Types Of Hydrogen Bonds Research Articles

Crystal structures of two polymorphs for fac-bromidotricarbonyl[4-(4-methoxyphenyl)-2-(pyridin-2-yl)thiazole-κ2 N,N′]rhenium(I)

Crystallization of the title compound, fac-[ReBr(ppt-OMe)(CO)3] (ppt-OMe = C15H12N2OS), from CH2Cl2/n-pentane (1:5 v/v) at room temperature gave two polymorphs, which crystallize in monoclinic (P21/c; α form) and orthorhombic (Pna21; β form) space groups. The ReI complex molecules in either polymorph adopt a six-coordinate octahedral geometry with three facially-oriented carbonyl ligands, one bromido ligand, and two nitrogen atoms from one chelating ligand ppt-OMe. In the crystal, both polymorph α and β form di-periodic sheet-like architectures supported by multiple hydrogen bonds. In polymorph α, two types of hydrogen bonds (C—H...O) are found while, in polymorph β, four types of hydrogen bonds (C—H...O and C—H...Br) exist.

PH-Independent Selective Formation of VO2+ Motif Incorporating a Family of Hydrazone Ligands: Synthesis, Structure, and Luminescence-Based Sensing Studies toward Selective Metal Ions.

Two new dioxidovanadium(V) compounds with the general formula [VVO2(L)] (L = hydrazone ligand) were synthesized using three different methods (acidic, neutral, and basic media) with either VIVOSO4. 5H2O, [VIVO(acac)2], or NH4VVO3 as the starting material and hydrazone ligands. In both cases, five coordinated V5+ ions adopted distorted square pyramidal geometry through the coordination of two oxido ligands and one hydrazone ligand. In compound 1, the presence of free hydroxyl groups stabilized the molecular species through intramolecular O-H•••N type hydrogen bond interactions. In compound 2, the free amino groups are involved in both intramolecular N-H•••N type and intermolecular N-H•••O type hydrogen bond interactions. Compound 1 showed highly selective luminescence turn-on behavior, along with a 33-nm blue shift in the presence of Al3+ ions in an aqueous medium. The experimental limit of detection (LOD) was found to be 66 nM. Whereas compound 2 showed luminescence quenching behavior in the presence of Fe3+, Al3+, and Cr3+ ions. The LODs were observed to be 312, 408, and 280 nM for Fe3+, Al3+, and Cr3+ ions, respectively. The luminescence response mechanisms of both compounds in the presence of metal ions have been correlated with molecular-level interactions.

Durability of epoxy and vinyl ester polymers in wet, seawater, and seawater sea sand concrete environments: Molecular dynamics simulations

Epoxy and vinyl ester (VE) deteriorate under harsh environmental conditions typical of marine and offshore applications. Enhancing their performance requires a deeper understanding of their molecular-level interactions with these environments. This study uses molecular dynamics simulations to investigate the behavior of epoxy and VE under dry, wet, Na2SO4, NaCl, NaOH, KOH, and simulated seawater sea sand concrete (SWSSC) pore solution environments. The effect of temperatures ranging from 300 K to 368 K was also explored. Key parameters, such as radial distribution function, hydrogen bond dynamics, diffusion coefficients of water molecules and ions, swelling ratio, and glass transition temperature (Tg), were analyzed. Results show that epoxy is more sensitive to environmental effects than VE. In the dry state, three types of hydrogen bonds (H-bonds) were identified, with 64 % of the hydroxyl (OH) group involved in epoxy and 34 % in VE. As temperature increases, polymer chain interactions weaken, leading to a decrease in H-bonds, with epoxy showing a faster decline. Absorbed water molecules accumulate near the polymer polar sites, particularly at the OH groups, breaking some polymer-polymer H-bonds and forming new ones with the polymer polar sites. The hydrogen atoms of most absorbed water molecules orient away from the OH group, creating binding sites for water clustering through water-water H-bonds, leading to plasticization and potential hydrolytic degradation. Ions increase the number of polymer-water H-bonds, significantly decreasing polymer-polymer H-bonds (by 59.22 % for epoxy and 51.52 % for VE in SWSSC), thus accelerating material deterioration. Free volume distribution and dynamics, the transition between bound and free water, hydrogen bond dynamics, as well as ion hydration and dehydration collectively influence the water diffusion process in the polymer networks. Ion species diffuse much slower than water molecules, with epoxy showing higher permeability to Cl- and OH- compared to VE. Glass transition temperature (Tg) of both polymers is sensitive to environmental exposure, with epoxy being more affected. The detrimental effect on Tg is ranked as SWSSC > KOH > NaOH > NaCl > Na2SO4 > Wet. These findings provide new nanoscale insights into the interactions between polymers and SWSSC environments, offering a foundation for accurately predicting the durability of polymer-reinforced SWSSC.

