Phase Transition and Thermochromism of the Hybrid (C12H25NH3)2FeCl4

2006 ◽  
Vol 111 ◽  
pp. 55-58
Author(s):  
L.L. Guo ◽  
Y.D. Dai ◽  
H.X. Liu ◽  
Shi Xi Ouyang
Keyword(s):  
Phase Transition ◽  
Structural Changes ◽  
Energy Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermal Gravimetry ◽  
Reversible Phase Transition ◽  
Rotational Motions ◽  
Xrd Patterns ◽  
Reversible Phase

This paper focuses on the structural change and the thermochromism of the phase transition of the hybrid (C12H25NH3)2FeCl4. The temperature and the structures of the phase transition is investigated by a thermal gravimetry (TG) and differential scanning calorimetry (DSC), an infrared spectra (IR) and X-ray diffraction (XRD) patterns. The UV adsorption spectra account for the thermochromism. The results suggest that the reversible phase transition arises from the structural changes of the organic chains. The thermochromism is presumably due to the electrons redistribution on the levels and to the energy transition to translational and rotational motions of the organic chains.

scholarly journals Tris(ethylenediamine) Cobalt(II) and Manganese(II) Nitrates

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 472
Author(s):  
Miguel Cortijo ◽  
Ángela Valentín-Pérez ◽  
Mathieu Rouzières ◽  
Rodolphe Clérac ◽  
Patrick Rosa ◽  
...  
Keyword(s):  
Phase Transition ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Orbital Contribution ◽  
X Ray ◽  
Reversible Phase Transition ◽  
Heat Capacity Measurements ◽  
Reversible Phase

Octahedral tris(ethylenediamine) coordination complexes demonstrate helicoidal chirality, due to the arrangement of the ligands around the metal core. The enantiomers of the nitrate salts [Ni(en)3](NO3)2 and [Zn(en)3](NO3)2 spontaneously resolve to form a mixture of conglomerate crystals, which present a reversible phase transition from space group P6322 to enantiomorphic P6522 or P6122, with the latter depending on the handedness of the enantiomer. We report here the synthesis and characterization of [Mn(en)3](NO3)2 and [Co(en)3](NO3)2, which are isostructural to the Zn(II) and Ni(II) derivatives. The Mn(II) analogue undergoes the same phase transition centered at 150(2) K, as determined by single-crystal X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The Co(II) derivative does not demonstrate a phase transition down to 2 K, as evidenced by powder X-ray diffraction and heat capacity measurements. The phase transition does not impact the magnetic properties of the Ni(II) and Mn(II) analogues; these high spin compounds display Curie behavior that is consistent with S = 1 and 5/2, respectively, down to 20 K, while the temperature-dependent magnetic moment for the Co(II) compound reveals a significant orbital contribution.

Reversible phase transition of pyridinium-3-carboxylic acid perchlorate

2010 ◽  
Vol 66 (3) ◽  
pp. 387-395 ◽  
Author(s):  
Heng-Yun Ye ◽  
Li-Zhuang Chen ◽  
Ren-Gen Xiong
Keyword(s):  
Phase Transition ◽  
Carboxylic Acid ◽  
Relative Displacement ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Cell Parameters ◽  
Dsc Measurements ◽  
Reversible Phase Transition ◽  
Reversible Phase ◽  
Hydrogen Bonded

Pyridinium-3-carboxylic acid perchlorate was synthesized and separated as crystals. Differential scanning calorimetry (DSC) measurements show that this compound undergoes a reversible phase transition at ∼ 135 K with a wide hysteresis of 15 K. Dielectric measurements confirm the transition at ∼ 127 K. Measurement of the unit-cell parameters versus temperature shows that the values of the c axis and β angle change abruptly and remarkably at 129 (2) K, indicating that the system undergoes a first-order transition at T c = 129 K. The crystal structures determined at 103 and 298 K are all monoclinic in P21/c, showing that the phase transition is isosymmetric. The crystal contains one-dimensional hydrogen-bonded chains of the pyridinium-3-carboxylic acid cations, which are further linked to perchlorate anions by hydrogen bonds to form well separated infinite planar layers. The most distinct differences between the structures of the higher-temperature phase and the lower-temperature phase are the change of the distance between the adjacent pyridinium ring planes within the hydrogen-bonded chains and the relative displacement between the hydrogen-bonded layers. Structural analysis shows that the driving force of the transition is the reorientation of the pyridinium-3-carboxylic acid cations. The degree of order of the perchlorate anions may be a secondary order parameter.

