Intermolecular Hydrogen-bonding Interactions Research Articles

Oxygen-Stable Electrochemical CO2 Capture and Concentration with Quinones Using Alcohol Additives

Current methods for CO2 capture and concentration (CCC) are energy intensive due to their reliance on thermal cycles, which are intrinsically Carnot limited in efficiency. In contrast, electrochemically driven CCC (eCCC) can operate with much higher theoretical efficiencies. However, most reported systems are sensitive to O2, precluding their practical use. In order to achieve O2-stable eCCC, we pursued the development of molecular redox carriers with reduction potentials positive of the O2/O2- redox couple. Prior efforts to chemically modify redox carriers to operate at milder potentials resulted in diminished CO2 binding. To overcome these limitations, we used common alcohol additives to anodically shift the reduction potential of a quinone redox carrier, 2,3,5,6-tetrachloro-p-benzoquinone (TCQ), by up to 350 mV, conferring O2 stability. Intermolecular hydrogen-bonding interactions with the dianion and CO2-bound forms of TCQ were correlated to alcohol pKa to identify ethanol as the optimal additive, as it imparts beneficial changes to both the reduction potential and CO2-binding constant, the two key properties of eCCC redox carriers. We demonstrated a full cycle of eCCC in aerobic simulated flue gas using TCQ and ethanol, two commercially available compounds. Based on the system properties, an estimated minimum of 21 kJ/mol is required to concentrate CO2 from 10 to 100% or twice as efficient as state-of-the-art thermal amine capture systems and other reported redox carrier-based systems. Furthermore, this approach of using hydrogen-bond donor additives is general and can be used to tailor the redox properties of other quinone/alcohol combinations for specific CO2-capture applications.

N,N'-bis(2-bromobenzylidene)-2,2'-diaminodiphenyldisulfide (BBDD): Insights of crystal structure, DFT, QTAIM, PASS, ADMET and molecular docking studies

In the present research work, a single crystal of N, N'-bis(2-bromobenzylidene)-2,2′-diaminodiphenyl disulfide (BBDD) is analyzed by S-XRD and computational technique. The crystal structure of BBDD is greatly stabilized by strong C—H⋯Br, C—H⋯S, and C—H⋯H intermolecular hydrogen bond interactions. DFT computation is used to obtain a better understanding of molecular properties. Hirshfeld surfaces analysis and 2D fingerprint plots were used to investigate the unique supramolecular topology produced by diverse intra and intermolecular interactions. The crystal structure was optimized using B3LYP/6-311++G(d, p) basis set and the energy difference between HOMO and LUMO is 3.69 eV indicating the possibility of charge transfer in the BBDD compound. Molecular electrostatic potential (MEP) was plotted to understand the charge distribution. In addition, the 3D topology of the molecular packing is visualized through energy frameworks, reduced density gradient (RDG) analyses are obtained from the quantum theory of atoms in molecules (QTAIM) framework. PASS analysis of compound BBDD has been performed to analyze Pa and Pi values. ADME and toxicity of the compound was also predicted by using pkCSM online tool. Further, molecular docking study of title compound (BBDD) with glycosyltransferace protein (PDB ID:3HZS) of S. aureus which showed good binding score (-7.7 kcal/mol).

Structure-Dependent Nontraditional Intrinsic Fluorescence of Aliphatic Hyperbranched Polyureas.

The nontraditional intrinsic fluorescence (NTIF) of polymers containing heteroatoms has gained considerable attention due to its promising applications in label-free bioimaging. Aliphatic hyperbranched polyureas (aBPUs), which have recently shown great promise in the field of nanomedicine, bear controllable urea groups distributed on the branch points and thus are potential candidate luminogens. However, their NTIF properties and how their structures influence the NTIF properties have not been illustrated yet. Here, we addressed these issues by synthesizing a series of aBPUs with different degrees of branching (DBs) or different modifications. aBPUs exhibited an obvious NTIF phenomenon and with the increase of DBs, the NTIF enhanced as well. Chemical modifications either at the branching ends or in the interior of aBPUs could affect the NTIF performances, which were highly dependent on the types of modification. Disruption of the intra-/intermolecular hydrogen-bonding interactions decreased the NTIF. In addition, poly(ethylene glycol) (PEG)-modified aBPUs could self-assemble into nanospheres, and the formation of nanoassembly led to 89% enhancement on NTIF compared with the homogeneous solution of aBPUs-PEG in dimethylformamide (DMF). Finally, aBPUs-PEG nanoassembly demonstrated a capability in realizing label-free material imaging in vitro. These results shed light on the rational design of the polymer structures to achieve desired fluorescence with unconventional luminophores.