Morphology studies, optic proprieties, hirschfeld electrostatic potential mapping, docking molecular anti-inflammatory, and dynamic molecular approaches of hybrid phosphate

The above current study intends to identify new prospects for developing viable epilepsy treatments. To attain this purpose, the created P-carboxylammonium di-hydrogen monohydrate called (I). The research reveals the existence of both intermolecular (O–H⋯O) as well as N–H⋯O intramolecular hydrogen bonding in crystal packing patterns. As the fingerprint plots illustrate the different sorts of interactions and the hybrid system's relative abundance of each, However, the molecular docking results clearly demonstrate five typical hydrogen bonds, with the best binding posture of −4.757 kcal/mol for Lys244, Val272, Arg241, and Glu273 proteins when docked with (I) ligand. As a result, we may deduce that if the (I) ligand is a pharmaceutical used to treat epilepsy, it will probably be more potent than the conventional medication. As a result, (I) was simulated using molecular dynamics (MD) and is proposed as a viable therapeutic target for antiepileptic therapy. Reduced Density Gradient (RDG) analysis, highlighted the presence of significant non-covalent interactions (NCI) that contribute to the stability and structural integrity of the compound, emphasizing the importance of these interactions in the context of its potential applications, particularly in drug design and molecular interactions. Finally, the ELF and LOL analyses collectively enhance the understanding of the electronic structure of compound I, revealing critical information about electron distribution, localization, and the nature of interactions within the molecular framework. These insights are essential for predicting the compound's reactivity and potential applications in fields such as pharmaceuticals and materials science.

Hydrogen Bond Integration in Potato Microstructure: Effects of Water Removal, Thermal Treatment, and Cooking Techniques

Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy (SEM) were used to study the effects of heat treatments and water removal by freeze-drying after different time intervals (6, 12, 24, 48, and 72 h) on the molecular structure of potato tubers. SEM images show structural differences between raw (RP), microwaved (MP), and boiled potato (BP). MP showed a cracked structure. BP was able to re-associate into a granule-like structure after 6 h of freeze-dying, whereas RP had dried granules within a porous matrix after 24 h of freeze-drying. These results are consistent with the moisture content and FTIR results for MP and BP, which demonstrated dried spectra after 6 h of freeze-drying and relatively coincided with RP results after 24 h of freeze-drying. Additionally, three types of hydrogen bonds have been characterized between water and starch, and the prevalence of water very weakly bound to starch has also been detected. The relative crystallinity (RC) was increased by thermal treatment, whereby microwaving recorded the highest value. A comparison of the FTIR and XRD results indicated that freeze-drying treatment overcomes heat effects to generate an integral starch molecule.

Role of Intermolecular Interactions in Deep Eutectic Solvents for CO2 Capture: Vibrational Spectroscopy and Quantum Chemical Studies.

