Tetrahedron clusters serving as a platform for foam-like structure design.

There are a number of exceptional examples indicating the unique position of tetrahedral symmetry in the vast landscape of different spatial organization pathways which can be sampled by matter. This work shows that the design and analysis of relatively simple tetrahedron clusters can lead to the formulation of a new type of dendritic structure together with unique periodic frameworks resembling clathrates and foams. A simple sequential protocol leading from regular tetrahedron clusters to more complex structural motifs can be employed to determine interesting repetitive building units.

Experimental and theoretical insights into the structure and molecular dynamics of 2,3,3',4'-tetramethoxy--stilbene - a chemopreventive agent.

The methoxy analogue of a -stilbene compound - 2,3,3',4'-tetramethoxy--stilbene - was selected to characterize its crystallographic structure, intermolecular interactions and molecular dynamics. The sample was studied using single-crystal X-ray diffraction (XRD), infrared spectroscopy (FT-IR), liquid and solid-state H and C nuclear magnetic resonance (NMR) and quasielastic neutron scattering (QENS). The compound crystallized in the orthorhombic space group.

An Investigation of the Sol-Gel Transition of Chitosan Lactate and Chitosan Chloride Solutions via Rheological and NMR Studies.

In recent years, intensive research has been carried out on the use of hydrogels obtained from natural polymers, mainly chitosan. These products are increasingly replacing solutions based on synthetic materials in medicine. This publication presents the results of studies on the sol-gel transition of chitosan solutions as the base material for the preparation of thermosensitive hydrogels for potential applications in tissue engineering.

Molecular Dynamics and Structure of Poly(Methyl Methacrylate) Chains Grafted from Barium Titanate Nanoparticles.

Core-shell nanocomposites comprising barium titanate, BaTiO (BTO), and poly(methyl methacrylate) (PMMA) chains grafted from its surface with varied grafting densities were prepared. BTO nanocrystals are high-k inorganic materials, and the obtained nanocomposites exhibit enhanced dielectric permittivity, as compared to neat PMMA, and a relatively low level of loss tangent in a wide range of frequencies. The impact of the molecular dynamics, structure, and interactions of the BTO surface on the polymer chains was investigated.

Combinations of Piperine with Hydroxypropyl-β-Cyclodextrin as a Multifunctional System.

Piperine is an alkaloid that has extensive pharmacological activity and impacts other active substances bioavailability due to inhibition of CYP450 enzymes, stimulation of amino acid transporters and -glycoprotein inhibition. Low solubility and the associated low bioavailability of piperine limit its potential. The combination of piperine with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) causes a significant increase in its solubility and, consequently, an increase in permeability through gastrointestinal tract membranes and the blood-brain barrier.

Hydroxypropyl-β-cyclodextrin as an effective carrier of curcumin - piperine nutraceutical system with improved enzyme inhibition properties.

The nutraceutical system of curcumin-piperine in 2-hydroxypropyl-β-cyclodextrin was prepared by using the kneading technique. Interactions between the components of the system were defined by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR). Application of hydroxypropyl-β-cyclodextrin as a carrier-solubiliser improved solubility of the curcumin-piperine system, its permeability through biological membranes (gastrointestinal tract, blood-brain barrier) as well as the antioxidant, antimicrobial and enzyme inhibitory activities against acetylcholinesterase and butyrylcholinesterase.

Kinetics of the thermal response of poly(N-isopropylacrylamide co methacrylic acid) hydrogel microparticles under different environmental stimuli: A time-lapse NMR study.

Hypothesis: Hydrogels of N-isopropylacrylamide and methacrylic acid (P(NIPAm-co-MAA)) display pH sensitivity and complex positively charged molecules through carboxylate groups, while having a critical solution temperature at which they reduce in volume and dehydrate. We aimed to elucidate how the responsiveness of MAA to environmental changes alters PNIPAm hydrogels at the molecular level using nuclear magnetic resonance (NMR). Time-lapse NMR allows us to follow the evolution of NMR signal under a temperature stimulus, providing unique information on conformational freedom of the hydrogel polymers.

