Informacja

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

Wyszukujesz frazę "molecular interactions" wg kryterium: Temat


Tytuł:
Exceptional molecular organization of canthaxanthin in lipid membranes
Autorzy:
Sujak, Agnieszka
Tematy:
molecular interactions
retinopathy
lipid membranes
canthaxanthin
Pokaż więcej
Wydawca:
Polskie Towarzystwo Biochemiczne
Powiązania:
https://bibliotekanauki.pl/articles/1039765.pdf  Link otwiera się w nowym oknie
Opis:
Canthaxanthin (β,β-carotene 4,4' dione) used widely as a drug or as a food and cosmetic colorant may have some undesirable effects on human health, caused mainly by the formation of crystals in the macula lutea membranes of the retina of an eye. Experiments show the exceptional molecular organization of canthaxanthin and a strong effect of this pigment on the physical properties of lipid membranes. The most striking difference between canthaxanthin and other macular pigments is that the effects of canthaxanthin at a molecular level are observed at much lower concentration of this pigment with respect to lipid (as low as 0.05 mol%). An analysis of the molecular interactions of canthaxanthin showed molecular mechanisms such as: strong van der Waals interactions between the canthaxanthin molecule and the acyl chains of lipids, restrictions to the segmental molecular motion of lipid molecules, modifications of the surface of the lipid membranes, effect on the membrane thermotropic properties and finally interactions based on the formation of the hydrogen bonds. Such interactions can lead to a destabilization of the membrane and loss of membrane compactness. In the case of the retinal vasculature, it can lead to an increase in the permeability of the retinal capillary walls and the development of retinopathy.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Interactions in Binary Organic Liquid Mixtures Containing Ethyl Oleate and Ethanol at 2MHz Frequency
Autorzy:
Manukonda, S.
Kumar, G. P.
Babu, C. P.
Tematy:
Ethyl Oleate
Ethanol
molecular interactions
adiabatic compressibility
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/412193.pdf  Link otwiera się w nowym oknie
Opis:
Molecular interactions of binary mixtures of Ethanol with a new organic compound Ethyl Oleate are investigated at a constant ultrasonic frequency of 2MHz under the temperature range of 303.15K-318.15K. The effect of mole fraction of Ethyl Oleate on velocity of sound wave and the density and viscosity of binary mixtures at various temperatures were studied. The effects on density (ρ), viscosity (η), adiabatic compressibility (βad), inter molecular free length (Lf) and internal pressure (Пi) also was studied.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inter- and inframolecular dynamics of iron porphyrins
Autorzy:
Okla, Dorota
Stanek, Jan
Dziedzic-Kocurek, Katarzyna
Opis:
The temperature dependent Mossbauer spectroscopy and EXAFS analysis of the dynamical properties of selected iron-porphyrin derivatives: FeTPPCl and FePPIXCl has been presented. It has been shown that these iron-porphyrin properties may be modified by the outer ligands, but they are also strongly influenced by the intermolecular interactions, which are reduced in frozen solutions of the studied complexes.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Inter - and inframolecular dynamics of iron porphyrins
Autorzy:
Dziedzic-Kocurek, K.
Okła, D.
Stanek, J.
Tematy:
EXAFS
Fe-porphyrins
molecular interactions
Mössbauer spectroscopy
Pokaż więcej
Wydawca:
Instytut Chemii i Techniki Jądrowej
Powiązania:
https://bibliotekanauki.pl/articles/147410.pdf  Link otwiera się w nowym oknie
Opis:
The temperature dependent Mössbauer spectroscopy and EXAFS analysis of the dynamical properties of selected iron-porphyrin derivatives: FeTPPCl and FePPIXCl has been presented. It has been shown that these iron-porphyrin properties may be modified by the outer ligands, but they are also strongly influenced by the intermolecular interactions, which are reduced in frozen solutions of the studied complexes.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical evaluation of ultrasonic velocities of binary liquid mixtures of 1-bromopropane in chlorobenzene at 303.15, 308.15, 313.15 and 318.15 K
Autorzy:
Babu, Ch. P.
Kumar, G. P.
Nagarjun, B.
Samatha, K.
Tematy:
ultrasonic velocities
molecular interactions
1-bromopropane and chlorobenzene
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/412079.pdf  Link otwiera się w nowym oknie
Opis:
Theoretical velocities of binary liquid mixtures of 1-bromopropane with chlorobenzene at 2 MHz and four different temperatures 303.15, 308.15, 313.15 and 318.15 K, have been evaluated as a function of concentration and temperature. The experimental values are compared with theoretical models of liquid mixtures such as Nomoto, Van Dael-Vangeel, Impedance Relation, Rao’s Specific Velocity Method, Junjie’s relations and Free Length Theory. In the chosen system there is a good agreement between experimental and theoretical values calculated by Nomoto’s theory. The deviation in the variation of U2exp/ U2imx from unity has also been evaluated for explaining the non ideality in the mixtures. The results are explained in terms of intermolecular interactions occurring in these binary liquid mixtures.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustical studies of binary liquid mixtures of p-chlorotoluene in benzene at different temperatures
Autorzy:
Kumar, G. P.
Babu, Ch. P.
Samatha, K
Jyosthna, A. N.
Showrilu, K.
Tematy:
ultrasonic velocity
thermodynamic parameters
p-chlorotoluene
molecular interactions
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/412275.pdf  Link otwiera się w nowym oknie
Opis:
Ultrasonic velocities (U), densities (ρ), and coefficient of viscosities (η) are measured for binary mixtures containing (i) p-chlorotoluene and (ii) benzene at 303.15 K, 308.15 K, 313.15 K and 318.15 K to understand the molecular interaction. Various acoustical parameters such as adiabatic compressibility (βad), free length (Lf), acoustic impedance (Z), free volume (Vf), molar volume (Vm), Rao’s constant (R), Wada’s constant (W) and internal pressure (πi), are calculated from the measured values of U, ρ, and η. The trend in acoustical parameters also substantiates to asses strong molecular interactions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustical studies of some synthesized Schiff base derivatives in dimethylsulphoxide at 303.15 K, by ultrasonic velocity measurement
Autorzy:
Gopi, C.
