, 55139 Samsun, Turkey.
authors.forename: İclal
authors.initials: İ
authors.lastname: Bulut
mesh_terms: D018360:Crystallography, X-Ray; D003503:Cyclobutanes / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D011725:Pyridines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D003503:Cyclobutanes; D011725:Pyridines; C058323:3-phenylpyridine; C030042:squaric acid
keywords: Non-linear optical materials; Quantum chemical calculations; Squaric acid; Strong hydrogen bonding; Vibrational spectra; X-ray diffraction