Toward Next-Generation Biohybrid Catalyst Design: Influence of Degree of Polymerization on Enzyme Activity.

Due to their capacity to conduct complex organic transformations, enzymes find extensive use in medical and industrial settings. Unfortunately, enzymes are limited by their poor stability when exposed to harsh non-native conditions. While a host of methods have been developed to stabilize enzymes in non-native conditions, recent research into the synthesis of polymer-enzyme biohybrids using reversible deactivation radical polymerization approaches has demonstrated the potential of increased enzymatic activity in both native and non-native environments.

The effect of substrate and surface plasmons on symmetry breaking at the substrate interface of the topological insulator BiTe.

A pressing challenge in engineering devices with topological insulators (TIs) is that electron transport is dominated by the bulk conductance, and so dissipationless surface states account for only a small fraction of the conductance. Enhancing the surface-to-volume ratio is a common method to enhance the relative contribution of such states. In thin films with reduced thickness, the confinement results in symmetry-breaking and is critical for the experimental observation of topologically protected surface states.

Molecular dynamics of 1-ethyl-3-methylimidazolium triflate ionic liquid studied by H and F nuclear magnetic resonances.

The molecular dynamics of an ionic liquid (IL) composed of a 1-ethyl-3-methylimidazolium cation and a triflate (trifluoromethanesulfonate) anion, abbreviated as [Emim][TfO], were studied by NMR spectroscopy. By measuring the temperature-dependent high-field 1H and F spin-lattice relaxation (SLR) rates, the frequency-dependent H and F SLR dispersion curves using fast-field-cycling relaxometry, and the temperature-dependent 1H and F diffusion constants, and by utilizing the fact that the primary NMR-active nucleus on the Emim cation is H, whereas on the TfO anion it is F, the cationic and anionic dynamics were studied separately. A single theoretical relaxation model successfully reproduced all the experimental data of both types of resonant nuclei by fitting all the data simultaneously with the same set of fit parameters.

Molecular and Vibrational Dynamics in the Cholesterol-Lowering Agent Lovastatin: Solid-State NMR, Inelastic Neutron Scattering, and Periodic DFT Study.

Molecular and vibrational dynamics of a widely used cholesterol-lowering agent, lovastatin, have been studied by combining nuclear magnetic resonance relaxation experiments (H NMR) with inelastic neutron scattering (INS) and periodic density functional theory modeling (plane-wave DFT). According to a complementary experimental study, lovastatin shows no phase transitions down to cryogenic conditions, while a progressive, stepwise activation of several molecular motions is observed below room temperature. The molecular packing and intermolecular forces were analyzed theoretically, supported by a C NMR study and further correlated with observed molecular dynamics.

In search of the mutual relationship between the structure, solid-state spectroscopy and molecular dynamics in selected calcium channel blockers.

Three isostructural 1,4-dihydropyridines (DHPs), namely, nifedipine, nitrendipine and nimodipine were selected to characterize their structure, intermolecular interactions and molecular dynamics. The studied samples were analyzed using powder X-ray diffraction (XRD), neutron (INS) and infrared spectroscopy (FT-IR) as well as solid-state nuclear magnetic resonance (NMR), where each technique was supported by the state-of-the-art theoretical calculations for solid-state. By combining multiple experimental techniques with advanced theoretical calculations we were able to shed light on the mutual relation between the structure, stabilizing intermolecular interactions and their spectral response.

Experimental and solid-state computational study of structural and dynamic properties in the equilibrium form of temazepam.

Structural properties and rotational dynamics of methyl groups in the most stable form of temazepam were investigated by means of (13)C CP MAS NMR, quasielastic neutron scattering (QENS), and (1)H NMR spin-lattice relaxation methods. The QENS and (1)H NMR studies reveal the inequivalency of methyl groups, delivering their activation parameters. The structural properties of the system were explored in frame of periodic density functional theory (DFT) computations, giving insight into the reorientational barriers and providing understanding of the solid-state NMR results.