Santhi, N.
Tematy:
density
viscosity
ultrasonic velocity
DMSO
acoustical parameters
molecular interactions
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/412151.pdf  Link otwiera się w nowym oknie
Opis:
The density, viscosity and sound velocity of five Schiff bases (1-5) derivatives in DMSO solutions have been studied at 303.15 K over a wide range of concentration. From these experimental data, some acoustical parameters such as Molar volume (Vm), Specific Acoustic Impedance (Z), Adiabatic compressibility (βad), Intermolecular Free Length (Lf), Rao’s Constant (R), Molar compressibility (W), Relaxation time(τ), van der Waals constant (b), Relaxation strength (r), Relative association (RA), Isothermal compressibility (βT ) , Isothermal expansion co-efficient (α) ,Free volume (Vf) and Internal pressure (πi) and Ultrasonic attenuation (α/f²) have been evaluated. A fairly good correlation between a given parameter and concentration is observed. The results are interpreted in terms of molecular interactions like solvent-solvent, solvent-solute and solute-solute interactions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Template driven self-assembly of the pentacene structure on the Si(553)-Pb surface
Autorzy:
Palotas, Krisztian
Dachniewicz, Marek
Jałochowski, Mieczysław
Krawiec, Mariusz
Nita, Paweł
Opis:
The self-assembly of the pentacene molecules on the Pb-ordered Si(553) surface is studied with scanning tunneling microscopy and density functional theory methods. Within the surface coverage up to a single monolayer, pentacene was found to form two different chain-like structures. They vary in molecular density, but both exhibit long-range, one-dimensional ordering with longer molecular axes aligned along step edges. The low-density phase consists of single discontinuous molecular rows and adapts the template surface periodicity, while the high-density phase features triple molecular chains with the unit cell determined by the length of the pentacene molecules. Such an arrangement of the molecules is controlled by a subtle balance between molecule–molecule and molecule–substrate interactions.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Triptycene Derivatives: From Their Synthesis to Their Unique Properties
Autorzy:
Woźny, Mateusz
Millo, Enrico
Mames, Adam
Ratajczyk, Tomasz
Współwytwórcy:
Millo, Enrico
Wydawca:
MDPI
Cytata wydawnicza:
Woźny, M.; Mames, A.; Ratajczyk, T. Triptycene Derivatives: From Their Synthesis to Their Unique Properties. Molecules 2022, 27, 250. https://doi.org/10.3390/molecules27010250
Opis:
Since the first preparation of triptycene, great progress has been made with respect to its synthesis and the understanding of its properties. Interest in triptycene-based systems is intense; in recent years, advances in the synthetic methodology and properties of new triptycenes have been reported by researchers from various fields of science. Here, an account of these new developments is given and placed in reference to earlier pivotal works that underpin the field. First, we discuss new approaches to the synthesis of new triptycenes. Progress in the regioselective synthesis of sterically demanding systems is discussed. The application of triptycenes in catalysis is also presented. Next, progress in the understanding of the relations between triptycene structures and their properties is discussed. The unique properties of triptycenes in the liquid and solid states are elaborated. Unique interactions, which involve triptycene molecular scaffolds, are presented. Molecular interactions within a triptycene unit, as well as between triptycenes or triptycenes and other molecules, are also evaluated. In particular, the summary of the synthesis and useful features will be helpful to researchers who are using triptycenes as building blocks in the chemical and materials sciences.
National Science Centre, Poland (SONATA No. 2017/26/D/ST5/00361)
Dostawca treści:
Repozytorium Centrum Otwartej Nauki
Artykuł
Tytuł:
Effect of temperature on thermo-physical properties of pyrazolo quinazoline derivatives by ultrasonic studies
Autorzy:
Baluja, Shipra
Ramavat, Paras
Nandha, Kajal
Tematy:
pyrazolo quinazoline derivatives
Acoustical parameter
Molecular interactions
Density
apparent molar compressibility
Pokaż więcej
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:
https://bibliotekanauki.pl/articles/1192659.pdf  Link otwiera się w nowym oknie
Opis:
Density (ρ), Sound velocity (U) and viscosity (ɳ) of pure solvent N,N-dimethylformamide (DMF) and solutions of pyrazolo quinazoline derivatives in DMF were taken at different concentration range and at different temperatures by using Antone paar. From these experimental data, some acoustical parameters such as adiabatic compressibility (κs), intermolecular free length (Lf), solvation number (Sn), apparent molar compressibility (fk), apparent molar volume (fv), internal pressure (π) etc., have been determined and correlated with the concentration (C).With concentration and temperatures, Linear or non-linear increases or decreases of acoustical parameters shows the existence of strong molecular interactions between solute and solvent. The results are interpreted in terms of solute-solute and solute-solvent interactions to understand the behavior of synthesized compounds in solutions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interactions of edelfosine with biological membrane components
Badanie oddziaływań edelfozyny ze składnikami błon biologicznych.
Autorzy:
Sobczyk, Wiesław
Opis:
This work was aimed at studying interactions of edelfosine – a new generation anticancer drug of a phospholipid-like structure with selected components of natural cellular membranes. Three phosphatidylcholines were selected for investigations: with both unsaturated acyl chains (DOPC), with one saturated (at C1) and the other unsaturated (at C2) – POPC, and with one unsaturated (at C1) and the other saturated (at C2) – OPPC. The investigations of molecular interactions were carried out in two-dimensional systems, using the Langmuir monolayer technique. From the registered surface pressure vs mean molecular area (A) dependencies, the parameters of interaction – both qualitative (A12 i Aexc) and quantitative (DGexc) were calculated. It has been found that unfavorable repulsive interactions exists between edelfosine and both phosphatidylcholines possessing one unsaturated chain (POPC and OPPC), while the interactions with the unsaturated phosphatidylcholine (DOPC) depend on the composition of mixed monolayer: they were repulsive for monolayers reach in phosphatidylcholine and attractive for monolayers reach in edelfosine.