Influence of intermolecular hydrogen bond interaction on fluorescence mechanism for ESIPT characteristic o-Hydroxybenzaldehyde

The excited state intramolecular proton transfer (ESIPT) processes and fluorescence mechanisms of the o-hydroxybenzaldehyde (OHBA) and OHBA-MeOH have been investigated in cyclohexane and methanol solvents, by means of the density functional theory and time-dependent density functional theory. For OHBA, there is not enol form in the first excited state, by analysis of geometric structure and infrared vibrational spectra. The optimized potential energy curve indicates that OHBA can undergo a barrier-free ESIPT process. The molecular dynamics process demonstrates that OHBA has a 502 nm fluorescence. In OHBA-MeOH, the optimized geometric structure shows that OHBA-MeOH has enol form on the first excited state. There is a 0.252 kcal/mol energy barrier in the ESIPT process of OHBA-MeOH, by reason of intermolecular hydrogen bonded interaction. The excited state dynamic process indicates that forward and backward ESIPT reaction both can occur in OHBA-MeOH, the enol and keto forms can emit fluorescence. The calculated fluorescence wavelengths are 362 nm and 439 nm in OHBA-MeOH, respectively. These results indicate that the intermolecular hydrogen bond interaction can cause the energy barrier in the ESIPT potential energy curve, which further influence the fluorescence mechanism of OHBA. Our research work can provide the valuable theoretical reference for the design and application of fluorescent probe field.

A shape programmable MXene-based supermolecular nanocomposite film

Stimulus-responsive MXene films demonstrate extensive application scenarios, such as artificial muscles and biomedical devices. However, the shape deformation of such materials entails continuous stimulation, thus limiting their implementation in specific fields when temporary shapes have to be maintained without external stimuli. This work fabricates a kind of shape-programmable MXene-based supermolecular nanocomposite film by integrating MXene and polyvinyl alcohol. In this film, MXene provides extra intermolecular hydrogen bond interaction between polyvinyl alcohol and acts as cross-linking points in the nanocomposite, thus endowing this film with a good shape-fixing property. Furthermore, with the osmotic plasticization of water on the polyvinyl alcohol chains, the as-prepared nanocomposite film demonstrates excellent water-responsive shape-memory performance. This material cannot only overcome the inability of traditional stimulus-responsive MXene films to maintain temporary structures without continuous stimulation, but also expands potential applications in some fields including controlled release and intelligent bio-robots.

A comprehensive theoretical analysis on the intermolecular hydrogen bond interactions with the Lewis bases having multiple hydrogen bonding abilities

AbstractThis work comprehensively studies the intermolecular H … O and H … N hydrogen bonding (HB) interactions between 3H‐pyrrol‐3‐one as a computationally simple model Lewis base (LB) comprising two different basic centers (sp2 hybridized O and N atoms) and hydrogen halides (Hal‐H, Hal = F, Cl, Br, and I) as common Lewis acids (LAs). In an equimolar mixture of LB and any of LAs, the formation of H … O and H … N HBs can compete with each other over the course of binary (dimer) complexation processes. Computed values of counterpoise‐corrected interaction energies (CP‐IE) together with energy decomposition analysis (EDA) through symmetry‐adapted perturbation theory (SAPT) reveal that these HBs should be classified as “weak‐to‐medium” ones which are mainly dominated with electrostatic interactions. Among many explored correlation analyses, within the binary complexes formation, the values of CP‐IE are perfectly linearly correlated with those of electron density at the bond critical points of the mentioned HBs, , leading to two different regression equations as ‐ . These equations allow that an accurate prediction of the value of CP‐IE for H … O and H … N HBs is made feasible using the value of easily and rapidly computable without an explicit (direct) calculation of the so costly CP‐IE. Such equations, also, were used to accurately and individually predict CP‐IE values in ternary (trimer) complexes where both of approximately pairwise additive H … O and H … N HBs can be formed at once. Moreover, in terms of the calculated values of cooperativity energies, these two HBs make each other weaken portraying an anticooperativity in the ternary complexes studied.

