The title compound, C18H20ClN3S, is a functionalized triazoline-3-thione derivative. The benzene ring is almost perpendic-ular to the planar 1,2,4-triazole ring [maximum deviation = 0.007 (1) Å] with a dihedral angle of 89.61 (5)° between them and there is an adamantane substituent at the 3-position of the triazole-thione ring. In the crystal, N-H⋯S hydrogen-bonding inter-actions link the mol-ecules into chains extending along the c-axis direction. The crystal packing is further stabilized by weak C-H⋯π inter-actions that link adjacent chains into a two-dimensional structure in the bc plane. The crystal studied was an inversion twin with a 0.50 (3):0.50 (3) domain ratio.
The asymmetric unit of the title complex, [Pd(C15H13FNO)2], contains one half of the mol-ecule with the Pd(II) cation lying on an inversion centre and is coordinated by the bidentate Schiff base anion. The geometry around the cationic Pd(II) centre is distorted square planar, chelated by the imine N- and phenolate O-donor atoms of the two Schiff base ligands. The N- and O-donor atoms of the two ligands are mutually trans, with Pd-N and Pd-O bond lengths of 2.028 (2) and 1.9770 (18) Å, respectively. The fluoro-phenyl ring is tilted away from the coordination plane and makes a dihedral angle of 66.2 (2)° with the phenolate ring. In the crystal, mol-ecules are linked into chains along the [101] direction by weak C-H⋯O hydrogen bonds. Weak π-π inter-actions with centroid-centroid distances of 4.079 (2) Å stack the mol-ecules along c.
The title salt, C5H11N2S(+)·C7H4ClO2 (-), comprises a 2-amino-3-ethyl-4,5-di-hydro-1,3-thia-zol-3-ium cation in which the five-membered ring adopts an envelope conformation with the methyl-ene C adjacent to the S atom being the flap, and a planar 3-chloro-benzoate anion (r.m.s. deviation for the 10 non-H atoms = 0.021 Å). The most prominent feature of the crystal packing are N-H⋯O hydrogen bonds whereby the two amine H atoms bridge two carboxyl-ate O atoms resulting in the formation of a centrosymmetric 12-membered {⋯HNH⋯OCO}2 synthon involving two cations and two anions. These aggregates are linked by C-H⋯O inter-actions to form a supra-molecular chain along the a-axis direction.
The title aza-stilbene derivative, C14H13NO2 {systematic name: (E)-2-[(4-meth-oxy-benzyl-idene)amino]-phenol}, is a product of the condensation reaction between 4-meth-oxy-benzaldehyde and 2-amino-phenol. The mol-ecule adopts an E conformation with respect to the azomethine C=N bond and is almost planar, the dihedral angle between the two substituted benzene rings being 3.29 (4)°. The meth-oxy group is coplanar with the benzene ring to which it is attached, the Cmeth-yl-O-C-C torsion angle being -1.14 (12)°. There is an intra-molecular O-H⋯N hydrogen bond generating an S(5) ring motif. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming zigzag chains along [10-1]. The chains are linked via C-H⋯π inter-actions, forming a three-dimensional structure.
In the title compound, C25H26N2O2S2, the central CN2S2 atoms are almost coplanar (r.m.s. deviation = 0.0058 Å). One phenyl ring clearly lies to one side of the central plane, while the other is oriented in the plane but splayed. Despite the different relative orientations, the phenyl rings form similar dihedral angles of 64.90 (3) and 70.06 (3)° with the central plane, and 63.28 (4)° with each other. The benzene ring is twisted with respect to the central plane, forming a dihedral angle of 13.17 (7)°. The S2C=N, N-N and N-N=C bond lengths of 1.2919 (19), 1.4037 (17) and 1.2892 (19) Å, respectively, suggest limited conjugation over these atoms; the configuration about the N-N=C bond is E. An intra-molecular O-H⋯N hydrogen bond is noted. In the crystal, phen-yl-meth-oxy C-H⋯O and phen-yl-phenyl C-H⋯π inter-actions lead to supra-molecular double chains parallel to the b axis. These are connected into a layer via meth-yl-phenyl C-H⋯π inter-actions, and layers stack along the a axis, being connected by weak π-π inter-actions between phenyl rings [inter-centroid distance = 3.9915 (9) Å] so that a three-dimensional architecture ensues.