scholarly journals Above Room Temperature Reversible Phase Transition Induces Distinct Dielectric and Nonlinear Optical Switching Response Behavior in Crown-Ether-Based Supramolecular Clathrate

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 184 ◽  
Author(s):  
Jing Jing ◽  
Fan Jiang ◽  
Yan-Li Wei ◽  
Chao Shi ◽  
Heng-Yun Ye ◽  
...  
Keyword(s):  
Phase Transition ◽  
Crown Ether ◽  
Optical Switching ◽  
Nonlinear Optical ◽  
Thermal Hysteresis ◽  
Switching Behavior ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Reversible Phase Transition ◽  
Reversible Phase

Stimuli-responsive materials with coexisting nonlinear optical (NLO) and dielectric properties are technologically important, which enable simultaneous conversion of optoelectronic properties between different states under external stimuli. By rationally screening guest cations (C6H5NF2)+ in the crown-ether inclusion system, we synthesized a crown-ether supramolecular compound [(C6H5NF2)(18-crown-6)][PF6] (1). Differential scanning calorimetry (DSC) showed that 1 undergoes a reversible phase transition above room temperatures (305 K/292 K), with a thermal hysteresis of 13 K. Temperature-dependent dielectric and NLO measurements show that the compound exhibits two distinct switching response behaviors. Structural analysis indicates that the order–disorder change of the host molecule 18-crown-6 and the guest organic cation during the phase transition induces the dielectric and NLO switching behavior of the compound.

A Reversible Non-disruptive Phase Transition Shown by the Zinc Iodide Dimethylformamide Complex ZnI2(dmf)2

1998 ◽  
Vol 54 (5) ◽  
pp. 663-670 ◽  
Author(s):  
R. A. Edwards ◽  
A. J. Easteal ◽  
O. P. Gladkikh ◽  
W. T. Robinson ◽  
M. M. Turnbull ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Intermolecular Forces ◽  
Scanning Calorimetry ◽  
Space Group ◽  
Cell Parameters ◽  
Reversible Phase Transition ◽  
Higher Temperature ◽  
High Temperature Form ◽  
Reversible Phase

At 228 K crystals of ZnI2(dmf)2 show a reversible phase transition which does not disrupt the lattice. Above the transition temperature the space group is C2/c and the cell contains eight symmetrically equivalent molecules. Cooling to below the transition temperature has little effect on the cell parameters or on the Zn- and I-atom positions, but the space group is now P21/n and the asymmetric unit comprises two conformationally different molecules. These arise from cooperative rotations of either ca +25 or −43° about the Zn—O bond of one of the dmf ligands in the high-temperature form. This displacive transition involves large movements of some atoms. The corresponding chloride and bromide are isomorphous with the higher temperature C2/c form, but it is only with the iodide that the weaker intermolecular forces permit the unusual phase change. The transition has been followed by differential scanning calorimetry, which gives an enthalpy change of 1.44 (5) kJ mol−1.

