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Manganese hydroxido (Mn-OH) complexes supported by a tripodal N,N,N″-[nitrilotris(ethane-2,1-diyl)]tris(P,P-diphenylphosphinic amido) ([poat]3-) ligand have been synthesized and characterized by spectroscopic techniques including UV-vis and electron paramagnetic resonance (EPR) spectroscopies. X-ray diffraction (XRD) methods were used to confirm the solid-state molecular structures of {Na2[MnIIpoat(OH)]}2 and {Na[MnIIIpoat(OH)]}2 as clusters that are linked by the electrostatic interactions between the sodium counterions and the oxygen atom of the ligated hydroxido unit and the phosphinic (P=O) amide groups of [poat]3-. Both clusters feature two independent monoanionic fragments in which each contains a trigonal bipyramidal Mn center that is comprised of three equatorial deprotonated amide nitrogen atoms, an apical tertiary amine, and an axial hydroxido ligand. XRD analyses of {Na[MnIIIpoat(OH)]}2 also showed an intramolecular hydrogen bonding interaction between the MnIII-OH unit and P=O group of [poat]3-. Crystalline {Na[MnIIIpoat(OH)]}2 remains as clusters with Na+---O interactions in solution and is unreactive toward external substrates. However, conductivity studies indicated that [MnIIIpoat(OH)]- generated in situ is monomeric and reactivity studies found that it is capable of cleaving C-H bonds, illustrating the importance of solution-phase speciation and its direct effect on chemical reactivity. Synopsis: Manganese-hydroxido complexes were synthesized to study the influence of H-bonds in the secondary coordination sphere and their effects on the oxidative cleavage of substrates containing C-H bonds.

The advancement of experimental methods has provided new information about the structure and structural fluctuations of water. Despite the appearance of numerous models, which aim to describe a wide range of thermodynamic and electrical characteristics of water, there is a deficit in systemic understanding of structuring in aqueous solutions. A particular challenge is the fact that even pure water is a heterogeneous, multicomponent system composed of molecular and supramolecular structures. The possibility of the existence of such structures and their nature are of fundamental importance for various fields of science. However, great difficulties arise in modeling relatively large supramolecular structures (e.g. extended hydration shells), where the bonds between molecules are characterized by low energy. Generally, such structures may be non-equilibrium but relatively long-lived. Evidently, the short times of water microstructure exchanges do not mean short lifetimes of macrostructures, just as the instability of individual parts does not mean the instability of the entire structure. To explain this paradox, we review the data from experimental and theoretical research. Today, only some of the experimental results on the lifetime of water structures have been confirmed by modeling, so there is not a complete theoretical picture of the structure of water yet. We propose a new hierarchical water macrostructure model to resolve the issue of the stability of water structures. In this model, the structure of water is presented as consisting of many hierarchically related levels (the stratification model). The stratification mechanism is associated with symmetry breaking at the formation of the next level, even with minimal changes in the properties of the previous level. Such a hierarchical relationship can determine the unique physico-chemical properties of water systems and, in the future, provide a complete description of them. [ABSTRACT FROM AUTHOR]

Allantoin represents a compound widely employed in pharmaceutical and cosmetic fields. Its safety has been acknowledged by regulatory bodies such as the US Food and Drug Administration, the European Commission for Cosmetics and Consumer and Health and European Directorate for the Quality of Medicines & HealthCare. This justifies its wide use in dermatological/cosmetic formulations and allows their safe use.Allantoin possesses an asymmetric carbon atom, resulting in two enantiomers, with the (S)-enantiomer predominating in plants, although racemization may potentially occur during manufacturing processes. Notably, literature currently lacks enantioselective LC methods for allantoin analysis.In this study, two zwitterionic Cinchona alkaloid-based chiral stationary phases (CSPs), commercially known as CHIRALPAK® ZWIX(+) (CSP1) and CHIRALPAK® ZWIX(-) (CSP2), were utilized for the enantioseparation of allantoin under polar-ionic conditions. By employing a mobile phase consisting of acetonitrile/methanol/water/acetic acid (96:2:2:0.1, v/v/v/v), nearly complete baseline separation (with α=1.08) of allantoin enantiomers was achieved in less than 15 min with both CSPs. Due to the “pseudo-enantiomeric” nature of the two chiral selectors (quinine-based in CSP1 and quinidine-based in CSP2), an inversion of the enantiomer elution order was observed with the two CSPs under identical experimental conditions. Remarkably, this represents a rare instance where these CSPs demonstrate the ability to enantioseparate a non-ionic, non-ionizable species.The application of a molecular dynamics in silico protocol proved useful in elucidating the retention mechanism in depth, casting light on the central role of the H-bond formation and the involvement of the anionic moiety of the CSP 1.

The advancement of experimental methods has provided new information about the structure and structural fluctuations of water. Despite the appearance of numerous models, which aim to describe a wide range of thermodynamic and electrical characteristics of water, there is a deficit in systemic understanding of structuring in aqueous solutions. A particular challenge is the fact that even pure water is a heterogeneous, multicomponent system composed of molecular and supramolecular structures. The possibility of the existence of such structures and their nature are of fundamental importance for various fields of science. However, great difficulties arise in modeling relatively large supramolecular structures (e.g. extended hydration shells), where the bonds between molecules are characterized by low energy. Generally, such structures may be non-equilibrium but relatively long-lived. Evidently, the short times of water microstructure exchanges do not mean short lifetimes of macrostructures, just as the instability of individual parts does not mean the instability of the entire structure. To explain this paradox, we review the data from experimental and theoretical research. Today, only some of the experimental results on the lifetime of water structures have been confirmed by modeling, so there is not a complete theoretical picture of the structure of water yet. We propose a new hierarchical water macrostructure model to resolve the issue of the stability of water structures. In this model, the structure of water is presented as consisting of many hierarchically related levels (the stratification model). The stratification mechanism is associated with symmetry breaking at the formation of the next level, even with minimal changes in the properties of the previous level. Such a hierarchical relationship can determine the unique physico-chemical properties of water systems and, in the future, provide a complete description of them.