Multiple spectroscopic techniques, such as fluorescence, absorption, and circular dichroism along with in silico studies were used to characterize the binding of a potent inhibitor molecule, CCG1423 to the major transport protein, human serum albumin (HSA). Fluorescence and absorption spectroscopic results confirmed CCG1423-HSA complex formation. A strong binding affinity stabilized the CCG1423-HSA complex, as evident from the values of the binding constant (Ka = 1.35 × 106-5.43 × 105 M-1). The KSV values for CCG1423-HSA system were inversely correlated with temperature, suggesting the involvement of static quenching mechanism. Thermodynamic data anticipated that CCG1423-HSA complexation was mainly driven by hydrophobic and van der Waals forces as well as hydrogen bonds. In silico analysis also supported these results. Three-dimensional fluorescence and circular dichroism spectral analysis suggested microenvironmental perturbations around protein fluorophores and structural (secondary and tertiary) changes in the protein upon CCG1423 binding. CCG1423 binding to HSA also showed some protection against thermal denaturation. Site-specific marker-induced displacement results revealed CCG1423 binding to Sudlow's site I of HSA, which was also confirmed by the computational results. A few common ions were also found to interfere with the CCG1423-HSA interaction.
Complex dielectric permittivity measurements of propylene glycol (PG) in ethanol at various mole fractions were measured by using open-ended coaxial probe technique at different temperatures in the frequency range 0.02hydrogen bonding.
In the title salt, C14H18N2(2+) · 2C9H5N4O(-), the 1,1'-diethyl-4,4'-bipyridine-1,1'-diium dication lies across a centre of inversion in the space group P21/c. In the 1,1,3,3-tetracyano-2-ethoxypropenide anion, the two independent -C(CN)2 units are rotated, in conrotatory fashion, out of the plane of the central propenide unit, making dihedral angles with the central unit of 16.0(2) and 23.0(2)°. The ionic components are linked by C-H...N hydrogen bonds to form a complex sheet structure, within which each cation acts as a sixfold donor of hydrogen bonds and each anion acts as a threefold acceptor of hydrogen bonds.
Hydrogen bonds are crucial factors that stabilize a complex ribonucleic acid (RNA) molecule's three-dimensional (3D) structure. Minute conformational changes can result in variations in the hydrogen bond interactions in a particular structure. Furthermore, networks of hydrogen bonds, especially those found in tight clusters, may be important elements in structure stabilization or function and can therefore be regarded as potential tertiary motifs. In this paper, we describe a graph theoretical algorithm implemented as a web server that is able to search for unbroken networks of hydrogen-bonded base interactions and thus provide an accounting of such interactions in RNA 3D structures. This server, COGNAC (COnnection tables Graphs for Nucleic ACids), is also able to compare the hydrogen bond networks between two structures and from such annotations enable the mapping of atomic level differences that may have resulted from conformational changes due to mutations or binding events. The COGNAC server can be accessed at http://mfrlab.org/grafss/cognac.
Four pyrazole compounds, 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde (1), 5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde (2), 1-[5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone (3) and 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]propan-1-one (4), have been prepared by condensing chalcones with hydrazine hydrate in the presence of aliphatic acids, namely formic acid, acetic acid and propionic acid. The structures were characterized by X-ray single crystal structure determination. The dihedral angles formed between the pyrazole and the fluoro-substituted rings are 4.64(7)° in 1, 5.3(4)° in 2 and 4.89(6)° in 3. In 4, the corresponding angles for molecules A and molecules B are 10.53(10)° and 9.78(10)°, respectively.
