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Journal of Structural Chemistry

2012 year, number 5

1.
STRUCTURE and SPECTRa of the molecules of Manganese, Iron, and cobalt trifluorides: A CCSD(T) study in the complete basis set

V. G. Solomonik, A. A. Mukhanov
Keywords: manganese trifluoride, iron trifluoride, cobalt trifluoride, structure of molecules, Jahn-Teller effect, vibrational frequencies, atomization enthalpy, coupled cluster method, extrapolation to the complete basis set limit
Pages: 830-848

Abstract >>
The coupled-cluster singles and doubles with perturbative triples (CCSD(T)) method in triple-, quadruple-, and quintuple-zeta basis sets with extrapolation to the complete basis set limit is used to analyze the properties of MnF3, FeF3, and CoF3 molecules. The relative energies of low-lying electronic states are determined. The Jahn-Teller effect is investigated in the ground electronic state 5E′ of the MnF3 molecule and the first excited electronic state 5E″ of the CoF3 molecule. Geometric parameters, atomization enthalpies, vibrational frequencies, intensities in the infrared and Raman spectra are found with high accuracy. The assignment of the bands observed in the low-frequency region of the IR and Raman spectra of MnF3 and CoF3 molecules are revised.
																								



2.
COMPUTER MODELING OF CHITOSAN ADSORPTION ON A CARBON NANOTUBE

J. Azimov, SH. Mamatkulov, N. Turaeva, B. L. Oxengendler, S. S. Rashidova
Keywords: carbon nanotube, chitosan, adsorption, molecular dynamics
Pages: 849-854

Abstract >>
Molecular dynamics (MD) simulation results for the adsorption process of chitosan oligomer on a carbon nanotube (CNT) are presented. An ab initio DFT calculation is performed to obtain the optimal geometric parameters and charge distribution in chitosan. Then by means of classic molecular dynamics the binding energy of a chitosan molecule with CNT calculated. It is found that the character of the interaction between a chitosan molecule and CNT is non-specific.
																								



3.
HYDROGEN BOND EFFECT ON THE STRUCTURE AND VIBRATIONAL SPECTRA OF COMPLEMENTARY PAIRS OF NUCLEIC ACID BASES. III. GUANINE-CYTOSINE

G. N. Ten, A. A. Yakovleva, V. V. Nechaev, V. I. Baranov
Keywords: guanine, cytosine, complementary base pair, vibrational spectra, hydrogen bond
Pages: 855-864

Abstract >>
Vibrational spectra of the isolated complementary guanine-cytosine pair are calculated at the B3LYP/6-311++G(d,p) level. The hydrogen bond effect on the structure, frequency positions, and intensities of normal vibrations of the pair are analyzed in comparison with the spectra of isolated guanine and cytosine molecules. Characteristic spectral features of the formation of the complementary guanine-cytosine base pair are revealed.
																								



4.
SOLVENT EFFECT IN THE PREPARATION OF IRON(III) AZOMETHINE COMPLEXES BASED ON 4,4′-DODECYLOXYBENZOYLOXYBENZOYL-4-SALICYLIDENE-N′-ETHYL-N-ETHYLENEDIAMINE

M. S. Gruzdev, U. V. Chervonova, A. M. Kolker, A. S. Golubeva
Keywords: azomethines, structure, solvent effect, iron(III) complexes, mass spectrometry, IR spectroscopy
Pages: 865-871

Abstract >>
Mono- and bis-chelate iron(III)-containing complexes with a tridentate azomethine ligand based on n-dodecyloxybenzoic acid ester derivatives with oxybenzoyl-4-salidene-N′-ethyl-N-ethylenediamine with counterions are obtained. The structure of the compounds is determined by IR spectroscopy, elemental analysis, and mass spectrometry (MALDI-ToF MS). It is found that the complexation of iron salts with tridentate ligands in a mixture of solvents (alcohol:benzene) results in the formation of bis-chelate compounds of the composition 1:2 with octahedral packing of iron in the complex, while in pure alcohol solutions, asymmetric mono-chelate complexes are obtained.
																								



