Temperature-Dependent Phase Transitions in Two Crystalline Host–Guest Complexes Derived from Mandelic Acid

1998 ◽  
Vol 54 (1) ◽  
pp. 82-93
Author(s):  
O. Hager ◽  
C. Foces-Foces ◽  
A. L. Llamas-Saiz ◽  
E. Weber
Keyword(s):  
Phase Transitions ◽  
Solid State ◽  
Low Temperature ◽  
Inclusion Complexes ◽  
Mandelic Acid ◽  
Temperature Dependent ◽  
Crystallographic Symmetry ◽  
Crystal Packings

The supramolecular inclusion complexes of two mandelic acid-based chiral host compounds with dimethylformamide (DMF), (1) and (2), show reversible solid–solid state phase transitions upon lowering the temperature. For both inclusion complexes, the low- [(1a) and (2a) at 170 K] and the high- [(1b) at 250 and (2b) at 270 K] temperature structures were solved. (R)-1,1-Bis(4-tert-butylphenyl)-2-phenylethan-1,2-diol–dimethylformamide (1/1), C28H34O2.C3H7NO (1a), T = 170 K, monoclinic, P21, a = 14.4530 (14), b = 6.0540 (2), c = 16.1117 (14) Å, β = 105.332 (7)°, V = 1359.6 (2) Å3, Z = 2, D x = 1.162 g cm−3; (1b), T = 250 K, monoclinic, P21, a = 24.8110 (20), b = 6.0739 (2), c = 18.8645 (10) Å, β = 98.100 (6)°, V = 2814.5 (3) Å3, Z = 4, D x = 1.123 g cm−3. (R)-1,1-Bis(4-tert-butylphenyl)-2-(4-methylphenyl)ethan-1,2-diol–dimethylformamide (1/1), C29H36O2.C3H7NO (2a), T = 170 K, monoclinic, P21, a = 24.4457 (38), b = 5.9519 (6), c = 20.4609 (38) Å, β = 101.95 (1)°, V = 2912.5 (8) Å3, Z = 4, D x = 1.117 g cm−3; (2b), T = 270 K, triclinic, P1, a = 14.4172 (28), b = 6.0303 (4), c = 17.5636 (56) Å, α = 88.74 (1), β = 101.43 (2), γ = 93.13 (1)°, V = 1494.4 (6) Å3, Z = 2, D x = 1.088 g cm−3. The low-temperature forms have the higher crystallographic symmetry. In (1b) half of the DMF guests are twisted by 45.0° with respect to those in (1a). A comparative discussion of the four crystal packings is presented.

DYNAMICS OF THE LOW TEMPERATURE GLASS-LIKE PHASE IN MANGANITES

2003 ◽  
Vol 17 (04n06) ◽  
pp. 842-847
Author(s):  
C. CASTELLANO ◽  
F. CORDERO ◽  
R. CANTELLI ◽  
M. FERRETTI
Keyword(s):  
Distribution Function ◽  
Phase Transitions ◽  
Quantitative Analysis ◽  
Low Temperature ◽  
Imaginary Part ◽  
Lattice Relaxation ◽  
Relaxation Processes ◽  
Temperature Dependent ◽  
Energy Barriers ◽  
Nanostructured State

We report anelastic spectroscopy measurements of La 1-x Ca x MnO 3 performed in order to better characterize the nature of the phase transitions and microscopic lattice relaxation processes present in these materials. A peak in the imaginary part of the elastic susceptibility presents a behaviour typical of inhomogeneous and glass-like systems. We have performed a quantitative analysis calculating the temperature dependent distribution function of the energy barriers of the fluctuations characterizing this nanostructured state.

scholarly journals Selected solid-state behaviour of three di-tert-butyl-substituted N-salicylideneaniline derivatives: temperature-induced phase transitions and chromic behaviour

2021 ◽  
Vol 77 (10) ◽  
pp. 659-667
Author(s):  
Helen E. Mason ◽  
Judith A. K. Howard ◽  
Hazel A. Sparkes
Keyword(s):  
Phase Transition ◽  
Hydrogen Bond ◽  
Phase Transitions ◽  
Solid State ◽  
Low Temperature ◽  
Schiff Bases ◽  
Photochromic Properties ◽  
Keto Form ◽  
Single Crystal Structures ◽  
State Behaviour

The synthesis, single-crystal structures and chromic behaviour of three related Schiff bases, namely, (E)-2,4-di-tert-butyl-6-{[(4-fluorophenyl)imino]methyl}phenol, C21H26FNO, 1, (E)-2,4-di-tert-butyl-6-{[(4-chlorophenyl)imino]methyl}phenol, C21H26ClNO, 2, and (E)-6-{[(4-bromophenyl)imino]methyl}-2,4-di-tert-butylphenol, C21H26BrNO, 3, are reported. Two polymorphs of 1 were obtained, which were found to have different photochromic properties. Schiff bases 2 and 3 were found to be isostructural and underwent a phase transition upon cooling which was attributed to the dynamic disorder in one of the tert-butyl groups resolving at low temperature. All of the structures were found to exist in the enol rather than the keto form based on the C—O(H) and imine C=N bond lengths, and contained an intramolecular O—H...N hydrogen bond alongside weaker intermolecular C—H...O contacts.