A major component of RNA structure stabilization are the hydrogen bonded interactions between the base residues. The importance and biological relevance for large clusters of base interactions can be much more easily investigated when their occurrences have been systematically detected, catalogued and compared. In this paper, we describe the database InterRNA (INTERactions in RNA structures database-http://mfrlab.org/interrna/) that contains records of known RNA 3D motifs as well as records for clusters of bases that are interconnected by hydrogen bonds. The contents of the database were compiled from RNA structural annotations carried out by the NASSAM (http://mfrlab.org/grafss/nassam) and COGNAC (http://mfrlab.org/grafss/cognac) computer programs. An analysis of the database content and comparisons with the existing corpus of knowledge regarding RNA 3D motifs clearly show that InterRNA is able to provide an extension of the annotations for known motifs as well as able to provide novel interactions for further investigations.
In this study, the proton dynamics of hydrogen bonds for two forms of crystalline aspirin was investigated by the Born-Oppenheimer molecular dynamics (BOMD) method. Analysis of the geometrical parameters of hydrogen bonds using BOMD reveals significant differences in hydrogen bonding between the two crystalline forms of aspirin, Form I and Form II. Analysis of the trajectory for Form I shows spontaneous proton transfer in cyclic dimers, which is absent in Form II. Quantization of the O-H stretching modes allows a detailed discussion on the strength of hydrogen-bonding interactions. The focal point of our study is examination of the hydrogen bond characteristics in the crystal structure and clarification of the influence of hydrogen bonding on the presence of the two crystalline forms of aspirin. In the BOMD method, thermal motions were taken into account. Solving the Schrödinger equation for the snapshots of 2D proton potentials, extracted from MD, gives the best agreement with IR spectra. The character of medium-strong hydrogen bonds in Form I of aspirin was compared with that of weaker hydrogen bonds in aspirin Form II. Two proton minima are present in the potential function for the hydrogen bonds in Form I. The band contours, calculated by using one- and two-dimensional O-H quantization, reflect the differences in the hydrogen bond strengths between the two crystalline forms of aspirin, as well as the strong hydrogen bonding in the cyclic dimers of Form I and the medium-strong hydrogen bonding in Form II.
The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10-40wt%. The thermoplastics were melt-mixed and then hot pressed at 140°C for 10min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young's modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30wt% agar content have the highest tensile strength. Higher content of agar (40wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, etc.
The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications.
The title compound, 3,5,7-triaza-1-azoniatricyclo[3.3.1.1(3,7)]decane 2,4-dinitrophenolate monohydrate, C6H13N4+*C6H3N2O5-*H2O, the 1:1 hydrate adduct of hexamethylenetetramine (HMT) and 2,4-dinitrophenol, undergoes a temperature phase transition. In the room-temperature phase, the adduct crystallizes in the monoclinic P2(1)/m space group, whereas in the low-temperature phase, the adduct crystallizes in the triclinic P1 space group. This phase transition is reversible, with the transition temperature at 273 K, and the phase transition is governed by hydrogen bonds and weak interactions. In both these temperature-dependent polymorphs, the crystal structure is alternately layered with sheets of hexamethylenetetramine and sheets of dinitrophenol stacked along the c axis. The hexamethylenetetramine and dinitrophenol moieties are linked by intermolecular hydrogen bonds. The water molecule in the adduct plays an important role, forming O-H...O hydrogen bonds which, together with C-H...O hydrogen bonds, bridge the adducts into molecular ribbons. Extra hydrogen bonds and weak interactions exist for the low-temperature polymorph and these interconnect the molecular ribbons into a three-dimensional packing structure. Also in these two temperature-dependent polymorphs, dinitrophenol acts as a hydrogen-bond acceptor and HMT acts as a hydrogen-bond donor.
The aim of this work was to recover the cellulose fibers from EFB using low-transition-temperature-mixtures (LTTMs) as a green delignification approach. The hydrogen bonding of LTTMs observed in 1H NMR tends to disrupt the three-dimensional structure of lignin and further remove the lignin from EFB. Delignification process of EFB strands and EFB powder were performed using standard l-malic acid and cactus malic acid-LTTMs. The recovered cactus malic acid-LTTMs showed higher glucose concentration of 8.07 mg/mL than the recovered l-malic acid LTTMs (4.15 mg/mL). This implies that cactus malic acid-LTTMs had higher delignification efficiency which led to higher amount of cellulose hydrolyzed into glucose. The cactus malic acid-LTTMs-delignified EFB was the most feasible fibers for making paper due to its lowest kappa number of 69.84. The LTTMs-delignified EFB has great potential to be used for making specialty papers in pulp and paper industry.