Polyaniline spinel particles with ultrahigh-performance liquid chromatography tandem mass spectrometry for rapid vitamin B9 determination in rice.

Rice is an important crop that provides energy and nutrients to humans, which undergoes the aging process, the quality decline is related to the exogenous storage conditions and the change of own enzyme activity. However, due to the complex composition of rice and serious matrix interference, the ageing identification of rice is still challenging. Hence, a novel spinel particles ZnFe2O4@PANI was designed and synthesized for adsorption and determination of vitamin B9, which can be used to distinguish rice in different years and analyze the degree of aging. The ZnFe2O4@PANI showed large specific surface area and fast mass transfer rate with good linear correlation coefficient (R2=0.9965), satisfactory recoveries (85.1%-99.9%) and relative standard deviations (RSD, 9.3%). Moreover, the π-π electron-donor-acceptor (EDA) and intermolecular hydrogen-bonding interactions of polyaniline coating provided selective adsorption on vitamin B9. Adsorption thermodynamics study suggested that the adsorption reactions were spontaneous, endothermic and thermodynamically favorable. Finally, ZnFe2O4@PANI was used to evaluate vitamin B9 in rice from different years, which laid a theoretical foundation for exploring the relationship between vitamin changes and the aging degree of the rice.

Development and characterization of chitosan/guar gum active packaging containing walnut green husk extract and its application on fresh-cut apple preservation

The aim of this work was to develop active packaging film by using chitosan/guar gum (CG) film matrix and walnut green husk extract (WE), for preservation of fresh-cut apple. WE was used as cross-linking agent to improve physicochemical properties, and as active substances to enhance antioxidant activity of CG films. Fourier transform infrared spectroscopy and scanning electron microscopy results showed WE formed intermolecular hydrogen bond interactions with the film matrix, and microstructures of the film were more compact. With the increase of WE content (0–4 wt%), the mechanical properties of composite films were significantly enhanced, while permeability of water vapor and oxygen was significantly decreased (p < 0.05). When the amount of extract reached 4 wt%, the DPPH radical scavenging activity of composite film was significantly increased to 94.59%. CG-WE and CG films were used as active packaging materials to preserve fresh-cut apple. When stored at 4 °C for 10 days, CG-WE films showed better performance in reducing firmness, weight loss, total soluble solids and inhibiting browning and microbial growth of fresh-cut apples. Therefore, as a new type of active food packaging material, CG-WE films have good physical properties, and great potential in ensuring food quality and extending shelf life.

Decreasing the hygroscopicity of ammonium dinitramide (ADN) through cocrystallization

To decrease the hygroscopicity of ADN—a energetic oxidizer, this study developed a new cocrystal composed of ADN and 18C6 (18-crown-6) at a 1:1 ​M ratio through cocrystallization using the solvent evaporation method. The structure of the ADN/18C6 cocrystal, which has been confirmed using single X-ray diffraction (SXRD), indicates that the formation of this cocrystal is attributed to the strong intermolecular hydrogen bond interactions between ammonium ions and crown ether cycles. The ADN/18C6 cocrystal has a melting point of 151.5 ​°C, which is significantly higher than those of its respective components: 93.6 ​°C of ADN and 43.2 ​°C of 18C6. Notably, the ADN/18C6 cocrystal is nearly non-hygroscopic compared with ADN. The cocrystal's hygroscopicity rate is 0.9% when exposed to the air with relative humidity (RH) of 60% and a temperature of 30 ​°C for 12 ​h. By comparison, ADN's hygroscopicity rate is 18% under the same conditions. In addition, the impact sensitivity of the ADN/18C6 cocrystal is 18 ​J, which is substantially lower than that of raw ADN (2.5 ​J). These results show that cocrystallization offers an effective way to reduce the hygroscopicity of ADN.

Crystal structure, Hirshfeld surface and computational study of 1-(9,10-dioxo-9,10-di-hydroanthracen-1-yl)-3-propano-ylthio-urea.

