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In the title compound, C17H11Cl6NO4, the configuration of the cycloalkene skeleton is endo,cis. The benzene ring is twisted by 58.94 (8)° from the attached pyrrolidine ring. Two carbonyl groups play a key role in the crystal packing. A short intermolecular C...O distance of 3.017 (3) Å reveals that one carbonyl group is involved in dipole–dipole interactions, which link two adjacent enantiomers into an inversion dimer. Another carbonyl group provides an acceptor for the weak intermolecular C—H...O hydrogen bonds which link these dimers into layers parallel to (011).

In the present study, the experimental and theoretical methods were used to analyze the binding interaction of food dye, curcumin with trypsin. The results of fluorescence spectroscopic measurements indicated that curcumin binding resulted in the obviously intrinsic fluorescence quenching with the increase concentration of curcumin. This binding interaction is a spontaneous process with the estimated enthalpy and entropy changes being −15.70 kJ mol −1 and 40.25 J mol −1 K −1 , respectively. Hydrogen bonds and hydrophobic forces played an important role in the complex formation between curcumin and trypsin. Moreover, curcumin could enter into the primary substrate-binding pocket and makes the activity of trypsin decrease remarkably with the increasing concentration of curcumin. [ABSTRACT FROM AUTHOR]

Highlights: [•] Molecular modeling and multi-spectroscopic methods were used. [•] TBBPA bound to DNA by groove mode. [•] The hydrophobic and hydrogen bonding forces were involved in the binding process. [•] DNA binding changed the electron cloud of TBBPA. [ABSTRACT FROM AUTHOR]

Interactions of bisphenol S, a new bisphenol analogue with bovine serum albumin and calf thymus DNA were investigated using different spectroscopic methods and molecular modeling calculation. According to the analysis of experimental and theoretical data, we concluded that hydrophobic interactions and hydrogen bonding primarily mediated the binding processes of bisphenol S with bovine serum albumin and DNA. In addition, the electrostatic force should not be excluded. Molecular modeling studies indicated that the binding site of bisphenol S to bovine serum albumin located in the subdomain IB, while bisphenol S was a groove binder of DNA. In addition, BPS did not obviously induce second structural changes of bovine serum albumin, but it induced a conformational change of calf thymus DNA. [ABSTRACT FROM AUTHOR]

Decabrominateddiphenyl ether (deca-BDE) and tetrabromobisphenol A (TBBPA) are known as brominated flame-retardants, which are commonly found in the environment. The binding mechanisms of deca-BDE and TBBPA with human serum albumin (HSA) are still unknown. In this report, the interactions of deca-BDE and TBBPA with HSA were investigated using different spectroscopic methods and molecular modeling. The experimental results indicated the formation of complexes between deca-BDE/TBBPA and HSA with different affinity. These interactions affected the secondary structure of HSA. Thermodynamic investigations revealed that hydrophobic forces mainly drove the binding interactions of deca-BDE/TBBPA with HSA. For TBBPA, hydrogen-bonding interactions were also involved in the binding process of TBBPA with HSA. According to the analysis of experimental and theoretical data, we concluded that the binding site of deca-BDE to HSA located in the subdomain IB, while TBBPA was near to subdomain IIA and Trp-214. The binding interactions of deca-BDE and TBBPA with the most prominent carrier protein in the human circulatory system could influence mechanisms of their biochemical processes. Thus, these binding interactions can play central roles in studying the distribution and toxicity mechanisms of brominated flame-retardants. [ABSTRACT FROM AUTHOR]

Abstract: The interactions between human hemoglobin and orange I (or orange II) were investigated by UV/vis absorption, circular dichroism, fluorescence spectra techniques, and molecular modeling method. Orange I and orange II effectively quenched the intrinsic fluorescence of human hemoglobin by static quenching. The processes of the binding orange I and orange II on human hemoglobin were spontaneous molecular interaction procedure with hydrogen bonds, van der Waals force, hydrophobic and electrostatic interactions according to van’t Hoff equation and molecular modeling. There is a single class of binding site of orange I (orange II) in human hemoglobin and the molecular modeling study shows that orange I and orange II are dipped into α2 chain. The results of CD, synchronous fluorescence and three-dimensional fluorescence spectra indicated a small loss of α-helical secondary structure of human hemoglobin induced by orange I and orange II. [Copyright &y& Elsevier]