Spectacular color change during a chemical reaction is always fascinating. A variety of chemosensors including Schiff bases have been reported for selective as well as sensitive recognition of ions. This review explains the use of Schiff bases as color changing agents in the detection of anions. This magic of colors is attributed to change in the electronic structure of the system during reaction. Schiff base chemosensors are easy to synthesize, inexpensive and can be used for visual sensing of different ions. Development of Schiff base chemosensors is commonly based on the interactions between polar groups of Schiff bases and ionic species and the process of charge transfer, electron transfer and hydrogen bonding between Schiff bases and ionic species cause the color of the resultant to be changed. Therefore, designing of simple Schiff base chemosensors which are capable of selective sensing of different anions has attracted considerable interest. In particular, naked eye sensing through color change is important and useful since it allows sensing of ions through color changes without using any instrumental technique.HighlightsNaked eye sensors are of much interest these days due to their visual detection properties rather employing complex instrumentation.Optical sensors are sensitive, selective, cost effective and robust.The magic of color change is fascinating factor in detection by these sensors.The color change may be attributed by interaction between anion and Schiff base by different mechanism i.e. electron transfer, charge transfer, hydrogen bonding, ICT etc.LOD data is an evidence of their great efficiency.
In the title isonicotinohydrazide hydrate, C14H12BrN3O2·H2O {systematic name: N'-[(1E)-1-(5-bromo-2-hy-droxy-phen-yl)ethyl-idene]pyridine-4-carbohydrazide monohydrate}, the central CN2O region of the organic mol-ecule is planar and the conformation about the imine-C=N bond is E. While an intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond is evident, the dihedral angle between the central residue and the benzene rings is 48.99 (9)°. Overall, the mol-ecule is twisted, as seen in the dihedral angle of 71.79 (6)° between the outer rings. In the crystal, hydrogen-bonding inter-actions, i.e. hydrazide-N-H⋯O(water), water-O-H⋯O(carbon-yl) and water-O-H⋯N(pyrid-yl), lead to supra-molecular ribbons along the a-axis direction. Connections between these, leading to a three-dimensional architecture, are mediated by Br⋯Br halogen bonding [3.5366 (3) Å], pyridyl-C-H⋯O(carbon-yl) as well as weak π-π inter-actions [inter-centroid separation between benzene rings = 3.9315 (12) Å]. The Hirshfeld surface analysis reveals the importance of hydrogen atoms in the supra-molecular connectivity as well as the influence of the Br⋯Br halogen bonding.
In the anion of the title salt hydrate, H5N2(+)·C7H5N2O4(-)·2H2O, the carboxyl-ate and nitro groups lie out of the plane of the benzene ring to which they are bound [dihedral angles = 18.80 (10) and 8.04 (9)°, respectively], and as these groups are conrotatory, the dihedral angle between them is 26.73 (15)°. An intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is noted. The main feature of the crystal packing is the formation of a supra-molecular chain along the b axis, with a zigzag topology, sustained by charge-assisted water-O-H⋯O(carboxyl-ate) hydrogen bonds and comprising alternating twelve-membered {⋯OCO⋯HOH}2 and eight-membered {⋯O⋯HOH}2 synthons. Each ammonium-N-H atom forms a charge-assisted hydrogen bond to a water mol-ecule and, in addition, one of these forms a hydrogen bond with a nitro-O atom. The amine-N-H atoms form hydrogen bonds to carboxyl-ate-O and water-O atoms, and the amine N atom accepts a hydrogen bond from an amino-H atom. The hydrogen bonds lead to a three-dimensional architecture. An analysis of the Hirshfeld surface highlights the major contribution of O⋯H/H⋯O hydrogen bonding to the overall surface, i.e. 46.8%, compared with H⋯H contacts (32.4%).