The title compound, C18H14N2O3S, crystallizes in the ortho-rhom-bic crystal system and Pbca space group. The thio-urea chromophore is planar to an r.m.s deviation of 0.032 Å with the thiol-ate sulfur atom being the most deviated. Bifurcated N-H⋯O intra-molecular hydrogen bonds result in an S(6) supra-molecular synthon. In the crystal, mol-ecules are linked by N-H⋯O inter-molecular hydrogen-bonding inter-actions and stabilized by C-H⋯π and π-π inter-actions. Hirshfeld surface analysis and fingerprint plot indicate the H⋯H inter-molecular contacts as the highest contributor to the overall surface contacts (38%) and this is supported by the high dispersive and electrostatic inter-action energies.

Synthesis, characterization, and crystal structure of LnIII – (1E,2E)-3-(furan-2-yl)-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine

New neodymium (1a) and samarium (1 b) complexes with the general formula [LnIII(NO3)3(H2O)3 L]·L (1) were synthesized based on the previously reported ligand L (L = (1E,2E)-3-(furan-2-yl)-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine) which were investigated by X-ray analysis. Through X-ray studies, it was shown that the Schiff base L coordinates to LnIII via κN-bonding of one of the triazole ring nitrogen atoms as a monodentate ligand, three κ2 OO′-bonded nitrate ions and three κO-bonded water molecules completing the coordination sphere around the LnIII ion, resulting in a tenfold-coordinated LnNO9 unit in a distorted bicapped square antiprismatic geometry. The mononuclear complex units [Ln(NO3)3(H2O)3·L] are linked to the L molecule through intermolecular hydrogen-bonding interactions to form a 2 D polymeric supramolecular architecture. The complexes are neutral and paramagnetic mononuclear complexes, as determined by conductivity and magnetic investigations at room temperature, as well as findings from FT-IR and UV–vis spectroscopy. Finally, thermogravimetric measurements confirm the presence of three water molecules in the coordination sphere. In the visible region, the spectrum of the complex shows typical parity forbidden narrow 4f–4f absorptions originating from the 4 I 9/2 ground state to the various excited states of NdIII.

Fabrication of high-temperature aromatic polyamides with ultra-high breakdown strength via complex-assisted chain arrangement

• Highly orientated polyamides were prepared via complex-assisted chain arrangement. • The breakdown strength of the polyamide increased from 460 to 641 kV/mm. • Cross-linking enhanced breakdown strength to 706 and 572 kV/mm at 25 and 150 °C. • Breakdown strength of the cross-linked polymer is higher than that of commercial film. • The polymer films presented excellent mechanical properties and dimensional stability. Improving the breakdown strength ( Eb ) of high-performance polymer films is critical for their use as high-temperature insulation films. In this study, we demonstrated HCl can complex with the benzimidazole units of heterocyclic aramid polymers, temporarily suppressing the intermolecular hydrogen-bonding interactions. Moreover, the weak interchain interactions led to improved mobility and extended the conformation of the macromolecular chain. Therefore, after HCl decomplexation, the macromolecular chains presented higher orientations and degrees of order during subsequent high temperature annealing, resulting in an increase the Eb of the films from 460 to 641 kV/mm at 25 °C. The Fourier-transform infrared spectroscopy and theoretical calculation results indicated that the hydrogen-bonding interactions were restored and enhanced after HCl decomplexation via annealing. In addition, trace amounts of O 2 were used to catalyze the cross-linking reaction between phenyl groups based on the high electron density of the benzimidazole moieties. Owing to the chemical cross-linking reaction, the Eb of the films further increased to 706 and 572 kV/mm at 25 °C and 150 °C, respectively, whereas the tensile strength of the films reached 337.4 MPa.

Stable Metal–Halide Perovskite Colloids in Protic Ionic Liquid

Stable Metal–Halide Perovskite Colloids in Protic Ionic Liquid

Molecular Modeling Study on the Interaction Mechanism between the LRRK2 G2019S Mutant and Type I Inhibitors by Integrating Molecular Dynamics Simulation, Binding Free Energy Calculations, and Pharmacophore Modeling.