Recent research and reviews on CO2 capture methods, along with advancements in industry, have highlighted high costs and energy-intensive nature as the primary limitations of conventional direct air capture and storage (DACS) methods. In response to these challenges, deep eutectic solvents (DESs) have emerged as promising absorbents due to their scalability, selectivity, and lower environmental impact compared to other absorbents. However, the molecular origins of their enhanced thermal stability and selectivity for DAC applications have not been explored before. Therefore, the current study focuses on a comprehensive investigation into the molecular interactions within an alkaline DES composed of potassium hydroxide (KOH) and ethylene glycol (EG). Combining Fourier transform infrared (FT-IR) and quantum chemical calculations, the study reports structural changes and intermolecular interactions induced in EG upon addition of KOH and its implications on CO2 capture. Experimental and computational spectroscopic studies confirm the presence of noncovalent interactions (hydrogen bonds) within both EG and the KOH-EG system and point to the aggregation of ions at higher KOH concentrations. Additionally, molecular electrostatic potential (MESP) surface analysis, natural bond orbital (NBO) analysis, quantum theory of atoms-in-molecules (QTAIM) analysis, and reduced density gradient-noncovalent interaction (RDG-NCI) plot analysis elucidate changes in polarizability, charge distribution, hydrogen bond types, noncovalent interactions, and interaction strengths, respectively. Evaluation of explicit and hybrid models assesses their effectiveness in representing intermolecular interactions. This research enhances our understanding of molecular interactions in the KOH-EG system, which are essential for both the absorption and desorption of CO2. The study also aids in predicting and selecting DES components, optimizing their ratios with salts, and fine-tuning the properties of similar solvents and salts for enhanced CO2 capture efficiency.

Insight into the phase equilibrium of mycophenolic acid cocrystals

In this study, mycophenolic acid-nicotinamide (MPA-NAM) and mycophenolic acid-acetoguanamine (MPA-AGA) cocrystals were synthesized and characterized using single-crystal X-ray diffraction, Fourier transform spectroscopy and thermal analysis. Intrinsic intermolecular interactions were investigated through Hirshfeld surface and electrostatic potential surface analysis. The results indicated that MPA-NAM and MPA-AGA cocrystals possessed the same types of hydrogen bonds but different hydrogen bond connectivity. Thermodynamic studies revealed that MPA-NAM and MPA-AGA cocrystals exhibited incongruent dissolution behaviors in the chosen solvent. Model regression results indicate that the 1:1 complex formation existed during the dissolution of the MPA-NAM cocrystal, whereas 1:1 and 1:2 solution complexes presented in the MPA-AGA cocrystal. The complicated complexation in the MPA-AGA cocrystal induced all fragments of MPA-AGA to possess higher energies, facilitating MPA-AGA cocrystal precipitation from the solution, which was testified by Energy calculations.

Effect of Solvent on the Optical Rotation of Azatryptophan Derivatives.

Chirally pure enantiomers of differently protected 7-azatryptophan derivatives (R-3c, S-3c, R-3i, S-3i, R-3m, S-3m, R-3aa, and S-3aa) were synthesized, which showed solvent-dependent optical rotation. The obtained results not only exhibited changes in the values but also showed the variation in sign (- or +) with the different solvents studied. The change in optical rotation value was essentially attributed to the electron-donating property, which can be correlated to the donor number of the solvents. There are two types of hydrogen bonds, intramolecular (i.e., form within the structure) and intermolecular (i.e., form with external groups such as solvents). These hydrogen bonds are responsible for the value and sign variations, and 1H NMR experiments were used to further characterize them. The NMR data suggested that hydrogen bond formation is occurring between the Fmoc NH group vicinal to the chiral center and donor group of the corresponding solvent.

Computational exploration of compounds in Xylocarpus granatum as a potential inhibitor of Plasmodium berghei using docking, molecular dynamics, and DFT studies

