Extensive Hydrogen Bonds Research Articles

Crystal structure of β-d-galactofuranosidase from Streptomyces sp. JHA19 in complex with an inhibitor provides insights into substrate specificity.

d-Galactofuranose (Galf) is widely distributed in glycoconjugates of pathogenic microbes. β-d-Galactofuranosidase (Galf-ase) from Streptomyces sp. JHA19 (ORF1110) belongs to glycoside hydrolase (GH) family 2 and is the first identified Galf-specific degradation enzyme. Here, the crystal structure of ORF1110 in complex with a mechanism-based potent inhibitor, d-iminogalactitol (Ki = 65 μm) was solved. ORF1110 binds to the C5-C6 hydroxy groups of d-iminogalactitol with an extensive and integral hydrogen bond network, a key interaction that discriminates the substrates. The active site structure of ORF1110 is largely different from those of β-glucuronidases and β-galactosidases in the same GH2 family. A C-terminal domain of ORF1110 is predicted to be a carbohydrate-binding module family 42 that may bind Galf. The structural insights into Galf-ase will contribute to the investigation of therapeutic tools against pathogens.

Elucidating Antibiotic Permeation through the Escherichia coli Outer Membrane: Insights from Molecular Dynamics.

Antibiotic resistance represents a critical public health threat, with an increasing number of Gram-negative pathogens demonstrating resistance to a broad range of clinical drugs. A primary challenge in enhancing antibiotic efficacy is overcoming the robust barrier presented by the bacterial outer membrane. Our research addresses a longstanding question: What is the rate of antibiotic permeation across the outer membrane (OM) of Gram-negative bacteria? Utilizing molecular dynamics (MD) simulations, we assess the passive permeability profiles of four commercially available antibiotics─gentamicin, novobiocin, rifampicin, and tetracycline across an asymmetric atomistic model of the Escherichia coli (E. coli) OM, employing the inhomogeneous solubility-diffusion model. Our examination of the interactions between these drugs and their environmental context during OM permeation reveals that extended hydrogen bond formation and drug-cation interactions significantly hinder the energetics of passive permeation, notably affecting novobiocin. Our MD simulations corroborate well with experimental data and reveal new implications of solvation on drug permeability, overall advancing the possible use of computational prediction of membrane permeability in future antibiotic discovery.

Synergistic impact of nano-supramolecular coordination polymer based on cadmium, ethyl nicotinate and thiocyanate ligands as efficient catalyst to remove harmful elements from wastewater.

Under ultrasonication, cadmium nitrate tetrahydrates, ethyl nicotinate (EN), and potassium thiocyanate as connecting ligand self-assembled to form the nanosized supramolecular coordination polymer (NSCP1) and the crystalline supramolecular coordination polymer (SCP1) [Cd(EN)2(SCN)2]. Single crystal SCP1 X-ray diffraction (XRD) revealed that CdII has an octahedral shape. The network structure of SCP1 is composed of chair conformation cyclic [Cd2(SCN)2] n building blocks that form a one dimensional (1D) chain with bilaterally coordinated EN. The 1D-chain is joined to the other by extensive hydrogen bonds, which arrange the chains into a three-dimensional network. By stacking π-π, the strands are fluttering the three-dimensional (3D) network even more. Several structural characterization methods and spectral analyses were used to analyze SCP1 and NSCP1. The heterogeneous catalysts SCP1 and NSCP1 have been shown to display exceptionally strong catalytic activity against the breakdown of the designated contaminant, indigo carmine (IC) color in very short durations under ultraviolet (UV) or ultrasonic wave conditions. The photoluminescence probing approach was utilized to determine the reactive oxygen species and reaction process using the disodium salt of terephthalic acid.

