Phase Transition in Hydrogen-Bonded 1-Adamantane-methanol

Crystal Growth & Design, 2017

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Crystal Growth & Design, 2014

The polymorphism of 2-adamantanone (C 10 H 14 O) has been investigated by means of X-ray diffraction and high-pressure thermal analysis. The intricate behavior of the low-temperature crystalline phases has been disentangled. The stable phase has been found to be orthorhombic (Cmc2 1 , Z=4), fully ordered, with lattice parameters a=6.8884(18) Å, b= 10.830(3) Å, c=10.658(3) Å, V/Z=198.8(1) Å 3. The metastable phase was determined to be monoclinic (P2 1 /c, Z=4) with lattice parameters a=6.5920(17) Å, b= 11.118(3) Å, c=12.589(3) Å, = 118.869(11) o , V/Z=202.0(1) Å 3. The pressure-temperature phase diagram irrefutably shows the stability relation between both phases and, accordingly, the long-time unknown polymorphic behavior is now revealed and gives coherent physical explanation of the literature published so far.

Journal of Physical Chemistry B, 2014

The polymorphism of two 2 X adamantane derivatives, X = Cl, X = Br, has been studied by X ray powder diffraction and normal and high pressure (up to 300 MPa) differential scanning calorimetry. 2 Br adamantane displays a low temperature orthorhombic phase (space group P2 1 2 1 2 1 , Z = 4) and a high temperature plastic phase (Fm3m, Z = 4) from 277.9 ± 1.0 K to the melting point at 413.4 ± 1.0 K. 2 Cl adamantane presents a richer polymorphic behavior through the temperature range studied. At low temperature it displays a triclinic phase (P1, Z = 2), which transforms to a monoclinic phase (C2/c, Z = 8) at 224.4 ± 1.0 K, both phases being ordered. Two high temperature orientationally disordered are found for this compound, one hexagonal (P6 3 /mcm, Z =6)at ca. 241 K and the highest one, cubic (Fm3m, Z = 4), being stable from 244 ± 1.0 K up to the melting point at 467.5 ± 1.0 K. No additional phase appears due to the increase in pressure within the studied range. The intermolecular interactions are found to be weak, especially for the 2 Br adamantane compound for which the Br•••Br as well as C−Br•••H distances are larger than the addition of the van der Waals radii, thus confirming the availability of this compound for building up diamondoid blocks.

Low Temperature Physics, 2015

Heat transport mechanisms present in 2-adamantanone and 1-cyanoadamantane crystals were investigated in a broad temperature range. To characterize scattering processes, thermal conductivity and heat capacity measurements were carried out. A particular care was paid to the cooling rate of specimen which influenced the thermal history of the samples. The experimental results led to a conclusion that under slow cooling the thermal conductivity reaches the highest values and resembles the behavior of ordered molecular crystals. As for fast cooling, the "quenching" resulted in changes in both the structure and the temperature dependence of the thermal conductivity, the latter resembling that of amorphous solids. In heat capacity measurements the thermal history made on samples did not reflect the preliminary findings known from thermal conductivity results, which could imply that the observed mechanisms are more complex. PACS: 44.35.+c Heat flow in multiphase systems; 61.43.-j Disorder solids; 65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.

Phys. Chem. Chem. Phys., 2016

Bimodal reorientational relaxations along the twofold (α) and threefold (α′) axes of the disordered Phase II (P4̄21c) of 1-F-adamantane.

Canadian Journal of Chemistry, 1993

The order–disorder behaviour of 1-chloroadamantane (1-C10H15Cl) has been investigated by differential scanning calorimetry, and variable-temperature vibrational and 13C NMR spectroscopy. The factor group splittings in the vibrational spectra are in accord with the known crystal structures of the two phases. The 13C spin-lattice relaxation times and dipolar dephasing measurements have been analysed to give the barriers to rotation in both phases and to determine the nature of the rotations in each phase. In the ordered phase, the motion is limited to rotation about the molecular axis. In the disordered phase, additional motions occur about axes through the tertiary carbon atoms.

Thermochimica Acta, 2014

Both enantiomeric (S-) and racemic (RS-) forms of 2-(2-nitro-1-phenylethyl)-1,3diphenyl-propane-1,3-dione (1) have been obtained from the same reaction media by fractional crystallization from toluene. First the racemic compound, (R,S)-1 has been precipitated (mp. 159.7°C), then, from the filtrate, its chiral form, (S)-1 (mp. 135.6°C) has crystallized. The absolute molecular configuration (S) and crystal structure of the latter one, which crystallizes in the orthorhombic crystal system (space group P2 1 2 1 2 1 (19), a = 10.6377(2) Å, b = 11.4348(2) Å, c = 31.3543(6) Å, Z = 8, Z' = 2), has been solved by single crystal X-ray diffraction (R = 0.0377). Powder XRD pattern of the racemic precipitation, (R,S)-1 could be indexed in the orthorhombic space group Pbca (61) (a = 22.18(7) Å, b = 17.08(3) Å, c = 9.96(3) Å, Z = 8, Z' = 1). Differences in the secondary bonding interactions and in crystal stability of the chiral and racemic compound are evaluated on the basis of their FT-IR spectrum, melting point and enthalpy of fusion. The eutectic type binary melting phase diagram of enantiomeric and racemic compounds are constructed based on the Differential Scanning Calorimetric (DSC) measurements and calculation of the liquidus curves according to the combination of the simplified Schröder-van Laar and Prigogine-Defay equations.

Journal für Praktische Chemie/Chemiker-Zeitung, 1997

The influence of the chemical structure of rigid starshaped multipodes composed of an adamantane central core and short rigid branches on the glass formation and crystallisation is analysed. It was found that esters of 1,3,5,7-adamantanetetracarboxylic acid with various phenols (3a-c) and esters of 1,3,5,7-tetrahydroxyadamantane with various benzoic acid derivatives (4a-c) display both crystalline and glassy states with high glass transition temperatures and melting temperatures. These quantities strongly depend on the restriction of the rotational motions about the ester groups connecting the core and the branches.

Chemical Physics Letters, 2000

We report angle dispersive X-ray diraction (ADXRD) measurements on adamantane carried out at SPRING-8 to the pressures of 25 GPa. The tetragonal phase observed at 0.5 GPa remains stable up to 12.5 GPa. In this pressure range the intermolecular hydrogen separation reduces from 2.37 to1.87 # A with relative angle of rotation of the two molecules increasing from 8X5°to 10X5°in agreement with values from energy minimization. At 16 GPa, the diraction pattern could be indexed either by a tetragonal or a monoclinic cell. Beyond 22 GPa only monoclinic cell indexes the patterns. The present ®ndings corroborate the earlier Raman results. Ó

Journal of Solid State Chemistry, 1997

The experimental two-component phase diagram between the orientationally disordered crystals 2-amino-2-methyl-1,3-propanediol (AMP) and 1,1,1-tris(hydroxymethyl)propane (PG) has been established from room temperature to the liquid state using thermal analysis and X-ray powder diffraction techniques. The intermolecular interactions in the orientationally disordered mixed crystals of the mentioned system and other related twocomponent systems are discussed by analyzing the evolution of the packing coefficient as a function of the the composition. A thermodynamic analysis of the presented phase diagram and the redetermined AMP/NPG (2,2-dimethyl-1,3-propanediol) is reported on the basis of the enthalpy-entropy compensation theory.