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Recent years have witnessed the rapid development of self‐healing and recyclable materials because they can extend the life of the material. For polysiloxane materials, exploring polysiloxanes with high‐strength and self‐healing properties remains a challenge. In this work, a high‐strength and self‐healing polysiloxane containing N‐acetyl‐L‐cysteine (NACL) side groups is prepared. The NACL is used to form strong hydrogen bonds to build a self‐healing network. Molecular simulations help explain the reasons and processes for the repair of modified polysiloxanes. On the one hand, the obtained modified polysiloxanes have good self‐healing properties. The self‐healing efficiency of modified polysiloxane can reach 96.9%. As the number of NACL increases, the tensile strength of the modified polysiloxane increases. For PMVS‐30%NACL, the tensile strength can reach 4.36 MPa, and the strain can reach 586%. On the other hand, modified polysiloxane has an apparent inhibitory effect on Staphylococcus aureus. With the increase in the number of NACL, the antibacterial effect of modified polysiloxane is more obvious. Furthermore, NACL is a bio‐based amino acid with excellent biocompatibility. This work expands the idea of designing and synthesizing high‐strength polysiloxanes with antibacterial properties. It has great potential in the field of polysiloxane antimicrobial coatings. [ABSTRACT FROM AUTHOR]

Ring‐opening transformations of donor‐acceptor (D‐A) cyclopropanes enable the rapid assembly of complex molecules. However, the enantioselective formation of chiral quaternary stereocenters using substrates bearing two different acceptors remains a challenge. Herein, we describe the first palladium‐catalyzed highly diastereo‐ and enantioselective (3+2) cycloaddition of vinyl cyclopropanes bearing two different electron‐withdrawing groups, a subset of D‐A cyclopropanes. The key to the success of this reaction is the remote stereoinduction through hydrogen bond from chiral ligands, which thereby addressed the aforementioned challenge. A variety of chiral five‐membered heterocycles were produced in good yields and with high stereoselectivity (up to 99 % yields, 99 : 1 er and >19 : 1 dr). In‐depth mechanistic investigations, including control experiments and theoretical calculations, revealed the origin of the stereoselectivity and the importance of H‐bonding in stereocontrol. [ABSTRACT FROM AUTHOR]

A non-peptide inhibitor that is metabolically stable, orally active and capable of crossing the blood–brain barrier has been a popular option for treating Alzheimer's disease (AD). To identify novel non-peptide inhibitors for AD drug development, a structure-based pharmacophore model (SBPM) was developed using the representative docked conformation of the recently discovered peptide inhibitor PGKLVYA in the potential binding site on the Aβ(17–42) protofibril. The best SBPM, consisting of two hydrophobic, one hydrogen bond donor, and one positive ionisable feature, was further validated using ligand pharmacophore mapping studies. The well-validated SBPM was then used as the 3D query in virtual screening to identify potential hits from the National Cancer Institute database. These hits were subsequently filtered by toxicity prediction and molecular docking, and their binding stabilities and affinities were validated by 20-ns molecular dynamics simulations and molecular mechanics Poisson–Boltzmann surface area analysis, respectively. Finally, two Hits (NSC35984 and NSC102747) were identified as potential leads, which exhibited higher binding stability and affinity towards Aβ compared with PGKVYA. Our results also suggest that these two Hits have the ability to prevent Aβ adopting toxic β-sheet structures, and can be easily synthesised and have structural novelty, indicating that they are promising candidates for treating AD. [ABSTRACT FROM AUTHOR]

Abstract: Two 2-D polymers, [Ln(bidc)(Ac)·H2O]n (Ln=Tb(1), Dy(2) H2bidc=benzimidazole-5,6-dicarboxylic acid, HAc=acetic acid), have been successfully synthesized under hydrothermal conditions at 150°C and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction. Single crystal X-ray diffraction analyses reveal that the two compounds are isomorphous and exhibit one new (4,4)-connected 2-nodal (44·62)(44·62) layer-like net, stabilized by the interchain hydrogen bonding N–H⋯O, O–H⋯O and π⋯π stacking interactions between two benzimidazole rings. 2-D layers are further connected by the interlayer O–H⋯O hydrogen-bonding interactions to form a 3-D supermoleculaer network. Moreover, the luminescent property of compound 1 and thermogravimetric analyses of the two complexes 1–2 are discussed in detail. [ABSTRACT FROM AUTHOR]

Various possible structures of adenine-uracil-formamide hydrogen-bond complexes were optimized at 6-311++G(d,p) level, and the binding energies of these complexes were also calculated at DFT B3LYP/6-311++G(d,p) level. Eight stable cyclic structures being involved in the interaction are found on the potential energy surface. By analyzing the structure, NPA charge and interaction energy of complexes, we obtain the most stable geometry structure. The results show that the interactions between formamide and adenine-uracil (A-U) base pair affect the stabilities of the base pairs. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [ABSTRACT FROM AUTHOR]