Two novel compounds based on [Re6Q8(CN)6]4– (Q = S, Se) and a small H-bond donor bis-amidinium dication of 2,2'-methylenediimidazolium (Cat) (Cat)2[Re6S8(CN)6]∙2H2O (1) and (Cat)2[Re6Se8 (CN)6]∙2H2O (2) are synthesized and structurally characterized. The dimensionality (2D or 3D) of the obtained network and the nature of the H-bond pattern change depending on the chalcogen atom (S or Se) in the cluster anion. [ABSTRACT FROM AUTHOR]

In nature, ceramides are a class of sphingolipids possessing a unique ability to self‐assemble into protein‐permeable channels with intriguing concentration‐dependent adaptive channel cavities. However, within the realm of artificial ion channels, this interesting phenomenon is scarcely represented. Herein, we report on a novel class of adaptive artificial channels, Pn‐TPPs, based on PEGylated cholic acids bearing triphenylphosphonium (TPP) groups as anion binding motifs. Interestingly, the molecules self‐assemble into chloride ion channels at low concentrations while transforming into small molecule‐permeable nanopores at high concentrations. Moreover, the TPP groups endow the molecules with mitochondria‐targeting properties, enabling them to selectively drill holes on the mitochondrial membrane of cancer cells and subsequently trigger the caspase 9 apoptotic pathway. The anticancer efficacies of Pn‐TPPs correlate with their abilities to form nanopores. Significantly, the most active ensembles formed by P5‐TPP exhibits impressive anticancer activity against human liver cancer cells, with an IC50 value of 3.8 μM. While demonstrating similar anticancer performance to doxorubicin, P5‐TPP exhibits a selectivity index surpassing that of doxorubicin by a factor of 16.8. [ABSTRACT FROM AUTHOR]

Characterizing molecular interactions at the microscopic level remains difficult and, therefore, represents a key target to better understand macromolecule and biomacromolecule behaviors in solution, alone, or in mixtures with others. Therefore, accurate characterization in liquid media, especially in aqueous solutions, without causing any perturbation of the system in which they are studied, is quite difficult. To this purpose, the present paper describes an innovative methodology based on fluorescence spectrophotometry. Two molecular fluorescent probes, namely 8-anilino-1-naphtalenesulfonic acid (ANS) and 2-benzofuryl-3-hydroxy-4(1H)-quinolone (3HQ-Bf), were selected to characterize, respectively, the dipole-dipole interactions and hydrophobic micro-domains, for the first one, and hydrogen bonding, for the second. As a support to study molecular interactions, xanthan, galactomannan, and corresponding mixtures of these substances which are well known to exhibit a synergy of interactions in well-defined mixture conditions were chosen. Once the methodology was set up, the existence of the three types of interactions in these systems was demonstrated, thus allowing the elucidation of the mechanisms of interactions at the molecular scale. [ABSTRACT FROM AUTHOR]

The development of stimuli‐responsive artificial H+/Cl− ion channels, capable of specifically disturbing the intracellular ion homeostasis of cancer cells, presents an intriguing opportunity for achieving high selectivity in cancer therapy. Herein, we describe a novel family of non‐covalently stapled self‐assembled artificial channels activatable by biocompatible visible light at 442 nm, which enables the co‐transport of H+/Cl− across the membrane with H+/Cl− transport selectivity of 6.0. Upon photoirradiation of the caged C4F‐L for 10 min, 90 % of ion transport efficiency can be restored, giving rise to a 10.5‐fold enhancement in cytotoxicity against human colorectal cancer cells (IC50=8.5 μM). The mechanism underlying cancer cell death mediated by the H+/Cl− channels involves the activation of the caspase 9 apoptosis pathway as well as the scarcely reported disruption of the autophagic processes. In the absence of photoirradiation, C4F‐L exhibits minimal toxicity towards normal intestine cells, even at a concentration of 200 μM. [ABSTRACT FROM AUTHOR]

Quercetin contains five hydroxy groups (OH) at positions 3, 5, 7, 3′, and 4′. The selective reaction of a hydroxy group in quercetin is an important strategy for the modulation of various properties of the derivatives. Herein, we report the synthesis of selective quercetin derivatives, wherein the oligoether chains were linked to the hydroxyl groups. Interestingly, the penta‐substituted quercetin derivative exhibited a higher fluorescence intensity than the tetra‐substituted one. The fluorescence behavior of synthetic derivatives was investigated using solvatochromism, molecular aggregations, computational calculations, and hydrogen bonds with solvents. The fluorescent penta‐substituted quercetin derivative did not show any cytotoxicity up to 600 μM concentration, showing a novel biocompatible fluorescent molecule. [ABSTRACT FROM AUTHOR]

A novel cellulose microfibril swelling (Cms) gene of Bacillus sp. AY8 was successfully cloned and sequenced using a set of primers designed based on the conserved region of the gene from the genomic database. The molecular cloning of the Cms gene revealed that the gene consisted of 679 bp sequences encoding 225 amino acids. Further in silico analysis unveiled that the Cms gene contained the NlpC/P60 conserved region that exhibited a homology of 98% with the NlpC/P60 family proteins found in both the strains, Burkholderialata sp. and Burkholderia vietnamiensis. The recombinant Cms enzyme had a significant impact on the reduction of crystallinity indices (CrI) of various substrates including a 3%, a 3.97%, a 4.66%, and a substantial 14.07% for filter paper, defatted cotton fiber, avicel, and alpha cellulose, respectively. Additionally, notable changes in the spectral features were observed among the substrates treated with recombinant Cms enzymes compared to the untreated control. Specifically, there was a decrease in band intensities within the spectral regions of 3000–3450 cm−1, 2900 cm−1, 1429 cm−1, and 1371 cm−1 for the treated filter paper, cotton fiber, avicel, and alpha cellulose, respectively. Furthermore, the recombinant Cms enzyme exhibited a maximum cellulose swelling activity at a pH of 7.0 along with a temperature of 40 °C. The molecular docking data revealed that ligand molecules, such as cellobiose, dextrin, maltose 1-phosphate, and feruloyated xyloglucan, effectively bonded to the active site of the Cms enzyme. The molecular dynamics simulations of the Cms enzyme displayed stable interactions with cellobiose and dextrin molecules up to 100 ns. It is noteworthy to mention that the conserved region of the Cms enzyme did not match with those of the bioadditives like expansins and swollenin proteins. This study is the initial report of a bacterial cellulose microfibril swellase enzyme, which could potentially serve as an additive to enhance biofuel production by releasing fermentable sugars from cellulose. [ABSTRACT FROM AUTHOR]

Optoelectronic attributes notwithstanding donor-acceptor covalent organic frameworks (D-A COFs) are not durable photocatalysts in many cases. Herein, a stabilization strategy of D-A COFs by intramolecular hydrogen (H)-bonds and a membrane-based mass transfer strategy for photocatalytic modulation are reported. The crystalline stability design of COF is cored at the strong M-M interactions and the H-bonds of adjacent tetrakis(4-formylphenyl)pyrene and naphthalenediimide units and the D-A charge transfer is designed for efficiency optimization. The well-defined, stable structure and charge dynamics of D-A COF, and the structure-controlled reactive oxygen species yields are confirmed. In two photoredox models, the COF presents both robust activity and stability and is further integrated with the mass transfer optimization of the COFs/polyvinylidene fluoride membrane. The membrane is recycled at least 15 times, and the turnover frequency value of g-scale amine coupling is as high as 62.4 h-1. This work offers a facile approach to the stabilization design of D-A COFs and explores a general membrane-based mass transfer strategy for photocatalysis. [ABSTRACT FROM AUTHOR]