Malaria remains a global health concern, with the emergence of resistance to the antimalarial drug atovaquone through cytochrome b (cyt b) being well-documented. This study was prompted by the presence of this mutation in cyt b to enable new drug candidates capable of overcoming drug resistance. Our objective was to identify potential drug candidates from compounds of Xylocarpus granatum by computationally assessing their interactions with Plasmodium berghei cyt b. Using computational methods, we modeled cyt b (GenBank: AF146076.1), identified the binding cavity, and analyzed the Ramachandran plot against cyt b. Additionally, we conducted drug-likeness and absorption, distribution, metabolism, excretion, and toxicity (ADMET) studies, along with density functional theory (DFT) analysis of the compounds. Molecular docking and molecular dynamics simulation (MDS) were used to evaluate the binding energy and stability of the cyt b-ligand complex. Notably, our investigation highlighted kaempferol as a promising compound due to its high binding energy of 7.67 kcal/mol among all X. granatum compounds, coupled with favorable pharmacological properties (ADMET) and antiprotozoal properties at Pa 0.345 > Pi 0.009 (PASS value). DFT analysis showed that kaempferol has an energy gap of 4.514 eV. MDS indicated that all tested ligands caused changes in bonding and affected the structural conformation of cyt b, as observed before MDS (0 ns) and after MDS (100 ns). The most notable differences were observed in the types of hydrogen bonds between 0 and 100 ns. Nevertheles, MDS results from a 100 ns simulation revealed consistent behavior for kaempferol across various parameters including root mean square deviation (RMSD), root mean square fluctuation (RMSF), radius of gyration (Rg), solvent-accessible surface area (SASA), molecular mechanics-Poisson Boltzmann surface area (MM-PBSA), and hydrogen bonds. The cyt b-kaempferol complex demonstrated favorable energy stability, as supported by the internal energy distribution values observed in principal component analysis (PCA), which closely resembled those of the atovaquone control. Additionally, trajectory stability analysis indicated structural stability, with a cumulative eigenvalue of 24.7 %. Dynamic cross-correlation matrix (DCCM) analysis revealed a positive correlation among catalytic cytochrome residues within the amino acid residues range 119–268. The results of our research indicate that the structure of kaempferol holds promise as a potential candidate against Plasmodium.

Novel base‐catalyzed acylation of benzenediols with vinyl acetate: a Hirshfeld surface study

AbstractBACKGROUNDThe present work describes the facile, fast and economic base‐catalyzed acylation of benzenediols with vinyl acetate. The Hirshfeld surface analysis of benzene‐1,4‐diol O,O′‐diacetate is also described. NaOH, KOH and K2CO3 were the bases used for the catalysis of the acylation of benzene‐1,x‐diols (x = 2, 3, 4) with vinyl acetate to obtain the corresponding O,O′‐diacetyl derivatives.RESULTSThe yields were quite good, up to 99% under solvent‐free conditions. This method represents an alternative ‘green’ process for the preparation of O‐acetyl derivatives of hydroxyaryls. The benzene‐1,4‐diol O,O′‐diacetate crystal structure was obtained and described using Hirshfeld surface analysis. A noticeable contribution of the C⋯H contacts is shown (16.7%), despite the insignificant area of the Hirshfeld surface occupied by the carbon atoms (9.4%). By using two‐dimensional fingerprint plots, it was proved that C⋯H contacts were due to the presence of π‐stacking. The O⋯H contacts (41.4%) were the most numerous ones, relating mainly to typical hydrogen bonds (de + di ≈ 2.6 Å). The high saturation of the C⋯H and O⋯H contacts (enrichment ratios (E) = 1.30 and 1.36, respectively), despite their smaller contribution to the overall surface as compared to the H⋯H contacts (E = 0.84), is shown.CONCLUSIONThe novelty of this work is the development of a method based on an inexpensive, safe and easy‐to‐use catalyst (K2CO3). This method is fast with high yields. Besides, it may be used for acylation at an industrial scale. © 2024 Society of Chemical Industry (SCI).