Leucine-rich repeat kinase 2 (LRRK2) has been reported in the pathogenesis of Parkinson's disease (PD). G2019S mutant is the most common pathogenic mutation in LRRK2-related PD patients. Inhibition of LRRK2 kinase activity is proposed to be a new therapeutic approach for PD treatment. Therefore, understanding the molecular basis of the interaction between LRRK2 and its inhibitors will be valuable for the discovery and design of LRRK2 inhibitors. However, the structure of human LRRK2 in complex with the inhibitor has not been determined, and the inhibitory mechanism underlying LRRK2 still needs to be further investigated. In this study, molecular dynamics (MD) simulation combined with the molecular mechanics generalized born surface area (MM-GBSA) binding free energy calculation and pharmacophore modeling methods was employed to explore the critical residues in LRRK2 for binding of inhibitors and to investigate the general structural features of the inhibitors with diverse scaffolds. The results from MD simulations suggest that the hinge region residues Glu1948 and Ala1950 play a significant role in maintaining the intermolecular hydrogen bond interaction with the G2019S LRRK2 protein and inhibitor. The strong hinge hydrogen bond with an occupancy rate of more than 95% represents the high activity of LRRK2 inhibitors, and the hydrogen bond interaction with the kinase catalytic loop region could compromise selectivity. Further pharmacophore modeling reveals that the high activity LRRK2 inhibitor should have one aromatic ring, one hydrogen bond acceptor, and one hydrogen bond donor. Hence, the obtained results can provide valuable information to understand the interactions of LRRK2 inhibitors at the atomic level that will be helpful in designing potent inhibitors of LRRK2.

Competitive hydrogen bonding induced phase separation in supramolecular comb-shaped diblock copolymer

In this study, a route to prepare nanostructure in miscible diblock copolymers by utilization of competitively intermolecular hydrogen-bonding interactions is demonstrated. Block copolymers poly(4-vinylpyridine-b-4-hydroxybutyl acrylate) (P4VP-b-P4HBA) with various block ratios were synthesized and they were demonstrated to be miscible due to the intramolecular hydrogen bonding. By combination of P4VP-b-P4HBA and 3-pentadecylphenol (PDP), the miscible block copolymer forms comb-shaped di-block copolymer complexes through the competition interactions between the hydroxyl groups of PDP (proton donors) and the nitrogen of the pyridine rings of the P4VP blocks (proton acceptors). Upon blending with PDP, we observed morphology change from sphere structure to cylindrical, and lamellar, in a manner strongly dependent on the P4HBA fraction. The microstructure of this special comb-shaped di-block copolymer shows a strong sensitivity to the temperature. The results from the in situ small angle X-ray scattering experiments have demonstrated that, even below the order-disorder temperature, the size of the phase domain decreases with increasing temperature due to decrease of the strength of the hydrogen bond upon heating.

In Situ Supramolecular Gel Formed by Cyclohexane Diamine with Aldehyde Derivative.

Low-molecular-weight gels have great potential for use in a variety of fields, including petrochemicals, healthcare, and tissue engineering. These supramolecular gels are frequently metastable, implying that their properties are kinetically controlled to some extent. Here, we report on the in situ supramolecular gel formation by mixing 1,3-cyclohexane diamine (1) and isocyanate derivative (2) without any catalysis at room temperature in various organic solvents. A mixture of building blocks 1 and 2 in various organic solvents, dichloromethane, tetrahydrofuran, chloroform, toluene, and 1,4-dioxane, resulted in the stable formation of supramolecular gel at room temperature within 60–100 s. This gel formation was caused by the generation of urea moieties, which allows for the formation of intermolecular hydrogen-bonding interactions via reactions 1 and 2. In situ supramolecular gels demonstrated a typical entangled fiber structure with a width of 600 nm and a length of several hundred μm. In addition, the supramolecular gels were thermally reversible by heating and cooling. The viscoelastic properties of supramolecular gels in strain and frequency sweets were enhanced by increasing the concentration of a mixed 1 and 2. Furthermore, the supramolecular gels displayed a thixotropic effect, indicating a thermally reversible gel.