Constructing chiral supramolecular assembly and exploring the underlying mechanism are of great significance in promoting the development of circularly polarized luminescence (CPL)‐active materials. Herein, we report a solvation‐mediated self‐assembly from single‐crystals to helical nanofibers based on the first protic acyclic (methoxy)(amino)carbenes (pAMACs) AuI‐enantiomers driven by a synergetic aurophilic interactions and H‐bonds. Their aggregation‐dependent thermally activated delayed fluorescence properties with high quantum yields (ΦFL) up to 95 % were proved to be attributed to packing modes of Au⋅⋅⋅Au dimers with π‐stacking or one‐dimensional extended Au⋅⋅⋅Au chains. Via drop‐casting method, supramolecular P‐ or M‐helices were prepared. Detailed studies on the helices demonstrate that formations of extended helical Au⋅⋅⋅Au molecular chains amplify supramolecular chirality, leading to strong CPL with high dissymmetry factor (|glum|=0.030, ΦFL=67 %) and high CPL brightness (BCPL) of 4.87×10−3. Our findings bring new insights into the fabrication of helical structures to improve CPL performance by modifying aurophilic interactions. [ABSTRACT FROM AUTHOR]

Perovskite hydrates have attracted extensive attention in diverse fields with intriguing optoelectronic properties, while their structural distortions usually cause large band gaps, which yield inferior light absorption and diminished optoelectronic device performance. Herein, modulating the structural distortion by steric hindrance effects is reported. Specifically, an N,N,N′,N′‐tetramethyl‐1,4‐phenylenediammonium (TMPD)2+ is adopted to template regular BiBr5 chains by interacting with bismuth bromide via weakening and reorienting H‐bonds, yielding a mixed 0D/1D (TMPD)2Bi2Br10.H2O with a narrow bandgap of 1.89 eV. The 0D/1D (TMPD)2Bi2Br10.H2O can be reversibly transformed into 0D (TMPD)2Bi2Br10 (Eg = 2.55 eV) with good cycling behavior. The (TMPD)2Bi2Br10.H2O turns out to be more stable than (TMPD)2Bi2Br10, and a mechanism involving vacancy‐assisted bromide ion migration is proposed for understanding the formation of BiBr5 chains. Density functional theory (DFT) calculations indicate that the (TMPD)2+ triggered hydration has a crucial impact on the downshift of the conduction band edge, thus decreasing the band gap. Moreover, the (TMPD)2Bi2Br10.H2O single crystal exhibits promising photoconductive behavior under a high moisture atmosphere, showing superiority over the conventional CH3NH3PbI3 perovskites that cannot survive moisture. This finding offers new insights into developing narrow band gap perovskite hydrates toward practical optoelectronic applications. [ABSTRACT FROM AUTHOR]

Clinical inhibitors of cell-cycle regulatory enzyme cyclin-dependent kinase 6 (CDK6) are not free of harmful consequences to human bodies. Flavonoids fisetin and chrysin bestow anti-cancer benefits by inhibiting the activities of CDK6 with strong binding affinities. To understand the structure requirement of such inhibitory behaviour, docking and molecular dynamics (MD) simulations were performed on chosen three derivatives each of fisetin and chrysin along with the parent flavonoids. Docking studies revealed more negative binding energies of the derivatives than the parent molecules. MD simulations suggested appreciable stability of the derivatives in the systems. CDK6 association with ring A OH was minute in fisetin, replacing the same with one α-naphtha group in fisetin_3 resulting in enhanced long-range interactions. Interaction of ring A OH groups was significant in chrysin. The additional fluorine atom along with ring C OH and OCH3substituents in chrysin_2 induced a greater number of favourable interactions with CDK6. The selected ligands were docked into the ATP competitive binding site of rigid receptor CDK6/cyclin D using AutoDock 4.2. Stable conformations of the ligands were searched using Lamarckian Genetic Algorithm. Lowest energy poses of the best docked derivatives that resembled experimental conformation of co-crystallised ligand fisetin (fisetin_3, chrysin_3 and chrysin_2), along with fisetin and chrysin which were subjected to MD simulations. Ligand protein interactions in an aqueous environment were modelled using CHARMM27 force field accommodated in GROMACS 2022. MM-PBSA binding free energies of the ligands to CDK6 were computed using g_mmpbsa module of GROMACS. [ABSTRACT FROM AUTHOR]

Unlike many other biologically relevant ions (Na+, K+, Ca2+, Cl−, etc) and protons, whose cellular concentrations are closely regulated by highly selective channel proteins, Li+ ion is unusual in that its concentration is well tolerated over many orders of magnitude and that no lithium‐specific channel proteins have so far been identified. While one naturally evolved primary pathway for Li+ ions to traverse across the cell membrane is through sodium channels by competing with Na+ ions, highly sought‐after artificial lithium‐transporting channels remain a major challenge to develop. Here we show that sulfur‐containing organic nanotubes derived from intramolecularly H‐bonded helically folded aromatic foldamers of 3.6 Å in hollow cavity diameter could facilitate highly selective and efficient transmembrane transport of Li+ ions, with high transport selectivity factors of 15.3 and 19.9 over Na+ and K+ ions, respectively. [ABSTRACT FROM AUTHOR]

Post-etching method using dilute acid solutions is an effective technology to modulate the surface compositions of metal-oxide catalysts. Here the α-MnO 2 catalyst treated with 0.1 mol/L nitric acid exhibits higher ozone decomposition activity at high relative humidity than the counterpart treated with acetic acid. Besides the increases in surface area and lattice dislocation, the improved activity can be due to relatively higher Mn valence on the surface and newly-formed Brønsted acid sites adjacent to oxygen vacancies. The remnant nitro species deposited on the catalyst by nitric acid treatment is ideal hydrophobic groups at ambient conditions. The decomposition route is also proposed based on the DRIFTS and DFT calculations: ozone is facile to adsorb on the oxygen vacancy, and the protonic H of Brønsted acid sites bonds to the terminal oxygen of ozone to accelerate its cleavage to O 2 , reducing the reaction energy barrier of O 2 desorption. [Display omitted] [ABSTRACT FROM AUTHOR]

Interactions between DNA and graphene are paramount for a wide range of applications, such as biosensing and nanoelectronics; nonetheless, the molecular details of such interactions remain largely unexplored. We employ atomically detailed molecular dynamics simulations with an enhanced sampling technique to investigate the adsorption and mobility of double-stranded DNA along the basal plane of graphene, in an electrolytic aqueous medium. The study focuses on physiologically relevant conditions, using a buffer of [NaCl] = 134 mM. DNA physisorption is shown to be fast and irreversible, leading to deformation and partial melting of the double helix as a result of π–π stacking between the terminal nucleobases and graphene. Denaturation occurs primarily at the termini, with ensemble averaged H-bond ratios of 47.8–62%; these can, however, reach a minimum of 15%. Transition between free-energy minima occurs via a thermodynamical pathway driving the nucleic acid from a radius of gyration of 1.5 nm to 1.35 nm. Mobility along the basal plane of graphene is dominant, accounting for ~90% of all centre-of-mass translation and revealing that the DNA’s apparent diffusivity is similar to diffusion along the endohedral volume of carbon nanotubes, but one order of magnitude faster than in other 2D materials, such as BC3 and C3N.