A polyurethane elastomer combining high strength and excellent self‐healing properties for waterproofing coatings

AbstractSelf‐healing materials have not been able to solve the problem of the coexistence of mechanical strength and self‐healing function. Despite years of research, high‐strength self‐healing materials still require external factors to accelerate their self‐healing process. For this reason, in this study, two kinds of chain extenders were inserted into the hard segment to design the molecular structure of polyurethane. The introduction of two chain extenders not only provided multiple binding modes for hydrogen bond recombination, but also formed more types of hydrogen bonds. Based on the design, a polyurethane elastomer PUGI‐D3B2 with high strength and excellent self‐healing properties was synthesized. Data such as FTIR and 1H NMR spectra clearly demonstrate the successful synthesis of PUGI‐D3B2. The mechanical strength of PUGI‐D3B2 is 15.34 MPa, and its surface scratches can completely disappear after self‐healing at 60°C for 10 h，and 98.02% of the mechanical strength is restored after 12 h of heal. Therefore, combining the excellent self‐healing properties of PUGI‐D3B2, we prepared a multifunctional superhydrophobic material (SHN‐SiO2/PUGI‐D3B2). It can be used in a wide range of applications such as waterproof coatings, biomedicine and flexible electronics, which provides a new idea for the future direction of multifunctional materials.

A monoclinic polymorph of chloro-thia-zide.

A new polymorph of the diuretic chloro-thia-zide, 6-chloro-1,1-dioxo-2H-1,2,4-benzo-thia-zine-7-sulfonamide, C7H6ClN3O4S2, is described. Crystallized from basic aqueous solution, this monoclinic polymorph is found to be less thermodynamically favoured than the known triclinic polymorph and to feature only N-H⋯O type inter-molecular hydrogen bonds as opposed to the N-H⋯O and N-H⋯N type hydrogen bonds found in the P1 form.

Fate of antibiotic resistance genes and EPS defence mechanisms during simultaneous denitrification and methanogenesis, coupled with the biodegradation of multiple antibiotics under zinc stress

High-strength nitrogen and antibiotics-containing wastewater can be efficiently eliminated by simultaneous denitrification and methanogenesis (SDM). Heavy metals and antibiotics are two critical factors that can lead to horizontal transfer of antibiotic resistance genes (ARGs), which can be simultaneously detected in wastewater. Unfortunately, the impacts of heavy metals on SDM and antibiotic biodegradation have not been fully elucidated. Herein, the effects of SDM and multiple antibiotics biodegradation, extracellular polymeric substances (EPSs) and protein response mechanisms, and ARG fate under Zn(II) stress were comprehensively evaluated. The results indicated that a high level of Zn(II) (≥5 mg/L) stress significantly decreased the degradation rate of multiple antibiotics and suppressed denitrification and methanogenesis. In addition, Zn(II) exposure prompted the liberation of proteins from microbes into the EPSs, and the combination of EPSs with small molecules quenched the original fluorescent components and destroyed the protein structure. The dominant proteins can bind to both Zn(II) and multiple antibiotics through several types of chemical interactions, including metallic and hydrogen bonds, hydrophobic interactions, and salt bridges, relieving the toxicity of harmful substances. Moreover, metagenomic sequencing revealed that the abundance of zinc resistance genes (Zn-RGs), ARGs (mainly tetracyclines), and mobile genetic elements (MGEs) increased under Zn(II) stress. Mantel test illustrated that the ARGs mecD, tetT, and tetB(60) were most affected by MGEs. Moreover, molecular network analysis revealed that several MGEs can bridge metal resistance genes (MRGs) and ARGs, facilitating the horizontal transfer of ARGs. This study provides theoretical guidance for the environmental risk control of antibiotics-containing wastewater treated by an SDM system.

3D-QSAR, molecular docking, ADMET, simulation dynamic, and retrosynthesis studies on new styrylquinolines derivatives against breast cancer