Two new supramolecular compounds, [(H4aobtc)0.5(H2O)0.5] (1) and [(H3aobtc)(H2bipy)0.5] (2) (H4aobtc = azoxybenzene-3,3′,4,4′-tetracarboxylic acid), were synthesized and characterized. Compound 1 has a complicated three-dimensional hydrogen bonding network with 4-connected {33.62.7} topology. Compound 2 also shows a three-dimensional supramolecular motif with hexagonal topology. The result indicated that hydrogen bonding interactions from different molecular synthons take important roles in the formation of supramolecular architectures. [ABSTRACT FROM PUBLISHER]

Abstract: Two novel polyoxotantalate derivatives, {[Cu(1,3-dap)2]2[Cu(1,3-dap)(H2O)]2[Ta6O19]}·8H2O (1) and [Cu(en)2]4[Ta6O19]·14H2O (2) (1,3-dap=1,3-diaminopropane, and en=ethylenediamine), which are constructed from the Lindqvist-type [Ta6O19]8− anion and copper–amine complexes, have been synthesized and characterized by elemental analyses, IR, XPS, TGA and single-crystal X-ray diffraction. In compound 1, each [Ta6O19]8− anion is bound to four copper fragments via the surface bridging oxygen atoms to form a neutral tetrasupported Lindqvist structure, which is further connected by water trimer via hydrogen-bonds to yield a one-dimensional (1D) supramolecular chain. In compound 2, the [Ta6O19]8− anions are linked together via the hydrogen bonds and Cu⋯O weak interaction to form an infinite 1D supramolecular chain, which is further connected to each other via hydrogen bonds with the cyclic water tetramer to yield a two-dimensional (2D) supramolecular network. [Copyright &y& Elsevier]

A polyoxoniobate, [Cu(en)2]4{[Nb6O19H2]K(H2O)5}2 ⋅ (H2en) ⋅ 17H2O (en = ethylenediamine) (1), has been synthesized and characterized by elemental analysis, IR, XPS, TGA, and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P1, with a = 12.3533(16) Å, b = 12.7188(16) Å, c = 29.626(4) Å, α = 93.235(2)°, β = 96.094(1)°, γ = 106.098(2)°, V = 4429.0(10) Å3, Z = 2. The polyoxoanion is composed of a Lindqvist-type [Nb6O19H2]6- dimer bi-bridged via two K+. K+ is 10-coordinate with 10 oxygens, three from one [Nb6O19H2]6-, one from a terminal oxygen of another [Nb6O19H2]6- moiety, and the other six from water molecule. Adjacent dimeric polyoxoanions are linked to form an infinite 1-D chain via O-H ··· O hydrogen-bonding interactions which exist between the two water trimers and the dimeric polyoxoanions. [ABSTRACT FROM AUTHOR]

The interactions of 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin were investigated by fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. The 2, 4-dinitrophenol and 2, 4-dichlorphenol effectively quenched the intrinsic fluorescence of trypsin via static quenching. The process of binding 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin was a spontaneous molecular interaction procedure. The electrostatic repulsion does favor the interaction between 2, 4-DNP and trypsin. However, the interaction of 2, 4-DCP and trypsin can be explained on the basis of hydrogen bonding and van der Waals. The results of synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra indicated that the structure of these trytophan and tyrosine residues environments were altered by 2, 4-DNP and 2, 4-DCP. [ABSTRACT FROM AUTHOR]

The article discusses the synthesis and characterization of novel optically active poly(urethane urea)s (PUU) with emphasis on the effect of left/right rotation conformation. It reports that the R/S helical PUU possess outstanding solvent resistance. The difference between the left-handed rotation structure and the right-handed rotation is attributed to the breaking of hydrogen bonds. It concludes that S-HPUU show optical activity, excellent thermal stability and network structures.