Characterizing molecular interactions at the microscopic level remains difficult and, therefore, represents a key target to better understand macromolecule and biomacromolecule behaviors in solution, alone, or in mixtures with others. Therefore, accurate characterization in liquid media, especially in aqueous solutions, without causing any perturbation of the system in which they are studied, is quite difficult. To this purpose, the present paper describes an innovative methodology based on fluorescence spectrophotometry. Two molecular fluorescent probes, namely 8-anilino-1-naphtalenesulfonic acid (ANS) and 2-benzofuryl-3-hydroxy-4(1H)-quinolone (3HQ-Bf), were selected to characterize, respectively, the dipole-dipole interactions and hydrophobic micro-domains, for the first one, and hydrogen bonding, for the second. As a support to study molecular interactions, xanthan, galactomannan, and corresponding mixtures of these substances which are well known to exhibit a synergy of interactions in well-defined mixture conditions were chosen. Once the methodology was set up, the existence of the three types of interactions in these systems was demonstrated, thus allowing the elucidation of the mechanisms of interactions at the molecular scale.

Polyampholyte hydrogels exhibit great antibacterial and antifouling properties, which make them attractive for biomedical applications, such as drug delivery, wound healing, and tissue engineering. They also have potential applications in food safety, wastewater treatment, and desalination. Since they are based on ionic interactions, polyampholytes are known to require lower amounts of chemical cross-linkers as compared with traditional gels. However, the effects of both chemical and physical interactions on the material's performance are yet to be fully understood and were examined in the present work. Here, four series of equimolar polyampholyte hydrogels were synthesized with anionic (acrylamidomethylpropane sulfonic acid sodium salt) and cationic monomers (acrylamidopropyl-trimethylammonium chloride) along with a cross-linker (N,N′-methylenebisacrylamide). The mechanical and rheological properties of the gels were characterized following changes to the initial monomer concentration and crosslinker ratios, which led to gels with different toughness, stretchability, and compressibility. The direct correlation of the cross-linking degree with the initial monomer concentration showed that the chemical crosslinker could be further reduced at a high monomer concentration of 30% by weight, which creates an inter-chain network at a minimal crosslinker concentration of 0.25%. Lastly, N′N-dimethylacrylamide was added, which resulted in an increase in the number of H-bonds in the structure, noticeably raising material performance. [ABSTRACT FROM AUTHOR]

Interactions between DNA and graphene are paramount for a wide range of applications, such as biosensing and nanoelectronics; nonetheless, the molecular details of such interactions remain largely unexplored. We employ atomically detailed molecular dynamics simulations with an enhanced sampling technique to investigate the adsorption and mobility of double-stranded DNA along the basal plane of graphene, in an electrolytic aqueous medium. The study focuses on physiologically relevant conditions, using a buffer of [NaCl] = 134 mM. DNA physisorption is shown to be fast and irreversible, leading to deformation and partial melting of the double helix as a result of π–π stacking between the terminal nucleobases and graphene. Denaturation occurs primarily at the termini, with ensemble averaged H-bond ratios of 47.8–62%; these can, however, reach a minimum of 15%. Transition between free-energy minima occurs via a thermodynamical pathway driving the nucleic acid from a radius of gyration of 1.5 nm to 1.35 nm. Mobility along the basal plane of graphene is dominant, accounting for ~90% of all centre-of-mass translation and revealing that the DNA's apparent diffusivity is similar to diffusion along the endohedral volume of carbon nanotubes, but one order of magnitude faster than in other 2D materials, such as BC3 and C3N. [ABSTRACT FROM AUTHOR]

For the first time AFM (atomic-force microscopy) was used to record significant changes in the geometric parameters of the image of erythrocytes in vitro under conditions of glycolytic starvation (ATP (Adenosine triphosphate) deficiency). The difference in the action of antioxidants, phenosan K, and Ihfan-10 on erythrocytes that we detected with AFM seems to be mainly due to their difference in hydrophobicity. We used the AFM method to research the self-organization of the components of the active center of P450 (Porphyrin-450) metalloenzymes that are part of a class of hemoproteins with functions of affinity to molecular oxygen O2. Stable supramolecular nanostructures in the form of triangular prisms based on the iron porphyrin complex with amino acids due to self-assembly involving intermolecular hydrogen bonds were received. A possible scheme for the formation of such structures is proposed. [ABSTRACT FROM AUTHOR]

Adding self‐healing properties to coatings is a promising way to increase their lifetime. Despite an increasing popularity, lots of self‐healing polymers are not suited for commercial coatings because they exhibit poor mechanical properties or require expensive products or high healing temperature (> 100°C). One way to obtain self‐healing abilities with good mechanical properties is by using dynamic H‐bonds as they also limit the healing temperature. To do so, urea groups are used since they are well‐known for their bonding capacity and can be readily synthesized. In this study, several methacrylate monomers containing urea groups in their side‐chain were synthesized from easily accessible amines and isocyanates in a one‐step, high‐yield synthesis. They were afterwards used in a copolymer containing methyl methacrylate and butyl acrylate monomers. The self‐healing properties of the resulting coatings were evaluated with gloss recovery and optical microscopy and the presence of H‐bonds in the most promising polymer was investigated with FTIR. The mechanical properties of the coatings as a function of time were checked by nanoindentation creep test. We were able to obtain an affordable, easily prepared polymer that suits the requirements for protective coating applications and shows a complete healing after heating at 75°C for 1 h. [ABSTRACT FROM AUTHOR]

In order to evaluate the influence of plasticizers on the behavior of the dielectric properties of polymers intended for the elaboration of flexible sensors, we have studied the influence of the addition of glycerol (10 wt%–40 wt%) in polyvinyl alcohol (PVA). Once processed, the PVA films were not subjected to any particular annealing and they were dried at room temperature for 24 h before being characterized. This choice allows both to take advantage of the presence of water in the bulk of the material, which will help to make the PVA more flexible (increase of plasticization effect produced by extra‐H‐bonding) and avoid a transient behavior of water absorption into the material, as we could verify. DSC and FTIR investigations confirm good intermolecular interaction between vinyl polymer chains, glycerol, and water molecules. Dielectric spectroscopy analysis, carried out in [25°C–110°C] temperature and [0.1 Hz–1 MHz] frequency ranges, reveals a significant increase in the dielectric constant when the glycerol content is higher (at 0.1 Hz: 322 for pure PVA, 1.3 × 106 with 40 wt% of glycerol). Polar hydrogen bonds introduced by the glycerol are the main reason for this increase. Ionic conductivity induced by these dipoles dominates the loss tangent response of the material. The activation energy obtained from the DC conductivity plateau obeys to a conventional Arrhenius law with a decreasing value at highest glycerol contents (1.35 eV for pure PVA against 0.46 eV with 40 wt% of glycerol). [ABSTRACT FROM AUTHOR]