Abstract Breast cancer is the most common illness among women, accounting for 25% of all diagnoses, as stated by the American Cancer Society. Current research focuses on 43 compounds of styrylquinoline derivatives as potential inhibitors of tubulin to design a new drug that could potentially be effective against breast cancer cells in humans. The target compounds were subjected to a three-dimensional quantitative structure-activity relationship/comparative molecular similarity indices analysis (CoMSIA) approach, where CoMSIA models were used; the best results obtained are (Q 2 = 0.84, R 2 = 0.97, r ext 2 {r}_{\text{ext}}^{2} = 0.91), H-bond acceptor field was discovered to be important for increasing inhibitory activity by examining the contour maps (54%), and it plays a key role in the prediction of anticancer activity. Based on the contour maps of the CoMSIA models, we obtained information that allows us to propose four new molecules with higher cancer inhibitory than the 43 compounds found in the literature. The molecular docking was applied to determine the likely types of binding between the tubulin protein (PDB ID: 4O2B) and the proposed compounds, and the results show that M1 has a higher total score of 6.53 and two interactions with important conventional hydrogen bond type, followed by compound M2 with a total score of 5.74. Furthermore, the designed molecules showed better pharmacokinetic properties based on absorption, distribution, metabolism, excretion, and toxicity properties. Molecular dynamics simulations at 100 ns were conducted to confirm the binding stability of the selected ligands (M1 and M2) with tubulin protein. The simulation parameters used in the current study are root mean square deviation, root mean square fluctuation, H-bond, Rg, solvent accessible surface area, and binding energy. As a result, the designed compounds (ligands M1 and M2) have shown noteworthy potential as a drug candidate for experimental in vivo and in vitro testing due to their potential inhibition of breast cancer. Finally, the study of retrosynthesis in this work facilitates the synthesis of drug candidates.

Chemical analysis of Moringa oleifera (Moringaceae) seed oil and potentiation of antibiotic activity against standard and multidrug-resistant bacterial strains

Moringa oleifera (“moringa”) seeds are sources of fixed oil with a composition of fatty acids important for their biological properties. This work aimed to verify the fixed oil of seed, regarding chemical composition, antibacterial activity alone and in association with antibiotics against standard and multidrug resistant bacterial strains. In the chemical composition of the fixed oil, the unsaturated fatty acids (78.26 %) predominated in relation to saturated fatty acids (17.34 %). The palmitic acid (5.88 %), behenic acid (4.27 %), stearic acid (4.17 %) and oleic acid (74.15 %) were the main constituents. Physicalchemical analyzes for moisture, acidity, pH, relative density, peroxide index and refractive index indicated chemical quality of the oil. We performed docking calculation to prioritize low affinity major molecules present in the chemical composition. The docking result of the all compounds showed that highest binding energy type Hydrogen bond, water hydrogen bond and hydrophobic interaction. The fixed oil did not show antibacterial activity alone with a minimum inhibitory concentration (MIC ≥ 1024 μg/mL) for the analyzed bacterial strains. Synergistic effects were verified in the association of the fixed oil with gentamicin, ofloxacin and penicillin against multiresistant strains, with reductions in MICs.

Supramolecular assemblies of Zn(II) complex based on dithiolate-amine binary ligands: Synthesis, crystal structure, Hirshfeld surface, DFT, molecular docking, and anticancer studies

In this article, synthesis of the novel zinc(II) complex [Zn(tren)(i-mnt)] from diethylenetriamine (tren) and 1,1-dicyano-2,2-ethylenedithiolate di-potassium salt (K2i-mnt) has been presented and characterized by spectroscopic methods. The trigonal bipyramidal geometry of [Zn(tren)(i-mnt)] in solid state has been confirmed by X-ray diffraction analysis where stacked assembly of parallel chains interlinked by N–H⋯S, N–H⋯N, and C–H⋯N type hydrogen bonds observed in 3D supramolecular packing. Hirshfeld Surface (HS) optimizations show prominent N⋯H/H⋯N (32%), S⋯H/H⋯S (21%), and C⋯H/H⋯C (18.5%) interactions that well corroborate with X-ray data. Moreover, Density Functional Theory (DFT) at B3LYP/6-31 g(d) and LMKLL/DZDP basis sets have been used to ascertain geometry and long-range interactions in the complex. In addition, DNA-binding analysis has been assessed by inspecting its binding capability to calf-thymus DNA (CT DNA) and cytotoxic effects of the complex, and K2i-mnt were investigated against Dalton’s Lymphoma (DL) malignant cancer cells to assess their anticancer activity. The molecular docking study shows that the complex has a better binding affinity for 3DK8 (Protein Data Bank ID), leading to a higher inhibition constant and interactions.