The effects of hydrogen bond interactions upon ionization potentials (IPs) and electron affinities (EAs) of adenine–formamide (AF) complexes have been investigated employing the density functional theory B3LYP. It is found that the hydrogen bond interactions between adenine and formamide play a more important role in the process of electron attachment than in the process of electron detachment. Meanwhile, the hydrogen bond interactions facilitate the adiabatical electron detachment and attachment but have different effects on the vertical electron detachment and attachment with different positions of formamide. Furthermore, when the complexes were dissociated to the free monomers, the processes AF- → A- + F and AF+ → A+ + F are energetically preferable for AF- and AF+, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen bonding of 1:1 complexes formed between formamide and formamide molecule has been completely investigated in the present study using density functional theory (DFT) method at varied basis set levels from 6-31G to 6-311++G(2d,2p). The large basis sets 6-311++G(d,p) and 6-311++G(2d,2p) have been employed to determine the equilibrium structure and vibrational frequencies of the interacting complexes. Five reasonable geometries on the potential energy hypersurface of formamide dimer system are considered with the global minimum, four of which are cyclic double-hydrogen bonded structure and one is one-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. Finally the solvent effects on the geometries of the formamide dimer have also been investigated using self-consistent reaction-field (SCRF) calculations at the B3LYP/6-311++G** level. The results indicate that the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers. [Copyright &y& Elsevier]

The hydrogen bonding complexes HO(H2O)n (n = 1-3) were completely investigated in the present study using DFT and MP2 methods at varied basis set levels from 6-31++G(d,p) to 6-311++(2d,2p). For n = 1 two, for n = 2 two, and for n = 3 five reasonable geometries are considered. The optimized geometric parameters and interaction energies for various complexes at different levels are estimated. The infrared spectrum frequencies and IR intensities of the most stable structures are reported. Finally, thermochemistry studies are also carried out. The results indicate that the formation and the number of hydrogen bonding have played an important role in the structures and relative stabilities of different complexes. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen bonding of the dimers of formylhalide has been completely investigated in the present study using density functional theory (DFT), HF and second-order Moller–Plesset Perturbation (MP2) methods with the 6-311++g(d,p) basis set. Four reasonable geometries on the potential energy hypersurface of the dimers of formylhalide system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers are estimated. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. [Copyright &y& Elsevier]

Abstract: In this work, we report a theoretical study on the discrimination of different chiral forms of hydrogen bonding complexes of lactic acid and hydrogen peroxide. Four complexes formed between two isolate chiral hydrogen peroxide (M and P) and two chiral lactic acid (R and S) molecules have been investigated by using DFT and MP2 theory at different basis set levels. All of them are cyclic double-hydrogen bonded structures. The optimized geometric parameters, interaction energies and chirodiastatic energy for various isomers at different levels are estimated. The infrared spectrum frequencies and IR intensities are reported, too. We found that the optical activity has no direct correction with the infrared spectrum. [Copyright &y& Elsevier]

Abstract: Density functional theory was used to study the hydrogen bonding between the dichlorine monoxide and the HO radical. The energetically low-lying minima is 1 (2A′), with hydrogen bonding occurring between the hydrogen atom in the HO radical and the oxygen atom in the dichlorine monoxide. Another hydrogen bond (structures five involving two hydrogen bonds) occurs between the chlorine atom in the dichlorine monoxide and hydrogen atom in the HO radical although it has one imaginary frequency. The optimized geometry parameters and interaction energies for various isomers were calculated at the B3LYP and MP2 levels. The infrared spectra and the vibrational frequency shifts are also reported. In order to discuss the interactional essence between molecules, we carry out nature bond orbit (NBO) analysis for the complexes at B3LYP/6-311++G** level. [Copyright &y& Elsevier]

The hydrogen bonding of 1:1 complexes formed between hydrogen peroxide and glycine molecule have been completely investigated in the present study using density functional theory method at varied basis set levels from 6-31g to 6-311++g(2d,2p). For comparison, we have also used the second-order Moller–Plesset Perturbation method at the 6-31+g(d,p) level. Five reasonable geometries on the potential energy hypersurface of hydrogen peroxide and glycine system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. [Copyright &y& Elsevier]

