Extensive Hydrogen-bonding Interactions Research Articles

Multifunctional wearable Spider-Silk Inspired fabric for personal protection in extreme environments

Personal protective equipment (PPE) plays a vital role in healthcare, industry, and military settings, offering essential protection against various environmental hazards. However, the growing environmental challenges and demand for multifunctional integration make developing PPE that outperforms traditional single-function equipment a significant challenge. Herein, we present a flexible and wearable sandwich-structured film, fabricated by integrating an MXene core layer with Gd(OH)3/TPU outer layers through electrospinning and vacuum filtration process, simultaneously offering neutron and electromagnetic interference (EMI) shielding, energy harvesting, and thermal management. Mimicking spider silk's crystalline and amorphous regions, the outer layers integrate Gd(OH)3 nanorods into TPU nanofibers, thereby enhancing hydrogen bonding and achieving a high tensile strength of 22.94 MPa. Extensive hydrogen-bonding interactions firmly bind the MXene conductive core layer to the gadolinium-rich magnetic outer layers, providing excellent neutron (μ = 22.95 cm−1) and EMI shielding (SE = 35.1 dB). Additionally, the film also functions as a triboelectric nanogenerator (TENG), capturing kinetic energy to power low-voltage electronic devices, reducing reliance on external power in harsh settings. Remarkably, its superior Joule heating capability rapidly reaches various temperature (up to 78.5 ℃) by regulating external voltage to meet diverse user requirements. This study paves the way for future advancements in the realm of multifunctional PPE.

Multifunctional Flexible MXene/AgNW Composite Thin Film with Ultrahigh Conductivity Enabled by a Sandwich-Structured Assembly Strategy.

Flexible composite films have attracted considerable attention due to great potential for healthcare, telecommunication, and aerospace. However, it is still challenging to achieve high conductivity and multifunctional integration, mainly due to poorly designed composite structures of these films. Herein, a novel sandwich-structured assembly strategy is proposed to fabricate flexible composite thin films made of Ag nanowire (AgNW) core and MXene layers by combination of spray coating and vacuum filtration process. In this case, ultrathin MXene layers play crucial roles in constructing compact composite structures strongly anchored to substrate with extensive hydrogen-bonding interactions. The resultant sandwich-structured MXene/AgNW composite thin films (SMAFs) exhibit ultrahigh electrical conductivity (up to 27193 S cm-1 ), resulting in exceptional electromagnetic interference shielding effectiveness of 16223.3 dB cm2 g-1 and impressive Joule heating performance with rapid heating rate of 10.4°C s-1 . Moreover, the uniform SMAFs can also be facilely cut into kirigami-patterned interconnects, which indicate superior strain-insensitive conductance even after long-term exposure to extreme temperatures. The demonstrated strategy offers a significant paradigm to construct multifunctional composite thin films for next-generation integrated flexible electronics with practical applications.

Imparting Reprocessability, Quadruple Shape Memory, Self-Healing, and Vibration Damping Characteristics to a Thermosetting Poly(urethane-urea)

The advent of dynamic covalent bond chemistry (DCBC) has sparked renewed research interest in reprocessability of thermosetting polymers. However, combining reprocessability with stimuli-responsiveness remains a challenge for futuristic applications. Usually, a combination of complementary DCBCs is employed to integrate reprocessability with shape memory as well as self-healing (SH) attributes in a single polymeric system. In the present work, we report two-component poly(urethane-urea) (PUU) networks, with varied hard segment (HS) concentrations, that exhibit quadruple shape memory (QSM), efficacious vibration damping, thermally activated intrinsic SH as well as multiple cycles of thermal reprocessability. The component A is an isocyanate capped bi-soft segment blend of polybutadiene diol and polypropylene glycol, while the second component comprises an aromatic diamine chain extender solubilized in an oligomeric polyoxypropylene triol. The networks characterized through FTIR as well as small- and wide-angle X-ray scattering (SAXS and WAXD) revealed a phase-separated morphology with extensive hydrogen-bonding (H-bonding) interactions in the HS domains of the PUU networks. Dynamic mechanical analysis (DMA) measurements revealed broad dissipation factor (tan δ) vs temperature and frequency profiles of the networks, which could be leveraged for efficacious passive vibration damping applications. A dissociative mechanism of urethane and urea bond exchange, evidenced from temperature-dependent FTIR studies enabling facile stress relaxation, is proposed to be the mechanistic origin of the reprocessability and SH of the networks. A broad dissipation factor (tan δ) vs temperature profiles endowed the networks with QSM characteristics. We posit that the study is relevant for expanding the scope of DCBCs for development of reprocessable thermosetting polyurethanes with multiple smart functionalities.