Manganese hydroxido (Mn–OH) complexes supported by a tripodal N,N′,N″ -[nitrilotris(ethane-2,1-diyl)]tris(P,P -diphenylphosphinic amido) ([poat]3−) ligand have been synthesized and characterized by spectroscopic techniques including UV–vis and electron paramagnetic resonance (EPR) spectroscopies. X-ray diffraction (XRD) methods were used to confirm the solid-state molecular structures of {Na 2 [MnIIpoat(OH)]} 2 and {Na[MnIIIpoat(OH)]} 2 as clusters that are linked by the electrostatic interactions between the sodium counterions and the oxygen atom of the ligated hydroxido unit and the phosphinic (P=O) amide groups of [poat]3−. Both clusters feature two independent monoanionic fragments in which each contains a trigonal bipyramidal Mn center that is comprised of three equatorial deprotonated amide nitrogen atoms, an apical tertiary amine, and an axial hydroxido ligand. XRD analyses of {Na[MnIIIpoat(OH)]} 2 also showed an intramolecular hydrogen bonding interaction between the MnIII–OH unit and P=O group of [poat]3−. Crystalline {Na[MnIIIpoat(OH)]} 2 remains as clusters with Na+---O interactions in solution and is unreactive toward external substrates. However, conductivity studies indicated that [MnIIIpoat(OH)]− generated in situ is monomeric and reactivity studies found that it is capable of cleaving C-H bonds, illustrating the importance of solution-phase speciation and its direct effect on chemical reactivity. Synopsis : Manganese–hydroxido complexes were synthesized to study the influence of H-bonds in the secondary coordination sphere and their effects on the oxidative cleavage of substrates containing C-H bonds. [Display omitted] • A synthetic MnIII–OH complex capable of C-H bond cleavage is reported • Reactivity of MnIII–OH complexes with H-bond acceptors • Modulating the secondary coordination sphere of metal-hydroxide complexes [ABSTRACT FROM AUTHOR]

• Concentrated MImBs additive is employed in alkaline aluminum-air batteries to construct a Water-in-Salt electrolyte. • Stronger H-bonding network is reconstructed to significantly reduce the water activity, so as to lower the erosion of Al anodes. • Interface adsorption behavior of MImBs involves in corrosion inhibition. In this work, we propose a Water-in-salt electrolyte based on concentrated ionic additive for Al-air batteries, aiming at inhibiting the unexpected severe hydrogen evolution self-corrosion. Computing calculations and experimental characterizations consistently confirm that the additive can significantly affect both the solvent structure and anode interface. A stronger H-bonding network is reconfigured and formed in the electrolyte, thus leading to a dramatic decrease in free water content and activity. Besides, the adsorption behavior of used additive molecules on Al anode surface plays an activating and stabilizing role, which is conducive to promoting the uniform dissolution of Al anode and improving the electrochemical performance. Owing to this dual modulation, the electrolyte system endows Al-air battery with extremely low self-corrosion rate (reduced by 89.6%) and remarkable discharge capacity of 2623 mAh/g. [ABSTRACT FROM AUTHOR]

A novel cellulose microfibril swelling (Cms) gene of Bacillus sp. AY8 was successfully cloned and sequenced using a set of primers designed based on the conserved region of the gene from the genomic database. The molecular cloning of the Cms gene revealed that the gene consisted of 679 bp sequences encoding 225 amino acids. Further in silico analysis unveiled that the Cms gene contained the NlpC/P60 conserved region that exhibited a homology of 98% with the NlpC/P60 family proteins found in both the strains, Burkholderialata sp. and Burkholderia vietnamiensis. The recombinant Cms enzyme had a significant impact on the reduction of crystallinity indices (CrI) of various substrates including a 3%, a 3.97%, a 4.66%, and a substantial 14.07% for filter paper, defatted cotton fiber, avicel, and alpha cellulose, respectively. Additionally, notable changes in the spectral features were observed among the substrates treated with recombinant Cms enzymes compared to the untreated control. Specifically, there was a decrease in band intensities within the spectral regions of 3000–3450 cm−1, 2900 cm−1, 1429 cm−1, and 1371 cm−1 for the treated filter paper, cotton fiber, avicel, and alpha cellulose, respectively. Furthermore, the recombinant Cms enzyme exhibited a maximum cellulose swelling activity at a pH of 7.0 along with a temperature of 40 °C. The molecular docking data revealed that ligand molecules, such as cellobiose, dextrin, maltose 1-phosphate, and feruloyated xyloglucan, effectively bonded to the active site of the Cms enzyme. The molecular dynamics simulations of the Cms enzyme displayed stable interactions with cellobiose and dextrin molecules up to 100 ns. It is noteworthy to mention that the conserved region of the Cms enzyme did not match with those of the bioadditives like expansins and swollenin proteins. This study is the initial report of a bacterial cellulose microfibril swellase enzyme, which could potentially serve as an additive to enhance biofuel production by releasing fermentable sugars from cellulose.

The thermal analysis and infrared (IR) spectroscopy were used to study cyclohexanol irreversible transformations from an orientationally disordered plastic state to metastable III and then to a stable II crystalline phase. It was found that the orientational glass transition in cyclohexanol occurs at Tg ∼ 163.5 K. Solid–solid transition from orientationally disordered phase I to metastable phase III occurs at 195 K. Crystal phase III nucleates at Ta = 203 K and converts into phase I at T = 233.7 K. The stable crystal phase II is formed by nucleation at 213 K. It converts into phase I at T = 250 K. It is shown by IR spectroscopy that the phase transitions in solid cyclohexanol are correlated with conformational changes in the cyclohexanol molecule. [ABSTRACT FROM AUTHOR]

Polyampholyte hydrogels exhibit great antibacterial and antifouling properties, which make them attractive for biomedical applications, such as drug delivery, wound healing, and tissue engineering. They also have potential applications in food safety, wastewater treatment, and desalination. Since they are based on ionic interactions, polyampholytes are known to require lower amounts of chemical cross-linkers as compared with traditional gels. However, the effects of both chemical and physical interactions on the material’s performance are yet to be fully understood and were examined in the present work. Here, four series of equimolar polyampholyte hydrogels were synthesized with anionic (acrylamidomethylpropane sulfonic acid sodium salt) and cationic monomers (acrylamidopropyl-trimethylammonium chloride) along with a cross-linker (N,N′-methylenebisacrylamide). The mechanical and rheological properties of the gels were characterized following changes to the initial monomer concentration and crosslinker ratios, which led to gels with different toughness, stretchability, and compressibility. The direct correlation of the cross-linking degree with the initial monomer concentration showed that the chemical crosslinker could be further reduced at a high monomer concentration of 30% by weight, which creates an inter-chain network at a minimal crosslinker concentration of 0.25%. Lastly, N′N-dimethylacrylamide was added, which resulted in an increase in the number of H-bonds in the structure, noticeably raising material performance.

