Ag Interactions Research Articles

Interaction of polyphenols and Ag on the surface plasmon resonance absorption and resonance Rayleigh scattering spectra

Polyphenols are a kind of vital biologically active substances in fruits and vegetables. In this study, with the reductive ability in the alkaline solution, eight polyphenols[(-)-Epigallocatechin gallate (EGCG), (-)-Epigallocatechin (EGC), (-)-Epicatechin gallate (ECG), (-)-Epicatechin (EC), (-)-Gallocatechin gallate (GCG), (-)-Gallocatechin (GC), (+)-Catechin (C) and Gallic acid (GA)] could produce silver nanoparticles(AgNPs) with [Ag(NH3)2]+. It was found that the AgNPs had intense surface plasmon resonance bands at 415 nm and RRS spectra signals at 450 nm, which were linearly related to the concentration of polyphenols. It was used for the spectrophotometric and RRS spectra determination of the former eight polyphenols with low detection limits. The developed method was applied for the determination of polyphenols in tea and products.

A highly selective fluorescent chemosensor probe for detection of Fe3+ and Ag+ based on supramolecular assembly of cucurbit[10]uril with a pyrene derivative

A new fluorescent probe composed of cucurbit[10]uril (Q[10]) and a water-soluble derivative of pyrene, aminopropyl-1-pyrenebutanamide (PBA), is designated. 1H NMR spectroscopy reveals that PBA is encapsulated into Q[10] in an aqueous solution to form a stable 1:1 host-guest inclusion complex of PBA@Q[10]. This complex behaves as a highly selective fluorescence quenching probe for Fe3+ in aqueous solutions that may be attributed to the efficient absorption of Fe3+, which hindering absorption of PBA@Q[10] probe at the excitation wavelength of 332 nm, and competitive experiments for the coexistence of Fe3+ with one or all of the other metal ions (37 metal ions) reveals that the selectivity of PBA@Q[10] to Fe3+ is not disturbed by the addition of 50.0 equiv. of the other metal ions. The limits of detection of Fe3+ was determined to be 0.55 mM. Furthermore, the fluorescence enhancing effect of PBA@Q[10] for Ag+ is detected at the above wavelength. According to the mechanistic studies, the fluorescence enhancing route involves interaction of Ag+ ions with the probe, mainly under an internal charge transfer between Ag+ and the probe. Outcomes of this study suggest that PBA@Q[10] probably functions as a potential and promising fluorescence sensor for monitoring of different polluting metal ions in waste waters.

Thermal, morphostructural and spectrometric characterization of an antibacterial kaolinite-based filter modified with silver for water treatment

The aim of this work is to synthesize and characterize a new structured silver–clay dried, calcined or sintered at different temperatures composite by TG–DTA analysis, FTIR spectrometry analysis, XRD and Rietveld refinement, WD-XRF spectrometry, FEG–SEM images and EDS chemical analysis and to evaluate the antibacterial capacity of the new composite by the diffusion disk test against E. coli strains to attend water potability parameters. TG–DTA curves of Bco_dried suggested the presence of kaolinite, muscovite and hydrotalcite by the different events of structural water loss at different atmospheres. The interaction of Ag–clay might have occurred with hydrotalcite as can be inferred by the disappearance of the event at 408.9 °C (N2) and 433.4 °C (air). FTIR spectra showed that the modification occurred because of the changes that can be observed in the band range of (750 ≤ ν ≤ 1350) cm−1 for inner –OH and Si–O bonds. The Bco_dried composition was quantified by XRD and Rietveld refinement, and crystalline phases are quartz, calcite, kaolinite, hydrotalcite, muscovite, and portlandite. After sintering, the material presented the formation of new crystalline phases, due to the loss of structural water. When modified, the sample had no characteristic peaks of hydrotalcite, suggesting an interaction with Ag species. The compositions estimated for all samples by WD-XRF are mostly of Si, Al, Ca, K, Mg, Fe, Ti, and Ag. After modification, Ag increased significantly for Pca4_dried and Pca4_sint. SEM images presented the hexagonal characteristic of layered clay material and showed the interaction with Ag added. The susceptibility test showed that Pca4_dried has an antibacterial capacity against E. coli JM107 strains.