Microsecond-long simulation reveals the molecular mechanism for the dual inhibition of falcipain-2 and falcipain-3 by antimalarial lead compounds.

The latest world malaria report revealed that human deaths caused by malaria are currently on the rise and presently stood at over 627,000 per year. In addition, more than 240 million people have the infection at any given time. These figures make malaria the topmost infectious disease and reiterate the need for continuous efforts for the development of novel chemotherapies. Malaria is an infectious disease caused majorly by the protozoan intracellular parasite Plasmodium falciparum and transmitted by mosquitoes. Reports abound on the central role of falcipains (cysteine protease enzymes) in the catabolism of hemoglobin for furnishing the plasmodium cells with amino acids that they require for development and survival in the hosts. Even though falcipains (FPs) have been validated as drug target molecules for the development of new antimalarial drugs, none of its inhibitory compounds have advanced beyond the early discovery stage. Therefore, there are renewed efforts to expand the collection of falcipain inhibitors. As a result, an interesting finding reported the discovery of a quinolinyl oxamide derivative (QOD) and an indole carboxamide derivative (ICD), with each compound demonstrating good potencies against the two essential FP subtypes 2 (FP-2) and 3 (FP-3). In this study, we utilized microsecond-scale molecular dynamics simulation computational method to investigate the interactions between FP-2 and FP-3 with the quinolinyl oxamide derivative and indole carboxamide derivative. The results revealed that quinolinyl oxamide derivative and indole carboxamide derivative bound tightly at the active site of both enzymes. Interestingly, despite belonging to different chemical scaffolds, they are coordinated by almost identical amino acid residues via extensive hydrogen bond interactions in both FP-2 and FP-3. Our report provided molecular insights into the interactions between FP-2 and FP-3 with quinolinyl oxamide derivative and indole carboxamide derivative, which we hope will pave the way towards the design of more potent and druglike inhibitors of these enzymes and will pave the way for their development to new antimalarial drugs.

Asymmetric multilayered MXene-AgNWs/cellulose nanofiber composite films with antibacterial properties for high-efficiency electromagnetic interference shielding

• Multilayer films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. • The effects of different conductive layers order and different number of layers on electromagnetic shielding performance were investigated. • Due to the excellent layered structure, the MXene-AgNWs/cellulose nanofiber composite film exhibits excellent EMI shielding capability at an ultra-thin thickness. • Benefiting from the properties of silver nanowires, the multifunctional shielding composite exhibits excellent antibacterial properties and better environmental adaptability. Flexible, lightweight, robust and versatile properties are essential for the next generation of wearable as well as intelligent electromagnetic interference (EMI) shielding materials. In this work, multilayered films containing cellulose nanofiber (CNF) layers, CNF/MXene layers, and CNF/silver nanowires (CNF/AgNWs) layers were fabricated by an efficient and easy-to-use vacuum filtration method. Compared with a uniformly mixed film, the resultant layered composite films that loaded with a low MXene and AgNWs content exhibit superior mechanical properties with a tensile strength of 137 MPa, a strain at break of 5.7%, excellent EMI shielding effectiveness (EMI SE) of 61.9 dB, and higher EMI SE/t of 20,653 dB cm −1 . This is attributed to the high-performance CNF substrate, the highly efficient layered structures, and extensive hydrogen-bonding interactions. In particular, a high degree of ohmic loss of multiple interfaces and polarization relaxation of local defects, as well as an abundance of terminal groups, favor the loss of electromagnetic waves (EMW) within the material. In addition, the prepared multifunctional layered composite films also show good antibacterial properties. As a result, the obtained new kind of flexible layered structure EMI shielding composite films with excellent EMI shielding performance, and mechanical properties present promising application prospects in the fields of EMI shielding and protection for aerospace, portable, and wearable flexible electronic devices.