A series of thiosemicarbazone derivatives of benzo-15-crown-5 were synthesized efficiently at room temperature using hydrogenchloride acid (HCl) as catalyst. Their anion recognition properties of a, b and c were studied, the result show they exhibit highly selective binding and sensing of F-, MeCO2- and n-C3H7CO2- in CH3CN (F- > n-C3H7CO2- > MeCO2- > > Cl-, Br- and I-). Especially receptor c shows different UV-Vis spectrum of F- from MeCO2-and C3H7CO2-, in addition to the color of the solution change from colorless to yellow upon the addition of F-, these two points make it suitable to be used as colorimetric anion sensor to identify fluoride anion from other halide anions and carboxylate anions by naked-eye. The connection between receptor and anion is by hydrogen bonding interactions, the binding ratio is 1:1, which have been confirmed by UV-vis inspection spectra in CH3CN and 1HMR in DMSO-d6. [ABSTRACT FROM AUTHOR]

Three novel self-catenated 4-connected uninodal (65·8)-mok metal–organic rotaxane frameworks (MORFs) containing cucurbit[6]uril were constructed from the in situ trans/cis-configuration (1 : 1) of rotaxanes by taking advantage of a d10 metal ion directed synthesis. It was revealed that the effect of hydrogen bonds and π–π stacking interactions play significant roles in the self-assembly process. [ABSTRACT FROM AUTHOR]

In the title compound, C14H6O7, strong O—H⋯O hydrogen-bonding inter­actions between the mol­ecules result in a one-dimensional chain-like supramolecular structure. [ABSTRACT FROM AUTHOR]

In the title mol­ecule, C17H15N3O, the pyrazole ring makes dihedral angles of 22.0 (2) and 66.5 (3)° with the two phenyl rings. In the crystal structure, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into ribbons running along the a axis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Smart hydrogels prepared using anionic surfactant and anionic photoresponsive additive. • Hydrogels prepared based on hydrogen bonding and steric hindrance regulation strategy. • Hydrogels exhibit the stimulus-responsiveness of both NaDC and trans -NaOMCA. • Bridging hydrogen bonds between DC− and trans -OMCA− lead to their synergistic effect. • Release of model drug from the prepared hydrogels was triggered by external stimuli. Developing natural biosurfactant-based smart hydrogels with low-toxicity, biocompatibility and multi-stimulus-responsiveness is of great importance in fundamental and applied science. Based on the strategy of hydrogen bonding and steric hindrance regulation, multi-stimulus-responsive hydrogels were constructed using electrostatically repulsive sodium deoxycholate (NaDC) and sodium salt of trans -ortho-methoxycinnamic acid (trans -NaOMCA). The rheological and DLS techniques, TEM, optical microscopy, 1H NMR, FT-IR and UV–vis spectrometers were used to investigate the stimulus-responsiveness and the controlled release of model drug. Molecular dynamics (MD) simulations were performed to provide molecular insights into the effect of stimuli on self-assembly, type and number of hydrogen bonds, etc. This study provides a new method to construct multi-stimulus-responsive hydrogels using anionic surfactant and anionic photoresponsive additive. The NaDC/ trans -NaOMCA/H 2 O mixed system exhibits reversible pH- and CO 2 -responses. FT-IR and 1H NMR spectra results and MD simulations reveal that, the formation and breaking of bridging hydrogen bonds involving H 3 O+ (including the acid salt structures) play key roles in reversible sol ⇌ gel transition, and the bridging hydrogen bonds between DC− and trans -OMCA− lead to a synergistic effect during the formation of HAc- and CO 2 -induced hydrogels. In addition, the HAc-induced hydrogels are thermosensitive and photoresponsive, exhibiting the stimulus-responsiveness of both NaDC and trans -NaOMCA. The stimulus-responsive mechanism has been proposed. The investigation of the release of methylene blue from the prepared hydrogels will provide guidance for practical applications. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of divalent metal salts and 4,6-dipyridyl-2-aminopyrimidine ligands gave rise to three metal–organic coordination compounds: [ZnL1(OOCCH3)2] (1), [Co(L2)2(OH)2]·3H2O (2), and [Cu2(L2)2(OH)2(H2O)2](NO3)2·0.5H2O (3) [L1=4,6-bis(2-pyridyl)-2-aminopyrimidine; L2=4-(2-pyridyl)-6-(4-pyridyl)-2-aminopyrimidine] and their crystal structures were determined via single-crystal X-ray diffraction. In the three structures, L1 and L2 both exhibit terminal coordination mode. As the ligands contain both hydrogen bonding donors and acceptors, hydrogen bonding interactions play a crucial role in construction of supramolecular structures. In compound 1, the mono-nuclear complexes were connected to dimer structure by hydrogen bondings; in compound 2, dimer units were constructed through intermolecular hydrogen bondings and the crystallographic water molecules link the dimers into a 1-D supramolecular chain; and in compound 3, a complicated 3-D supramolecular architecture was formed via a series of hydrogen bondings. Moreover, the compounds 1–3 display room-temperature luminescent properties. [Copyright &y& Elsevier]