Thermal, spectroscopic and structural analysis of a thermosalient phase transformation in tapentadol hydrochloride

2019 ◽  
Vol 75 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Pablo Gaztañaga ◽  
Ricardo Baggio ◽  
Emilia Halac ◽  
Daniel R. Vega
Keyword(s):  
Phase Transformation ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Covalent Interaction ◽  
Cell Parameters ◽  
Reversible Phase Transition ◽  
Abrupt Changes ◽  
Structural Differences ◽  
Interaction Scheme ◽  
Reversible Phase

Presented herein are detailed optical, thermal, spectroscopic and structural analyses of the phase transformation occurring in tapentadol hydrochloride (C14H24NO+·Cl−), a phenomenon already reported [Fischer et al. (2006); Patent: WO 2006000441 A2]. The thermal behaviour of the compound was studied using single-crystal X-ray diffraction, differential scanning calorimetry and Raman scattering measurements. The compound undergoes a first-order reversible phase transition at T heat = 318.0 (1) K, T cool = 300.0 (1) K, as assessed by the coexistence of both phases in the vicinity of the transition and the abrupt changes observed in the unit-cell parameters with temperature. The process is accompanied by clear thermosalient behaviour, with a conspicuous movement of the samples. On cooling, the transformation leads from a P212121 symmetry (Z′ = 1) to P21, with an abrupt change in β [90 ↔ 94.78 (1)°] and duplication of the asymmetric unit contents (Z′ = 2). The main structural differences observed across the transition are extremely small, with almost no changes in the stronger, non-covalent interaction scheme involving the `conventional' (N—H...Cl, O—H...Cl) hydrogen bonds.

scholarly journals Reversible phase transition in laser-shocked 3Y-TZP ceramics observed via nanosecond time-resolved x-ray diffraction

2012 ◽  
Vol 111 (5) ◽  
pp. 053526 ◽  
Author(s):  
Jianbo Hu ◽  
Kouhei Ichiyanagi ◽  
Hiroshi Takahashi ◽  
Hiroaki Koguchi ◽  
Takeaki Akasaka ◽  
...  
Keyword(s):  
Phase Transition ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Reversible Phase Transition ◽  
Reversible Phase

A low temperature reversible phase transition for 1,1'-bis-(ferrocenyldimethylsilyl)ferrocenylene, (η5-FcSiMe2C5H4)2Fe, an oligomeric model for silyleneferrocenylene polymers

2000 ◽  
Vol 78 (11) ◽  
pp. 1511-1518 ◽  
Author(s):  
Mikhail Yu Antipin ◽  
Ivan I Vorontsov ◽  
Irene I Dubovik ◽  
Vladimir Papkov ◽  
Francisco Cervantes-Lee ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Phase Space ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Space Group ◽  
Reversible Phase Transition ◽  
Reversible Phase

We have reinvestigated the solid state structure of 1,1'-bis-(ferrocenyldimethylsilyl)ferrocenylene, (η5-FcSiMe2C5H4)2Fe, Fc = (η5-C5H5)Fe(η5-C5H4). Using a DSC technique we observed a reversible phase transition for this compound at 169(3)K with ΔH = 1.1 kJ/mol, and ΔS = 6.54 J/mol K. A single crystal X-ray diffraction study has demonstrated that this phase change involves a transformation from a high temperature phase, space group P21/c, Z = 2, to a triclinic low temperature phase, space group P[Formula: see text], Z = 4. The phase transition involves the loss of the molecular crystallographic center of symmetry and rotations about the terminal and central cyclopentadienyl ring pairs. The results are compared to those reported for ferrocene.Key words: solid state, phase transition, silyleneferrocenylene.

An unprecedented structural phase transition in struvite-type compounds: dimorphism of KMgAsO4(H2O)6

2019 ◽  
Vol 74 (1) ◽  
pp. 9-14
Author(s):  
Matthias Weil
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Diffraction Data ◽  
Structural Changes ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Continuous Type ◽  
Reversible Phase Transition

AbstractThe crystal structure of struvite-type KMgAsO4(H2O)6 has been redetermined from single crystal X-ray diffraction data at room temperature. The previous structure model based on powder X-ray diffraction data was confirmed with higher precision and accuracy and with all hydrogen atoms located. KMgAsO4(H2O)6 undergoes a reversible phase transition of the continuous type at 263(2) K, changing the symmetry from orthorhombic to monoclinic. The corresponding Pnm21→P1121 symmetry reduction is of a translationengleiche type with index 2 and was monitored by temperature-dependent powder X-ray diffraction measurements. Such a phase transition is unprecedented for struvite-type compounds. The crystal structure of the monoclinic polymorph was determined from a two-domain crystal at 100 K. Except for the motion of one of the water molecules towards stronger hydrogen-bonding interactions, structural changes between the two polymorphs are small.