Niniejsza praca miała na celu przebadanie oddziaływań edelfozyny – nowej generacji leku przeciwnowotworowego o strukturze imitującej naturalne fosfolipidy – z wybranymi składnikami naturalnych błon komórkowych. Do badań wybrano 3 fosfatydylocholiny posiadające oba nienasycone łańcuchy acylowe w cząsteczce (DOPC); jeden nasycony (przy C1) a drugi nienasycony (przy C2) - POPC i odwrotnie – jeden nienasycony (przy C1) a drugi nasycony (przy C2) – OPPC. Badania oddziaływań międzycząsteczkowych prowadzono w układach dwuwymiarowych z wykorzystaniem techniki monowarstw Langmuira. Zarejestrowano izotermy ciśnienia powierzchniowego w funkcji powierzchni przypadającej na cząsteczkę (A) dla każdego z w/w układów i na ich podstawie obliczono parametry oddziaływań międzycząsteczkowych, zarówno jakościowe (A12 i Aexc), jak i ilościowe (DGexc). Stwierdzono występowanie oddziaływań odpychających w mieszaninach edelfozyny z fosfatydylocholinami posiadającymi jeden łańcuch nienasycony (POPC i OPPC), natomiast dla mieszanin z nienasyconą fosfatydylocholiną (DOPC) oddziaływania zależały od składu mieszanej monowarstwy i były odpychające dla monowarstw zawierających nadmiar fosfolipidu, zaś przyciągające dla monowarstw bogatszych w edelfozynę.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Molecular interactions of chiral ionic liquids with fungal membranes : thermodynamic and molecular dynamics simulation insights
Autorzy:
Kobierski, Jan
Chachaj-Brekiesz, Anna
Feder-Kubis, Joanna
Łukawski, Krzysztof
Dynarowicz-Łątka, Patrycja
Wnętrzak, Anita
Petelska, Aneta D.
Opis:
The development of selective antifungal agents is crucial to improve therapeutic options while minimizing side effects. This study assessed the potential antimicrobial efficacy of ionic liquids, particularly against fungal pathogens. For this, a functionalized chiral ionic liquid (FCIL) with a naturally occurring (1R,2S,5R)-(−)-menthol moiety and a long alkyl chain was synthesized and characterized using spectral and thermal methods. The antifungal potential of this FCIL was evaluated by examining interactions with artificial fungal and mammalian membranes modeled as Langmuir monolayers. Thermodynamic analyses, complemented by adsorption and penetration experiments, Brewster angle microscopy, polarization modulation infrared reflection absorption spectroscopy, and molecular dynamics simulations, showed that FCIL incorporated into membranes and caused fungal membrane disintegration. This can be related to π-π interactions with ergosterol, a primary fungal membrane sterol, and favorable assimilation into membranes containing dioleoylphosphatidylcholine, an unsaturated phospholipid abundant in fungal cells. Conversely, interactions with mammalian membranes modeled using dipalmitoylphosphatidylcholine and cholesterol were thermodynamically unfavorable due to their tighter packing. These findings underline the FCIL's ability to selectively disrupt fungal membranes and suggest its potential use as a targeted antifungal agent with reduced mammalian cell toxicity. This research highlights the benefit of integrating experimental and computational methods to understand the molecular mechanics driving selective antifungal activity.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Elektrooptyczny efekt Kerra w chemii
Electrooptic Kerr effect in chemistry
Autorzy:
Prezhdo, O.
Olan, K.
Zubkowa, W.
Preżdo, W.
Tematy:
elektrooptyczny efekt Kerra
analiza konformacyjna
wewnątrzcząsteczkowe oddziaływania
oddziaływania wewnątrzcząsteczkowe
oddziaływania międzycząsteczkowe
polaryzowalność
moment dipolowy
stała Kerra
electro-optical Kerr effect
conformational analysis
intra-molecular interactions
intermolecular interactions
polarizability
dipole moment
Kerr constant
Pokaż więcej
Wydawca:
Polskie Towarzystwo Chemiczne
Powiązania:
https://bibliotekanauki.pl/articles/171825.pdf  Link otwiera się w nowym oknie
Opis:
The electro-optical Kerr effect finds wide application in conformational analysis of molecules and molecular aggregates [1–5], particularly in cases where the standard X-ray and NMR techniques cannot be used. For instance, NMR allows to establish conformations of linear and cyclic unsaturated organic compounds. However, it is less effective in an analysis of molecular complexes, particularly of those that have several rotational symmetry axes. In such cases a combination of techniques based on molecular dipole moments, electro-optical Kerr effect, optical Kerr effect, IR spectroscopy, and Rayleigh scattering can be applied [6]. The foundations of conformational analysis of molecular complexes using several complementary physical approaches are developed in Ref. [7]. The electro-optical methods are particularly useful for an investigation of intramolecular interactions [8–18]. The strength, direction and other details of intramolecular interactions can be determined by analyzing the deviations of the experimental molar Kerr constant (mK) from its value calculated according to the tensor-additive scheme that operates with polarizability tensors of molecular cores and functional groups [19, 20]. For instance, using this approach it has been shown that weakening of conjugation in an electron donor-acceptor chain can lead to flattening of the molecular structure [21]. The Kerr constant is also very sensitive to intermolecular interactions [22–29]. In order to assess quantitatively an extent of the solvent effect on the mK values, both molecular and continuum models of solution structure have been used [30, 31]. The mK values are greatly affected by the mutual orientation of solvent and solute molecules, which interact by dispersive, inductive and dipole-dipole forces [32]. Hydrogen and donor-acceptor bonding have an even stronger influence on the mK values [33]. The equimolar mixtures approach developed in Ref. [34] allows to determine the molar Kerr constant (mK), dipole moment (m), equilibrium constant (K) and, ultimately, structure of a molecular complex based on measurements of the Kerr constant (B), dielectric permittivity (e), density (d) and refractive index (n) of a series of dilute solutions of the complex. Future trends in the development of the electro-optical methods in chemistry are discussed. Theories that relate the electric-optic proprieties of molecules with their reactivity are particularly important. Such theories should be able to predict the changes in the polarizabilities and dipole moments of bonds, molecules and molecular aggregates during the course of chemical reactions.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wieloskładnikowe kryształy i kompozyty krystaliczne oparte na hybrydowych architekturach molekularnych z udziałem anionowych kompleksów płaskokwadratowych