TiO 2 nanoparticles are the most widely used metal oxide nanoparticles and have oxidative toxicity. Catalase is an important antioxidant enzyme. Here the understanding of an effect of TiO 2 nanoparticles on the activity and structure of catalase is crucial to characterize the toxicity of TiO 2 nanoparticles. These experimental data revealed that TiO 2 nanoparticles could bind to catalase by the electrostatic and hydrogen bonding forces. On binding TiO 2 nanoparticles, catalase got destabilized with the decrease of α-helices content, the solvent polarity of environment around the fluorescence chromophores on catalase were also affected. In addition, TiO 2 nanoparticles also affected the activity of catalase. TiO 2 nanoparticles acted as an activator of catalase activity at a low molar concentration and as an inhibitor at a higher molar concentration. With regard to human health, the present study could provide a better understanding of the potential nanotoxicity of TiO 2 nanoparticles. [ABSTRACT FROM AUTHOR]

In the title compound, C16H17ClN2O4, all bond lengths and angles show normal values. The dihedral angle between the pyrazole ring and the benzene ring is 5.75 (8)°. The molecules are linked into a network by intermolecular C—Cl...π interactions. [ABSTRACT FROM AUTHOR]

Abstract: The binding interactions of lysozyme with 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were investigated by UV–vis absorption, CD, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. The binding constants, quenching mechanism, and the number of binding sites were determined by the quenching of lysozyme fluorescence in presence of chlorophenols. H-bonds and hydrophobic interactions played major roles in stabilizing the chlorophenols–lysozyme complex. The distances r between chlorophenols and lysozyme were calculated to be 1.94nm, 2.75nm, 3.54nm, and 3.76nm for 2-CP, 2,4-DCP, 2,4,6-TCP, and PCP, respectively. The effects of chlorophenols on the conformation of lysozyme were analyzed using CD, synchronous fluorescence and three-dimensional fluorescence spectra. [Copyright &y& Elsevier]

Abstract: By pH-value adjustment, the reactions of zinc salt, 1,3,5-benzenetricarboxylic acid (H3btc) and 4,4′-bipyridine (bpy) yield three coordination polymers, formulated as [Zn3(btc)2(bpy)(H2O)2] n (1), [Zn(Hbtc)(bpy)(H2O)] n ·3nH2O (2) and [Zn(Hbtc)(bpy)(H2O)] n ·4nH2O (3), respectively. The structure of 1 is a 3D network containing channels filled with bpy ligands. Compound 2 consists of twofold interpenetrating (10,3)-b networks, while compound 3 is a 2D layer structure. The fluorescent studies reveal that they exhibit intense violet luminescence in solid state. [Copyright &y& Elsevier]