5.
CONFORMATIONAL ANALYSIS OF 2-ANTHRYLETHYLENE DERIVATIVES: PHOTOCHEMICAL AND COMPUTATIONAL INVESTIGATION

U. Srinivas, P. Arun kumar, Srinivas Kolupula, K. Bhanuprakash, V. Jayathirtha rao
Keywords: 2-anthryethylene derivatives, photochemical cis-trans isomerization, fluorescence, charge transfer, conformational analysis, theoretical studies
Pages: 872-886

Abstract >>
2-Anthrylethylene derivatives 1E-5E and 1Z are synthesized to study the cis-trans photoisomerization. Interestingly, unlike 9-anthrylethylene derivatives, 2-anthrylethylene derivatives 1E to 5E do not exhibit E (trans) to Z (cis) photoisomerization upon direct and triplet sensitization. One-way Z (cis) to E (trans) photoisomerization of 1Z is found to be very efficient under direct and triplet sensitization conditions, demonstrating the involvement of both singlet and triplet states. 1E-5E exhibits excitation wavelength dependent fluorescence indicating the existence of conformers (rotamers) at room temperature, which is confirmed by fluorescence lifetimes measurements of compounds 1E and 2E. Theoretical studies are carried out at DFT and ab initio methodology and the calculated relative energy difference of the conformers is very small; it ranges between 2.9 kJmol-1 to 6.3 kJmol-1 for both ground and excited states.
																								



6.
CHARACTERIZATION OF HETEROBIMETALLIC AND MIXED-VALENCE COMPLEXES OF MOLYBDENUM(V) DERIVED FROM BIS(2-HYDROXY-1-NAPHTHALDEHYDE)MALONOYLDIHYDRAZONE

A. Kumar, O.B. Chanu, R. Borthakur, R.A. Lal
Keywords: synthesis, characterization, molybdenum(V), heterometal, hydrazone, spectroscopic studies
Pages: 887-895

Abstract >>
Heterobimetallic complexes [UO2MoV(CH2L)(hzd)(H2O)2]n, [ZnMoV(CH2L)(hzd)(H2O)2]n and mixed-valence complexes [MoVIO2MoV(CH2L)(hzd)(H2O)2]n (where hzdH3 = inhH3, n = 1; slhH3, n = 2) are synthesized fr om bis(2-hydroxy-1-naphthaldehyde)malonoyldihydrazone (CH2LH4) and monometallic precursor complexes [Mo(CH2LH2)(hzd)]nH2O (n = 0, 1) in ethanol. The composition of the complexes is established based on the data obtained from the elemental analysis. The structure of the complexes is discussed in the light of data obtained from molar conductance, magnetic moment, electronic, EPR, and IR spectroscopic studies. All complexes have μB values in the range 1.59-1.64 B.M., slightly lower than that required for one unpaired electron. The heterobimetallic complexes show two bands, while mixed-valence complexes show only one band in the visible region assigned to the d-d transition. The g-values decrease in going from uranyl-to-molybdenyl-to-zinc complexes containing the isonicotinoyldiazenido (inh) group, however, no such regular trend is observed in the case of complexes containing the salicyloyldiazenido (slh) group in the coordination sphere. In all complexes, the principal dihydrazone ligand is present in the enol form as a bridging hexadentate ligand in the anti-cis configuration wh ere hydrazide ligands are coordinated to the metal centre as a trinegative bidentate ligand in the diazenido form.
																								



7.
A STUDY OF THE ELECTRONIC STRUCTURE OF PHENYLSILANES BY X-RAY EMISSION SPECTROSCOPY AND QUANTUM CHEMICAL CALCULATION METHODS

T. N. Danilenko, M. M. Tatevosyan, V. G. Vlasenko
Keywords: electronic structure, phenylsilanes, X-ray emission spectroscopy, density functional theory
Pages: 896-903

Abstract >>
The electronic structure of a series of phenylsilanes Ph4-nSiHn (n = 0-3) is studied by X-ray emission spectroscopy and quantum chemical calculations by the density functional theory method. Based on the calculations theoretical X-ray emission SiKβ1 spectra of phenylsilanes Ph4-nSiHn (n = 0-4) are constructed and their energy structure and shape turn out to be well consistent with experiment. The distribution of the electron density of states with different symmetry of Si, C, H atoms are also constructed. An analysis of the obtained X-ray fluorescent SiKβ1 spectra and the distribution of the electron density of states in Ph4Si and Ph3SiH compounds shows that their energy structure is mainly determined by a system of the energy levels of phenyl ligands weakly perturbed by interactions with valence AOs of silicon. In the energy structure of MOs of the PhSiH3 compound, energy orbitals related to t2 and a1 levels of tetrahedral SiH4 are mainly presented.
																								



8.
STRUCTURAL AND THERMODYNAMIC CHARACTERISTICS OF AMIDE SOLVENTS

A. M. Zaichikov
Keywords: internal pressure, intermolecular interactions, structural and thermodynamic characteristics, amide solvents
Pages: 904-911

Abstract >>
The structural and thermodynamic characteristics of amide solvents are calculated with different types of molecular self-assembly through hydrogen bonding. Under a model-based approach, the specific and nonspecific components of the total energy of intermolecular interactions are identified for primary, secondary, and tertiary amides of carboxylic acids. It is found that similarly to water, primary amides have a network of hydrogen bonds and belong to the class of liquids characterized by an increase in nonspecific interactions with temperature. In secondary amides with the chain self-assembly, the contribution of these interactions is practically independent of temperature, and in tertiary amides it decreases with an increase in temperature. The molar values of the specific and nonspecific components are used to analyze the intermolecular interactions and the structural properties of amides with different degrees of N-substitution.
																								



9.
ION SOLVATION OF AQUEOUS SOLUTIONS OF ALKALI, ALKALINE EARTH, AND TRANSITION METAL HALIDES

V. N. Afanas'ev, A. N. Ustinov
Keywords: ion solvation, adiabatic compressibility, coordination compounds, solvation numbers
Pages: 912-921

Abstract >>
The published data on the density and velocity of ultrasound are used to determine the ion solvation parameters of sodium, magnesium, and cobalt chlorides. It is shown that the solvation of typical coordination compounds, such as cobalt chloride, is determined by the same underlying systems and interactions as that of electrolytes with ions of alkali and alkaline earth metals.
																								



10.
POLYMORPHISM OF KNaNbOF5 CRYSTALS

A. D. Vasiliev, N. M. Laptash
Keywords: potassium-sodium oxopentafluoroniobate, crystal structure, O/F order, concomitant polymorphism
Pages: 922-926

Abstract >>
X-ray crystallography is used to analyze the concomitant polymorphism of KNaNbOF5 crystals. The second β-modification of the compound, crystallizing in the tetragonal crystal system is found for the first time: space group P4/nmm, a = 5.9352(2) Å, =8.5487(5) Å, V = 301.14(2) Å3, Z = 2, R1 = 0.0095. Parameters of the orthorhombic noncentrosymmetric structure of the α-phase, previously described by Poeppelmeier et al. (J. Am. Chem. Soc., 129, 13963-13969 (2007)), are refined and a comparative analysis of both structures is performed. The structures are characterized by the complete ordering of oxygen and fluorine atoms, the Nb-O distance in the α-phase (1.738(1) Å) being noticeably longer than that in the β-phase (1.709(2) Å). In β-KNaNbOF5, alternating NbOF5 and NaOF5 octahedra share vertices, while in α-KNaNbOF5, they share both vertices and edges. The existence of the non-polar centrosymmetric β-modification of KNaNbOF5 cancels the assumption of the substantial contribution of potassium cations to the polar structure of α-KNaNbOF5.
																								



11.
CRYSTAL STRUCTURE AND RAMAN SPECTRA OF [Fe(2)6]3+()332

L. S. Skogareva, G. V. Shilov, A. I. Karelin
Keywords: iron(III) perchlorate nonahydrate, crystal structure, Raman spectra
Pages: 927-934

Abstract >>
Single crystal X-ray diffraction is used to study the structure of colorless crystals isolated from the saturated aqueous solution of trivalent iron perchlorate (TIP) in 67.5% perchloric acid. It is found that the compound crystallizes in the trigonal crystal symmetry; parameters of the hexagonal unit cell: a = b = 16.079(2) Å, c = 11.369(2) Å, α = β = 90, γ = 120, space group (S6), Z = 6, ρcalc = 2.021 g/cm3. The structural form of the crystal hydrate is [Fe(2)6]3+()332. The structure contains two independent complex iron cations. Each of them is in the special position but retains the regular octahedral structure: average bond lengths are r(Fe-O) = 1.997(1) Å, ∠O-Fe-O bond angles differ from 90 by only 0.93. Independent [Fe(2)6]3+ cations form short H-bonds (΅ 2.64 Å) with three crystallization water molecules and somewhat longer H-bonds (΅O 2.73 Å) with three anions. The anion is disordered over two positions with occupancies of 0.62(2) and 0.37(2). Both positions correspond to the general position. The outer-sphere crystallization water molecule is characterized by the tetrahedral direction of H-bonds, which it forms with two anions and two independent [Fe(2)6]3+ cations. All water molecules are in the general position. The Raman spectroscopic study of polycrystalline samples reveals weak bands belonging to the internal vibrations of two types of water molecules. The least broad bands are assigned to the transitions of crystallization water molecules whose symmetry is insignificantly lowered by two anion-molecular H-bonds. Anomalously broad bands are assigned to the transitions of a coordinated water molecule whose symmetry is more lowered by intermolecular and anion-molecular H-bonds.
																								



