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Tytuł:
Investigations of hydrogen bonding in the poly(urethane-urea)-based membrane materials by using FTIR spectroscopy
Autorzy:
Wolińska-Grabczyk, A.
Kaczmarczyk, B.
Jankowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/779462.pdf
Data publikacji:
2008
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
spektroskopia w podczerwieni
wiązanie wodorowe
poliuretany
infrared spectroscopy
hydrogen bonding
polyurethanes
Opis:
FTIR analysis was used to study the hydrogen bonding in 4,4'-diaminodiphenylmethane-based segmented poly(urethane-urea)s varying in the length of the poly(tetramethylene oxide) (PTMO)-based soft segments. Experiments were designed to follow the IR absorption of both the NH and carbonyl regions as a function of temperature in order to directly investigate the extent and strength of the hydrogen bonds, and thereby to gain some information about the possible alteration of the initial phase-segregated morphology as a result of the applied thermal treatment.
Źródło:
Polish Journal of Chemical Technology; 2008, 10, 4; 53-56
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Doświadczalne metody badań hydratów gazowych
Experimental investigations methods of gas hydrates
Autorzy:
Lorenc, M.
Warowny, W.
Powiązania:
https://bibliotekanauki.pl/articles/299345.pdf
Data publikacji:
2011
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
nukleacja
hydrat
klatraty
metan
eksperymentalne
niestechiometryczne
inhibitor
wiązanie van der Waalsa
wiązanie wodorowe
krystaliczne
hydrate
clathrate
methane
experimental
nucleation
nonstoichiometric
van der Waals bond
hydrogen bond
crystalline
Opis:
Poznanie natury hydratów gazowych opiera się głównie na badaniach doświadczalnych w skali laboratoryjnej i ćwierć-technicznej oraz na teorii popartej obliczeniami i symulacjami komputerowymi. W pracy przedstawiono metody pomiarowe dotyczące tworzenia lub/i zapobiegania tworzenia się hydratów gazowych, badania ich właściwości oraz wykorzystanie w nowych technologiach. Generalnie badania doświadczalne hydratów gazowych i hydratacji można podzielić na kilka grup tematycznych: doświadczalne i obliczeniowe wyznaczanie równowag fazowych, badania parametrów fizykochemicznych i strukturalnych, pomiary kinetyczne, w tym nukleacji i aglomeracji cząsteczek, badania wpływu na hydratację inhibitorów i surfaktantów, możliwość zastosowań technologicznych, w szczególności hydratu metanu, w tym wydobycia, przesyłu, magazynowania i oczyszczania, plus badania geologiczne i geofizyczne w celu oszacowania zasobów hydratu metanu.
Knowledge of the nature gas hydrates is connected mainly with experimental studies in laboratory and pilot plant and theory supported by calculations and computer simulations. In work have been given methods of measurement dealing with: formation and/or prevention of formation gas hydrates, studies their properties, and utilization in new technologies. Generally, studies of the gas hydrates and hydratation can be divided on several thematic groups: experimental and calculated determination of phase equilibrium, studies of the physicochemical and structural parameters, kinetic measurements, including nucleation, and agglomeration of particles, studies influence of inhibitors and surfactants on the hydratation process, possibility of technological applications, especially hydrate of methane, including getting out, transport, storage and purification, plus geological and geophysical studies carried out in order to estimation methane hydrate deposits.
Źródło:
Wiertnictwo, Nafta, Gaz; 2011, 28, 1-2; 227-251
1507-0042
Pojawia się w:
Wiertnictwo, Nafta, Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Keratyna : źródła, właściwości, zastosowanie
Keratin : origins, properties, application
Autorzy:
Staroń, P.
Banach, M.