Crystal structure and DNA cleavage properties of a vanadium complex [NH4][VO(O2)2(pm-im)]⋅3H2O containing 2-(1H-imidazol-2-yl)pyrimidine ligand

A new diperoxovanadium compound, [NH4][VO(O2)2(pm-im)]⋅3H2O (1) (pm-im = 2-(1H-imidazol-2-yl)pyrimidine), has been prepared from aqueous solution and its crystal structure has been determined by single-crystal X-ray diffraction. It belongs to the monoclinic P21/n space group with a = 6.798(4) Å, b = 11.468(6) Å, c = 18.073(9) Å, β = 96.020(6)°, V = 1401.3(13) Å3, and Z = 4. The asymmetric unit of 1 consists of a diperoxovanadium [VO(O2)2(pm-im)]− anion, one free NH4 + counterion, and three lattice water molecules, which are further stacked to form a three-dimensional (3D) supramolecular structure through intra- and intermolecular hydrogen bond interactions. The solution stability of the ion ([VO(O2)2(pm-im)]−) was explored using a combination of multinuclear (1H, 13C, and 51V) magnetic resonance and variable temperature NMR in a 0.15 mol L−1 NaCl/D2O solution that mimics physiological conditions. Additionally, the compound exhibits significant DNA cleavage ability under light, and the electrophoretic result shows that the super helix DNA seems to be directly cleaved into single stranded DNA.

Strong CPL-active liquid crystal materials induced by intermolecular hydrogen-bonding interaction and a chirality induction mechanism.

A novel co-assembly material can emit strong CPL signals (λem = 485 nm, glum = +0.076/-0.064) from an achiral AIE-active β-cyanostilbene (CYS) liquid crystal dye through intermolecular hydrogen bond (HB) interaction and chirality induction after a rapid cooling quench treatment.

Unveiling the crucial contributions of electrostatic and dispersion interactions to the ultralong room-temperature phosphorescence of H-bond crosslinked poly(vinyl alcohol) films.

Organic phosphors exhibiting room-temperature phosphorescence (RTP) in the amorphous phase are promising candidates for optoelectronic and biomedical applications. In particular, noncovalently embedding organic phosphors into a poly(vinyl alcohol) (PVA) matrix has emerged as the most commonly used yet effective approach to obtain amorphous organic RTP materials. While the role of intermolecular hydrogen-bonding interactions in determining the RTP properties of doping PVA systems has been well documented, we show that electrostatic and dispersion interactions contribute crucially to the ultralong RTP properties of doping PVA films. This impressive outcome reveals the nature of non-covalent interactions existing in doping PVA systems for the first time. We demonstrate this through detailed experimental and computational studies for a series of hydrogen-bond crosslinked PVA films where star-shaped organic phosphors containing active groups of carboxy, hydroxy, and amino act as multisite crosslinkers for the construction of extensive hydrogen-bonding networks. More importantly, we successfully obtain an ultralong RTP lifetime of up to 1.74 s by tuning the electrostatic and dispersion interactions between organic phosphors and the PVA matrix through simply modifying active groups of organic phosphors. This instructive work will provide new guiding principles for the exploration of amorphous organic RTP systems.

Synthesis, elucidation, DFT computations, Hirshfeld surface analysis and docking study of 6-chloro-3-[(4-fluoro-phenoxy)methyl][1, 2, 4]triazolo[4,3-b]pyridazine against fungi pathogen

Pyridazine and its derivatives are used in the agriculture field as molluscicidal, anti-feedant, insecticidal, herbicidal, plant growth regulators, and other agrochemical uses. In this article, the synthesis, structure elucidation, and docking study of the novel pyridazine derivative, 6-Chloro-3-[(4-fluorophenoxy)methyl][1, 2, 4]triazolo[4,3-b]pyridazine (4) is reported. The 3D structure of the compound was confirmed by single crystal X-ray structural analysis. In the structure, C-H…F and C-H…N type intermolecular hydrogen bond interactions are observed. To analyze and understand these intermolecular hydrogen bonds, Hirshfeld surface analysis was carried out. Further, 2D fingerprint plots reveal the percentage of the interactions of each type of contact within the structure. The density functional theory calculations were performed to compare the computational and experimental results. The frontier molecular orbitals (HOMO-LUMO) and molecular electrostatic potential (MEP) map of compound (4) were analyzed. Molecular docking studies of compound (4) were carried out against the fungus Fusarium oxysporum.