The role of ligands in the regulation of the catalytic activity of Ni-complexes (Ni(acac)2) in green process-selective ethylbenzene oxidation with O2 into α-phenyl ethyl hydroperoxide is considered in this article. The dual function of phenol (PhOH) included in the coordination sphere of the nickel complex as an antioxidant or catalyst depends on the ligand environment of the metal. The role of intermolecular H-bonds and supramolecular structures (AFM method) in the mechanisms of selective catalysis by nickel complexes in chemical and biological oxidation reactions is analyzed. [ABSTRACT FROM AUTHOR]

• GO is one of promising materials in biomedical applications. • Efficient interactions of GO with both drug and environment are key factors in drug delivery systems preparation. • Size of the GO model have no significant impact on the interaction energy with other molecule on the graphene flake edges. • Substituent number, position and configuration play a key role in H-bonds formation and their magnitude upon hydration. The biomedical applications of graphene-based materials become one of hot scientific and technological topics in the last few years. Flake graphene oxide (GO) is considered as one of the promising materials for biomedical use due to a number of specific properties, in particular in design of advanced drug delivery systems (DDS). The key factor in the formation of non-covalently bonded complexes for drug transport is the strength of non-covalent interactions of the carrier with both the drug and the environment. In the current work, we have focused on molecular modeling of solvation of zigzag-edged graphene oxide, functionalized with hydroxyl and carboxyl substituents. The hydration was determined from the magnitude of weak intermolecular interactions of GO with one or two water molecules. Our goal was to establish the dependence of the degree and type of functionalization, as well as the size of graphene flakes and the position of hydrophilic substituents on the number and strength of H-bonds. All calculations were performed using density functional theory (DFT) at the B3LYPD3BJ/6-311++G** level. The effect of water solvent was established using an explicit (discrete) model of solvent. [ABSTRACT FROM AUTHOR]

In the last decade, ammonium hexafluorosilicate (AHFS) and ammonium hexafluorosilicates with biologically active cations (AHBAC), which have certain advantages over traditional fluoride medicinal substances, have been actively studied as anti-caries agents. In particular, an important feature of the action of AHFS is its ability to cause prolonged occlusion of the dentinal tubules with a precipitate of calcium fluoride; when using AHBAС there is a possibility of strengthening the anti-caries activity of the substance due to the pharmacological potential of the cation. The purpose of the review is to analyze the effects of the cation on the physicochemical properties and biological activity of ammonium hexafluorosilicates as potential anti-caries agents. Research methods – bibliosemantic, content analysis. It was drew the attention to the peculiarity of the AHBAC structure: salt structures are formed on the basis of systems of strong interionic H-bonds, mainly of the NH···F type, which have a significant effect on the properties of hexafluorosilicates in the crystalline state and their behavior in solutions. It was demonstrated the non-trivial nature of the change of solubility in water of AHBAC with heterocyclic and aromatic cations, which consists in the decrease of solubility with increasing number of hydrophilic fragments in the structure of cations. Adequate 2D QSPR models for interpretation and virtual screening of AHBAC water solubility have been constructed. Accounting for the effect of H-bonds on the solubility of AHBAC was detailed. It was assumed that the process of hydrolysis of AHBAC in aqueous solutions can be stimulated by elongation of the Si–F anion bonds due to the effects of H-bonds. It is shown that the thermal stability of AHBAC with pyridinium cations symbatically correlates with the number of strong and medium H-bonds in salt structures. The action of the pharmacological effects of the cation on the biological activity of AHBAC is manifested in the form of an increase in the caries-prophylactic efficacy of AHBAC in comparison with a similar effect of AHFS. Attempts to establish a relationship between the anti-caries activity of AHBAC and a certain pharmacological action of the cation have led to mixed results. This obviously reflects the complex mechanism of the influence of the biological activity of the cation on the caries-prophylactic efficacy of hexafluorosilicates, which is not limited to any one, albeit dominant, type of activity.

• Self-healing polyurethanes have incomplete ionized ionic groups. • Self-healing can be achieved at room temperature and accelerated dramatically in the presence of water. • Self-healing strengthening effect is achieved with self-healing efficiency of 104.72%. • Mechanism analysis by experiment and molecular dynamics (MD) simulations reveal the enhanced molecular movement and further ionized. Self-healing polymers with microphase separation structure typically require external stimuli to achieve self-healing, and their performance often degrades. To solve these issues, we introduce tertiary amine and carboxyl groups into polymer. The intermolecular ionic interactions and H-bonds contribute to the formation of microphase separation structures, endowing polyurethane elastomers (PU-n) outstanding mechanical properties with a maximum tensile strength and toughness of 20.61 MPa and 59.02 MJ/m3, respectively. The self-healing of the prepared PU-n can be achieved at room temperature and accelerated significantly by water because hard phases can be dissociated, resulting in enhanced molecular movement. After self-healing with water, the enhanced molecular movement and further ionization of ionic groups lead to stronger H-bonds and ionic interactions, promoting more distinct microphase separation. Thus, the mechanical strength is strengthened and the self-healing efficiency can reach 104.72 %. The enhanced molecular movement and strengthened intermolecular interactions when self-healing with water can also be verified through in-depth analysis of molecular dynamics (MD) simulations of the self-healing process. Furthermore, PU-n display remarkable shape memory and can be recycled through exposure to solvents and hot water. This study provides a novel and general method for preparing materials that can self-heal with water and self-strengthen after self-healing. [ABSTRACT FROM AUTHOR]

The central problem in transduction is to explain how the energy caught from sunlight by chloroplasts becomes biological work. Or to express it in different terms: how does the energy remain trapped in the biological network and not get lost through thermalization into the environment? The pathway consists of an immensely large number of steps crossing hierarchical levels – some upwards, to larger assemblies, others downwards into energy rich molecules – before fuelling an action potential or a contracting cell. Accepting the assumption that steps are executed by protein domains, we expect that transduction mechanisms are the result of conformational changes, which in turn involve rearrangements of the bonds responsible for the protein fold. But why are these essential changes so difficult to detect? In this presentation, the metabolic pathway is viewed as equivalent to an energy conduit composed of equally sized units – the protein domains – rather than a row of catalysts. The flow of energy through them occurs by the same mechanism as through the cytoplasmic medium (water). This mechanism is based on the cluster-wave model of water structure, which successfully explains the transfer of energy through the liquid medium responsible for the build up of osmotic pressure. The analogy to the line of balls called "Newton's cradle" provides a useful comparison, since there the transfer is also invisible to us because the intermediate balls are motionless. It is further proposed that the spatial arrangements of the H-bonds of the α and β secondary structures support wave motion, with the linear and lateral forms of the groups of bonds belonging to the helices and sheets executing the longitudinal and transverse modes, respectively. [ABSTRACT FROM AUTHOR]