Janus-inspired flexible cellulose nanofiber-assisted MXene/Silver nanowire papers with fascinating mechanical properties for efficient electromagnetic interference shielding

MXene-based nanocomposites are highly desirable for electromagnetic interference (EMI) shielding applications. However, it is crucial but challenging to obtain an excellent trade-off between mechanical properties and EMI performances. Herein, inspired by Janus structure, flexible cellulose nanofiber-assisted MXene/silver nanowires (CNF-MXene/AgNWs) papers (CMAPs) are developed by a scalable sequential self-assembly plus a hot-pressing strategy. The ingenious introduction of highly conductive AgNWs into MXene forms a complementary leaf-like nanostructure, synergistically constructing highly effective conductive frameworks. Contributed by the designed Janus architecture, high-performance CNF substrate, and extensive hydrogen-bonding interactions, the resultant Janus CMAPs (J-CMAPs) with a low MXene/AgNWs addition of 30 wt% possess a high electrical conductivity (1066.85 S/cm), excellent mechanical strength (224.04 MPa) and modulus (9.98 GPa), exceptional EMI shielding effectiveness of 43.65 dB, and record-high EMI SE/t of 16788.51 dB cm−1 and SSE/t of 10543.18 dB cm2 g−1 with a reflection-dominant shielding mechanism, successfully achieving an outstanding balance between mechanical properties and EMI shielding performances. More importantly, high frequency structure simulator (HFSS) simulation in the frequency domain is further conducted to intuitively comprehend the attenuation process of electromagnetic waves and shield mechanism, verifying fascinating EMI shielding performances. Besides, the Janus paper also presents desirable Joule heating performances at low input voltage, short response time (<10 s), and superb heating stability and long-term steady reliability. We believe that the J-CMAPs demonstrate the great potential and advantage for advanced EMI shielding and portable thermal management applications.

Geometric isomers of dichloridoiron(III) complexes of CTMC (5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradecane).

Both trans and cis iron-CTMC complexes, namely, trans-dichlorido[(5SR,7RS,12RS,14SR)-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradecane]iron(III) tetrachloridoferrate, [Fe(C14H32N4)Cl2][FeCl4] (1a), the analogous chloride methanol monosolvate, [Fe(C14H32N4)Cl2]Cl·CH3OH (1b), and cis-dichlorido[(5SR,7RS,12SR,14RS)-5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradecane]iron(III) chloride, [Fe(C14H32N4)Cl2]Cl (2), were successfully synthesized and structurally characterized using X-ray diffraction. The coordination geometry of the macrocycle is dependent on the stereoisomerism of CTMC. The packing of these complexes appears to be strongly influenced by extensive hydrogen-bonding interactions, which are in turn determined by the nature of the counter-anions (1a versus 1b) and/or the coordination geometry of the macrocycle (1a/1b versus 2). These observations are extended to related ferric cis- and trans-dichloro macrocyclic complexes.

The Chemistry of the Passivation Mechanism of Perovskite Films with Ionic Liquids

Passivation of perovskite films by ionic liquids (ILs) improves the performance (efficiency and stability) of perovskite solar cells (PSCs). However, the role of ILs in the passivation of perovskite films is not fully understood. Here, we report the reactions of commonly used ILs with the components of perovskites. The reaction of ILs with perovskite precursors (PbI2 and methylammonium iodide or formamidinium iodide) in a 1:1:1 molar ratio affords one-dimensional (1D) salts composed of the IL cation interspersed along infinite 1D polymeric [PbI3]-n chains. If the IL is applied in excess, the resulting crystal is composed of six cations surrounding a discrete [Pb3I12]6- cluster. All the isolated salts were unambiguously characterized by single-crystal X-ray diffraction analysis, which also reveals extensive hydrogen-bonding interactions.