Kowalski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1220028.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
Tematy:
keratyna
białko
aminokwas
wiązanie wodorowe
α-helisa
beta-harmonijka
β-harmonijka
keratin
protein
amino acids
hydrogen bond
alpha-helix
α-helix
beta-sheet
β-sheet
Opis:
Celem artykułu jest scharakteryzowanie keratyny. Należy ona do rodziny białek fibrylarnych. Głównym źródłem naturalnego występowania keratyny są odpadowe pióra z przemysłu drobiarskiego. W skali globalnej powstaje ponad 4 mln ton tego odpadu w ciągu roku i należy go unieszkodliwiać. Keratyna charakteryzuje się dużą odpornością na czynniki fizyczne i chemiczne, dlatego niezwykle ważne jest poszukiwanie nowych metod przerobu odpadów keratynowych. Pozwoli to uniknąć problemu składowania odpadowego pierza. W pracy przedstawiono ponadto sposoby otrzymywania, degradacji oraz zastosowania keratyny.
The aim of the article is the keratin characterization. Keratin belongs to the group of fibril proteins. The main source of natural occurrence of keratin are feathers from poultry industry. In the whole world there are 4 M tones a year of feathers, which should be utilized. Keratin has a high immunity to physical and chemical factors and it is the reason of searching for a new methods of keratin waste conversion. It would help to avoid a problem with storage of feather waste. The scientific work represents also methods of receiving, degradation and application of keratin.
Źródło:
Chemik; 2011, 65, 10; 1019-1026
0009-2886
Pojawia się w:
Chemik
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:
Wiązanie wodorowe i inne oddziaływania typu kwas Lewisa-zasada Lewisa
The hydrogen bond and the other Lewis acid-Lewis base interactions
Autorzy:
Grabowski, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/171998.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie wodorowe
wiązanie halogenowe
wiązanie wodorkowe
oddziaływanie kwas Lewisa-zasada Lewisa
teoria Atomy w Cząsteczkach
hydrogen bond
halogen bond
hydride bond
Lewis acid-Lewis base interaction
atoms in molecules theory
AIM
Opis:
Hydrogen bond is analyzed very often since its importance in numerous chemical, physical and biological processes is very well known. It covers the broad range of various interactions; sometimes this is the subject of discussions and polemics if some of them may be classified as hydrogen bonds. This is because there are numerous definitions of hydrogen bond interaction, often they are hardly accepted since they are not univocal. For example one can mention different types of the proton acceptors for hydrogen bonds; one center electronegative atoms, multi-center acceptors such as đ-electrons or even ó-electrons. There are the other interactions which play the key role in various processes and phenomena. All are often named as no-covalent interactions but the other term, Lewis acid–Lewis base interactions seems to be more accurate. One can mention halogen bond, hydride bond or dihydrogen bond. These interactions may be treated as counterparts or competitors of hydrogen bond. The common characteristic for them, including hydrogen bond, is the electron charge transfer from the Lewis base to the Lewis acid. It was found that the amount of this transfer corresponds roughly to the strength of the interaction. In recent years the ó-hole concept was introduced and developed and it was applied to the Lewis base–Lewis acid interactions. According to this concept the atomic centers are characterized by the presence of the regions of positive and negative electrostatic potentials; very often both regions are detected even for atoms which are commonly known as electronegative ones. In such a way halogen atoms, especially if connected by covalent bond with carbon, may act as Lewis acids and also as Lewis bases. In the first case the halogen bond is formed, recently extensively studied. In this review the characteristics of different Lewis base–Lewis acid interactions are given as well as their common features are presented.
Źródło:
Wiadomości Chemiczne; 2011, 65, 11-12; 975-1001
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Skręty zwrotne w peptydach i białkach. Mimetyki skrętów zwrotnych. Część 1
Reverse turns in peptides and proteins. Reverse turns mimetics. Part 1
Autorzy:
Owińska, M.