Multi-component crystals and crystal composites based on hybrid molecular architectures with the participation of anionic square planar complexes
Autorzy:
Głosz, Dorota
Opis:
Oddziaływania anion-π są stosunkowo niedawno odkrytym typem oddziaływań supramolekularnych. Mają one charakter niekowalencyjny, kierunkowy, a także kooperatywny i polaryzowalny. Głównymi przyczynkami tego typu interakcji jest wkład elektrostatyczny związany z momentem kwadrupolowym cząsteczki aromatycznej oraz polaryzacja indukowana oddziaływaniem układu π-elektronowego z anionem. Blokami budulcowymi adduktów anion-π są cząsteczki aromatyczne z wyraźnym deficytem gęstości elektronowej w obrębie szkieletu węglowego (π kwasy organiczne) oraz aniony proste, a także anionowe kompleksy metali o różnych geometriach. Dobór tektonów decyduje o ich wzajemnej orientacji, wyglądzie struktury oraz o sile interakcji. W ramach pracy badawczej uzyskano dwa nowe addukty supramolekularne (PPh4)2{[PtCl4][HAT(CN)6]}·3MeCN (1 Cl–) oraz (PPh4)2{[PtBr4][HAT(CN)6]}·3MeCN (1 Br–), oparte o oddziaływania anion-π, będące analogami wcześniej opisanej struktury 1 CN–, gdzie anionem kompleksowym jest [Pt(CN)4]2–. Płaskokwadratowe kompleksy anionowe oraz cząsteczki π-kwasu oddziałują na zasadzie interakcji anion-π i tworzą naprzemienne kolumny rozdzielone kationami organicznymi. Mimo niewielkich różnic strukturalnych, zaobserwowano znaczne różnice spektroskopowe, które są efektem odmiennego charakteru zastosowanych ligandów. Zaprezentowano również wstępne, udane próby utworzenia kompozytów krystalicznych typu core-shell złożonych z dwóch faz.
Anion-π interactions are relatively recently discovered type of supramolecular interactions. They are non-covalent, directional and also have cooperative and polarizable character. Main contributions to this type of interactions are electrostatic part associated with the quadrupole moment of aromatic molecule and polarization induced by interaction of a π-electronic system with an anion. The building blocks of anion-π adducts are aromatic molecules with a substantial electron density deficit within the carbon skeleton (π-organic acids) and simple anions, as well as anionic metal complexes of various geometries. The choice of tectons determines their mutual orientation, structure features and strength of interaction. As a part of research work, two new supramolecular adducts: (PPh4)2{[PtCl4][HAT(CN)6]}·3MeCN (1 Cl–) and (PPh4)2{[PtBr4][HAT(CN)6]}·3MeCN (1 Br–), based on anion-π interactions, were obtained. They are analogous to previously described structure (1 CN–), where the complex anion is [Pt(CN)4]2–. Anionic square planar complexes and π-acid molecules interact with each other and form alternate columns separated by organic cations. Despite small structural differences, significant spectroscopic differences were observed, which are the result of different nature of ligands used. Preliminary successful attempts towards creation of two-phase core-shell crystal composites were also presented.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Określenie zdolności teorii funkcjonałów gęstości do dokładnego przewidywania widm UV-VIS wybranych kryształów molekularnych
Determinations of the ability of density functional theory to accurately predict the UV-vis spectra of mixed molecular crystals
Autorzy:
Vasseur, Laurine
Opis:
W ramach niniejszej pracy magisterskiej wykorzystano różne poziomy teorii funkcjonałów gęstości (funkcjonał PBE+D3 oraz funkcjonały wyższego rzędu), aby przewidzieć spektroskopowe właściwości kilku układów wykazujących oddziaływania anion-π. Jako pierwsząprzeprowadzono analizę stanu podstawowego układów krystalicznych złożonych z [ReV(CN)4N]2-, [PPh4]+ i trzech różnych ligandów (BPE, FBP i DPY). Wyniki potwierdziły ogólne tendencje zaobserwowane w eksperymentalnych widmach emisyjnych, przede wszystkim w ustaleniu związku pomiędzy obliczoną przerwą energetyczną a długością fali emisyjnej. Różnice w kształtach widm (szczególnie dla tych, które wykazywały wielopasmową strukturę) związane są z różnicami w energiach orbitali molekularnych wywodzących się z pirydyny, co wpływa zarówno na pozycję LUMO liganda w stosunku do poziomu Fermiego kryształu, jak i na poziom nakładania się orbitali wiązania Re-N. Ogólnie biorąc, funkcjonał PBE+D3 jest w stanie zidentyfikować wszystkie różnice jakościowe, zidentyfikowane przez funkcjonał HSE06. Wyraźnie więc widać, że wykorzystanie funkcjonału PBE+D3 jest w tym przypadku (diamagnetycznego metaloorganicznego kryształu molekularnego ze znacząco dużą przerwą energetyczną) wystarczające do dokładnego modelowania właściwości chemicznych, pomimo ilościowych niezgodności.Druga część pracy magisterskiej dotyczyła dwóch tzw. układów TCP, które zostały zaprojektowane wokół oddziaływań anion- π (nazwanych TCP_1 i TCP_3). Widma, obliczone w ramach przybliżenia RPA (Random-Phase Approximation) wydają się wskazywać na zwiększoną intensywność absorpcji przy wyższych długościach fali w TCP_3 w porównaniu do TCP_1 (co zgadza się z eksperymentem), ale ostatecznie zarówno metoda RPA, jak i IPA (Independent Particle Approximation) nie są w stanie odtworzyć wyników eksperymentalnych, ani przy użyciu PBE+D3, ani HSE06.W ostatniej części pracy przeprowadzono strukturalną i elektronową analizę struktury materiałów BCy (mających strukturę podobną do grafenu). Pozwoliło to uzupełnić ostatnie badania, które opisały funkcję dielektryczną i związane z nią własności wysoce symetrycznej struktury CB. Analiza konformacyjna materiałów BC w większej (p2x2) komórce symulacyjnej potwierdziła, że półprzewodząca struktura C6B2jest bardziej stabilna i skutkuje zasadniczo odmiennymi właściwościami elektronowymi i dielektrycznymi. W tym przypadku funkcjonał PBE+D3 jakościowo poprawnie przewiduje termodynamiczną stabilność rozważanych struktur, ale opisuje strukturę elektronową C6B2 w sposób niezgodny z przewidywaniami funkcjonałów HSE06 oraz GW. Wydaje się, że spektroskopia fotoelektronów z rozdzielczością kątową (ARPES) będzie w stanie pomóc w identyfikacji struktury CB, w przypadku jej udanej syntezy w laboratorium.W pracy magisterskiej wykazano, że funkcjonał PBE+D3 opisuje niektóre własności badanych układów zgodnie z wynikami obliczeń metodą HSE06.