Sustainable, temperature-tolerant, dual network conductive pressure sensitive adhesive from cellulose and rosin for wearable sensing

Conductive pressure sensitive adhesives (PSA) used for wearable and smart electronic sensors have attracted a significant amount of attention recently. However, achieving multifunctional conductive PSA with the feature of temperature tolerance and sustainability via a convenient and environment-friendly approach still remains challenge. Herein, a novel cellulose-rosin based poly(esterimide) (PEI) was first prepared by esterification and imidization. Then, the cellulose-rosin based PEI was integrated with polymerizable deep eutectic solvents (PDES, 2-hydroxyethyl acrylate and triethanolamine as hydrogen bond donor, choline chloride as hydrogen bond receptor) and performed UV-induced polymerization for formation of the conductive PSA with dual network (DN). The DN structure and the existence of extensive hydrogen bonds endowed these cellulose-rosin based conductive PSA with excellent adhesion property (shear resistance more than 70 h, tack of 14.6 N and 180° peel strength of 148.1 N/m, are higher than that of some typical commercial PSA), exceptional UV-blocking, solvent-resistance (usable in low polar solvent) and temperature tolerance (perform well between −25 °C to 140 °C). Furthermore, these conductive PSA could be used as wearable sensor to monitor subtle movements and achieve real-time monitoring of interface adhesion states even under extreme environmental conditions. This work provides a green strategy for the next-generation of multifunctional PSA.

Atomistic insights into the reentrant phase-transitions in polyuracil and polylysine mixtures.

The phase separation of protein and RNA mixtures underpins the assembly and regulation of numerous membraneless organelles in cells. The ubiquity of protein-RNA condensates in cellular regulatory processes is in part due to their sensitivity to RNA concentration, which affects their physical properties and stability. Recent experiments with poly-cationic peptide-RNA mixtures have revealed closed-loop phase diagrams featuring lower and upper critical solution temperatures. These diagrams indicate reentrant phase transitions shaped by biomolecular interactions and entropic forces such as solvent and ion reorganization. We employed atomistic simulations to study mixtures with various RNA-polylysine stoichiometries and temperatures to elucidate the microscopic driving forces behind reentrant phase transitions in protein-RNA mixtures. Our findings reveal an intricate interplay between hydration, ion condensation, and specific RNA-polylysine hydrogen bonding, resulting in distinct stoichiometry-dependent phase equilibria governing stabilities and structures of the condensate phase. Our simulations show that reentrant transitions are accompanied by desolvation around the phosphate groups of RNA, with increased contacts between phosphate and lysine side chains. In RNA-rich systems at lower temperatures, RNA molecules can form an extensive pi-stacking and hydrogen bond network, leading to percolation. In protein-rich systems, no such percolation-induced transitions are observed. Furthermore, we assessed the performance of three prominent water force fields-Optimal Point Charge (OPC), TIP4P-2005, and TIP4P-D-in capturing reentrant phase transitions. OPC provided a superior balance of interactions, enabling effective capture of reentrant transitions and accurate characterization of changes in solvent reorganization. This study offers atomistic insights into the nature of reentrant phase transitions using simple model peptide and nucleotide mixtures. We believe that our results are broadly applicable to larger classes of peptide-RNA mixtures exhibiting reentrant phase transitions.

Synthesis, characterization, crystal structure, molecular dynamics simulations, MM-GBSA analysis, and bioactivity studies of pyrazine- and pyrimidine-modulated unsymmetrical dipyridylamide complexes