Understanding the nature of H-bonding interactions is essential to modern sciences, such as biology, chemistry, and physics. Using density functional theory calculations, herein, we have identified two unique H-bonding types existing in a single sheet of a mixed water–hydroxyl phase on close-packed metal surfaces, in sharp contrast to conventional H-bonds in liquid water and water ices. Interestingly, the shallow H-bonds show reduced electrostatic and Pauli repulsion interactions, with an electrostatic polar character resulted from complete σ resonances, whereas the deep H-bonds exhibit enhanced electrostatic and Pauli repulsion interactions, with an electrostatic dipolar feature originated from hybrid orbital interactions. A trade-off-like cooperativity law of the two types of H-bonds was discovered, that is, strengthening in the internal bonds (dO–H) leads to weakening in the external bonds (dO:H) or vice versa. However, the shallow H-bonds exhibit a non-linear cooperativity, whereas the deep H-bonds show a linear cooperativity. We also identified an oxygen backbone cooperativity rule that strengthening the adsorbate–metal interactions has a net effect in analogy to reducing the O–O repulsion within the adlayer. Furthermore, we have discovered several universality classes in geometrical, vibrational, and electronic spaces for the two H-bonding types. Although shared by electronic universality classes, the two contrasting H-bonding types are featured by divergent trends with significant overlapping, where competitive variations in the electrostatic and Pauli repulsion strengths are basic rules for the cooperative H-bonding types. The knowledge of the unconventional H-bonding types expands our current understanding of H-bonding interactions in liquid water and water ices and points to the importance of H-bonding manipulation at electronic levels. These findings not only shed new light on probing the fundamental nature of H-bonds in general but also have insightful implications for resolving the cooperative H-bonding nature of interfacial water, liquid water, water ices, and aqueous solutions.

• Seven supramolecular systems have been prepared and structurally featured. • All the supramolecular systems possess excessive non-covalent interactions. • Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis. • The graph-set descriptors were also analyzed. In this job eight new multicomponent crystalline systems (including 2 cocrystals + 5 salts) from active pharmaceutical ingredient (API) minoxidil (mnd) and organic acids were successfully prepared via the very common slow solution evaporation method and featured by the structural and spectral characterizations. In these systems the mnd and its partners were coupled through the N H···O/O H···O linkages which are authenticated to be the most frequent associates (created in all), even in the coexistence of the other underlying disruptive non-covalent linking fragments. Apart from the N H⋯O/O H···O H-bonds, the O H···N H-bonds were also set up in 1 – 5 and 7. Close inspection of the crystal pilings uncovered that under the help of an array of subsidiary O···C, O···O, O···N, Cl···O, N···Cl, CH 2 ···C, CH···N, CH···O/CH 2 ···O, CH 2 ···Cl, CH···π/CH 2 ···π, NH···π, O···π, CH···CH 2 /CH 2 ···CH 2 and π···π forces, the systems were stretched into 2D-3D motifs. Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis for understanding the noncovalent interactions which stabilized the crystal packings. Thanks to the delicate equilibrium of the multiple associates, the homo/hetero synthons or both were set up, here the general R 2 2(8) graph has appeared with the highest frequency. This work verifies that careful check of the multicomponent systems comprised of various acids for a given API where multiplex molecular impacts struggle to dictate the material structures can engender rich and striking outcomes. [Display omitted] [ABSTRACT FROM AUTHOR]

For improving the adsorption behaviors of the adsorbent, including large adsorption capacity, high selectivity for Pb2+ and Cd2+, as well as good separability from wastewater, bioresource chitosan (CS) was introduced to modify SUZ-4 zeolite to form SUZ-4@CS beads for the first time. The adsorption ability of SUZ-4@CS beads was optimized when the mass ratio (SUZ-4:CS) was 1:1, and the aging time in NaOH solution was 24 h, and the conventional drying method was adopted rather than the vacuum one. The optimal adsorption ability of beads was 499.5 and 234.6 mg/g for Pb2+ and Cd2+, respectively. The parameters in the adsorption were adopted as 0.0075 g adsorbent for 50 mL, 250 mg/L Pb2+ solution, and 0.015 g adsorbent for 50 mL, 100 mg/L Cd2+ solution, pH = 6, t = 120 min. The connection between SUZ-4 and CS in the composite was verified to be through H-bonds rather than mechanical mixing by the characterizations. Ion exchange, precipitation, and surface complexation were involved in the ion uptake. Moreover, the prepared SUZ-4@CS(1:1) beads displayed good recyclability for both Pb2+ and Cd2+ during six recycles. Notably, SUZ-4@CS(1:1) beads could effectively remove Pb2+ and Cd2+ from the actual industrial wastewater to meet regulatory requirements. These findings demonstrate that SUZ-4@chitosan beads can be a promising adsorbent for water purification. [Display omitted] • SUZ-4@CS beads show excellent capacity and selectivity for Pb2+ and Cd2+ adsorption. • Effect of synthesis conditions of beads on adsorption is studied for the first time. • The interaction force of CS and SUZ-4 in the beads is verified to be hydrogen bonds. • The adsorption mechanism of SUZ-4@CS beads for Pb2+ and Cd2+ in water is proposed. [ABSTRACT FROM AUTHOR]

The native structure of the glycine-rich antifreeze protein from snow flea, sfAFP, its conformational stability and cooperative folding-unfolding transitions represent a challenge for the current understanding and rationalization of protein folding and stability. The hydrophobic effect, the main stabilizing factor of folded structures, is redefined in terms of the solvent-excluded volume associated with the insertion of a given structure in water to arrive at a different molecular mechanism. The need to minimize the solvent-excluded volume in order to maximize the translational entropy gain of water molecules drives protein folding and determines the globular shape of folded structures. The burial of nonpolar side chains from water contact, as emphasized by the sfAFP folded structure, is not a necessary condition. In fact, a large fraction of nonpolar surface is water-accessible in the folded structures of globular proteins. The significant reduction in water accessible surface area upon chain folding is the necessary and fundamental condition, and rationalizes the conformational stability and cooperativity of sfAFP native structure. HIGHLIGHTS •The stability and folding characteristics of antifreeze protein from snow flea, sfAFP, are challenging. •The globular shape of sfAFP is not dictated by nonpolar side chains - water contact. •The balance between the translational entropy of water molecules and the conformational entropy of the chain is important in protein folding. •The balance between the formation of intramolecular peptide-peptide H-bonds and the breaking of intermolecular peptide-water H-bonds is important in protein folding.