This project aims to evaluate how the PBE + D3 functional compares to the spectroscopic predictions of higher-level computational methods, and this done by studying three different systems that can exhibit anion-π interactions. First, the analysis of the electronic structure of the ground state of crystal systems composed of [ReV(CN)4N]2-, [PPh4]+ and three different ligands (bpe, fbp and dpy) was performed. This analysis helped to rationalize very well the trends that were observed between ligands in the experimental emission spectra, demonstrating first that there is a link between the calculated band gap and the emission wavelength. However, the differences in the shapes of the experimental emission curves (especially for the bpe-ligand structure which presented a multi-peaked fine structure) are proposed to be better explained as coming from the different splitting of pyridine-based molecular orbitals; this splitting is induced by the central chain of the ligand molecule and affects both the alignment of the ligand’s LUMO with the Fermi level of the crystal and the strength of the orbital overlap contribution to the Re-N bond (bpe exhibits a much stronger interaction with the metal complexes than the other ligands). Overall, it was found that the PBE+D3 method is able to identify all the qualitative differences that HSE06 determines, which indicates that the PBE+D3 is sufficient in this case (of a diamagnetic organometallic molecular crystal with a significantly large band gap) to accurately model the chemistry, despite its disagreement in a quantitative sense. The second project focused on two so-called TCP systems that were designed around anion- interactions (called TCP_1 and TCP_3). The experimental UV-vis spectrum of the structures is known but does not relate to the calculated band gaps. The computed spectra within the framework of the Random-Phase Approximation (RPA) seem to indicate an increased intensity of higher-wavelength absorptions in TCP_3 vs. TCP_1 (which agrees with experiment), but ultimately the RPA and IPA (Independent Particle Approximation) methods are not able to represent the experimental results in a quantitative sense, using neither PBE+D3 nor HSE06. Finally, a structural and electronic analysis of the structure of BxCy materials (a graphene-like structure) was carried out to complement a recent study that reported the dielectric function (and related properties) of a highly symmetric but metastable CB structure with a 1:1 stoichiometry. A conformational analysis of BC materials in a larger (p2x2) simulation cell confirmed that a semiconducting C6B2 – composition structure is more stable and results in fundamentally different electronic and dielectric properties. In this case, the PBE+D3 method correctly predicts the qualitative thermodynamic stabilities of the considered structures, but ultimately fails to describe the electronic structure of the C6B2 – structure in agreement with HSE06 or GW methods. It is proposed that ARPES studies should be capable of helping identify what CB structure is made, should it be successfully synthesized in the laboratory. The project has been able to highlight the PBE + D3 density functional as a great deal to reproduce HSE06 calculations results. This has once again shown the strict system-dependence of methods effectiveness
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Molecular Dynamics Simulations of the Affinity of Chitin and Chitosan for Collagen: the Effect of pH and the Presence of Sodium and Calcium Cations
Autorzy:
Przybyłek, Maciej
Bełdowski, Piotr
Tematy:
chitin
chitosan
collagen
intermolecular interactions
molecular dynamics
Pokaż więcej
Wydawca:
Sieć Badawcza Łukasiewicz - Polskie Towarzystwo Chitynowe
Powiązania:
https://bibliotekanauki.pl/articles/58310034.pdf  Link otwiera się w nowym oknie
Opis:
Chitosan and chitin are promising biopolymers used in many areas including biomedical applications, such as tissue engineering and viscosupplementation. Chitosan shares similar properties with hyaluronan, a natural component of synovial fluid, making it a good candidate for joint disease treatment. The structural and energetic consequences of intermolecular interactions are crucial for understanding the biolubrication phenomenon and other important biomedical features. However, the properties of biopolymers, including their complexation abilities, are influenced by the nature of the aqueous medium with which they interact. In this study, we employed molecular dynamics simulations to describe the effect of pH and the presence of sodium and calcium cations on the stability of molecular complexes formed by collagen type II with chitin and chitosan oligosaccharides. Based on Gibbs free energy of binding, all considered complexes are thermodynamically stable over the entire pH range. The affinity between chitosan oligosaccharide and collagen is highly influenced by pH, while oligomeric chitin shows no pH-dependent effect on the stability of molecular assemblies with collagen. On the other hand, the presence of sodium and calcium cations has a negligible effect on the affinity of chitin and chitosan for collagen.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowe addukty molekularne pomiędzy aromatycznymi pi-kwasami oraz kompleksami anionowymi o liczbie koordynacyjnej 6-8
Novel molecular adducts between pi - acidic aromatic compounds and anionic complexes with coordination number 6-8
Autorzy:
Kobylarczyk, Jędrzej
Opis:
Oddziaływania supramolekularne odgrywają kluczową rolę w układach makromolekularnych oraz biologicznych. Zainteresowanie tymi oddziaływaniami jest znaczące ze względu na potencjał ich wykorzystania do projektowania nowych multifunkcjonalnych materiałów molekularnych, katalizatorów, sensorów oraz układów naśladujących zachowania biologiczne. W niniejszej pracy przedstawiono syntezę , struktury krystaliczne oraz właściwości fizykochemiczne sześciu nowych adduktów molekularnych opartych na pi – kwasowym układzie aromatycznym HAT(CN)6 (heksaazatrifenylenoheksakarbonitrylu) oraz polianionowych kompleksach: X[Fe(CN)6], X[Fe(CN)6], X[W(CN)8], X = (PPh4+, AsPh4+). Dopasowanie strukturalne i elektronowe użytych pi – kwasów oraz polianionowych kompleksów pozwoliło na spontaniczne utworzenie łańcuchowych polimerów supramolekularnych stabilizowanych oddziaływaniami anion –pi tworzonymi pomiędzy facjalnymi grupami ligandów CN- a centroidami pierścieni pirazynowych receptora HAT(CN)6. Pomiary widm absorpcyjnych wykazały charakter przeniesienia ładunku (CT) oraz obecność oddziaływań w roztworze co może w przyszłości pozwolić na sterowanie równowagami procesów samoskładania wielocentrowych kompleksów opartych na policyjanometalanowych blokach buldulcowych.
Supramolecular interactions play crucial role in macromolecular and biological systems. Interest in supramolecular contacts is significant from the viewpoint of creating novel multifunctional molecular materials, catalysts, sensors and systems imitating biological behavior. Herein synthesis, crystal structures and physicochemical properties of six novel molecular adducts, based on HAT(CN)6 (hexaazatriphenylenehexacarbonitrile) and polianionic complexes: X[Fe(CN)6], X[Fe(CN)6], X[W(CN)8], X = (PPh4+, AsPh4+) were presented. Spontaneous formation of chain-like supramolecular polymers stabilized by anion – pi interactions between facial CN- ligands and centroids of HAT(CN)6 receptor was based on structural and electronic matching. Absorption spectra measurements in solid state and solution revealed charge transfer character (CT) and presence of anion – pi interactions in solution. Observed interactions in solution could effect on self-assembly of policyanometallate based polynuclear compounds.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Modelling drug-receptor interactions in an average binding site for NK2
Autorzy:
Alagona, G.
Ghio, C.
Monti, S.
Tematy:
receptor modelling
docking
non covalent interactions
molecular mechanics
molecular dynamics
substituent effects
Pokaż więcej
Wydawca:
Politechnika Gdańska
Powiązania:
https://bibliotekanauki.pl/articles/1953954.pdf  Link otwiera się w nowym oknie
Opis:
A tentative procedure applied to the search for a new antagonist of neurokinin A (NKA) is presented. In parallel a tentative 3-D model of the NK2 receptor was created, using bacteriorhodopsin (BRD) as a template. The residue substitutions were performed in BRD to obtain the sequence for NK2R_H and the seven a-helical segments were optimized forcing the a-helical backbone to match the corresponding aligned parts of BRD, while the arrangements of the side chains were model built based on available site-directed mutagenesis studies. Constrained MM and molecular dynamics simulations were carried out H-bonding a low energy conformer of the known drugs to residues in the receptor site, allowing both the receptor site and drugs to relax. The Connolly surface for each ligand allowed to determine an "average" binding site in which all the low energy conformers of known and prospective drugs were docked and classified according to a statistical index. The whole procedure was repeated exploiting the lately published structure of an actual G protein coupled receptor as a better template, thus producing a cavity in the binding site to directly dock the drugs. Corollary validations of the force fields used are also mentioned. In addition intra- and intermolecular interactions suitable to produce more active drugs were evaluated.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania oddziaływań cholesterolu i wody oraz agregacji cholesterolu w środowisku polarnym metodą symulacji dynamiki molekularnej
The study of cholesterol-water interactions and cholesterol self-assembly in polar environment based on molecular dynamics simulations
Autorzy:
Nguyen, Tuyet Linh
Opis:
Cholesterol is characterized with amphipathic properties – the steroid rings and the aliphatic tail attached to C17 contribute to its hydrophobic character, while ring A’s hydroxyl group is responsible for the hydrophilic interactions. On the cellular level cholesterol is an essential component of plasma membranes, regulating their stability and permeability. Moreover, cholesterol is the precursor of steroid compounds – vitamin D, bile salts and steroid hormones. On the contrary, cholesterol is involved in numerous pathophysiological processes, including atherosclerosis and bile salt formation. Cholesterol nucleation in water is suspected to be the initial stage of those processes.Multiple studies confirmed that cholesterol aggregation occurs in water with monohydrate crystal phase being the final state of cholesterol self-assembly. The presence of cholesterol bilayer domains was observed in saturated phospholipid membranes. Nonetheless, it is unknown whether similar bilayers are formed in water. In this thesis, molecular dynamics simulations were carried out in order to analyse the initial stages of cholesterol-water interaction and water reorientation around cholesterol. Cholesterol molecules were also investigated in context of their self-assembly in systems comprising of two, three and four hydrated molecules. In particular, we studied the stability and geometry of the final cholesterol aggregates. Water formed a steady structure around cholesterol at approximately 5 ps. The orientation of water molecules was mostly determined by carbons located in the cholesterol rings. We have demonstrated that in the time period from 100 fs to 30 ps water molecules quickly diffused from the first hydration sphere, while the decrease rate was slower from 35 ps until the end of MD simulation. Cholesterol self-assembly occurred faster for steroid pairs, though they were less stable than three- or four-cholesterol aggregates. In cholesterol pairs the reorientation occurred frequently, as individual molecules tended to rotate by 180° about the horizontal axis. Self-assembly of four cholesterol molecules occurred after a longest period of time (10 ns) and was preceded by pair formation. In the final aggregates cholesterols were connected through smooth surfaces and were oriented in parallel planes.