By using unsymmetrical pyrazine- and pyrimidine-modulated oligo-α-pyridylamine ligand N-(4-methylpyrimidin-2-yl)pyrazin-2-amine (Hmpmpza) (1), 1D copper(II) coordination polymer {[Cu(mpmpza)(CH3COO)](CH3OH)(H2O)}n (2) and mononuclear copper(II) complex [Cu(Hmpmpza)(NO3)2] (3) were first successfully synthesized and structurally characterized. In complex (2), Cu(II) is six-coordinated in an elongated octahedral geometry. The Hmpmpza molecule coordinates with the Cu(II) as a tridentate ligand, in which the pyrimidine and amine group nitrogen atoms link the coordination units to an infinite 1-D chain polymer. Extensive hydrogen bonds between amino groups, acetate anions, methanol, and water molecules are observed in 2, resulting in a 3D network of the 2. Complex 2 provides the first example of the complex with a modulated Hdpa ligand, in which nitrogen atoms both of the pyrazine and pyrimidine cycles participated in the coordination with the metal center. There are two crystallographically independent molecules in a mononuclear complex 3 and the Cu(II) atom is six-coordinated in an elongated octahedral geometry. Hmpmpza in complex 3 coordinates to the Cu(II) in an anti-anti conformation as a bidentate ligand. The hydrogen bonds between amino groups and coordinated nitrate anions in complex 3, link its molecules to a 1-D chain structure. However, no hydrogen bonding linkage between the 1-D chains is observed. The temperature dependence magnetic susceptibility measurement for complex 2 described by the Bonner-Fischer approximation shows a weak antiferromagnetic coupling between Cu(II) ions. The best fitting results were obtained with parameters g = 2.141, J = −0.73 cm−1 and R = 4.85 × 10−6. The molecular dynamics (MD) simulations of the 2-hAChE, 3-hAChE, 2-hBChE, and 3-hBChE complexes offer comprehensive insights into the stability and dynamic behavior of ligand-protein interactions. These findings contribute to a detailed understanding of the specific dynamics governing the stability of acetylcholinesterase and butyrylcholinesterase complexes.

Structure, Characterizations, Photocurrent Response, and Theoretical Study of One Chained Hybrid Iodoplumbate

AbstractExploring new haloplumbate hybrids and understanding the structure‐activity relationships are of great significance for further promoting their applications in the photovoltaic fields. Herein, with the in situ‐formed [Hmd]+ (md = 2‐methyl‐1,3‐diazinane) templates, a new organic–inorganic hybrid iodoplumbate, namely [Hmd]PbI3 (1), is successfully constructed and then structurally characterized using multiple technical approaches. X‐ray crystallography studies show that compound 1 features the typical 1D chain‐like motifs of [Pb2I6]n2n−, generating the 3D supermolecular network by the extensive hydrogen bond interactions. Interestingly, compound 1 exhibits the semiconductive behavior, with an optical band gap of 2.72 eV. More attractively, the title compound has good photoelectric switching performances under the alternating light irradiation, whose photocurrent densities compete well with or surpass those of many metal halide counterparts. Further theoretical analyses reveal that the title compound has a more dispersive band structure (especially the value band) that facilitates the transport of charge carriers, which may be the main origin of its excellent optoelectronic performance. Presented in this paper also bring the studies of Hirshfeld surface, X‐ray photoelectron spectroscopy (XPS) as well as thermogravimetric analysis.

1H/17O Chemical Shift Waves in Carboxyl-Bridged Hydrogen Bond Networks in Organic Solids.

We report solid-state 1H and 17O NMR results for four 17O-labeled organic compounds each containing an extensive carboxyl-bridged hydrogen bond (CBHB) network in the crystal lattice: tetrabutylammonium hydrogen di-[17O2]salicylate (1), [17O4]quinolinic acid (2), [17O4]dinicotinic acid (3), and [17O2]Gly/[17O2]Gly·HCl cocrystal (4). The 1H isotropic chemical shifts found for protons involved in different CBHB networks are between 8.2 and 20.5 ppm, which reflect very different hydrogen-bonding environments. Similarly, the 17O isotropic chemical shifts found for the carboxylate oxygen atoms in CBHB networks, spanning a large range between 166 and 341 ppm, are also remarkably sensitive to the hydrogen-bonding environments. We introduced a simple graphical representation in which 1H and 17O chemical shifts are displayed along the H and O atomic chains that form the CBHB network. In such a depiction, because wavy patterns are often observed, we refer to these wavy patterns as 1H/17O chemical shift waves. Typical patterns of 1H/17O chemical shift waves in CBHB networks are discussed. The reported 1H and 17O NMR parameters for the CBHB network models examined in this study can serve as benchmarks to aid in spectral interpretation for CBHB networks in proteins.