5-Phenyl-3-(2-phosphono-eth-yl)-1,2,3-triazol-1-ium chloride.

The new triazole-functionalized phospho-nic acid 5-phenyl-3-(2-phosphono-eth-yl)-1,2,3-triazol-1-ium chloride, C10H13N3O3P+·Cl- (PTEPHCl), was synthesized by the 'click' reaction of the alkyl azide diethyl-(2-azido-eth-yl)phospho-nate with phenyl-acetyl-ene to give the dieth-yl[2-(4-phenyl-1H-1,2,3-triazol-1-yl)eth-yl]phospho-nate ester, which was then hydrolyzed under acidic conditions (HCl) to give the 'free' phospho-nic acid. The use of HCl for the hydrolysis caused protonation of the triazole ring, rendering the compound cationic, charged-balanced by a Cl- anion. There are extensive hydrogen-bonding inter-actions in the structure of PTEPHCl, involving the phospho-nic acid (-PO3H2) group, the triazolium ring and the Cl- anion.

Synthesis and Structural Characterization of New Ladder Organostannoxanes Derived from Sulfonic Acid Derivatives

Two new ladder n-dibutyltin(IV) compounds with general formulae [n-Bu₂Sn]₄(<i>μ₃</i>-O)₂(<i>μ₂</i>-OH)₂(OSO₂R)₂ with R=4-HO-C₆H₄-(1) and CH₃-(2) have been synthetized and characterized by elemental analysis, FT-IR, ¹H NMR and Mass spectroscopies techniques as well as single crystal X-ray diffraction study. The complex 1 crystallizes in the triclinic space group <i>P</i>1 with <i>a=</i>12.808 (8), <i>b</i>=15.391 (9), <i>c</i>=15.803 (10) Å, <i>α=</i>87.910 (5), <i>β=</i>66.650 (6), <i>γ=</i>80.283 (5)°, <i>V=</i>2817.6 (3) ų and <i>Z</i>=1. The crystal structure reveal them to be tetranuclear tin (IV) ladder-like structure containing two deprotonated ligands an three-rung-staircase Sn₄O₄ core. The structure is a centro-symmetric dimer of an oxoditin (IV) unit having a central four-member ring. In this complex, the central tin (IV) atoms are pentacoordinated, where the sulfonate base acts as monodentate ligands. Supramolecular architecture is formed by extensive hydrogen-bonding interactions, O-H…O.

Synthesis, structure, optical properties and Hirshfeld surface analysis of bis(azepanium) hexachlorostannate(IV)

The organic-inorganic hybrid material bis(azepanium) hexachlorostannate(IV) (BAHCS) has been synthesized from azepanium chloride at room temperature. The hybrid was characterized by IR, TG-DTA, UV-DRS and PL spectroscopy and single-crystal X-ray diffraction. The structure of the compound exhibited extensive hydrogen-bonding interactions among azepanium cation and SnCl6 2- anion. BVS of tin in BAHCS was calculated based on Sn-Cl bond distances obtained from X-ray structural analysis as 4.00, which is a formal oxidation state of 4+. This is the first report which established the formal oxidation state of tin in a hybrid material. The thermal analysis confirms the proposed formula of the compound.

Stabilization of Haloalkane Dehalogenase Structure by Interfacial Interaction with Ionic Liquids

Ionic liquids attracted interest as green alternatives to replace conventional organic solvents in protein stability studies. They can play an important role in the stabilization of enzymes such as haloalkane dehalogenases that are used for biodegradation of warfare agents and halogenated environmental pollutants. Three-dimensional crystals of haloalkane dehalogenase variant DhaA80 (T148L+G171Q+A172V+C176F) from Rhodococcus rhodochrous NCIMB 13064 were grown and soaked with the solutions of 2-hydroxyethylammonium acetate and 1-butyl-3-methylimidazolium methyl sulfate. The objective was to study the structural basis of the interactions between the ionic liquids and the protein. The diffraction data were collected for the 1.25 Å resolution for 2-hydroxyethylammonium acetate and 1.75 Å resolution for 1-butyl-3-methylimidazolium methyl sulfate. The structures were used for molecular dynamics simulations to study the interactions of DhaA80 with the ionic liquids. The findings provide coherent evidence that ionic liquids strengthen both the secondary and tertiary protein structure due to extensive hydrogen bond interactions.

