title: Synthesis, an experimental and quantum chemical computational study: proton sharing in 4-Morpholinium bis(hydrogen squarate).
abstract: The experimental and theoretical investigation results of a novel organic squarate salt of 4-Morpholinium bis(hydrogen squarate) (1), C₆H₁₄ON(+)·C₈H₃O₈(-), were reported in this study. The crystal structure of the title compound was found to crystallize in the triclinic P-1 space group. In the crystals of 1 the morpholine ring adopts the chair conformation with the ethyl group in the equatorial and hydrogen atoms in axial positions. The hydrogen squarate anions are linked into a homoconjugated anion, [(HSQ)₂H], by a short symmetric, nonlinear O₈⋯H₂⋯O₂ hydrogen bond of 2.444 (2)Å. The structural and vibrational properties of the compound were also studied by computational methods of ab-initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The obtained calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 obtained are presented and compared with the X-ray analysis result. On the other hand the molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are 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, 55139 Kurupelit, Samsun, Turkey. Electronic address: ukkorkmaz@gmail.com.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Korkmaz
authors.affiliation: Ondokuz Mayıs University, Faculty of Engineering, Chemical Engineering Department, 55139 Kurupelit, Samsun, Turkey.
authors.forename: Yıldıray
authors.initials: Y
authors.lastname: Topçu
authors.affiliation: Department of Chemistry, Faculty of Arts and Sciences, Giresun University, 28049 Giresun, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Taş
authors.affiliation: Department of Physics, Faculty of Arts and Sciences, Ondokuzmayıs University, 55139 Kurupelit, Samsun, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Bulut
mesh_terms: D060326:Chemistry Techniques, Synthetic; D018360:Crystallography, X-Ray; D003503:Cyclobutanes / Q000138:chemical synthesis / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D009025:Morpholines / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
chemical_list: C000601649:4-morpholinium bis(hydrogen squarate); D003503:Cyclobutanes; D009025:Morpholines; D011522:Protons; C030042:squaric acid
keywords: Quantum chemical calculations; Squaric acid; Strong hydrogen bonding; Vibrational spectra; X-ray diffraction