Powiązania:
https://bibliotekanauki.pl/articles/171726.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
skręt zwrotny
wiązanie wodorowe
konformacja
kąt dwuścienny
reverse turn
hydrogen bond
conformation
dihedral angle
Opis:
The secondary structure of the proteins can be divided into α-helix, βsheet and reverse turns. A reverse turn is defined as a site where a polypeptide chain reverses its overall direction. It leads the chain to fold back on itself by almost 180°. Another condition for defining this motif is the amount of amino acid residues involved in forming the turn that can not be greater then six and polypeptide chain in this region can not be in helical conformation [1]. Turns are classified as: γ-turn, β-turn, α-turn and π-turn, which are formed by 3-, 4-, 5- and 6- amino acid residues, respectively. Turns defined as “closed” are stabilized by intramolecular hydrogen bonds between the main chain carbonyl group from the first residue and the main chain amide group from the last residue in the turn. This results in formation of 7-, 10-, 13- and 16-membered pseudo-rings, respectively (Fig. 1, Fig. 2). The other group of turns also stabilized by hydrogen bond, but conversely between the main chain amide group of the first residue and the carbonyl group of the last residue, are δ-turn (2-residues, 8-membered pseudo-ring) and ε-turn (3-residues, 11-membered pseudo-ring) (Fig. 2) [10–13]. These are seldom found in proteins. Turns are considered irregular structures due to the lack of clearly defined torsion angle preferences. because of that, each of the turn types can be further divided into several different subtypes (Table 1, 2 and 3) [1, 15, 31]. The “open” type structures are not stabilized by hydrogen bonds, but Cα-Cα distance between the first and the last residue in main chain is up to 10 A [10]. As turns can be found mostly on the surface of the proteins they play the important role in folding processes, thus enabling the formation of the tertiary structure [2]. The turns are also responsible for the interactions between proteins, recognition processes and ligand-receptor interactions [3–8]. In the following article, the classification and characterization of the turn types is described. The particular attention was given to the γ and β turns, as these are most commonly found in proteins structure.
Źródło:
Wiadomości Chemiczne; 2016, 70, 9-10; 598-611
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Borowce jako centra kwasów Lewisa w oddziaływaniach międzycząsteczkowych : porównanie z wiązaniami wodorowymi
Triels as centers of Lewis acids in intermolecular interactions : comparison with hydrogen bonds
Autorzy:
Grabowski, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/172397.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie wodorowe
wiązanie borowcowe
potencjał elektrostatyczny
dziura σ
dziura π
przesunięcie ładunku elektronowego
struktury krystaliczne
hydrogen bond
triel bond
electrostatic potential
σ-hole
π-hole
electron charge shift
crystal structures
Opis:
The triel bonds are analyzed and compared with the hydrogen bond interaction. The triel bonds belong to the class of interactions that are named as the σ-hole and π-hole bonds. The σ-hole bond is an interaction between the σ-hole characterized by the positive electrostatic potential and the electron rich regions such as lone electron pairs, π-electron systems, in other words, centers paying a role of Lewis bases. The σ-holes may be observed for elements of the 14–18 groups of the periodic system and the corresponding interactions with Lewis bases are named; tetrel, pnicogen, chalcogen, halogen and aerogen bonds, respectively. On the other hand, π-holes also characterized by the positive electrostatic potential are observed for centers in planar molecules or planar fragments of molecules in regions above those planes. π-holes may be attributed to triel centers (13th group of the periodic system). The boron and aluminium trihydrides and trihalides are examples of molecules where triels are characterized by π-holes. The mechanism of the triel bond formation is very similar to the mechanism of the formation of the hydrogen bond. It is the Lewis acid – Lewis base interaction where the electron charge transfer from the base unit to the acid one is observed. Next there is outflow of the electron charge from the triel center to the other parts of the Lewis acid unit; in other words the positive charge of the triel center increases as a result of complexation. The triel bonds are often very strong and often they possess characteristics of typical covalent bonds; this is confirmed by the QTAIM (Quantum Theory of Atoms in Molecules) and NBO (Natural Bond Orbital) approaches. For example, for the triel bonds the bond paths between the triel center and the Lewis base center are observed with the bond critical points (BCPs) attributed to those paths. Similarly for the A-H…B hydrogen bonds the H…B bond paths are observed. The parameters of those BCPs often indicate the covalent character of the triel bonds and analogously those characteristics for H-bonds may also indicate the covalent character of the latter interactions. It is very interesting that the triel bonds are observed experimentally in the real systems; for example in crystal structures. The triel center which is trivalent and possesses the trigonal configuration is hypovalent; it means that the octet rule is not obeyed here because of the valence electrons´ deficiency (the triel center possesses six valence electrons in such species). Thus it may interact with one Lewis base ligand reaching rather stable octet and tetrahedral configuration. If the trivalent triel center interacts with two Lewis base ligands thus it may lead to the configuration of the trigonal bipyramid with the hypervalent and pentavalent triel center. These kinds of the triel species occur in crystal structures that are described here.