12.
STRUCTURAL CHARACTERIZATION OF A NEW DECAVANADATE COMPOUND WITH ORGANIC MOLECULES AND INORGANIC IONS

S.-Y. Luo, X.-L. Wu, Q.-P. Hu, J.-X. Wang, C.-Z. Liu, Y.-Y. Sun
Faculty of Material Science and Chemistry, China University of Geosciences, Engineering Research Center of Nano-Geo Materials of Ministry of Education
Keywords: decavanadate cluster, three-dimensional array, crystal structure, single crystal X-ray analysis, metal-organic compounds
Pages: 935-940

Abstract >>
A new decavanadate compound V10O28[Co(H2O)6]3(C8H18O6N2S2)2 (I) is synthesized and characterized by single crystal X-ray diffraction, thermogravimetric analysis, FT-IR spectroscopy, and scanning electron microscopy. The sizes of the monoclinic unit cell are as follows: a = 13.2851(16) Å, b = 22.769(3) Å, c = 13.1883(16) Å, β = 117.555(2), V = 3536.7(7) Å3, C2/m space group, Z = 2. The studies revealed that different moieties in the compound show a three-dimensional framework structure, in which {CoO6}, the decavandate cluster anions, and 1,4-piperazinediethanesulfonic acid (PIPES) interact with each other by intermolecular forces and strong hydrogen bonding. Bond valence calculations were used to calculate the valence states of the atoms.
																								



13.
SPECTROSCOPIC CHARACTERIZATION AND CRYSTAL STRUCTURE OF cis-bis(N-(2-BENZOYL)-N′,N′-DIPHENYLTHIOUREATO-k2O,S)NICKEL(II)

H. P??rez, R.S. Corr??a, B. O???reilly, A.M. Plut??n, C.C.P. Silva, Y.P. Mascarenhas
Keywords: nickel(II) complex, acylthiourea derivatives, spectroscopic analysis, crystal structure, molecular assembly, Hirshfeld surface
Pages: 941-945

Abstract >>
The title compound [Ni(C20H15N2OS)2] is prepared by the reaction of metal acetate with the corresponding acylthiourea derivative. The complex is characterized by elemental analysis, IR, 1H and 13C NMR, and its structure is determined by single crystal X-ray diffraction. The Ni(II) ion is coordinated by the S and O atoms of two N-benzoyl-N′,N′-diphenylthiourea ligands in a slightly distorted square-planar coordination geometry. The two O and two S atoms are mutually cis to each other. The substance crystallizes triclinic (P-1 space group) with cell dimensions a = 10.7262(9), b = 12.938(3), c = 14.2085(12) Å, α = 74.650(4), β = 78.398(4), γ = 68.200(5), and two formula units in the unit cell. The structure is very close to the related N-(2-furoyl) Ni complex reported previously.
																								



14.
CRYSTAL STRUCTURE OF COMPOUNDS [Ln(H2O)8]3+4CCl3COO-4H2O2(4-bpy)(4-bpyH)+ (Ln(III) = Gd, Tb, Er, and Tm)

A. Czylkowska, R. Kruszy??ski, A. Kaczmarek, M. Markiewicz
Institute of General and Ecological Chemistry, Technical University of Lodz, Lodz
agnieszka.czylkowska@p.lodz.pl
Keywords: lanthanide compounds, 4, 4?-bipyridine, trichloroacetates, crystal structure
Pages: 946-950

Abstract >>
Novel compounds of Gd(III), Tb(III), Er(III), and Tm(III) with 4,4′-bipyridine (4-bpy) and trichloroacetates are prepared. The title compounds are isomorphic and isostructural in the solid state. All atoms in the studied compound lie in general positions of the Cc space group. The coordination polyhedra around central atoms can be described as bicapped trigonal prisms slightly disordered towards a square antiprism. All 4-bpy molecules are located in the outer coordination sphere together with four trichloroacetate anions and four water molecules. One of the nitrogen atoms of one 4-bpy is protonated due to stoichiometry.
																								