VHTS and 3D-QSAR for the Identification of Novel Phyto-inhibitors of Farnesyltransferase: Validation of Ascorbic Acid inhibition of Farnesyltransferase in an Animal Model of Breast Cancer.

Farnesyltransferase (FTase) is a zinc enzyme that has been the subject of attention in anti-cancer research over the past. In this study, phytochemicals from Curcuma longa L., Taraxacum officinale, and Spondias mombin plants were screened for their inhibitory potentials on the human farnesyltransferase. A three-dimensional quantitative structure-activity relationship (3D-QSAR) model for the inhibition of farnesyltransferase was generated and the inhibition of farnesyltransferase by the hit, ascorbic acid was validated in an animal model of breast cancer. The lead compound, ascorbic acid makes extensive hydrogen bond interactions with key residues, lys-353, tyr-300, gly-290, leu-290 within the active site of farnesyltransferase. It downregulated the expression of FNTA mRNA in an animal model of breast cancer. The 3D-QSAR generated herein is robust, thoroughly validated, and should be employed in the pipelining of novel farnesyltransferase inhibitors. Ascorbic acid demonstrates its anticancer potentials through the inhibition of farnesyltransferase.

A Molecular Crystal Shows Multiple Correlated Magnetic and Ferroelectric Switchings

Simultaneous control of the magnetic and electric properties of materials is crucial for their application in next-generation memory and sensor devices. Herein, we report a single-crystal Co(II) co...

Development of a Highly Water-Soluble Lycopene Cyclodextrin Ternary Formulation by the Integrated Experimental and Modeling Techniques.

Lycopene, the aliphatic hydrocarbon carotenoid with abundant bioactivities, has instability, extremely poor water solubility, and low oral bioavailability. The study aimed to develop a highly water-soluble and practical lycopene formulation to improve the oral bioavailability and efficiency of lycopene. Environment-friendly hot-melt extrusion (HME) technique was applied to fabricate lycopene-cyclodextrin-polyethylene glycol 6000 (PEG 6000) ternary systems, which possessed highly aqueous solubility (897.665μgmL-1), almost 32-fold higher than that of the reported lycopene binary inclusion (27.1 ± 3.2μgmL-1). The dissolution rate was significantly accelerated compared to pure lycopene. The molecular mechanism was further investigated by the integrated experimental and modeling tools. Molecular dynamics (MD) simulation revealed lycopene molecule was wrapped within the aggregates of hydroxypropyl-beta-cyclodextrin (HP-β-CD) and PEG 6000 through extensive hydrogen bond interactions, which was experimentally validated by DSC, XRD, and FTIR spectrum analysis. The third component PEG 6000 facilitated the process of HME and augmented hydrogen bond interactions with HP-β-CD. Moreover, lycopene inclusions exhibited significant antitumor activity via inhibiting cell proliferation and inducing apoptosis. The pharmacokinetic studies showed the relative bioavailability of lycopene ternary preparation was up to 313.08% and the Cmax was 4.9-fold higher than that of the marketed tablet. In conclusion, the lycopene cyclodextrin ternary formulation developed by the modified HME techniques is suitable for industrial production, while PEG 6000 plays a vital part in the multicomponent systems to increase solubility, dissolution rate, and oral bioavailability of lycopene. The combination of experimental and computational tools is able to benefit the development of multicomponent formulations accurately and effectively.

Structures of the SARS-CoV-2 nucleocapsid and their perspectives for drug design.