Rhodamine B associated Ag/r-GO nanocomposites as ultrasensitive fluorescent sensor for Hg2+

This work represents the designing of rhodamine B (RhB) based fluorescence sensors for detection of mercury (II) ion in aqueous media with low cost and efficient technique where silver nanoparticle decorated reduced graphene oxide (Ag/r-GO) nanocomposites act as a quencher. Transmission electron microscope (TEM) and scanning electron microscope (SEM) analysis of nanocomposites are carried out to investigate the structural properties. In this work, Ag/r-GO nanocomposite plays two important roles for sensing of Hg2+ ion i.e. (i) it interacts with Rhodamine B (RhB) through π–π interaction and dispersive interaction; (ii) it acts as adsorbent for Hg2+ ion. The fluorescence of RhB is quenched with addition of Ag/r-GO nanocomposites. After that the fluorescence spectra of quenched RhB is increased with addition of Hg2+ ion due to the soft–soft interaction, cationic–π interaction and interaction of Ag and Hg2+ ion in the nanocomposites. The present fluorescence approach shows very small limit of detection (LOD) of 2 nM at optimized pH and optimized contact time. The selectivity of the nanocomposites towards Hg2+ ion in water is carried out in the presence of other metal ions. The prepared Ag/r-GO@RhB nanocomposites can be applied in all real water samples for detection of mercury.

Bipyridyl/carbazolate silver(I) and gold(I) N‐heterocyclic carbene complexes: A systematic study of geometric constraints and electronic properties

A series of silver(I) and gold(I) carbene complexes of the type [M(L)(2,2′‐bipyridine)][PF6] (L = 1‐benzyl‐3‐(2‐pyridylmethyl)benzimidazolylidene; M = Ag (1); M = Au (3)) and [M(L)(carbazole)] (M = Ag (2); M = Au (4)) were synthesized and analyzed using a range of spectroscopic and crystallographic techniques. Inspection of the solid‐state structures of 1, 2 and 4 revealed a number of intermolecular noncovalent interactions. In the solid‐state structure adopted by 1, π–π and Ag–Ag interactions directed the complexes to orient in a head‐to‐tail fashion. The photophysical properties were found to be influenced by the ancillary ligands in solution as well as in the solid‐state. Calculations were performed to support the aforementioned structural and optoelectronic assignments.

Silver nanoparticle and Ag+-induced shifts of microbial communities in natural brackish waters: Are they more pronounced under oxic conditions than anoxic conditions?

With the burst of silver nanoparticles (AgNPs) applications, their potential entry into the environment has attracted increasing concern. To date, researches about the impacts of AgNPs on microbial communities have been scarcely conducted in the brackish waters. Here, the effects of interactions of AgNPs and Ag+ (as a positive control) with dissolved oxygen on natural brackish water microbial communities were investigated for 30 d. The introduction of AgNPs and Ag+ in natural brackish waters resulted in distinct bacterial community composition and structure as well as reduction of the richness and diversity, effects that were not eliminated completely during the tested periods. Anoxic conditions could attenuate the effects of AgNPs and Ag+ on the community, and dissolved oxygen made more contributions to community compositions for short-term exposure. High doses of AgNPs had more pronounced long-term impacts than Ag+ amendment. Compared with the controls, two general AgNP and Ag+ responses, namely, sensitivity and resistance, were observed. Sensitive species mainly included those of the genera Synechococcus and unclassified_f_Rhodobacteraceae, while resistant species mostly belonged to the phylum Bacteroidetes and participated in carbon metabolic processes. Our results indicated that the microbial communities that were involved in nutrient cycles (such as carbon, nitrogen, and sulfide) and photoautotrophic bacteria that contained bacteriochlorophyll were adversely affected by AgNPs and Ag+. In addition, dissolved oxygen could further change the microbial communities. These results implied that under different oxygen conditions AgNPs possibly resulted in varying microbial survival strategies and affected the biogeochemical cycling of nutrients in natural brackish waters.

