Phase changes of tris(glycinato)chromium(III) monohydrate crystal systematically studied by thermal analyses, XRPD, FTIR, and Raman combined with ab initio calculations

[Display omitted] •Structural, vibrational and thermal properties of Cr(C2H4NO2)3·H2O were studied.•IR and Raman modes were assigned from DFT calculations.•Phase transformation process at high temperature occurred due to water loss.•XRPD and Raman at low temperatures suggested a conformational change near 140–160 K.•The b lattice parameter as a function of temperature showed an anomalous behavior. Tris(glycinato)chromium(III) monohydrate [Cr(C2H4NO2)3·H2O] crystals were grown through the slow solvent evaporation method. The crystals were studied by Fourier transform infrared (FTIR) and Raman spectroscopy at room temperature. The assignments of vibration modes were performed using the Density Functional Theory (DFT). Thermal analyses (TGA, DTA, and DSC), X-ray diffraction (XRD), and Raman were used to study the phase changes on the crystals under high- and low-temperature conditions. Temperature-dependent XRPD measurements were carried out in the interval of 473–12 K. Several changes were observed in the patterns, like the appearance of new peaks and the disappearance of peaks occurring within 373–393 K due to water loss. In addition, the Raman measurements were performed in the 423–10 K interval. Several changes on the inter and intramolecular vibration bands during the cooling, such as decreasing bands' intensities, the appearance of vibration modes, and discontinuities on the modes’ behavior, were observed. These spectral modifications occurred at about 370 K and within 120–220 K, thus, confirming that the crystals undergo two phase changes, one being structural and the other one conformational, respectively, at high- temperature and low-temperature conditions. Finally, thermal investigations corroborated the structural and vibrational results under high temperatures.