Źródło:
Wiadomości Chemiczne; 2017, 71, 7-8; 447-471
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Struktura a nieelastyczne rozpraszanie neutronów przez kryształy molekularne z wiązaniami wodorowymi
Structure and inelastic neutron scattering by the molecular crystals with the hydrogen bonds
Autorzy:
Rok, M.
Bator, G.
Sobczyk, L.
Powiązania:
https://bibliotekanauki.pl/articles/171492.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kompleksy molekularne
wiązanie wodorowe
struktura krystaliczna
rozpraszanie neutronów
dynamika cząsteczek w fazie stałej
molecular complexes
hydrogen bonds
crystal structure
neutron scattering
molecular dynamics in the solid state
Opis:
The molecular crystals, which are built of organic or organic-inorganic molecules, are characterized by the weak intermolecular interactions. From the viewpoint of the potential applications in electronics or optoelectronics the electric properties of the crystals are essential. In turn these properties are related to their crystal structure as well as the dynamics of the molecules in the solid state. The existence of the hydrogen bonds in the crystal structures, conventional and unconventional, is crucial from the viewpoint of the electric properties of the crystals. The dynamics of methyl groups present in the structure can be a measure of the molecular interactions in the crystals. In this work the dynamical properties, first of all taking into account the research results concerning the neutron scattering, will be discussed. The neutron technique is very effective as regards the methyl group dynamics investigations. The relationship between a formation of the conventional and unconventional hydrogen bonds and a tunneling of the methyl groups at low temperature will be discussed. The method of the interpretation of the INS spectra will be described taking into account the theoretical model, the parameters of which are fitted to the experimental data. The examples will regard the following molecular crystals: p-N,N’-1,10-tetraacethyldiaminodurene (TADD) (Figs. 2 and 4), 2,3,5,6-tetramethylpyrazine with chloranilic acid (TMP·CLA) (Figs. 5, 6 and 7), 2,3,5,6- tetramethylpyrazine with bromanilic acid (TMP·BRA) (Figs. 5 and 6) and the crystal of 3,4,7,8-tetramethylphenantroline (Me4phen) and its complex with picric acid (Me4phen·PIC) (Figs. 8 and 9). In this paper we have shown that the surrounding of the methyl group and its interactions with the adjacent molecules has a stronger effect than the changes in the electronic charge density in the molecule.
Źródło:
Wiadomości Chemiczne; 2017, 71, 7-8; 533-557
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie metod dynamiki molekularnej w badaniach nad układami z wiązaniami wodorowymi
An application of molecular dynamics methods in investigations of systems with hydrogen bonds
Autorzy:
Jezierska, A.
Panek, J. J.