COVID-19, caused by SARS-CoV-2, has resulted in severe and unprecedented economic and social disruptions in the world. Nucleocapsid (N) protein, which is the major structural component of the virion and is involved in viral replication, assembly and immune regulation, plays key roles in the viral life cycle. Here, we solved the crystal structures of the N- and C-terminal domains (N-NTD and N-CTD) of SARS-CoV-2 N protein, at 1.8 and 1.5Å resolution, respectively. Both structures show conserved features from other CoV N proteins. The binding sites targeted by small molecules against HCoV-OC43 and MERS-CoV, which inhibit viral infection by blocking the RNA-binding activity or normal oligomerization of N protein, are relatively conserved in our structure, indicating N protein is a promising drug target. In addition, certain areas of N-NTD and N-CTD display distinct charge distribution patterns in SARS-CoV-2, which may alter the RNA-binding modes. The specific antigenic characteristics are critical for developing specific immune-based rapid diagnostic tests. Our structural information can aid in the discovery and development of antiviral inhibitors against SARS-CoV-2 in the future.

N-N=N-N]-linked fused triazoles with π-π stacking and hydrogen bonds: Towards thermally stable, Insensitive, and highly energetic materials

It is the main task and challenge to reach a fine balance between high energy density and good molecular stability in energetic material research. In this study, two series of energetic compounds, 3-amino-7,7′-azo-[1,2,4] triazolo[4,3–b][1,2,4]triazole and 3,6-diamino-7,7′-azo-[1,2,4]triazolo[4,3–b][1,2,4] triazole featuring the N4 [N-N=N-N] linkage and fused triazoles, are presented. Their structures were determined by single crystal X-ray diffraction, elemental analysis, NMR, and IR spectroscopy. Their properties were studied in terms of density, thermal stability, detonation performance, and mechanical sensitivity. The N4 [N-N=N-N] linkages accord these compounds with high heat of formation, thus increasing the detonation performance. All fused triazoles exhibit planar structures, which result in low mechanical sensitivity. Through careful investigation of crystal data, strong π-π stacking and extensive hydrogen-bonding interactions were observed between molecules, which gives positive impact on mechanical sensitivity and thermal stability. The properties between different cations (or ions) were carefully studied. Quantum chemistry calculations were performed to investigate the potential relationship between structures and properties. Among them, compound 5 possesses high thermal stability (Td: 275 °C), good detonation performance (D: 8677 m s−1; P: 36.1 GPa), and excellent insensitivity (IS: 40 J; FS: 360 N), which makes it a balanced and promising energetic material.

Ultraflexible and Mechanically Strong Double-Layered Aramid Nanofiber-Ti3C2Tx MXene/Silver Nanowire Nanocomposite Papers for High-Performance Electromagnetic Interference Shielding.

High-performance electromagnetic interference (EMI) shielding materials with ultraflexibility, outstanding mechanical properties, and superior EMI shielding performances are highly desirable for modern integrated electronic and telecommunication systems in areas such as aerospace, military, artificial intelligence, and smart and wearable electronics. Herein, ultraflexible and mechanically strong aramid nanofiber-Ti3C2Tx MXene/silver nanowire (ANF-MXene/AgNW) nanocomposite papers with double-layered structures are fabricated via the facile two-step vacuum-assisted filtration followed by hot-pressing approach. The resultant double-layered nanocomposite papers with a low MXene/AgNW content of 20 wt % exhibit an excellent electrical conductivity of 922.0 S·cm-1, outstanding mechanical properties with a tensile strength of 235.9 MPa and fracture strain of 24.8%, superior EMI shielding effectiveness (EMI SE) of 48.1 dB, and high EMI SE/t of 10 688.9 dB·cm-1, benefiting from the highly efficient double-layered structures, high-performance ANF substrate, and extensive hydrogen-bonding interactions. Particularly, the nanocomposite papers show a maximum electrical conductivity of 3725.6 S·cm-1 and EMI SE of ∼80 dB at a MXene/AgNW content of 80 wt % with an absorption-dominant shielding mechanism owing to the massive ohmic losses in the highly conductive MXene/AgNW layer, multiple internal reflections between Ti3C2Tx MXene nanosheets and polarization relaxation of localized defects, and abundant terminal groups. Compared with the homogeneously blended ones, the double-layered nanocomposite papers possess greater advantages in electrical, mechanical, and EMI shielding performances. Moreover, the multifunctional double-layered nanocomposite papers exhibit excellent thermal management performances such as high Joule heating temperature at low supplied voltages, rapid response time, sufficient heating stability, and reliability. The results indicate that the double-layered nanocomposite papers have excellent potential for high-performance EMI shielding and thermal management applications in aerospace, military, artificial intelligence, and smart and wearable electronics.