Amfipatyczne właściwości cholesterolu uwarunkowane są obecnością pierścieni steroidowych oraz łańcucha alifatycznego w pozycji 17-tej – elementy te nadają cząsteczce hydrofobowy charakter, natomiast grupa hydroksylowa w pierścieniu A jest odpowiedzialna za oddziaływania hydrofilowe. Na poziomie komórkowym cholesterol stanowi nieodzowny składnik błony komórkowej, regulując jej stabilność oraz przepuszczalność. Ponadto, cholesterol jest prekursorem wielu związków steroidowych, m.in. witaminy D, kwasów żółciowych oraz hormonów steroidowych. Wykazano również udział cholesterolu w patogenezie blaszek miażdżycowych oraz kamieni żółciowych. Podejrzewa się, że nukleacja cholesterolu stanowi początkowy etap tych procesów.W badaniach doświadczalnych niejednokrotnie zaobserwowano agregację cholesterolu w wodzie. Naukowcy odnotowali, iż cholesterol w końcowej fazie agregacji tworzy monokryształ. Wykazano obecność dwuwarstwowych domen cholesterolu przesyconych błonach fosfolipidowych, jednakże dotychczas nie udało się ustalić, czy w wodzie cholesterol również spontanicznie tworzy dwuwarstwy. Przeprowadzono symulacje dynamiki molekularnej w celu zbadania początkowych etapów oddziaływania cholesterolu z wodą oraz procesu reorientacji wody wokół cholesterolu. Analizowaliśmy również agregację cholesterolu w układach zawierających dwie, trzy oraz cztery uwodnione cząsteczki cholesterolu.Udało nam się zaobserwować, iż woda utworzyła stabilną struktorę wokół cholesterolu po około pięciu pikosekundach. Odnotowaliśmy szybką ,,ucieczkę” cząsteczek wody z pierwszej sfery hydratacyjnej w czasie od 100-tu fs do 30-tu ps, natomiast po czasie 35-ciu ps proces ten miał mniej gwałtowny przebieg. Wykazaliśmy również, iż agregacja cholesterolu nastąpiła szybciej, kiedy cząsteczki miały możliwość utworzenia par, jednakże agregaty zbudowane z trzech oraz czterech cholesteroli cechowały się większą stabilnością. Reorientacja przebiegała z większą częstotliwością w przypadku par – pojedyncze cząsteczki rotowały o 180° wzdłuż osi horyzontalnej. W przypadku czterech cholesteroli najpierw nastąpiło utworzenie par, które po dziesięciu nanosekundach utworzyły czterocholesterolowy agregat. W końcowych agregatach cholesterol były ułożone w równoległych płaszczyznach oraz stykały się ze sobą gładkimi powierzchniami.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Inne
Tytuł:
Polymer Reinforced DNAN/RDX Energetic Composites: Interfacial Interactions and Mechanical Properties
Autorzy:
Qian, W.
Chen, X.
Luo, G.
Tematy:
energetic composites
dinitroanisole
molecular dynamics
interfacial interactions
mechanical properties
Pokaż więcej
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Powiązania:
https://bibliotekanauki.pl/articles/358170.pdf  Link otwiera się w nowym oknie
Opis:
2,4-Dinitroanisole (DNAN) has excellent properties as a replacement for 1,3,5-trinitrotoluene (TNT) in melt-cast explosives, and the polymeric modifier used is critical to the mechanical modification of the DNAN/RDX energetic composite. In our research, the typical polymeric modifier acrolein-pentaerythritol resin (APER) was successfully added experimentally to the DNAN/RDX system, and the effects of interfacial interactions on the mechanical properties of these polymers in reinforcing the DNAN/RDX energetic composites were investigated by molecular dynamics simulations, scanning electron microscopy (SEM) and mechanical testing. The results showed that strong attractive interactions exist between the polymer and the explosives, wherein van der Waals forces were found to play the main role. The morphological micro-images also showed tight binding between the polymer/explosive interfaces, which supported the calculated strong interfacial interactions. The mechanical tests confirmed that adding the polymers can obviously reinforce the mechanical strength and toughness of DNAN/RDX systems. The above observations revealed that the cooperative effects of the APER polymer can help to reinforce the interfacial interactions and mechanical properties of DNAN/RDX composites, which is of importance in the formulation and mechanical evaluation of advanced energetic composites.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Construction of $CN^{-}$-bridged molecular squares employing penta-, hexa- and octa-coordinated metal ions
Autorzy:
Stadnicka, Katarzyna
Korzeniak, Tomasz
Sieklucka, Barbara
Nowicka, Beata
Nitek, Wojciech
Majcher, Anna
Opis:
Three new cyanido-bridged discrete bimetallic assemblies based on $\left [ W\left ( CN \right )_{6}\left ( bpy \right ) \right ]^{2-}$ building block have been synthesised and structurally characterised. Neutral molecular square $\left \{ \left [ Ni\left ( bpy \right )_{2} \right ]_{2}\left [ W\left ( CN \right )_{6}\left ( bpy \right ) \right ]_{2} \right \}\cdot nH_{2}O \left ( 1 \right )\left ( bpy=2,{2}'-bipyridine \right )$ has been constructed from $\left [ Ni^{II} \left ( pby \right )_{2}\left ( H_{2}O_{2} \right )\right ]^{2+}$ complex. Since the attempt to obtain analogous structure with Cu(II) ion was unsuccessful, we introduced tetradentate blocking ligand tren (tren = tris(2-aminoethyl)amine) on Cu, which resulted in dinuclear molecule $\left \{ \left [ Cu\left ( tren \right ) \right ]\left [ W\left ( CN \right )_{6}\left ( bpy \right ) \right ] \right \}\left ( 2 \right )$. In order to create square cluster with Cu(II) ions we employed tridentate ligand di-(2-picolyl)amine (dpa), which yielded the desired structure of $\left \{ \left [ Cu\left ( dpa \right ) \right ]_{2} \left [ W\left ( CN \right )_{6}\left ( bpy \right ) \right ]_{2}\right \} \left ( 3 \right )$. Compounds (1) and (3), the first molecular squares based on $\left [ W\left ( CN \right )_{6}\left ( bpy \right ) \right ]^{2-}$ building block, are paramagnetic and follow the Curie law.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Lutein and zeaxanthin in the lipid bilayer : similarities and differences revealed by computational studies