15.
Molecular structure and conformation study of p-[N,N-bis(2-chloroethyl)amino]benzaldehyde-4-phenyl thiosemicarbazone

S. Anitha1, J. Karthikeyan1, A. Nityananda shetty2
1 Department of Chemistry, Sathyabama University
2 Department of Chemistry, National Institute of Technology Karnataka
jkarthik_chem@rediffmail.com
Keywords: phenyl thiosemicarbazone, thiosemicarbazone, p-[N, N-bis(2-chloroethyl)amino]benzaldehyde-4-phenyl thiosemicarbazone, spectral studies
Pages: 951-956

Abstract >>
The crystal structure of p-[N,N-bis(2-chloroethyl)amino]benzaldehyde-4-phenyl thiosemicarbazone(CEAB-4-PTSC) is described. The compound crystallizes in the monoclinic crystal system, P21/c space group, Z = 4, calculated density = 1.327 Mg/m3, V = 1978.2(6) Å3 with unit cell parameters a = 16.240(3) Å, b = 12.821(2) Å, c = 9.8543(16) Å, β = 105.382(6). The crystal structure reveals that the compound exists in the thione form and S1 and N2 are at trans-conformation to each other with respect to the N3-C12 bond. The packing of molecules in the crystal lattice is stabilized by intramolecular hydrogen bonds.
																								



16.
5-(3,4-DICHLOROPHENYL)-3-{[4-(2-PYRIDYL)PIPERAZINE-1-YL]METHYL}- 1,3,4-OXADIAZOLE-2(3H)-ONE: SYNTHESIS, CHARACTERIZATION, X-RAY AND DFT STRUCTURES

Z.S. ??ahin1, İ. Özkan2, M. K??ksal2, Ş. Işık1
1 Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University
2 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Yeditepe University
Keywords: 1, 3, 4-oxadiazole, piperazine ring, synthesis, X-ray crystallography, DFT
Pages: 957-961

Abstract >>
5-(3,4-Dichlorophenyl)-3-{[4-(2-pyridyl)piperazine-1-yl)]methyl}-1,3,4-oxadiazole-2(3H)-one C18H17Cl2N5O2 (3) is synthesized and characterized by IR, 1H NMR, 13C NMR, elemental analyses, single-crystal X-ray diffraction, and the molecular structure is also optimized at the B3LYP/6-31G(d,p) level using density functional theory (DFT). All data obtained from the spectral studies support the structural properties of 3. The molecules are linked principally by C-H⋯O hydrogen bonds involving carbonyl atoms and carboxylate O atoms, forming (16) and (20) rings that link to give a one-dimensional network of molecules. An extensive two-dimensional network of C-H⋯O hydrogen bonds and π⋯π interactions are responsible for crystal stabilization.
																								



17.
SINGLE CRYSTAL X-RAY ANALYSIS OF ISOMERIC 2-(2,4,4-TRIMETHYL-3,4-DIHYDRO-2H-BENZO[h]CHROMEN-2-YL)-1-NAPHTHYL ACETATE AND 3-(2,4,4-TRIMETHYL-3,4-DIHYDRO-2H-BENZO[g]CHROMEN-2-YL)- 2-NAPHTHYL ACETATE

B.R. Srinivasan1, P. Raghavaiah2, R.N. Shirsat1, J.C.J.M.D.S. Menezes1, S.P. Kamat1
1 Department of Chemistry, Goa University
2 School of Chemistry, National Single Crystal X-ray Diffractometer Facility, University of Hyderabad
Keywords: 2-(2, 4, 4-trimethyl-3, 4-dihydro-2H-benzo[h]chromen-2-yl)-1-naphthyl acetate, 3-(2, 4, 4-trimethyl-3, 4-dihydro-2H-benzo[g]chromen-2-yl)-2-naphthyl acetate, naphthopyran, benzoflavans, crystal structure, structural isomers
Pages: 962-966