Powiązania:
https://bibliotekanauki.pl/articles/172356.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
CPMD
dynamika molekularna Cara-Parrinello
klasyczna dynamika molekularna
wewnątrzcząsteczkowe wiązanie wodorowe
międzycząsteczkowe wiązanie wodorowe
zasada Schiffa
zasada Mannicha
N-tlenki
białka
Car-Parrinello molecular dynamics
classical MD
intramolecular HB
intermolecular HB
Schiff base
Mannich base
N-oxides
proteins
Opis:
Modern computational chemistry offers a wide variety of methods allowing us to investigate very complex systems. In the current study, we would like to focus on ab initio and classical molecular dynamics to show their applications in our research. Car-Parrinello molecular dynamics (CPMD) was carried out to study compounds possessing intra- and intermolecular hydrogen bonds. Our simulations were performed in vacuum, in solvent and in crystalline phase. It is well known that intramolecular hydrogen bonding stabilizes 3D structure of molecules. The strength of the bonding and its features are influenced by inductive and steric effects. Our short overview on CPMD application to systems with intramolecular HB we start from Schiff and Mannich bases -model compounds to investigate intramolecular hydrogen bonding. Other examples reported here derive from the class of N-oxide type compounds. Special attention was devoted to another representative structure in such investigations – picolinic acid N-oxide. In some examples listed above proton transfer phenomena occurred making these compounds interesting objects for future excited state studies. Aliphatic boronic acid was used as a model example to study intermolecular hydrogen bonds based on CPMD method. Further, classical molecular dynamics was applied to investigate proteins. Here, we would like to report our results for two biomolecules. The first one is proteinase K for which the impact of mercury(II) on its catalytic center was studied. The second one is streptavidin. For the latter one its complexes with biotinylated ligands were investigated. We close our review with a paragraph describing further development and perspectives related to CPMD method.
Źródło:
Wiadomości Chemiczne; 2017, 71, 7-8; 473-495
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
Tytuł:
Efekt kooperatywności oddziaływań iekowalencyjnych w wybranych układach molekularnych stabilizowanych wiązaniami wodorowymi i halogenowymi
Cooperativity effect in noncovalent interactions of selected molecular complexes stabilised by hydrogen and halogen bonds
Autorzy:
Domagała, Małgorzata
Dominikowska, Justyna
Palusiak, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/172440.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie halogenowe
wiązanie wodorowe
energia oddziaływania
efekt kooperatywny
modelowanie molekularne
halogen bond
hydrogen bond
interaction energy
cooperativity effect
molecular modelling
Opis:
Among various so-called weak interactions, a halogen bond [8 and references therein] is currently probably one of more explored by researchers. This is due to the fact that it has several properties in common with the hydrogen bonding, and thus, similarly as already well characterised H-bond, it may have a crucial role in different physical, chemical, and biological processes. This bond is formed due to stabilising interactions between a region of positive charge located on a surface of the halogen atom and the other atomic center possessing the electron charge surplus (e.g. a lone pair) [8]. The region of positive charge appears on the halogen atom surface due to deformation of its electron cloud resulting in its ellipsoidal shape with the short axis opposite the covalent bond and the long axis in the perpendicular direction [11]. This results in a particular distribution of local charges on the atomic surface, as shown in Figure 1. As a consequence the halogen atom may exhibit a dual character, acting as either electron charge donor or acceptor, depending on the type of interaction and the direction of the appearing interactomic contact. A good example of such situation is shown in Figure 2. Thus, one may consider the situation when two interactions are formed simultaneously and the halogen atom acts as an electron charge donor and acceptor at the same time. For such situation the synergism of both interactions may strengthen complexation. In order to analyze that case, various representative complexes were investigated [13, 17, 18, 20, 21] by means of many-body interaction approach [5, 6]. In general, it appears that as distinct to hydrogen bond [2–4], the synergism is rather weak, with some exceptions for iodine atom due to stronger halogen bonds formed by that atomic centre [13, 17, 18]. In the case of halo-amine tetramers [21] the additional stabilising effect derived from back bonding of π type was found – for the first time for a halogen bond.
Źródło:
Wiadomości Chemiczne; 2019, 73, 1-2; 33-52
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Właściwości wewnątrzcząsteczkowych wiązań wodorowych w wybranych N-tlenkach pochodnych chinoliny
Intramolecular hydrogen bonds properties in selected N-oxides of quinoline derivatives
Autorzy:
Jezierska, Aneta
Panek, Jarosław J.