Autorzy:
Markiewicz, Michał
Makuch, Krzysztof
Pasenkiewicz-Gierula, Marta
Hryc, Jakub
Opis:
Lutein and zeaxanthin are two similar carotenoids of the xanthophyll subgroup. Carotenoids are synthesized almost entirely by plants but are also present in significant amounts in animals. They are essential components of the lipid matrix of biomembranes, and one of their functions is to protect cells from light radiation, free radicals and oxidative stress. Carotenoids, depending on their chemical structure, can locate at various positions and in different orientations in the bilayer. Xanthophylls (XAN) are polar and in the bilayer are positionally restricted. In the case of lutein and zeaxanthin, whose both ionone rings are hydroxy-substituted and as such are anchored in the lipid bilayer interfaces, the position is generally transmembrane. However, both experimental and computer modelling studies indicate that lutein can also locate horizontally below the bilayer interface. This location has never been observed for zeaxanthin. To find a molecular-level explanation for the difference in the orientations of the XAN molecules in the bilayer, a number of phosphatidylcholine-XAN bilayers were constructed and molecular dynamics (MD) simulated for 1.1 mu s each. The all-trans XAN molecules were initially placed either parallel or perpendicular to the bilayer surface. With the exception of one lutein, the horizontally placed molecules adopted the transmembrane orientation within 100-600 ns. On the basis of detailed analyses of the XAN orientations and the numbers and lifetimes of their interactions in the bilayer, a plausible explanation is offered as to why a lutein molecule may remain in the horizontal orientation while zeaxanthin does not. Contrary to common believe, lutein horizontal orientation is not related to the epsilon-ring rotation around the C6'-C7' bond.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł
Tytuł:
Molecular Dynamics Simulation Studies of the CL-20/DNB Co-crystal
Autorzy:
Sun, T.
Xiao, J. J.
Ji, G. F.
Zhao, F.
Xiao, H. M.
Tematy:
CL-20/DNB co-crystal
composite
interactions
mechanical properties
molecular dynamics simulation
Pokaż więcej
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Powiązania:
https://bibliotekanauki.pl/articles/358075.pdf  Link otwiera się w nowym oknie
Opis:
Molecular dynamics (MD) simulation was conducted for a DNB (1,3-dinitrobenzene) crystal, a ε-CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) crystal, a CL-20/DNB co-crystal and a CL-20/DNB composite. From the calculated maximum bond length (Lmax) of the N−NO2 trigger bond, the cohesive energy density (CED) and the binding energy (Ebind), it was found that the CL-20/DNB co-crystal is more insensitive than its composite. Its thermal stability is also better than that of its composite. The pair correlation function (PCF) analysis method was applied to investigate the interfaces between different molecular layers in the CL-20/DNB co-crystal, and in the composite. Additionally, the calculated mechanical data showed that the moduli of the CL-20/DNB co-crystal and its composite are smaller and their elastic elongation and ductility are better than those of the ε-CL-20 and DNB crystals.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
DPPA as a potential cell membrane component responsible for binding amyloidogenic protein human cystatin C
Autorzy:
Zhukov, Igor
Orlikowska, Marta
Górniewicz-Lorens, Magdalena
Jurczak, Przemyslaw
Sikorska, Emilia
Kępczyński, Mariusz
Opis:
A phospholipid bilayer is a typical structure that serves crucial functions in various cells and organelles. However, it is not unusual for it to take part in pathological processes. The cell membrane may be a binding target for amyloid-forming proteins, becoming a factor modulating the oligomerization process leading to amyloid deposition-a hallmark of amyloidogenic diseases-e.g., Alzheimer’s disease. The information on the mechanisms governing the oligomerization influenced by the protein–membrane interactions is scarce. Therefore, our study aims to describe the interactions between DPPA, a cell membrane mimetic, and amyloidogenic protein human cystatin C. Circular dichroism spectroscopy and differential scanning calorimetry were used to monitor (i) the secondary structure of the human cystatin C and (ii) the phase transition temperature of the DPPA, during the protein-membrane interactions. NMR techniques were used to determine the protein fragments responsible for the interactions, and molecular dynamics simulations were applied to provide a molecular structure representing the interaction. The obtained data indicate that the protein interacts with DPPA, submerging itself into the bilayer via the AS region. Additionally, the interaction increases the content of $\alpha$-helix within the protein’s secondary structure and stabilizes the whole molecule against denaturation.
Dostawca treści:
Repozytorium Uniwersytetu Jagiellońskiego
Artykuł

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