scholarly journals Synthesis, Structure, and Dielectric Properties of (3-Nitroanilinium) (18-Crown) (PF6)

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1028
Author(s):  
Le Wang ◽  
Liu-lei Qin ◽  
Yang Liu ◽  
Peng Wang ◽  
Hui-ting Xu ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Structural Phase ◽  
Dielectric Measurements ◽  
Slow Evaporation ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
One Dimensional ◽  
X Ray ◽  
Potential Energy Calculations

(3-Nitroanilinium) (18-crown) (PF6) (1), which is an organic-inorganic hybrid containing one-dimensional chains of hydrogen-bonded supramolecular cations, was synthesized under slow evaporation conditions and subjected to differential scanning calorimetry, temperature-dependent dielectric measurements, and variable-temperature single-crystal X-ray diffraction analysis. These analyses revealed the occurrence of a reversible structural phase transition [P21/n P21/c] at 223 K and a dielectric anomaly, which, based on the results of structural analysis and potential energy calculations, was attributed to the synergistic effect between the pendulum-like motion of the nitro group in the supramolecular cation, (3-nitroanilinium)(18-crown), and the order-disorder motion of PF6− anions.

scholarly journals Inorganic Anion Regulates the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

2017 ◽  
Author(s):  
Yuan Chen ◽  
Yang Liu ◽  
Binzu Gao ◽  
Chuli Zhu ◽  
Zunqi Liu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Variable Temperature ◽  
Structural Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Space Group ◽  
X Ray

Two novel inorganic–organic hybrid supramolecular assemblies, namely, (4-HNA)(18-crown-6)(HSO4) (1) and (4-HNA)2(18-crown-6)2(PF6)2(CH3OH) (2) (4-HNA = 4-nitroanilinium), were synthesized and characterized by infrared spectroscopy, single X-ray diffraction, differential scanning calorimetry (DSC), and temperature-dependent dielectric measurements. The two compounds underwent reversible phase transitions at about 255 K and 265 K, respectively. These phase transitions were revealed and confirmed by the thermal anomalies in DSC measurements and abrupt dielectric anomalies during heating. The phase transition may have originated from the [(4-HNA)(18-crown-6)]+ supramolecular cation. The inorganic anions tuned the crystal packings and thus influenced the phase-transition points and types. The variable-temperature X-ray diffraction data for crystal 1 revealed the occurrence of a phase transition in the high-temperature phase with the space group of P21/c and in the low-temperature phase with the space group of P21/n. Crystal 2 exhibited the same space group P21/c at different temperatures. The results indicated that crystals 1 and 2 both underwent an iso-structural phase transition.

Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Simon Engelbert ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Driving Force ◽  
Room Temperature ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

scholarly journals Growth, Optical and Microhardness Studies of 2-Aminothiazole- 3, 5-Dinitrobenzoic Acid Complex

2019 ◽  
Vol 1 (1) ◽  
pp. 42-45
Author(s):  
Tamiloli Devendhiran ◽  
Keerthika Kumarasamy ◽  
Mei–Ching Lin
Keyword(s):  
Room Temperature ◽  
Grown Crystal ◽  
Optical Transmittance ◽  
Dielectric Measurements ◽  
Slow Evaporation ◽  
X Ray Diffraction ◽  
Acid Complex ◽  
X Ray ◽  
Slow Evaporation Technique ◽  
Evaporation Technique

Single crystals of 2-Aminothiazole 3,5-Dinitrobenzoic acid has been synthesized and good quality optical crystals were grown by slow evaporation technique at room temperature. The crystallinity nature of the grown crystal was confirmed from X-ray diffraction technique. An optical transmittance study was also carried out by UV – Vis spectra. FTIR spectra confirm the presence of functional groups in the grown crystal. The dielectric measurements were carried out in the range of 50Hz to 2MHz. The dielectric constant was seen to increase exponentially at lower frequencies. The microhardness studies were carried out using Vickers hardness indenter. Photoluminescence study shows that maximum emission occurs at 435nm.

Using Ultrathin-Film, Modulated Composites to Control the Reaction Mechanism of Ternary Compound Formation

1991 ◽  
Vol 238 ◽  
Author(s):  
Loreli Fister ◽  
David C. Johnson
Keyword(s):  
Ternary Compound ◽  
Reaction Pathway ◽  
Experimental Parameter ◽  
Ultrathin Film ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Compound Formation ◽  
One Dimensional ◽  
X Ray ◽  
Made In

ABSTRACTA predictable, controllable approach to the synthesis of ternary compounds through known intermediates is presented. Thin and ultrathin film superlattices were made in the Mo-Se, Cu-Se and Mo-Cu systems. Differential scanning calorimetry, low- and high-angle x-ray diffraction were used to assess the interdiffusion and nucleation reactions between elemental layers in these one-dimensional crystals. The experimental parameter modulation distance was used to influence the interfacial reactions. The results from each binary system were then used to predict the reaction pathway in the synthesis of a ternary compound, Cu2Mo6Se8. Superlattices with two different lengthscales were investigated. In the first, only one intermediate, MoSe2 which typically crystallizes at ∼200'C, is observed prior to the crystallization of Cu2Mo6Se8. In the second, no crystalline intermediates are observed below 6000 C.

