Crystal structures together with enthalpies and temperatures of fusion of two substituted amino acids, N-acetylsarcosinamide (NASarA) and N-acetyl-L-isoleucinamide (NAIA), were determined by single crystal X-ray analysis and differential scanning calorimetry, respectively. The results were compared with those of some analogous amino acid derivatives previously studied. The detailed knowledge of crystallographic parameters is undoubtedly useful for discussing the thermodynamic results and rationalizing the fusion behaviour, owing to the rather poor knowledge of the molecular interactions occurring in the melt.
Authors:Y. P. Liu, Y. Y. Di, W. Y. Dan, and D. H. He
researches are focused on phase transitions of (1-C 12 H 25 NH 3 ) 2 CuCl 4 , (1-C 14 H 29 NH 3 ) 2 CuCl 4 , and (1-C 16 H 33 NH 3 ) 2 CuCl 4 . However, the crystalstructure, lattice potential energy, and some basic thermochemical data of (1-C 8 H 17 NH 3
Authors:Timo Hatanpää, Kaupo Kukli, Mikko Ritala, and Markku Leskelä
thermal analysis (SDTA) measurements and vacuum sublimation experiments. Crystalstructures of four new compounds, [Y(OCEt 2 t Bu) 3 ] 2 , [La(OCEt 2 t Bu) 3 ] 2 , [Gd(OC i Pr 3 ) 3 ] 2 , and [La(OC i Pr 3 ) 3 ] 2 were solved. In addition, some ALD
’s group at Clemson University, in order to correlate CNT’s crystalstructure and chemical activity [ 6 ]. In addition, for the first time, molecular beam scattering data have been collected on CNTs in collaboration with Turro’s group at Columbia University
The effect of certain promoters on TiO2 crystal structure transformation was studied by mean thermal and X-ray analyses. It was found that the addition of rutile nuclei and potassium, phosphorus, zinc, magnesium, and aluminium compounds to hydrated titanium dioxide before calcination process influences on the initial temperature and anatase transformation.
It is well known that by the coordinated action of atoms arranged in rows and planes in the crystal lattice, the motion of
charged particles such as protons, alpha particles and heavier ions can be influenced so that their range in the single crystals
is considerably enhanced in low-index directions. A technique has been developed based on such enhanced penetration (channeling)
of radioactive atoms (220Rn) emitted by recoil with a 100 keV energy from a224Ra point source to record channeling patterns which show the crystal structure. The radioactive recoil atoms impinging from
this source on the surface of a single crystal penetrate deeper in places where their direction of impact is identical with
low index crystal directions and planes. These places can be visualized by autoradiography when having first stripped a thin
layer from the surface corresponding to the random range of the atoms. This technique is generally applicable in close packed
crystals and gives information about the crystal structure of very thin surface layers.
The results of theoretical analysis of the crystal structure and bonding in relation to thermal decomposition process in anhydrous
mercury oxalate are presented. The methods used Bader’s Quantum Theory of Atoms in Molecules formalism with bond order model
(by Cioslowski and Mixon), applied to electron density obtained from ab initio calculations carried out with FP-LAPW Wien2k
package (Full Potential Linearized Augmented Plane Wave Method) and Brown’s Bond Valence Model are described. The analysis
of the obtained results shows that most probably the thermal decomposition process of mercury oxalate should lead to metal
and CO2 as products (as it is experimentally observed). Presented results (as well as the results of our similar calculations carried
out previously for zinc, cadmium silver, cobalt and calcium oxalates) allow us to state that such methods (topological and
structural), used simultaneously in analysis of the crystal structure and bonding properties, provide us with the additional
insight into given compound’s behavior during thermal decomposition process. As a result, these methods can be considered
as valuable supporting tool in the analysis of thermal decomposition process in given compound.
Authors:S. De Angelis Curtis, Krystyna Kurdziel, S. Materazzi, and S. Vecchio
The crystal structure of a manganese(II) 1-allylimidazole complex ([Mn(1-AIm)3(NO3)2], where 1-Aim=1-allylimidazole), was characterized by X-ray diffraction (XRD) using SHELX-97. The thermal behaviour of the
complex was investigated by thermogravimetry (TG) coupled with an FTIR unit. The complex showed a multi-step decomposition
related to the release of the ligand molecules, followed by oxidation. The final residue at 1073 K was found to be manganese(II)
oxide. Evolved gas analysis allowed to prove the oxidative decomposition pattern of the examined complex, initially proposed
by the percentage mass loss data. Finally, a kinetic analysis of the oxidative decomposition steps was made using the Kissinger
equation, while the complex nature of the decomposition kinetics was revealed by the isoconversional Ozawa-Flynn-Wall method.
Authors:T. Sato, F. Ambe, K. Endo, M. Katada, and H. Sano
The crystal structures of oxo-centered trineclear cobalt-iron chloroacetate complex [CoIIFe
O(CH2ClCO2)6(H2O)3]·3H2O (1) was compared with that of previously reported trinuclear iron complex [FeIIFe
O(CH2ClCO2)6(H2O)3]·3H2O (2) which has an isomorphous structure to 1. Compound 1 crystallizes in space group P21/n with Z=4 in a unit cell of a=14.826 (4) Å, b=4.536 (8) Å, c=14.000 (4) Å, =100.32 (2)0 and V=2968 (11) Å3. The structure was refined to R=0.75 and Rw=0.82. The coordination geometries of the three iron atoms are observed equivalent in 1 indicating a static disorder of the position among cobalt and iron atoms. Two distinct FeIII doublets observed in Mössbauer spectra of 1 become an indistinguishable broad doublet by dehydration of crystal water. On the other hand, no significant line-broadening is observed after the dehydration in complex 2. The results indicate that the dehydration in 2 induces a local environmental change reordering of an electronic configuration around iron atoms, whereas the remaining disordering is reflected in Mössbauer spectrum after the dehydration in 1.