Conformational Change of the Cation−Anion Pair of an Ionic Liquid Related to Its Low-Temperature Solid-State Phase Transitions

2004 ◽  
Vol 108 (26) ◽  
pp. 9246-9250 ◽  
Author(s):  
Sándor Kunsági-Máté ◽  
Beáta Lemli ◽  
Géza Nagy ◽  
László Kollár
Keyword(s):  
Ionic Liquid ◽  
Phase Transitions ◽  
Solid State ◽  
Low Temperature ◽  
Conformational Change

Solid-state behaviors of imines: Colossal biaxial positive thermal expansion, motion capability, and phase transitions

CrystEngComm ◽  
2021 ◽  
Author(s):  
Navkiran Kaur Juneja ◽  
Ethan Zahid ◽  
Daniel K Unruh ◽  
Kristin M Hutchins
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Phase Transitions ◽  
Solid State ◽  
Single Component ◽  
Temperature Dependent ◽  
Static Disorder ◽  
Pedal Motion

Pedal motion or static disorder in single-component solids containing imine groups is demonstrated. Unique solid-state behaviors including colossal biaxial positive thermal expansion in one solid and a temperature-dependent phase transition...

Temperature-Dependent Solid-state Luminescence and Reversible Phase Transition of (n-Bu4N)[Au(SC6H3-3,5-Me2)2]

2003 ◽  
Vol 32 (11) ◽  
pp. 1002-1003 ◽  
Author(s):  
Seiji Watase ◽  
Takayuki Kitamura ◽  
Nobuko Kanehisa ◽  
Masami Nakamoto ◽  
Yasushi Kai ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Temperature Dependent ◽  
Reversible Phase Transition ◽  
Reversible Phase ◽  
State Luminescence

scholarly journals Host–Guest Inclusion Complexes of Essential Oils with Strong Antibacterial and Antifungal Features in Beta-Cyclodextrin for Solid-State Pharmaceutical Applications

2021 ◽  
Vol 11 (14) ◽  
pp. 6597
Author(s):  
Aldo Arrais ◽  
Marta Manzoni ◽  
Alessia Cattaneo ◽  
Valentina Gianotti ◽  
Nadia Massa ◽  
...  
Keyword(s):  
Solid State ◽  
Essential Oil ◽  
Essential Oils ◽  
Inclusion Complexes ◽  
Production Costs ◽  
Good Tolerance ◽  
Actual Application ◽  
Beta Cyclodextrin ◽  
Ft Ir ◽  
Antibacterial And Antifungal

Essential oils are widely recognized as natural alternatives to pharmaceutical antibacterial and antifungal agents. With respect to standard pharmaceutics, the advantages of essential oils are their (i) low production costs, (ii) lack of chemical and biochemical drawbacks that are intrinsic to the synthetic production process and (iii) good tolerance by humans. On the other hand, the liquid nature of essential oils poses concerns about their actual application in different therapeutic issues regarding their persistence and the ability to control or prolong drug release. In this study, two essential oils from oregano and winter savory showing antibacterial and antifungal features were complexed in a solid state with beta-cyclodextrin. Host–guest inclusion complexes were characterized using FT-IR spectroscopy, ESI-MS and GC-MS techniques. Manyfold terpenic and non-terpenic components of the oils could be observed and unambiguously identified as being included inside the carbohydrate hosts. Many of them provided a specific biocidal action. Indeed, essential oil host–guest inclusion products were tested against two Candida species and an S. aureus reference strain, showing that the oils effectively maintained their liquid performances. Solid-state tablets of the essential oil inclusion complexes embedded in polyvinylpyrrolidone could be obtained. These results pave the way for the solid-state application of essential oils in antibacterial and antifungal pharmaceutical treatments.

On the nature of the phase transitions of aluminosilicate perrhenate sodalite

2020 ◽  
Vol 235 (6-7) ◽  
pp. 213-223
Author(s):  
Hilke Petersen ◽  
Lars Robben ◽  
Thorsten M. Gesing
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Decomposition Temperature ◽  
Second Phase ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Structure Property Relationships ◽  
Heat Capacity Measurements

AbstractThe temperature-dependent structure-property relationships of the aluminosilicate perrhenate sodalite |Na8(ReO4)2|[AlSiO4]6 (ReO4-SOD) were analysed via powder X-ray diffraction (PXRD), Raman spectroscopy and heat capacity measurements. ReO4-SOD shows two phase transitions in the investigated temperature range (13 K < T < 1480 K). The first one at 218.6(1) K is correlated to the transition of dynamically ordered $P\overline{4}3n$ (> 218.6(1 K) to a statically disordered (<218.6(1) K) SOD template in $P\overline{4}3n$. The loss of the dynamics of the template anion during cooling causes an increase of disorder, indicated by an unusual intensity decrease of the 011-reflection and an increase of the Re-O2 bond length with decreasing temperature. Additionally, Raman spectroscopy shows a distortion of the ReO4 anion. Upon heating the thermal expansion of the sodalite cage originated in the tilt-mechanism causes the second phase transition at 442(1) K resulting in a symmetry-increase from $P\overline{4}3n$ to $Pm\overline{3}n$, the structure with the sodalites full framework expansion. Noteworthy is the high decomposition temperature of 1320(10) K.

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.

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