Crystal structure of 1-(1,3-benzothiazol-2-yl)-3-(4-bromobenzoyl)thiourea

The chemical reaction of 4-bromobenzoylchloride and 2-aminothiazole in the presence of potassium thiocyanate yielded a white solid formulated as C15H10BrN3OS2, which consists of 4-bromobenzamido and 2-benzothiazolyl moieties connected by a thiourea group. The 4-bromobenzamido and 2-benzothiazolyl moieties are in a trans conformtion (sometimes also called s-trans due to the single bond) with respect to the N—C bond. The dihedral angle between the mean planes of the 4-bromophenyl and the 2-benzothiazolyl units is 10.45 (11)°. The thiourea moiety, —C—NH—C(=S) —NH— fragment forms a dihedral angle of 8.64 (12)° with the 4-bromophenyl ring and is almost coplanar with the 2-benzothiazolyl moiety, with a dihedral angle of 1.94 (11)°. The molecular structure is stabilized by intramolecular N—H...O hydrogen bonds, resulting in the formation of an S(6) ring. In the crystal, pairs of adjacent molecules interact via intermolecular hydrogen bonds of type C—H...N, C—H...S and N—H...S, resulting in molecular layers parallel to the ac plane.

Crystal structure, Hirshfeld surface analysis and photophysical properties of disubstituted 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dianiline

Two independent molecules of the crystal structure of the title compound C18H14N4S were found to occupy the asymmetric unit of the space group. The flanking 4-anilines were not coplanar with the central benzothiadiazole. In the crystal, two unique types of hydrogen bonds were found: i) one set between two NH2 of two molecules in the asymmetric unit and ii) another set between hydrogen atoms of the second aniline NH2 and the nitrogen atom of benzothiadiazole. The two-dimensional fingerprint plots along with the Hirshfeld surface confirmed the most important contributions for the crystal packing were C···H, H···H and N···H interactions. The compound was also solvatochromic with both its emission wavelength and quantum yield contingent on the solvent polarity. The fluorophore had a reversible oxidation. This was used to induce both a reversible color change from yellow to blue and emission off/on with an applied potential.

Features of the crystal structure and surface of superprotonic conductor caesium hydrogen sulfate phosphate.

The crystal structure of superprotonic conductor caesium hydrogen sulfate phosphate [Cs4(HSO4)3(H2PO4)] have been analyzed using neutron diffraction methods. Additionally, its structure and surface layers have been investigated using atomic force microscopy. From the diffraction data obtained, Fourier syntheses of neutron scattering densities were calculated, and the localization of hydrogen atoms and the parameters of three types of hydrogen bonds in the crystal structure were accurately determined. Correlation of surface characteristics of samples obtained by atomic force microscopy with their crystal structure is shown.

Chemical bonds and hair behaviour-A review.

When undertaking any review of the structure of the hair and its mechanical properties it becomes apparent that the overall behaviour of keratin fibres is commonly attributed to the presence of hydrogen, disulfide and ionic bonds. The action of physico-chemical agents used during various cosmetic treatments is viewed as the result of an interaction with these bonds. Thus, the breaking of bonds by chemical agents, or via mechanical or thermal stresses, affects the relative balance of disulfide and hydrogen bonds and the contribution of hydrophobic interactions, which are all important factors that may alter hair behaviour. Generally, these chemical bonds are considered as responding homogeneously to the environmental and cosmetic factors. This unitary image is challenged, however, by evaluating the results of chemical, nanomechanical, tensile and thermal measurements, which suggest that disulfide bonds may be grouped into several types, according to their location within the fibre and the way they respond to various agents. A compensatory effect of newly formed hydrogen bonds for broken disulfide bonds may also be seen, and additionally involves different types of hydrogen bonds. As a result, the picture of chemical bonding in hair appears to be far from a homogeneous one. In addition, it is apparent that further investigation is required for clarifying the action of ionic bonds and hydrophobic interactions within the hair fibre. The present review aims, thus, at offering a deeper background for understanding how the hair behaves under various conditions.