Błaziak, Kacper
Powiązania:
https://bibliotekanauki.pl/articles/171511.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
DFT
teoria funkcjonału gęstości
MP2
metoda rachunku zaburzeń drugiego rzędu Møllera-Plesseta
CPMD
dynamika molekularna Cara-Parrinello
wewnątrzcząsteczkowe wiązanie wodorowe
N-tlenki pochodnych chinoliny
density functional theory
Møller-Plesset second order perturbation method
Car-Parrinello molecular dynamics
intramolecular HB
N-oxides of quinoline derivatives
Opis:
In the current article we would like to summarize our research shedding light onto properties of intramolecular hydrogen bonds present in N-oxide quinoline derivatives. The compounds for the current study were chosen to contain diverse types of hydrogen bonds. Therefore, in the current study we analyze three kinds of hydrogen bonding and their properties. It is well known, that the presence of intramolecular hydrogen bonds stabilizes conformations of molecules. Substituent effects (inductive and steric) influence the strength of the H-bonding as well as its features. Moreover, the intramolecular hydrogen bond in the studied N-oxides belongs to the family of resonance assisted hydrogen bonds (RAHB). Our short overview presents the summary of results obtained for twelve N-oxides of quinoline derivatives. Quantum-chemical simulations were performed on the basis of static models (classical DFT and MP2 approaches) as well as ab initio molecular dynamics (Car-Parrinello MD). The metadynamics method was applied to reproduce the maps of free energy for the motion of the bridged proton. The computations were performed in the gas and in the crystalline phases. Electronic ground state is a natural framework in which chemical compounds exist most of the time. However, in many chemical species we observe a spontaneous internal reorganization of their chemical bonds and atoms e.g. proton transfer phenomenon and the appearance of tautomeric forms already in the ground state. Therefore, it was interesting to investigate some N-oxides in the excited electron state knowing that they exhibit excited- state-induced proton transfer (ESIPT effect). At the end of the article we draw some conclusions related to the intramolecular H-bond properties present in the discussed N-oxides of quinoline derivatives.
Źródło:
Wiadomości Chemiczne; 2019, 73, 1-2; 75-95
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling electromagnetic nanostructures and experimenting with nanoelectric elements to form periodic structures
Modelowanie nanostruktur elektromagnetycznychieksperymenty z elementami nanoelektrycznymi w celu tworzenia struktur okresowych
Autorzy:
Steinbauer, Miloslav
Pernica, Roman
Zukal, Jiri
Kadlec, Radim
Bachorec, Tibor
Fiala, Pavel
Powiązania:
https://bibliotekanauki.pl/articles/1841336.pdf
Data publikacji:
2020
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
nanomaterial
graphene
graphite
experimental modeling
hydrogen bond
periodic structure
nanomateriał
grafen
grafit
modelowanie eksperymentalne
wiązanie wodorowe
struktura okresowa
Opis:
We discuss the numerical modeling of electromagnetic, carbon-based periodic structures, including graphene, graphane, graphite, and graphyne. The materials are suitable for sub-micron sensors, electric lines, and other applications, such as those within biomedicine,photonics, nano-and optoelectronics; in addition to these domains and branches, the applicability extends into, for example, microscopic solutions for modern SMART elements. The proposed classic and hybrid numerical models are based on analyzing a periodic structure with a high repeatability, and they exploitthe concept of a carbon structure having its fundamental dimension in nanometers. The models can simulate harmonic and transient processes;are capable of evaluating the actual random motion of an electric charge as a source of spurious signals; and consider the parameters of harmonic signal propagation along the structure. The results obtained from the analysis are utilizable for the design of sensing devices based on carbon periodic structures andwere employed in experiments with a plasma generator.The aim is to provide a broader overview of specialized nanostructural modeling, or, more concretely, to outline a model utilizable in evaluating the propagation of a signal along a structure’s surface.