Cellulose nanofiber-connected covalent organic framework nanosheets composite membrane for proton conduction

Covalent organic framework (COF) nanosheets have been considered as promising materials for proton exchange membranes (PEM) due to their orderly, adjustable pores and relatively improved membrane forming properties. Here, we introduced the one-dimensional sulfonated bacterial cellulose nanofibers (SBCNF), originating from coconut and binding TpBd-2SO3H nanosheets to prepare a series of SBCNF/TpBd-2SO3H composite membranes. The composite membranes present a typical layered structure due to the presence of SBCNF. Moreover, extensive hydrogen bond network is formed between the embedded TpBd-2SO3H nanosheets and SBCNF, which is beneficial for improving the proton conductivity and mechanical strength of the membrane. As a result, the composite membrane achieved a proton conductivity of 147.5 mS/cm at 80 °C, 100 %RH and a highest tensile strength of 88.49 MPa.

A water structure indicator suitable for generic contexts: Two-liquid behavior at hydration and nanoconfinement conditions and a molecular approach to hydrophobicity and wetting.

In a recent work, we have briefly introduced a new structural index for water that, unlike previous indicators, was devised specifically for generic contexts beyond bulk conditions, making it suitable for hydration and nanoconfinement settings. In this work, we shall study this metric in detail, demonstrating its ability to reveal the existence of a fine-tuned interplay between the local structure and energetics in liquid water. This molecular principle enables the establishment of an extended hydrogen bond network, while simultaneously allowing for the existence of network defects by compensating for uncoordinated sites. By studying different water models and different temperatures encompassing both the normal liquid and the supercooled regime, this molecular mechanism will be shown to underlie the two-state behavior of bulk water. In addition, by studying functionalized self-assembled monolayers and diverse graphene-like surfaces, we shall show that this principle is also operative at hydration and nanoconfinement conditions, thus generalizing the validity of the two-liquid scenario of water to these contexts. This approach will allow us to define conditions for wettability, providing an accurate measure of hydrophobicity and a reliable predictor of filling and drying transitions. Hence, it might open the possibility of elucidating the active role of water in the broad fields of biophysics and materials science. As a preliminary step, we shall study the hydration structure and hydrophilicity of graphene-like systems (parallel graphene sheets and carbon nanotubes) as a function of the confinement dimensionality.

Potential antiprostatic performance of novel lanthanide-complexes based on 5-nitropicolinic acid

Two new lanthanide-complexes based on the 5-nitropicolinate ligand (5-npic) were obtained and fully characterized. Single-crystal X-ray diffraction revealed that these compounds are isostructural to a Dy-complex, previously published by us, based on dinuclear monomers link together with an extended hydrogen bond network, providing a final chemical formula of [Ln2(5-npic)6(H2O)4]·(H2O)2, where Ln = Dy (1), Gd (2), and Tb (3). Preliminary photoluminescent studies exhibited a ligand-centered emission for all complexes. The potential antitumoral activity of these materials was assayed in a prostatic cancer cell line (PC-3; the 2nd most common male cancerous disease), showing a significant anticancer activity (50–60% at 500 μg·mL−1). In turn, a high biocompatibility by both, the complexes and their precursors in human immunological HL-60 cells, was evidenced. In view of the strongest toxic effect in the tumoral cell line provided by the free 5-npic ligand (~ 40–50%), the overall anticancer complex performance seems to be triggered by the presence of this molecule.Graphical

A facile strategy for preparing of cross‐linkable natural fibers based on a Schiff base reaction