Abstract >>
Single crystal X-ray structure characterization of isomeric 2-(2,4,4-trimethyl-3,4-dihydro-2H-benzo[h]chromen-2-yl)-1-naphthyl acetate (1) and 3-(2,4,4-trimethyl-3,4-dihydro-2H-benzo[g]chromen-2-yl)-2-naphthyl acetate (2) is described. Compound 1 crystallizes in the centrosymmetric monoclinic space group P21/c with all atoms situated in general positions. Isomeric compound 2 crystallizes in the centrosymmetric triclinic space group P-1 and its structure consists of two crystallographically independent molecules with all atoms located in general positions. In addition to intramolecular C-H⋯O bonding, 2 is involved in two intermolecular C-H⋯O interactions resulting in a one-dimensional H-bonded network.
																								



18.
MOLECULAR AND CRYSTAL STRUCTURE OF (PYRAZIN- 1-IUM-1-YL)(PERFLUOROPYRIDIN-4-YL) AND (4,4′-BIPYRIDIN- 1-IUM-1-YL)(PERFLUOROPYRIDIN-4-YL)AMIDES

G. I. Borodkin, A. Y. Vorob'ev, Y. V. Gatilov
Keywords: N-imines of bipyridine and pyrazine, C-F-π interactions, π stacking, hydrogen bond, single crystal X-ray diffraction study, quantum chemical calculations
Pages: 967-972

Abstract >>
The single crystal X-ray diffraction study of (pyrazin-1-ium-1-yl)(perfluoropyridin-4-yl) and (4,4′-bipyridin)-1-ium-1-yl(perfluoropyridin-4-yl)amides is performed. In all cases, the N+-N- bond length is less than that of the single Nplanar.-Nplanar. bond, but considerably more than that of the double N=N bond, which indicates a weak involvement of the N- lone pair of the C5NF4N- group in conjugation with pyrazine or bipyridine moieties. Quantum chemical calculations by DFT/(PBE/L1), B3LYP/L1, and RI-MP2/L1 methods provide the geometry of amides similar to the experimental one. Crystals of (pyrazin-1-ium-1-yl)(perfluoropyridin-4-yl)amide form stacks mainly through F-π interactions. The stacks are joined in 3D architecture by weak C-HN and C-HF hydrogen bonds. In the case of (4,4′-bipyridin)-1-ium-1-yl(perfluoropyridin-4-yl)amide crystals, an essential role is played by the π stacking interactions of heteroaromatic rings.
																								



19.
molecular structure of 1,2,6,6,10,16,17- HEPTAMETHYL-20-(ACETOXYMETHYL)PENTACYCLO [12.8.0.02.11.05.10.015.20]DOCOS-17-EN-7-YL ACETATE

O. B. Kazakova, É. F. Khusnutdinova, N. I. Medvedeva, A. N. Lobov, K. Y. Suponitskii
Keywords: 3?, 28-diacetoxy-18?H, 19?H-ursan-20-en (1, 2, 6, 6, 10, 16, 17-heptamethyl-20-(acetoxymethyl)pentacyclo[12.8.0.02.11.05.10.015.20]docos-17-en-7-yl acetate), single crystal X-ray diffraction study
Pages: 973-976

Abstract >>
The molecular structure of 3β,28-diacetoxy-18αH,19βH-ursan-20-en is determined. Compound C34H54O4 II crystallizes in the P212121 chiral space group: a = 8.2721(6) Å, b = 11.2728(8) Å, c = 32.559(2) Å.
																								



20.
DFT INVESTIGATION ON THE DOUBLE HYDROGEN-BONDED SYSTEM: THE OXIDATION AND HYDRATION EFFECT P.Y. Cui, B.P. Liu, S. Yan

P.Y. Cui, B.P. Liu, S. Yan
School of Chemistry and Chemical Engineering, Qufu Normal University
pinglysh@gmail.com
Keywords: density functional theory, oxidation effect, frontier molecular orbital, ionization potential, double hydrogen-bonded system
Pages: 977-984

Abstract >>
The trustworthy B3LYP/6-311+G* method is employed to investigate the double hydrogen-bonded system with a special emphasis on the oxidation and hydration effect. Proton transfer occurs spontaneously upon oxidation from the amido group to the adjacent imidazole fragment. The larger the pH value of the environment, the significant the effect on the geometry structure is. The electron population on the HOMO determines the IR vibrational frequency of the H bond, being blue-shift or red-shift. The complex prefers to be oxidized under the basic condition. The weak acidic environment is recommended to prevent the DNA mutation.
																								



