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Janczak J.,Institute of Low Temperature And Structure Research
Crystal Growth and Design | Year: 2015

A family of supramolecular complexes of 1-(diaminomethylene)thiourea with aliphatic dicarboxylic acids, HOOC(CH2)nCOOH, with odd and even numbers of methylene groups in the carbon chain of the acids has been characterized. Using solvent-assisted and evaporation-based techniques, crystallization of 1-(diaminomethylene)thiourea with aliphatic dicarboxylic acids from water solutions yielded ionic supramolecular complexes with base to acid ratio of 2:1 or 1:1. Malonic, succinic, adipic, and sebacic acids with 1-(diaminomethylene)thiourea form supramolecular complexes of 2:1 ratio (1, 2, 4, and 8), whereas glutaric, pimelic, azelaic, and suberic acids form supramolecular complexes of 1:1 ratio (3, 5, 6, and 7). Within all supramolecular complexes only one with adipic acid crystallizes as a hydrate containing water molecules of crystallization. In the hydrated crystal with adipic acid, the O-H···O chains of water molecules interact with adipiate(2-) anions forming anionic layers, and the charge is compensated by 1-(diaminomethylene)thiouron-1-ium cations. The 2:1 supramolecular complexes further interact each other via N-H···O hydrogen bonds forming two- or three-dimensional supramolecular structure. Within 1:1 supramolecular complexes, the singly deprotonated aliphatic dicarboxylic acids are linked together via strong symmetrical O···H···O hydrogen bonds into infinitive chains. The chains are further linked by 1-(diaminomethylene)thiouron-1-ium cations to form a two- or three-dimensional hydrogen bonding network. Interaction between the 1-(diaminomethylene)thiouron-1-ium and the singly or doubly deprotonated aliphatic dicarboxylic acid units in solid of 1-8 supramolecular complexes were also analyzed by vibrational spectroscopy. © 2015 American Chemical Society.

Crystal structures of two polymorphs of [H2m4na]Cl (1α,1β) and (H2m4na)2SnCl6·H2O (2), where 2m4na = 2-methyl-4-nitroaniline are shown and comparison of these crystal structures with the bromide salt reported earlier is presented. In all the presented crystal structures, alternatively arranged cations and anions form chain and ring hydrogen-bonding patterns of weak unconventional N-H⋯Cl hydrogen bonds. Interrelations among the elementary graph-set descriptors and descriptors of the hydrogen-bonding patterns are presented. Nonhydrogen bonding interactions between the nitro groups are also described using graph-set descriptors. Comparison of the experimental, also for deuterated 1α polymorph, and theoretical, for H2m4na+ ion with B3LYP/6-31G(d,p), spectra showed good agreement among the frequencies due to very weak interactions existing in studied compounds. Detailed analysis of the spectra revealed that the interaction between adjacent -NO2 groups in 1α is stronger than the other types involving the nitro group. The bands were assigned on the basis of theoretical calculations of vibrational frequencies for H2m4na+ ion and PED analysis. © 2013 American Chemical Society.

Daszkiewicz M.,Institute of Low Temperature And Structure Research
CrystEngComm | Year: 2013

Perpendicular arrangement of two nitro groups of adjacent molecules was found in 104 structural fragments deposited in the Cambridge Structural Database. In the most cases, this non-hydrogen bonding O NO2⋯π(N)NO2 interaction is shorter than 3 Å. Ab initio calculations of the interaction energy indicates the attractive nature of this interaction, comparable to the Eint of C-H⋯O. © 2013 The Royal Society of Chemistry.

Zaleski T.A.,Institute of Low Temperature And Structure Research
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

The excitations of strongly interacting bosons confined in a two-dimensional square lattice are studied. Using a combined Bogoliubov method and the quantum-rotor approach, the Hamiltonian of strongly interacting bosons is mapped onto the U(1)-phase action. This allows to calculate the momentum- and energy-resolved one-particle spectral function and its dependence on the presence of the superfluid phase. It is shown that the destruction of the ordered phase leads to the opening of the gap in the excitation spectrum in k=0. On the other hand, superfluidity manifests itself as a sharp coherence peak resulting from the emergence of the long-range order. Correlation effects lead to the appearance of a smearing of the band structure of incoherent particles although the remnants of the Bogoliubov excitations are still present in the coherent part of the spectrum. © 2012 American Physical Society.

Daszkiewicz M.,Institute of Low Temperature And Structure Research
Journal of Molecular Structure | Year: 2013

New hybrid organic-inorganic compound, bis(1,4-H2-1,2,4- triazolium) hexachloridostannate(IV) monohydrate, [(1,4H2t) 2SnCl6]ṡH2O crystallizes in P2 1/c space group. Weak hydrogen bonds exist in the structure. The route of protonation of the 1,2,4-triazole and tautomer equilibrium constants for the cationic forms were theoretically studied by means of B3LYP/6-31G · method. The 1,4H2t+ cation turned out to be the most stable form of mono-protonated species. Calculated IR and Raman spectra for 1,4H2t+ cation (gas phase) are in very good agreement with the experimental data. Infrared and Raman bands were assigned on the basis of PED analysis. © 2012 Elsevier B.V. All rights reserved.

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