AbstractThe exploitation and utilization of natural fibers still face many challenges due to their high crystallinity and extensive hydrogen bond network. Therefore, sustainable and effective modification strategies are currently essential. In this work, we investigate the processing and mechanical performances of natural fibers modified by combining sodium periodate oxidation and subsequent Schiff base reaction. Steam‐exploded hemp fibers (HFs) were firstly oxidized with sodium periodate, and subsequently grafted with 1,10‐diaminodecane. A decrease in the glass transition temperature of oxidized‐aminated HFs (OAHFs) from 225 to 150°C was achieved as the dosage of periodate increased. Admirable mechanical properties were achieved despite a lower dosage of periodate due to melt bonding and chemical cross‐linking between the fibers during heat processing. Particularly, dynamic compression molding was applied to heat processes and effectively improved the melt bonding and the chemical crosslinking, which increased flexural strength from 58.2 to 69.9 MPa. This strategy was moderate and low cost. The resulted material has good processing performance and excellent mechanical properties, which have large industrial application prospects and potential in the field of biodegradable environment‐friendly materials.

Self-Healing and Wide Temperature-Tolerant Cellulose-Based Eutectogels for Reversible Humidity Detection.

A kind of ionic conductive gel (also named eutectogel) is developed from an inorganic salt (ZnCl2)-based deep eutectic solvent (DES). The ternary DES consists of ZnCl2, acrylic acid, and water, and cotton linter cellulose is introduced into the DES system to tailor its mechanical and conductive properties. Enabled by the extensive hydrogen bonds and ion-dipole interactions, the obtained eutectogel displays superior ionic conductivity (0.33 S/m), high stretchability (up to 2050%), large tensile strength (1.82 MPa), and wide temperature tolerance (-40 to 60 °C). In particular, the water-induced coordination interactions can tune the strength of hydrogen/ionic bonds in the eutectogels, imparting them with appealing humidity sensing ability in complex and extreme conditions.

Three-Dimensional Hydrogen-Bonded Porous Metal-Organic Framework for Natural Gas Separation with High Selectivity.

A 3D hydrogen-bonded metal-organic framework, [Cu(apc)2]n (TJU-Dan-5, Hapc = 2-aminopyrimidine-5-carboxylic acid), was synthesized via a solvothermal reaction. The activated TJU-Dan-5 with permanent porosity exhibits a moderate uptake of 1.52 wt% of hydrogen gas at 77 K. The appropriate BET surface areas and decoration of the internal polar pore surfaces with groups that form extensive hydrogen bonds offer a more favorable environment for selective C2H6 adsorption, with a predicted selectivity for C2H6/CH4 of around 101 in C2H6/CH4 (5:95, v/v) mixtures at 273 K under 100 kPa. The molecular model calculation demonstrates a C-H···π interaction and a van der Waals host-guest interaction of C2H6 with the pore walls. This work provides a strategy for the construction of 3D hydrogen-bonded MOFs, which may have great potential in the purification of natural gas.

Beyond the coupled distortion model: structural analysis of the single domain cupredoxin AcoP, a green mononuclear copper centre with original features.

Cupredoxins are widely occurring copper-binding proteins with a typical Greek-key beta barrel fold. They are generally described as electron carriers that rely on a T1 copper centre coordinated by four ligands provided by the folded polypeptide. The discovery of novel cupredoxins demonstrates the high diversity of this family, with variations in terms of copper-binding ligands, copper centre geometry, redox potential, as well as biological function. AcoP is a periplasmic cupredoxin belonging to the iron respiratory chain of the acidophilic bacterium Acidithiobacillus ferrooxidans. AcoP presents original features, including high resistance to acidic pH and a constrained green-type copper centre of high redox potential. To understand the unique properties of AcoP, we undertook structural and biophysical characterization of wild-type AcoP and of two Cu-ligand mutants (H166A and M171A). The crystallographic structures, including native reduced AcoP at 1.65 Å resolution, unveil a typical cupredoxin fold. The presence of extended loops, never observed in previously characterized cupredoxins, might account for the interaction of AcoP with physiological partners. The Cu-ligand distances, determined by both X-ray diffraction and EXAFS, show that the AcoP metal centre seems to present both T1 and T1.5 features, in turn suggesting that AcoP might not fit well to the coupled distortion model. The crystal structures of two AcoP mutants confirm that the active centre of AcoP is highly constrained. Comparative analysis with other cupredoxins of known structures, suggests that in AcoP the second coordination sphere might be an important determinant of active centre rigidity due to the presence of an extensive hydrogen bond network. Finally, we show that other cupredoxins do not perfectly follow the coupled distortion model as well, raising the suspicion that further alternative models to describe copper centre geometries need to be developed, while the importance of rack-induced contributions should not be underestimated.