H2A.Bbd, the most divergent histone variant among all known H2A type histones, is involved in gene transcription, spermiogenesis, DNA replication and RNA splicing. Incorporation of H2A.Bbd-H2B dimer, a fundamental unit of H2A.Bbd nucleosome, modulate structures of nucleosome or chromatin, but the underlying mechanism remains elusive. Here we determined a crystal structure of H2A.Bbd-H2B dimer at 2.6 Å resolution. Although the H2A.Bbd-H2B dimer structure largely resembles that of H2A-H2B, substitution of H2A αC helix residues by H2A.Bbd counterparts lead to the transition of a long αC-helix to the short 3 10 -helix, likely owing to the rearrangement of the hydrogen-bond network. Moreover, structural comparison revealed a strikingly altered electrostatic potential surface for H2A.Bbd-H2B dimer displaying a diminished DNA binding capability. Our study provides the first high-resolution structure of histone variant H2A.Bbd and shed a light on biological function of H2A.Bbd. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen bonding of 1:1 complexes formed between formamide and serine molecules has been completely investigated in the present study using density functional theory (DFT) method at varied basis set levels from 6-31G to 6-311++G(d,p). Fifteen reasonable geometries on the potential energy hypersurface of formamide and serine system are considered with the global minimum, 13 of them are cyclic double-hydrogen bonded structures and the other two are one-hydrogen bonded structures. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. [Copyright &y& Elsevier]

Abstract: For the first time, the hydrogen bonding of 1:1 complexes formed between formamide and hydrogen peroxide molecule have been completely investigated in the present study using density functional theory (DFT), second-order Moller-Plesset Perturbation (MP2) and Hartree-Fock (SCF) method at varied basis set levels from 6-31g to 6-31++g(d,p). Five reasonable geometries on the potential energy hypersurface of formamide and hydrogen peroxide system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The relative stability order of the five structures is FH1>FH2>FH3>FH4≈FH5. The infrared spectrum frequencies, IR intensities and the vibrational frequency shifts are reported. Finally the solvent effects on the geometries of the formamide–hydrogen peroxide complexes have also been investigated using self-consistent reaction-field (SCRF) calculations at the B3LYP/6-31++g(d,p) level. The results indicate that the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers. In water, FH2 disappears and the relative stability order changes to FH3>FH1>FH5≈FH4 which is not in consistent with the gas phase one. [Copyright &y& Elsevier]

The discrimination of different chiral forms of ROOH (R=H, CH3) dimer have been investigated using DFT and MP2 methods at varied basis set levels from 6-31+g(d,p) to 6-31++g(2d,2p). The optimized geometric parameters, interaction energies and chirodiastatic energies for various isomers at different levels are estimated. To take into account water solvation effect, the polarized continuum model (PCM) method has been used to evaluate the ΔGsolv. The gas phase results show that the heterochiral six-membered ring dimer and homochiral five-membered ring dimer are the most stable ones for the two pair of chiral enantiomers. In polar solvent, the relative stability is reversed. [Copyright &y& Elsevier]

The hydrogen bonding of 1:1 complexes formed between diacetamide and methanol molecule have been completely investigated in the present study using density functional theory and second order Moller–Plesset perturbation (MP2) method. Various basis sets from 6-31G to 6-311++G** have been employed to determine the equilibrium structure of the interacting complexes. Three reasonable geometries on the potential energy hypersurface of diacetamide with methanol system are considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers at different levels are estimated showing that the two carbonyl groups have about the same proton acceptor ability. Special attention was paid to the basis set superposition error and zero-point energy corrections that were not given appropriate attention in previous studies. Finally, the solution phase studies are also carried out using the Onsager reaction field model at B3LYP/6-311++G** level for the hydrogen-bonded complex of diacetamide with methanol. The results indicate the polarity of the solvent has played an important role on the structures and relative stabilities of different isomers or the proton acceptor ability of two carbonyl groups. [Copyright &y& Elsevier]

The hydrogen bonding of 1:1 complexes formed between formamide and methanol has been investigated using DFT and MP2 methods at varied basis set levels from 6-31g to 6-31++g(2d, 2p). Five reasonable geometries are considered with the global minimum being a cyclic double-hydrogen bonded structure. The IR intensities and vibrational frequency shifts are reported. The solvent effects on the geometries of the complex have also been investigated using SCRF calculations at the B3LYP/6-31+g(d, p) level. The results indicate the polarity of the solvent has played an important role on the structures and the relative stabilities of different isomers. [Copyright &y& Elsevier]