The CO 2 /N 2 -triggered switchable sol–gel transition based on sodium deoxycholate (NaDC) and sodium chloride (NaCl) aqueous solutions has been investigated using both experiments and molecular dynamics (MD) simulations. The effects of CO 2 on the phase behavior, viscosity, pH, electrical conductivity, and microstructure of the NaDC/NaCl mixed system were explored. The mixed system exhibits a recycled CO 2 /N 2 response, and switching between solution state and gel state with six orders of magnitude variation in shear viscosity was achieved within a narrow pH range of 7.82–7.20. The FT-IR and 1H NMR spectra of the mixed system before and after CO 2 bubbling were measured. The experimental results indicate that NaDC is not directly protonated to deoxycholic acid by the small amount of CO 2 present; instead, an acid salt structure with a strong hydrogen bond, that is, [RCOOH⋯OOCR]−, is formed. MD simulation results reveal that, in the aqueous mixed NaDC/NaCl/CO 2 system, three types of bridging hydrogen bonds between two deoxycholate (DC−) anions and one H 3 O+ or HCO 3 − ion are key factors for the formation of hydrogels. These bridging hydrogen bonds promote the formation of DC− pairs bridged by H 3 O+ or HCO 3 − ions (including the acid salt structure) and are beneficial to the growth of micelles and formation of hydrogels. It is worth noting that the bridging hydrogen bond connected by HCO 3 − ions is an aspect of CO 2 -induced hydrogels that distinguishes them from acid-induced hydrogels. In addition, the results indicate that CO 2 and NaCl have a synergistic effect when inducing hydrogel formation. Based on experiments and MD simulations, a CO 2 /N 2 -switchable sol–gel transition mechanism for an aqueous mixed NaDC/NaCl system has been proposed. Unlabelled Image • CO 2 and NaCl have a synergistic effect on inducing the formation of hydrogels. • The acid salt structure [RCOOH⋯OOCR]− was verified by experiment and MD simulation. • The bridging hydrogen bonds connected by H 3 O+ or HCO 3 − ions play important roles. • Formation and breaking of the bridging hydrogen bonds cause sol⇌gel transition. [ABSTRACT FROM AUTHOR]

Herein, we report a simple and novel approach for the design of fluorescent chemosensor through the self-assembly of functionalized monomer molecules. According to these approach, a novel supramolecular fluorescent chemosensor (SPMS) was successfully constructed by self-assembly of a quinoline hydrazone functionalized pillar[5]arene monomer PM. Interestingly, upon the addition of CN−, the solution of SPMS instantly shows dramatic fluorescent enhancement and emitting bright blue emission. Meanwhile, the fluorescence quantum yields show distinct increase from 0.0582 of SPMS to 0.3952 of SPMS + CN−. The detection limit (LOD) of SPMS for CN− is 9.70 × 10−8 M, which indicated high sensitivity. Moreover, the SPMS is selective for CN− even in the presence of other anions, the fluorescent detection process of SPMS for CN− was not interfered by other competitive anions (F−, Cl−, Br−, I−, N 3 −, OH−, SCN−, HSO 4 −, AcO−, H 2 PO 4 − and ClO 4 −). Notably, in the CN− sensing process, the self-assembly structure of the supramolecular chemosensor SPMS didn't show any disassembly. This work provides a novel approach for instant detection of CN− through a self-assembled supramolecular fluorescent chemosensor in aqueous system. Moreover, the test strips based on SPMS were fabricated, which could serve as convenient and efficient CN− test kits. Herein, we report a novel supramolecular chemosensor SPMS was successfully constructed by self-assemble of a quinoline hydrazone functionalized pillar[5]arene in DMSO-H 2 O (water fraction 20%, v/v) binary solution. Interestingly, the SPMS could selectively and sensitively detect CN− through hydrogen bonds and ICT mechanism. Moreover, the test strips based on SPMS were fabricated, which could serve as convenient and efficient CN− test kits. Unlabelled Image • Fluorescent supramolecular chemosensor SPMS was constructed by assembly of PM. • The SPMS show sensitive fluorescent "turn-on" response for CN− (LOD = 9.70 × 10−8 M). • High selectivity, other competing anions could not influence the CN− detection process. • The SPMS could selectively and sensitively detect CN− through hydrogen bonds and ICT mechanism. • CN− detection test kits based on SPMS were prepared. [ABSTRACT FROM AUTHOR]

The title compound, [Zn(C10H12N2O)2(ClO4)2], crystallizes as mononuclear mol­ecules with distorted octa­hedral ZnII coordination. 3-Dimethyl­amino-l-(2-pyrid­yl)prop-2-enone ions are coordinated to ZnII as bidentate ligands, while the perchlorate ions are monodentate. The Zn atom lies on a centre of symmetry. [ABSTRACT FROM AUTHOR]