Insensitive ionic energetic salts and a green metal-free primary explosive based on furazan-triazole

To balance the properties and stability of the energetic materials, the synthesis of the new energetic materials 3-amino-4-(4-amino-5-hydrazine-1,2,4-triazole-3-yl) furazan and its energetic salts were reported which show excellent performance and safety. Also, the azo compound 1,2-bis(4-(5-azido-1,2,4-triazol-3-yl) -furazan-3-yl) was prepared and got two -N3 groups unexpectedly. All the new compounds were fully characterized by nuclear magnetic resonance spectroscopy (NMR) and infrared spectroscopy (IR), elemental analysis (EA), and differential scanning calorimetry (DSC). In addition, the structure of compounds 2, 4, 7 were confirmed by single crystal X-ray diffraction analysis. The X-ray date shows that energetic salts have extensive hydrogen bonds which are good to the stability of these energetic salts, and it also shows that azo compound has two conformations. In order to get detonation properties of these synthesized compounds, EXPLO5 was used to calculate. According to the calculated results, all ionic salts are inductive energetic materials with good detonation performances (D= 8064-8698m s−1, P= 25.8-31.8GPa) and azo compound has the detonation speed of 8190 m s−1 and achieved the detonation pressure at 24.9GPa. Additionally, the azo compound was tested through the initiation test which shows that it has good detonation ability, has the chance to be the green metal-free primary explosive.

Hidden Beneath the Layers: Extending the Core/Shell Model of Reverse Micelles.

Reverse micelles (RMs) provide a unique and highly tunable model system to study water in confined environments. The complex properties of water within RMs arise from the disruption of extended hydrogen bond (H-bond) networks that mediate local and long-range dynamics in bulk aqueous systems. Modulating the water pool size influences its H-bond dynamics, with smaller RMs increasingly restricting the H-bond network rearrangements leading to slower dynamics; however, within small confined systems, the dynamics of the surfactants also influence the water dynamics. Using ultrafast two-dimensional infrared spectroscopy, we investigate the effects of RM size on the surfactant headgroup rotamer populations and picosecond interfacial H-bond dynamics of aerosol-OT surfactants. We find that the increased water penetration accelerates H-bond dynamics, with larger RMs showing faster dynamics. These results imply that the changes in the RM structure alter the physical structure of the RM interface and thus alter the solvation dynamics. The findings in this study can be used for developing models for structure-specific solvation dynamics that account for the surfactant packing and hydration at the interface.

Probing a distinct druggable tubulin binding site with gatorbulins 1–7, their metabolic and physicochemical properties, and pharmacological consequences