The effects of hydrogen bonding, existing between hydroxyls of TSOS (trisilanolheptaphenyl POSS) molecules and carbonyls of PLLA chains, on the crystallization behaviors of PLLA have been detailedly investigated by DSC and temperature-programmed FTIR. The results of DSC scanning demonstrate that the recrystallization capability of quenched PLLA melts is remarkably enhanced in cold crystallization after introducing TSOS molecules due to the nucleating of TSOS molecules and hydrogen bonding interactins. In isothermal melt crystallization, TSOS molecules play a dual role of both inhibitors of crystallization because of hydrogen bonding interactions and nucleating agents resulting from aggregated TSOS molecules. Hydrogen bonding interaction between carbonyls of PLLA and hydroxyls of TSOS is determined by FTIR. Owing to the hydrogen bonding interaction in PLLA/TSOS nanocomposite, mobility and folding of PLLA chains are highly impeded, resulting in decrease of the overall crystallization rate in melt crystallization. The melt crystallization kinetics show that hydrogen bonding interaction plays a predominant role in determining the overall crystallization of PLLA. Besides, hydrogen bonding interactions in PLLA/TSOS blending system are further substantiated by a control experiment of PLLA/OVS blending system, where there is no existence of hydrogen bonding interaction. Because of high specific area of TSOS nano-filler, TSOS readily aggregates into POSS grains, which is detected by SEM and wide angle XRD. Image 1 • Hydrogen bonding developed between hydroxyls of TSOS molecules and carbonyls of PLLA in PLLA/TSOS hybrid blending systems. • Hydrogen-bonded TSOS molecules played a complex role in affecting crystallization behaviours of PLLA. • Hydrogen bonding interactions were detected by temperature-programmed FTIR and substantiated by a control experiment. • Dramatically nano-reinforcing of POSS molecules for PLLA//TSOS nanocomposites. [ABSTRACT FROM AUTHOR]

Studies are currently exploring strategies for development of recyclable materials that do not rely on petrochemical resources to alleviate increased environmental pollution. Polysiloxane is a non-toxic and non-hazardous polymeric material that is not produced from petrochemical resources, but has limited application due to its poor mechanical properties. In the present study, a novel supramolecular polysiloxane (SPSO) with excellent mechanical properties, exceptional reprocessing molding, and superior multiple recyclability was fabricated through incorporation of 2-ureido-4[1H]-pyrimidinone (UPy) into the main chains. The quadruple hydrogen bond interaction of UPy induces the aggregation of UPy, leading to phase separation and physical crosslinking in the SPSO. The rigid hard phase region acts as a reinforcing filler to further enhance the mechanical strength of the SPSO. The maximum tensile strength of the material was 7.28 MPa, which was significantly higher than that of traditional silicone rubber at 0.5 MPa. The mechanical properties of the SPSO retained 100% of the original properties even after three generations of recycling, indicating excellent multiple recyclability. The material exhibited excellent adhesive properties due to the high number of hydrogen bonds. The maximum adhesive strength of the SPSO to wood was 4.8 MPa. SPSO composite sponge was prepared by adding chopped carbon fiber reinforcement. The superhydrophobic SPSO composite sponge had a high water contact angle of 153°, indicating that it can be used for oil-water separation. The maximum separation efficiency of the material was 96%. A simple and versatile approach was used to introduce hydrogen bonds into the backbone of polysiloxane to form physical cross-links and enhance microphase separation. The findings from this study provide a basis for constructing polysiloxane materials with high recyclability and strong mechanical properties. High strength, transparent and recoverable SPSO is synthesized by the interaction of UPy multiple hydrogen bonds. As a hot-melt adhesive, it can achieve efficient adhesion to a variety of substrates. The mechanical strength is further improved by carbon fiber reinforcement of supramolecular polysiloxane resin. It is super hydrophobic after being made into a sponge, and further realizes efficient oil-water separation. [Display omitted] • The mechanical properties of SPSO did not change after multiple recycling. • SPSO had good bonding properties for a variety of interfaces. • The carbon fiber composite sponge has super hydrophobic properties that efficiently separate oil and water. [ABSTRACT FROM AUTHOR]

Abstract: Three one-dimensional zinc complexes, namely, [Zn(pzdc)·3H2O]·H2O (1), [Zn2(pzdc)2 ·4H2O]·2.5H2O (2), and [Zn(pzdc)(phen)·4H2O] n (3) (H2pzdc, pyrazine-2,3-dicarboxylic acid, phen=1,10-phenanthroline), have been synthesized successfully under hydrothermal condition. X-ray diffraction analyses reveal that complex 1 is a square-wave-like chain and complex 2 shows a 1D ladder-like infinite chain, while complex 3 has 1D zigzag chain structure. In all cases, the Zn(II) centers have octahedral coordination geometries. Through hydrogen bonding (such as O–H···O, O–H···N and C–H···O) and/or π–π stacking interactions, three-dimensional supramolecular networks are constructed in three complexes. Furthermore, the IR, TGA and luminescent properties are also investigated in this work. [Copyright &y& Elsevier]