The role of ligands in the regulation of the catalytic activity of Ni-complexes (Ni(acac)2) in green process-selective ethylbenzene oxidation with O2 into α-phenyl ethyl hydroperoxide is considered in this article. The dual function of phenol (PhOH) included in the coordination sphere of the nickel complex as an antioxidant or catalyst depends on the ligand environment of the metal. The role of intermolecular H-bonds and supramolecular structures (AFM method) in the mechanisms of selective catalysis by nickel complexes in chemical and biological oxidation reactions is analyzed.

The study of the high-pressure behavior of molecular crystals helps find limits of their stability, as well as obtain previously unknown new phases. This may result in the creation of new materials and their forms for a variety of applications: pharmaceutics, optoelectronics, etc. Nevertheless, until recently, there was no practical unified scheme for high-pressure studies of organic molecules, paying close attention to various inter- and intramolecular interactions. In this work, we compare different computational methods for the high-pressure research of molecular crystals in terms of the energy of particular interactions. Tolazamide polymorphs are taken as a representative system. It is shown that not only "structure-forming" interactions, e.g. H-bonds and stacking interactions, but also multiple van der Waals interactions should be taken into account. Moreover, we compare two different concepts for studying particular H-bonds in terms of absolute and relative energies, showing their importance in understanding the high-pressure behavior of tolazamide polymorphs. Finally, several important details about the high-pressure research of organic crystals at a molecular level by computational methods are formulated. [ABSTRACT FROM AUTHOR]

Quantitative single crystal neutron-diffraction in diamond anvil cells has so far been limited by the neutron flux available at the various neutron sources. As a result, highly precise measurements of the exact position of light elements have not been possible preventing, for example, structural studies of hydrogen and hydrogen bonds under pressure. Here we report experiments carried out on SNAP at the Spallation Neutron Source (ORNL, TN, USA) to explore the possibility and current limits of such studies. Furthermore, we benchmarked the obtained data quality with reference experiments carried out on TOPAZ, a dedicated single-crystal instrument. We show that measuring single-crystal diffraction intensities on SNAP is possible to such a precision that we are able to resolve the hydrogen bonds in potassium dideuterium phosphate (DKDP) as well as in ice VI. [ABSTRACT FROM AUTHOR]

A new approach to the research of supramolecular complexes by the AFM method and the possible role of hydrogen bonds in the formation of nanostructures of metal complexes simulating the active centers of enzymes was proposed. The formation of these structures occurs due to non-covalent intermolecular interactions, and to a certain extent reflects the structure of the complexes involved in the mechanisms of homogeneous and enzymatic catalysis, as well as during morphological changes of cells. [ABSTRACT FROM AUTHOR]

We showed that the Atomic force microscopy (AFM) method allows monitoring the morphological changes of biological structures fixed on the surface due to H-bonds, as well as studying the self-organisation of porphyrins -- amino acid complexes simulating the active centres of enzymes into stable nanostructures due to intermolecular hydrogen bonds. Quantitative relationships were found between the three subpopulations of mitochondria of pea seedlings, differing in size, at the changing conditions for the growth of pea seedlings and at natural antioxidant resveratrol action. Resveratrol treatment of pea seeds reduced part of the big swollen mitochondria and caused the biogenesis of small active mitochondria under stressful conditions. It was researched also the self-organisation of stable supramolecular nanostructures in the form of trigonal prisms based on the porphyrin complex of iron with tyrosine and histidine due to self-assembly involving intermolecular hydrogen bonds. Similar complexes can be the components of active centres of the P450 cytochromes present in the respiratory chain of mitochondria and microsomes. [ABSTRACT FROM AUTHOR]

Heteroatoms (N, O, and F) and hydrogen groups are important elements for forming the H-bonds. It is well known that a large number of hydrogen groups are formed after curing reaction of epoxy. However, literatures about epoxy resins containing heteroaromatic ring and the H-bonds after cure reaction of the epoxy resins are seldom published. To bridge the gap, a kind of new epoxy monomer containing pyridine ring (EMP) has been synthesized in this work, andit is further cured by 4,4-diaminodiphenyl methane (DDM). The properties of cured EMP/ DDM are evaluated by DSC, DMA, and static contact angle measurement. Moreover, the formation and the role of H-bonds in EMP/DDM are characterized by temperature-dependent FT-IR. The results show that the nitrogen heteroatom in pyridine ring effectively involves in the H-bonds and contributes a lot to the thermo-mechanical performances of cured EMP/DDM. We hope that the results presented in this work can work as a meaningful guide for utilization of the H-bonds to regulate the properties of epoxy resin. [ABSTRACT FROM AUTHOR]

Forward stimulated Raman scattering in pure water and H2O2–H2O mixture solutions are investigated under different pump laser energies. Three characteristic peaks are observed in mixture solutions due to the enhancement of hydrogen bonds (H‐bonds) structure of water molecules by H2O2. Simultaneously, stimulated Raman scattering lines indicate that high‐pressure ice‐phase is formed in mixture solutions, which is attributed to the reduction of the laser breakdown threshold of liquid water by H2O2, resulting in a strong dynamic high pressure. [ABSTRACT FROM AUTHOR]

• Eight organic adducts have been prepared via solvent mediated crystallization. • The adducts were formed and stabilized by the classical hydrogen bonds as well as the non-covalent associates. • The non-covalent associates were confirmed by the XRD. • The synthons were also analyzed. Cocrystallization experiments between the widely popular active pharmaceutical ingredient (API) minoxidil and an array of aryl acids coformers were carried out, successfully yielding 8 multi-component samples consisting of 3 co-crystals and 5 salts. Most of them are hydrates. The nature of the samples have been featured by XRD, IR and EA, the melting points were also gauged. The structural and supramolecular aspects are investigated in detail. In all adducts the N-oxide shows various nonbonding contacts. The Hmnd dimer was established at both 1 and 4 by a pair of symmetric N H···O H-bonds. In all cases the minoxidil and coformers were connected by the N H···O/O H···O synthon which is proved to be the highest extensive associates (appearing in 8/8 structures), even in the coexistence of other potentially disruptive non-covalent bonding moieties. Interestingly, the piperidine moieties as effective H-bond acceptor never participated in accepting the H-bonds. The pyrimidine amino also only acts as the H-bond donors. The outcomes unveil that the crystal packing is relied on the strong N H⋯O/O H···O H-bonds. Deep insight into the crystal packing uncovered that a different set of extra O N/O O, CH···C, N H···C, CH···O/CH 2 O, CH CH/CH 2 CH/CH 2 CH 2 , CH 2 Cl, CH 3 -π/CH 2 -π, NH-π, O-π, and π-π contacts contribute to the stabilization and expansion of the total structures. For the synergism of the various nonbonding forces there had the homo/hetero supramolecular synthons. Some classical graph set notations of R 2 2(9) and R 4 2(8) were present in the relative high frequency. [Display omitted] [ABSTRACT FROM AUTHOR]