Microtubules, consisting of α/β-tubulin heterodimers, are prime targets for anticancer drug discovery. Gatorbulin-1 (GB1, 1a) is a recently described marine natural product that targets tubulin at a new, seventh pharmacological site at the tubulin intradimer interface. Using our previously developed robust route towards GB1 (1a), we synthesized simplified, first-generation gatorbulins, GB2–7 (1b–1g) of this highly modified cyclodepsipeptide (GB1) that does not contain any proteinogenic amino acid. We systematically investigated the structure-activity relationship at the biochemical and cellular level using GB1-susceptible ovarian and cervical cancer cells. We validated that the hydroxamate moiety in the N-methyl-alanine residue is critical for activity. All other structural modifications present in GB1, including C-hydroxylation of asparagine, methylation at C-4 of proline, and sp2 hybridization in dehydro-alanine, were proven to be functionally relevant. Replacement of the primary amide with a methyl ester also resulted in reduced activity, indicating the intricate scaffold optimization by the GB1-producing cyanobacterium. Inhibition of tubulin polymerization in vitro and binding affinities correlated very well, translating into differentials in cellular efficacy. We used docking and molecular dynamics to evaluate the effects of the chemical simplification at the structural level, indicating that each modification resulted in loss of target interactions, although energetically modest. Similar to cevipabulin that targets two different sites on the tubulin dimer, GB1 promotes proteasome-mediated tubulin degradation but by an unknown mechanism, presumably distinct from that of cevipabulin. Comparison with cevipabulin indicated that this compound binds to the same tubulin region as GB1 (1a), although the binding mode is distinct. Cevipabulin almost exclusively interacts with α-tubulin, including nonexchangeable GTP. In contrast, GB1 (1a) makes extensive contact and hydrogen bonds with both α- and β-chains of tubulin. GB1-7 showed excellent solubility and much higher than that of paclitaxel. Hepatic microsome stability was excellent, human cytochrome P450s were not inhibited and plasma binding was minimal with high free fractions. Passive permeability was predicted to be high based on PAMPA. Parent compound GB1 (1a) was further evaluated using a cellular model with MDCK cells stably transduced with the human efflux transporter MDR1/P-gp, showing similar permeability with and against transporter gradient, indicating that GB1 (1a) is a poor P-gp substrate.

Natural UCST hydrogel with long-term stability, recyclability, thermoplasticity, frost resistance and adhesive properties

Thermosensitive hydrogels have received great research interest, but the elaborate experimental design, inferior mechanical and anti-freeze properties have limited the practical application of thermosensitive hydrogels. For address these challenges, here, polyol (glycerol, xylitol, and sorbitol) and deionized water were selected as mixed solvents to fabricate multifunctional natural gelatin UCST hydrogels by simple physical blending. XRD and FT-IR indicate that the polyol assists the gelatin molecular chain to form short-range β-sheets without affecting the triple helix structure. The short-range β-sheets acts as the physical cross-linking point, which leads to a denser three-dimensional network of the hydrogel. The results indicate that the phase transition temperature and mechanical properties of UCST hydrogels can be modulated by simply changing the amount of polyol in the solvent mixture. In addition, the polyol forms extensive hydrogen bonds with water, which gives the hydrogel excellent freeze resistance, anti-drying and adhesive properties. In this paper, natural UCST gelatin hydrogels with long-term stability, recyclability, thermoplasticity, anti-freeze and adhesive properties were prepared by a simple scheme, and the facile process and cheap cost lays the foundation for the application of UCST hydrogels in drug delivery, skincare products and wearable devices.

Polyvalent Ionic Energetic Salts Based on 4-Amino-3-hydrazino-5-methyl-1,2,4-triazole.

The synthesis of the new energetic material 4-amino-3-hydrazino-5-methyl-1,2,4-triazole, which shows excellent performance and reliable safety, has drawn attention recently. To fully characterize this material, a comprehensive analysis was performed using various techniques, including differential scanning calorimetry (DSC), infrared spectroscopy (IR), elemental analysis, and 1H and 13C NMR spectroscopy. Additionally, three compounds, 3, 5 and 9, were further characterized using single X-ray diffraction. The X-ray data suggested that extensive hydrogen bonds affect molecular structure by means of intermolecular interactions. In order to evaluate the explosive properties of these synthesized compounds, detonation pressures and velocities were calculated using EXPLO5 (V6.01). These calculations were carried out utilizing experimental data, including density and heat of formation. Among the explosives tested, compounds 7 and 8 exhibited zero oxygen balance and demonstrated exceptional detonation properties. Compound 7 achieved the highest recorded detonation pressure, at 34.2 GPa, while compound 8 displayed the highest detonation velocity, at 8887 m s-1.