Molecular motions of a tetraphenylethylene-derived AIEgen directly monitored through in situ variable temperature single crystal X-ray diffraction

CrystEngComm ◽  
2021 ◽  
Author(s):  
Wei Meng ◽  
Lin Du ◽  
Lin Sun ◽  
Lian Zhou ◽  
Xiaopeng Xuan ◽  
...  
Keyword(s):  
Single Crystal ◽  
Phenyl Ring ◽  
Functional Group ◽  
Variable Temperature ◽  
Molecular Motions ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Conformation Changes

One organic functional group was introduced to distinguish the four phenyl ring of tetraphenylethylene, and the In situ temperature-dependent crystal structures were determined to exhibit the conformation changes of tert-butyl...

The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2]

2019 ◽  
Vol 75 (6) ◽  
pp. 1144-1151
Author(s):  
Tamara J. Bednarchuk ◽  
Wolfgang Hornfeck ◽  
Vasyl Kinzhybalo ◽  
Zhengyang Zhou ◽  
Michal Dušek ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Room Temperature ◽  
Variable Temperature ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Hybrid Compound ◽  
Space Group ◽  
X Ray

The organic–inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling–heating cycles over the temperature ranges 290–100–290 K. In the room-temperature phase (I), space group C2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinic X2/c(α,0,γ)0s superspace group (where X is ½, ½, 0, ½) with modulation wavevectors q = (0.2943, 0, 0.5640) and q = (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinic P{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.

scholarly journals Temperature-dependent structural change of 1D ice, water nanopipe, in crystal

2014 ◽  
Vol 70 (a1) ◽  
pp. C565-C565
Author(s):  
Akio Wakahara ◽  
Yasuko In
Keyword(s):  
Structural Change ◽  
Water Molecules ◽  
Fold Axis ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Crystal Axis ◽  
One Dimensional ◽  
X Ray ◽  
Ice Water ◽  
Cluster Unit

One-dimensional ice (1D ice) is formed in the single crystal prepared by mixing tryptophan and pyridoxal-5-phosphate in aqueous solution. This ice (diameter=1.649nm at 90K) consists of a hollow-type nanowire, viz., water nanopipe, and the structure is constructed by piling up the cluster unit of 15 water molecules, five independent waters (W1,--W5) of which are arranged around a 3-fold axis. As can be seen from the side view of this nanopipe, a tape structure is made of the continuous chair-type six-membered rings running parallel to the longest crystal axis, and its three tapes arranged around 3-fold axis are linked together via two kinds of hydrogen bonds of W5 (W5-W2 and W5-W4). Thus, the overall structure of this 1D ice could be described as three-square nanometric column. In order to investigate the temperature-dependent structural change of 1D ice, the crystal structure was refined using the X-ray diffraction data measured at different temperature between 90K and 293K. From these results, it was confirmed that the nanopipe structure is stable under 200K, but W5 and W4 disappear at 220K and 273K, respectively, indicating the importance of W5 for the structural stability of 1D ice.

Star mesogens — Synthesis and structural characterization using 1D and 2D solution NMR techniques and mesophase characterization

2013 ◽  
Vol 91 (3) ◽  
pp. 196-205 ◽  
Author(s):  
A. Shanavas ◽  
T. Narasimhaswamy ◽  
B.V.N. Phani Kumar ◽  
A. Sultan Nasar
Keyword(s):  
Chain Length ◽  
Liquid Crystalline ◽  
Variable Temperature ◽  
2D Nmr ◽  
Smectic Layer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Techniques ◽  
Terminal Chain

Novel star mesogens based on trimesic acid and symmetrical side arm cores with terminal alkoxy groups were synthesized via a divergent approach. The central core and side arms were connected through alkyl spacers. All the synthesized mesogens and their intermediates were characterized thoroughly using Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), 13C NMR, and mass spectrometers. One representative mesogen was subjected to the two-dimensional (2D) NMR experiments to ascertain the structure of the mesogens. The mesophase characterization was carried out using hot-stage optical polarizing microscopy (HOPM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques. Many of the molecules with an ethyloxy spacer were found to be nonmesogenic, whereas all the molecules with a butyloxy spacer showed liquid crystalline phases. The increase of terminal chain length decreased the transition temperatures. The nematic phase was observed for the mesogens with short terminal chain length, whereas smectic polymorphism was observed on increasing the terminal chain length. The results of a variable temperature powder X-ray diffraction of the representative sample support the smectic layer ordering.

Tautomeric polymorphism of the neuroactive inhibitor kynurenic acid

2019 ◽  
Vol 75 (6) ◽  
pp. 793-805
Author(s):  
Dorota Pogoda ◽  
Jan Janczak ◽  
Sylwia Pawlak ◽  
Michael Zaworotko ◽  
Veneta Videnova-Adrabinska
Keyword(s):  
Solid State ◽  
Kynurenic Acid ◽  
Variable Temperature ◽  
Neurological Diseases ◽  
Crystal Form ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Kynurenic acid (KYN; systematic name: 4-hydroxyquinoline-2-carboxylic acid, C10H7NO3) displays a therapeutic effect in the treatment of some neurological diseases and is used as a broad-spectrum neuroprotective agent. However, it is understudied with respect to its solid-state chemistry and only one crystal form (α-KYN·H2O) has been reported up to now. Therefore, an attempt to synthesize alternative solid-state forms of KYN was undertaken and six new species were obtained: five solvates and one salt. One of them is a new polymorph, β-KYN·H2O, of the already known KYN monohydrate. All crystal species were further studied by single-crystal and powder X-ray diffraction, thermal and spectroscopic methods. In addition to the above methods, differential scanning calorimetry (DSC), in-situ variable-temperature powder X-ray diffraction and Raman microscopy were applied to characterize the phase behaviour of the new forms. All the compounds display a zwitterionic form of KYN and two different enol–keto tautomers are observed depending on the crystallization solvent used.

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