W artykule omówiony został procesnumerycznegomodelowaniaelektromagnetycznych, węglowych struktur okresowych, w tym grafenu, grafanu, grafitu i grafinu. Materiały te nadają się do czujników submikronowych, przewodów elektrycznych i innych zastosowań, takich jak biomedycyna, fotonika, nano-i optoelektronika.Oprócz tych dziedzin i gałęzi przemysłu, zastosowanie materiałów pokrywa się także na przykład z mikroskopijnymirozwiązaniamidla nowoczesnych elementów SMART. Proponowane klasyczne i hybrydowe modele numeryczneopierają się na analizie okresowej struktury o wysokiej powtarzalności i wykorzystują koncepcję struktury węglowej o podstawowym wymiarze w nanometrach. Modele mogą symulować procesy harmoniczne i przejściowe,potrafią ocenić rzeczywisty losowy ruch ładunku elektrycznego jako źródła fałszywych sygnałówi uwzględniająparametry propagacji sygnału harmonicznego wzdłuż konstrukcji. Rezultaty uzyskane w wyniku analizy można wykorzystać do projektowania czujników opartych na węglowych strukturach okresowych oraz do eksperymentów z generatorem plazmy. Celem jest zapewnienie szerszego przeglądu specjalistycznego modelowania nanostrukturalnego lub, bardziej konkretnie, zarysumodelu nadającego się do oceny propagacji sygnału wzdłuż powierzchnistruktury.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2020, 10, 4; 4-14
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling electromagnetic nanostructures and experimenting with nanoelectric elements to form periodic structures
Modelowanie nanostruktur elektromagnetycznychieksperymenty z elementami nanoelektrycznymi w celu tworzenia struktur okresowych
Autorzy:
Steinbauer, Miloslav
Pernica, Roman
Zukal, Jiri
Kadlec, Radim
Bachorec, Tibor
Fiala, Pavel
Powiązania:
https://bibliotekanauki.pl/articles/1841381.pdf
Data publikacji:
2020
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
nanomaterial
graphene
graphite
experimental modeling
hydrogen bond
periodic structure
nanomateriał
grafen
grafit
modelowanie eksperymentalne
wiązanie wodorowe
struktura okresowa
Opis:
We discuss the numerical modeling of electromagnetic, carbon-based periodic structures, including graphene, graphane, graphite, and graphyne. The materials are suitable for sub-micron sensors, electric lines, and other applications, such as those within biomedicine,photonics, nano-and optoelectronics; in addition to these domains and branches, the applicability extends into, for example, microscopic solutions for modern SMART elements. The proposed classic and hybrid numerical models are based on analyzing a periodic structure with a high repeatability, and they exploitthe concept of a carbon structure having its fundamental dimension in nanometers. The models can simulate harmonic and transient processes;are capable of evaluating the actual random motion of an electric charge as a source of spurious signals; and consider the parameters of harmonic signal propagation along the structure. The results obtained from the analysis are utilizable for the design of sensing devices based on carbon periodic structures andwere employed in experiments with a plasma generator.The aim is to provide a broader overview of specialized nanostructural modeling, or, more concretely, to outline a model utilizable in evaluating the propagation of a signal along a structure’s surface.
W artykule omówiony został procesnumerycznegomodelowaniaelektromagnetycznych, węglowych struktur okresowych, w tym grafenu, grafanu, grafitu i grafinu. Materiały te nadają się do czujników submikronowych, przewodów elektrycznych i innych zastosowań, takich jak biomedycyna, fotonika, nano-i optoelektronika.Oprócz tych dziedzin i gałęzi przemysłu, zastosowanie materiałów pokrywa się także na przykład z mikroskopijnymirozwiązaniamidla nowoczesnych elementów SMART. Proponowane klasyczne i hybrydowe modele numeryczneopierają się na analizie okresowej struktury o wysokiej powtarzalności i wykorzystują koncepcję struktury węglowej o podstawowym wymiarze w nanometrach. Modele mogą symulować procesy harmoniczne i przejściowe,potrafią ocenić rzeczywisty losowy ruch ładunku elektrycznego jako źródła fałszywych sygnałówi uwzględniająparametry propagacji sygnału harmonicznego wzdłuż konstrukcji. Rezultaty uzyskane w wyniku analizy można wykorzystać do projektowania czujników opartych na węglowych strukturach okresowych oraz do eksperymentów z generatorem plazmy. Celem jest zapewnienie szerszego przeglądu specjalistycznego modelowania nanostrukturalnego lub, bardziej konkretnie, zarysumodelu nadającego się do oceny propagacji sygnału wzdłuż powierzchnistruktury.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2020, 10, 4; 4-14
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 20

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