21.
HONEYCOMB-LIKE LAYERS CONSTRUCTED BY HYDROGEN BONDS. SYNTHESIS, STRUCTURE, AND PROPERTY OF TWO NEW SUPRAMOLECULAR COMPOUNDS BASED ON POLYOXOTUNGSTATE

Q.-J. Kong, C.-X. Zhang, Y.-G. Chen
Key Laboratory of Polyoxometalate Science of Ministry of Education, College of Chemistry, Northeast Normal University
chenyg146@nenu.edu.cn
Keywords: polyoxotungstate, dimeric coordination cation, hydrogen bonding, supramolecular compound, luminescence
Pages: 985-990

Abstract >>
Two new compounds based on polyoxotungstate [Co2(PCA)4(H2O)6][SiW12O40]8H2O (1), [Cd2(PCA)4(H2O)6][SiW12O40]8H2O (2) (PCA = pyridine-4-carboxylic acid) are prepared and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and thermal analysis. The results of the single crystal X-ray diffraction analysis reveal that 1 and 2 are isomorphic and two water molecules in the compounds act as the bridging groups of two cobalt or cadmium atoms, forming dinuclear coordination cations. The ligand PCA adopts a monodentate coordination mode and its uncoordinated carboxyl oxygen atom and the protonized nitrogen atom form hydrogen bonds with other ligands, by which the cations are linked into a supramolecular 2D network with hexagonal grids. The polyoxotungstate anions are arranged above and below the cationic grids. A strong emission peak at 420 nm of 2 is attributed to a ligand-metal transition.
																								



22.
POLYMORPHIC TRANSFORMATIONS AND THERMAL DEFORMATIONS OF MONOCLINIC n-PARAFFINS 3062 AND 3266

N. V. Platonova, E. N. Kotel'nikova, S. K. Filatov, G. A. Puchkovskaya, I. I. Gnatyuk, J. Baran, M. Drozd
Keywords: monoclinic even long chain n-paraffins, phase transformations, crystalline and rotationally crystalline states, thermal X-ray diffraction, IR spectroscopy, differential scanning calorimetry
Pages: 991-1005

Abstract >>
Thermal deformations and polymorphic transformations of even long chain monoclinic normal paraffins 3062 and 3266 (homological purity 97-99%) are studied. Thermal deformations and temperature limits of the existence of crystalline (1Mcryst and 2Mcryst), low-temperature rotationally crystalline triclinic (Tcrot.1), monoclinic (Mrot.1), and orthorhombic (Orrot.1) and high-temperature rotationally crystalline hexagonal (Hrot.2) phases of these n-paraffins are estimated by the character of changes in their diffraction patterns and unit cell parameters (thermal X-ray diffraction). The molecular structure and conformational composition of these n-paraffins in different phase states are determined (IR spectroscopy). In order to determine the temperatures of phase transitions differential scanning calorimetry is also applied. The data of all three methods are in good agreement with each other. The initial sample of 3062 n-paraffin at room temperature is characterized by a two-layer monoclinic 2M crystalline modification. When the melt is rapidly cooled, it crystallizes in monolayer monoclinic 1M and orthorhombic Or modifications (two-phase mixture 1M+Or). The initial sample of 3266 n-paraffin at room temperature is characterized by the monolayer monoclinic modification 1M. When the melt is rapidly cooled, as well as 3062 n-paraffin, it crystallizes in monolayer monoclinic 1M and orthorhombic Or modifications (two-phase mixture 1M+Or). It is found that both n-paraffin undergo irreversible polymorphic transformations from the crystalline state cryst to the low-temperature rotationally crystalline state rot.1. For 3062 n-paraffin the transition is performed by the scheme 2Mcrystrot.1Orrot.1, and for 3266 n-paraffin it is performed by the scheme 1McrystTcrot.1. Both paraffins do not undergo the transition to the high-temperature rotationally crystalline state rot.2 (hexagonal phase Hrot.2), similarly to monoclinic 2858 n-paraffin studied previously. These and previously obtained data allow us to consider that as the molecular chain length increases, differences in the polymorphic modification of initial crystalline phases cease to be significant and the sequence of polymorphic transformations is mainly determined by the length of the molecule.
																								



23.
SELF-ASSEMBLY AND GEL FORMATION PROCESSES IN AN AQUEOUS SOLUTION OF L-CYSTEINE AND SILVER NITRATE

P. V. Komarov, I. V. Mikhailov, V. G. Alekseev, S. D. Khizhnyak, P. M. Pakhomov
Keywords: physical gel, cysteine-silver solution, self-assembly, gel formation, computer simulation
Pages: 1006-1023

Abstract >>
The experimental and theoretical study of self-assembly and gel formation processes in an aqueous solution of L-cysteine and silver nitrate (CSS) is performed. A method to obtain CSS-based hydrogel is described. Its characteristic feature is the formation of a spatial gel network at a low concentration of the dispersed phase (~0.01%) and the thixotropic behavior. The experimental examination of this system provides the formulation of a phenomenological model of the gel formation. Based on it, an atomistic computer model is made to verify our assumptions. It is shown that due to the formation of donor-acceptor sulfur-silver bonds there form clusters from silver mercaptide (SM) zwitterions, from which in turn filamentous aggregates form. An analysis of the molecular configurations formed shows that the filamentous aggregates are stabilized by the interaction of and -C(O)O- groups belonging to SM zwitterions in the composition of the neighboring clusters. The obtained conclusions underlie the mesoscopic model based on which we managed to illustrate the processes of generation and growth of filamentous aggregates in large spatial scales.
																								



24.
STRUCTURE OF BIS(HEXAMETHYLENETETRAMINE)HEXAAQUANICKEL(II)HEXAFLUOROTITANATE(IV) MONOHYDRATE - [Ni(OH2)6][TiF6](Ur)2H2O

É. B. Miminoshvili, T. N. Sakvarelidze, K. É. Miminoshvili
Keywords: complex compounds, synthesis, structural analysis, titanium, nickel, hexamethylenetetramine
Pages: 1024-1028

Abstract >>
The X-ray diffraction study of a single crystal with the composition NiTiF6(Ur)27H2O is performed, where Ur = C6H12N4 is an urotropine (hexamethylenetetramine) molecule. The compound crystallizes in the triclinic P-1 space group: a = 8.7220(5) Å, b = 9.1004(5) Å, c = 17.533(1) Å, α = 75.074(1), β = 88.530(1), γ = 62.558(1), Z = 2, dx = 1.756 g/cm3, μ = 1.228 mm-1, R = 0.0351. The crystalline compound is ionic. The structural unit consists of [Ni(OH2)6]2+ and [TiF6]2- ions and Ur and H2O molecules. The structural formula of the compound is [Ni(OH2)6][TiF6](Ur)2H2O. Hydrogen bonds in the compound are studied and analyzed.
																								



25.
X-RAY STRUCTURAL ANALYSIS OF 4-BROMO-2,2-DIMETHYL- 5-OXY-6,6,7,7,8,8,9,9,9-NONAFLUORONONAN-3-ONE

P. A. Slepukhin, V. I. Filyakova, V. N. Charushin
Keywords: ?-bromo-?-hydroxy ketones, X-ray diffraction study
Pages: 1029-1030

Abstract >>
The features of the molecular and crystal structures of 4-bromo-2,2-dimethyl-5-oxy-6,6,7,7,8,8,9,9,9-nonafluorononan-3-one are determined by XRD.
																								



26.
CRYSTAL AND MOLECULAR STRUCTURE OF 1-PHENYL-2-NITROGUANIDINE

A. M. Astakhov, A. D. Vasiliev, V. A. Revenko
Keywords: nitrimines, nitroguanidine, single crystal X-ray diffraction study, molecular structure
Pages: 1031-1034

Abstract >>
The molecular structure of 1-phenyl-2-nitroguanidine is nonplanar, but contains two almost planar fragments: nitroguanyl and phenyl groups. Unlike previously studied nitroguanidines, in 1-phenyl-2-nitroguanidine, the nitro group is turned to the secondary amino group. However, the structural parameters of the nitroguanyl group are little different from those of nitroguanidine and its alkyl derivatives. In the benzene ring, the symmetry in the geometric parameters is not observed, which is explained by the intermolecular interaction with the neighboring molecule.