Dinuclear cobalt and nickel complexes of a mercaptoacetic acid substituted 1,2,4-triazole ligand: syntheses, structures and urease inhibitory studies.

Because of its versatile coordination modes and strong coordination ability, the mercaptoacetic acid substituted 1,2,4-triazole 2-{[5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetic acid (H2L) was synthesized and characterized. Treatment of H2L with cobalt and nickel acetate afforded the dinuclear complexes {μ-3-[(carboxylatomethyl)sulfanyl]-5-(pyridin-2-yl)-4H-1,2,4-triazol-4-ido-κ2N1,N5:N2,O}bis[aqua(methanol-κO)cobalt(II)] methanol disolvate, [Co2(C9H6N4O2S)2(CH3OH)2(H2O)2]·2CH3OH (1), and {μ-3-[(carboxylatomethyl)sulfanyl]-5-(pyridin-2-yl)-4H-1,2,4-triazol-4-ido-κ2N1,N5:N2,O}bis[diaquanickel(II)] methanol disolvate dihydrate, [Ni2(C9H6N4O2S)2(H2O)4]·2CH3OH·2H2O (2), respectively. Complex 1 crystallized in the monoclinic space group P21/c, while 2 crystallized in the tetragonal space group I41/a. Single-crystal X-ray diffraction studies revealed that H2L is doubly deprotonated and acts as a tetradentate bridging ligand in complexes 1 and 2. For both of the obtained complexes, extensive hydrogen-bond interactions contribute to the formation of their three-dimensional supermolecular structures. Hirshfeld surface analysis was used to illustrate the intermolecular interactions. Additionally, the urease inhibitory activities of 1, 2 and H2L were investigated against jack bean urease, where the two complexes revealed strong urease inhibition activities.

Synthesis, structure, spectroscopy, thermal analysis and electron spin resonance of classical paddle–wheel binuclear and unusual polynuclear copper(II) compounds with benzoate and salicylamide

Two copper(II)benzoate compounds formulated in a fashion type of [Cux[RCOO]yLz] which are compound 1 or [Cu(C6H5COO)2(C6H5(OH)CONH2)]2 and compound 2 or [Cu(C6H5COO)(H2O)2]n·n(C6H5COO)·nH2O, {where (C6H5COO) = benzoate or (C6H5(OH)CONH2) = salicylamide}, have been successfully synthesized and characterized. Single crystal X-ray diffraction results confirmed the triclinic unit cell with a space group of P1¯ of the classical paddle–wheel binuclear compound 1 and the monoclinic unit cell with a space group of C2/c of polynuclear compound 2. Novel binuclear 1 has salicylamide as ancillary ligand and consists of a distorted square pyramidal [CuO4 + O] chromophore. Polynuclear 2 consists of the monomeric [Cu(C6H5CO)(H2O)2]n+ moiety which is furthered tribridged by coordinated ligands, generated the octahedral [CuO4 + O2] core and the polymeric [Cu(C6H5CO)(H2O)2]n+ chain. Compound 2 is stabilized by water and benzoate counter parts via CH⋯O and CH⋯π weak hydrogen bondings. The Fourier-Transform infrared spectrometer as well as the solid state ultraviolet visible spectra confirmed their components, geometries and weak interactions. The thermogravimetry analysis of compounds 1 and 2 started with the releasing of water molecules and were followed by the decompositions of the organic ligands. The thermograms also indicated the strong and extensive hydrogen bond interactions. The final thermal decomposition products were copper oxide. The electron spin resonance (ESR) spectra measured at room temperature illustrating the signals of triplet. The broader field ESR spectra of 2 than 1 are also noticed.