Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "molecules" wg kryterium: Temat

  Lista filtrów
Wyrównaj
    Wyświetlanie 1-3 z 3
    Tytuł:
    Crystal Structure Prediction and Charge Density Distribution of Highly Energetic Dimethylnitraminotetrazole: a First Step for the Design of High Energy Density Materials
    Autorzy:
    Arputharaj, D. S.
    Srinivasan, P.
    Asthana, S. N.
    Pawar, R. B.
    Kumaradhas, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/358205.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    energetic materials
    crystal structure prediction
    charge density analysis
    atoms in molecules
    electrostatic potential
    Opis:
    The crystal structure of dimethylnitraminotetrazole has been predicted, based on systematically searching for densely packed structures within common organic crystal coordination types, followed by lattice energy minimization. The predicted crystal structures almost match the reported crystal structure determined by X-ray diffraction analysis. To understand the effect of the initial molecular geometry on the crystal packing, the crystal structure simulation was carried out for molecules taken from different environments, such as the X-ray structure (crystal field) and also from ab initiocalculations (gas phase). The predicted crystal structures from both environments are very similar to the reported X-ray structure with a maximum deviation of 4.5%. The crystal density predicted from both methods is close to that reported. The bond topological, energetic and electrostatic properties of the isolated molecule from the predicted crystal structure have been determined using Bader's theory of atoms in molecules. The bond topological characterization reveals that the C-N bond is the weakest bond in the molecule. A large electronegative potential is found in the vicinity of the NO2group and the nitrogen-rich region of the tetrazole ring; these are probably the reactive sites of this molecule.
    Źródło:
    Central European Journal of Energetic Materials; 2012, 9, 3; 201-217
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Strukturalne konsekwencje wiązania wodorowego
    Strustural consequences of the h-bonding
    Autorzy:
    Krygowski, T.M.
    Szatyłowicz, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/171995.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    wiązanie wodorowe
    podstawione fenole
    podstawione aniliny
    aromatyczność
    AIM
    NBO
    H-bond
    substituted phenols
    substituted anilines
    aromaticity
    atoms in molecules
    natural bond orbital
    NBO analysis
    Opis:
    Hydrogen bonding belongs to the most important chemical interactions in life and geochemical processes as well as in technologies, that is documented in many review articles [1-10], monographs [11-17] and numerous publications. Figure 1 presents how "popular" are studies concerning hydrogen bonds (the term H-bond/bonding/bonded in a title, key-words or in abstract) in the last decade. First information about H-bond formation appeared at the end of XIX and a few other at beginning of XX centuries [19-24]. Most common definition of H-bonding stems from Pauling [27], whereas the newest IUPAC definition was published very recently [26]. Most frequently H-bonding is experimentally described by geometry parameters [28, 32] - results of X-ray and neutron diffraction measurements, but NMR and IR/Raman spectroscopies are also in frequent use. Characteristic of interactions by H-bonding is usually discussed in terms of energies [29-31], with use of various quantum chemical theories [54-57] and applications of various models as AIM [35, 41, 42, 45-48] and NBO [43, 44] which allowed to formulate detailed criteria for H-bond characteristics [35, 48]. H-bonds are classified as strong, mostly covalent in nature [7, 29, 34], partly covalent of medium strength [35] and weak ones, usually non-covalent [7, 29, 34, 35]. Theoretical studies of H-bonding mainly concern equilibrium systems, however simulation of H-bonded complexes with controlled and gradually changing strength of interactions [61-71] are also performed. The latter is main source of data referring to effect of H-bonding on structural properties: changes in the region of interactions, short and long-distance consequences of H-bonding. Application of the model [61] based on approaching hydrofluoric acid to the basic center of a molecule and fluoride to the acidic one, (Schemes 2 and 3) allows to study changes in molecular structure of para-substituted derivatives of phenol and phenolate [62, 64] in function of dB…H, or other geometric parameter of H-bond strength (Fig. 2). It is also shown that CO bond lengths in these complexes is monotonically related to H-bond formation energy and deformation energy due to H-bond formation [65]. Alike studies carried out for para-substituted derivatives of aniline and its protonated and deprotonated forms [77, 78, 81] give similar picture (Fig. 3). AIM studies of anilines [77, 78] lead to an excellent dependence of logarithm of electron density in the bond critical point and geometric parameter of H-bond strength, dB…H presented in Figure 4. Substituents and H-bond formation affect dramatically geometry of amine group [66] in H-bonded complexes of aniline as shown by changes of pyramidalization of bonds in amine group (Fig. 5). Some short- and long-distance structural consequences of H-bonding are shown by means of changes in ipso angle (for amine group) in the ring and ipso-ortho CC bond lengths (Fig. 6). Moreover, the mutual interrelations are in line with the Bent-Walsh rule [84, 86]. Changes of the strength of H-bonds in complexes of p-substituted aniline and its protonated and deprotonated derivative are dramatically reflected by aromaticity of the ring66 estimated by use of HOMA index [87, 88] (Fig. 7), where strength of H-bonding is approximated by CN bond lengths. Scheme 4 presents application of the SESE [91] (Substituent Effect Stabilization Energy) for description in an energetic scale joint substituent and H-bond formation effects.
    Źródło:
    Wiadomości Chemiczne; 2011, 65, 11-12; 953-974
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Charakterystyka mocy poszczególnych wiązań wodorowych w parach zasad DNA
    Characterizing strength of individual hydrogen bonds in DNA base-pairs
    Autorzy:
    Szatyłowicz, Halina
    Sadlej-Sosnowska, Nina
    Jezierska, Aneta
    Powiązania:
    https://bibliotekanauki.pl/articles/172292.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    wiązanie wodorowe
    pary zasad Watsona-Cricka
    NBO
    koncepcja naturalnych orbitali wiązań
    AIM
    metoda atomy w cząsteczce
    hydrogen bond
    Watson-Crick base pairs
    natural bond orbital method
    atoms in molecules
    Opis:
    The main idea of the current review is to present methods useful to characterize the strength of individual hydrogen bonds in nucleic acids base-pairs. In the paper, the Authors discuss the energy definition of intermolecular interactions taking into account the presence of one intermolecular hydrogen bond (HB) as well as the situation when several intermolecular interactions (namely intermolecular hydrogen bonds) are present. In the Section 2 of the review a general overview of methods developed to estimate the strength of the individual intermolecular hydrogen bond in DNA/RNA base-pairs is presented. Thus, the reader can find detailed information on the methods used so far: the rotational method (2003), compliance constants method (2004), the EML equation application (2006), the atom replacement method (2007), the estimation of hydrogen bond energy on the basis of electron density (calculated by using the AIM theory) at BCP values (2009), the application of NBO method (2010), the comparison of HB strength based on the last two approaches (2015) and the application of coordinates interaction approach (2017). It should be emphasized, that these methods allow to estimate the strength of intermolecular interactions both in the model base-pairs and in other systems with several intermolecular hydrogen bonds. The discussion of the presented methods is supported by Tables 1-10, containing numerical values characteristics of the strength of the particular HB, and Figures 1–2. The section 3 contains a critical comparison of results based on the presented methods. Concluding remarks are given in the last Section.
    Źródło:
    Wiadomości Chemiczne; 2019, 73, 1-2; 53-74
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

      Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies