Crystal structure, differential scanning calorimetric, infrared spectroscopy and theoretical studies of C(NH2)2(NH)*CH2CHCOOH noncentrosymmetric crystal

The X-ray and vibrational spectroscopic analysis of a new molecular complex of guanidine and acrylic acid are reported. The crystal of C(NH2)2(NH)*CH2CHCOOH belongs to Pna21 space group of orthorhombic system with Z = 4, a = 9.9242(34) Å, b, c = 8.3951(14) Å. In the crystal structure the macroscopic symmetry center is absent.The differential scanning calorimetric (DSC) experiment of powder sample indicates on continuous phase transition at 235.8 K.The room temperature infrared spectrum of guanidine*acrylic acid powder sample has been measured. The spectrum is discussed on the basis of crystallographic data. The IR spectra for the powder sample were also measured at low temperatures (12–300 K). The temperature relationships of band position for obtained spectra are analyzed.Additionally, the results of theoretical calculation of vibrational spectra, equilibrium structure, HOMO, LUMO and first order hyperpolarizability are presented.

Hydrogen bonds system in investigated crystal.Figure optionsDownload as PowerPoint slideHighlights
► New molecular complex of guanidine and acrylic acid was synthesised.
► The second order phase transition at ca. 240 K was detected.
► On the basis of X-ray diffraction studies both phases of crystal belong to noncetrosymmetric crystallographic system.