Die quaternären Systeme ZnAl2S4-ZnGa2S4, ZnAl2S4-CdAl2S4 und ZnAl2S4-ZnAl2Se4. Röntgenographische und schwingungsspektroskopisehe Untersuchungen / Investigation of the Quaternary Systems ZnAl2S4-ZnGa2S4, ZnAl2S4-CdAl2S4 and ZnAl2S4-ZnAl2Se4 by X-Ray Diffraction and Vibrational Spectroscopy

1983 ◽  
Vol 38 (3) ◽  
pp. 311-316 ◽  
Author(s):  
H. Haeuseler ◽  
A. Cansiz
Keyword(s):  
Phase Transition ◽  
Vibrational Spectroscopy ◽  
Solid Solutions ◽  
Homogeneity Range ◽  
Binary Systems ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reversible Phase Transition ◽  
Reversible Phase ◽  
Fir Spectra

The quasi-binary systems Zn1-xCdxAl2S4, ZnAl2(1-x)Ga2xS4 and ZnAl2S4(1-x)Se4x have been investigated by X-ray diffraction and vibrational spectroscopy. In the spinel ZnAI2S4 up to 20% of Zn can be replaced by Cd. In the two other systems, ZnAl2S4 has no detectable homogeneity range. The thiogallate phases have much broader ranges of homogeneity. The compositions of the compounds at the phase boundary of the thiogallate phase are Zn0.4Cd0.6Al2S4, ZnGa0.4Al1.6S4, and ZnAl2S2.8Se1.2. At approximately 950 °C ZnAl2Se4 undergoes a reversible phase transition to a wurtzite-type structure. This phase transition is also observed for the solid solutions ZnAl2S4(1-x)Se4x; with 1.0 > x > 0.3. The FIR spectra are discussed.

scholarly journals A Reversible Phase Transition of 2D Coordination Layers by B–H∙∙∙Cu(II) Interactions in a Coordination Polymer

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3204 ◽  
Author(s):  
Lei Gan ◽  
Pol G. Fonquernie ◽  
Mark E. Light ◽  
Gantulga Norjmaa ◽  
Gregori Ujaque ◽  
...  
Keyword(s):  
Phase Transition ◽  
Coordination Polymer ◽  
Thermal Activation ◽  
Bet Surface Area ◽  
Co2 Uptake ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reversible Phase Transition ◽  
Open Metal Sites ◽  
Reversible Phase

Materials that combine flexibility and open metal sites are crucial for myriad applications. In this article, we report a 2D coordination polymer (CP) assembled from CuII ions and a flexible meta-carborane-based linker [Cu2(L1)2(Solv)2]•xSolv (1-DMA, 1-DMF, and 1-MeOH; L1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane). 1-DMF undergoes an unusual example of reversible phase transition on solvent treatment (i.e., MeOH and CH2Cl2). Solvent exchange, followed by thermal activation provided a new porous phase that exhibits an estimated Brunauer-Emmett-Teller (BET) surface area of 301 m2 g−1 and is capable of a CO2 uptake of 41 cm3 g−1. The transformation is reversible and 1-DMF is reformed on addition of DMF to the porous phase. We provide evidence for the reversible process being the result of the formation/cleavage of weak but attractive B–H∙∙∙Cu interactions by a combination of single-crystal (SCXRD), powder (PXRD) X-ray diffraction, Raman spectroscopy, and DFT calculations.

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