Proximity Enforced Agostic Interactions Involving Closed-Shell Coinage Metal Ions.

A proximity enforcing diarylsilane ligand is reported, which gives rise to unusual Si-H···M interactions with the d10 metal ions Cu+ and Ag+ upon complexation. These interactions are studied in detail both experimentally and computationally and can be classified to be weakly agostic in nature for the Si-H···Cu interaction. The Si-H···Ag interaction has more signatures of an electrostatic contact.

Interaction of Ag+ with soil organic matter: Elucidating the formation of silver nanoparticles.

Naturally silver nanoparticles (AgNPs) have been widely observed in ore deposits, coal, natural water and soil environment. Identifying the source of these naturally AgNPs could be helpful for the elucidation of the geochemical cycle of Ag+ and AgNPs. This paper presents the formation of AgNPs by reducing Ag+ in the presence of soil organic matter (SOM) under various environmentally relevant conditions. The formation of AgNPs associated with various SOM (peat humic acid (PHA), peat fulvic acid (PFA), and commercial humic acids (HA-1 and HA-2)) was determined and compared. The physicochemical properties of the tested SOM were studied by electron paramagnetic resonance (EPR) and attenuated total reflection-infrared (ATR-FTIR) techniques. The formation of AgNPs depended on reductive reactions mediated by SOM. Other influential parameters that influenced the formation of AgNPs included concentrations of Ag+ and SOM and the reaction temperature on AgNPs. The produced AgNPs were characterized by transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The mean hydrodynamic diameters of AgNPs associated with PHA and PFA were in range from 2.5 to 15nm, which were smaller than that produced from HA-1 and HA-2 in the range from 20 to 120nm. Two different Ag states, i.e., Ag2O and Ag0 species, were observed by XPS technique. The results indicated that the formation of AgNPs depends largely on the types and the properties of natural organic matter. These findings have important implications for the fate of AgNPs under the soil environment.

Anion-directed assembly of three cationic silver(I) coordination polymers with bis(imidazolyl)-based linker: Structural characterization and anion exchange study

Three cationic silver(I) coordination polymers, namely {[Ag2(μ-bib)3](SO3CF3)2·(CH3CN)}n (1), {[Ag(μ-bib)](NO3)·(H2O)}n (2), and {[Ag(μ-bib)]BF4}n (3), have been prepared using flexible bis(imidazolyl)butane (bib) ligand and silver salts of different anions. All compounds are characterized by FT-IR, PXRD, elemental analysis, and single-crystal X-ray diffraction. Compound 1, containing triflate (SO3CF3−) anions, exhibits a two dimensional 63-hcb network with an amazing ABCDEF packing mode of the single hexagonal layers. Compound 2, containing nitrate ions, forms a simple one dimensional wavy chain, while compound 3 with BF4− anions, shows a double helix DNA-shaped structure stabilized by Ag⋯Ag interactions between the two strands. The anions in the structures 1–3 are non-coordinating and participate in weak H-bonding, while imidazolyl rings are involved in π⋯π stacking interactions. Anion exchange experiments in aqueous solution, monitored by FT-IR and PXRD analyses, reveal interesting structural transformations.

Transport properties of Ag decorated zigzag graphene nanoribbons as a function of temperature: a density functional based tight binding molecular dynamics study

The systemic study of the electronic transport (ET) properties of transition metal (TM) functionalized graphene was done with the aid of self-consistent charge density functional based tight binding (DFTB) method. Results show that among the TM considered, Silver metal adsorbed in the surface of graphene and its lower dimensional analogue zigzag graphene nanoribbon (ZGNR) can open its gapless bandstructure. This can be attributed to the breaking of bond and inversion symmetry. Further, the inherent effect of phonons (lattice vibrations) on the transport properties Ag-adsorbed ZGNR were investigated based on DFTB molecular dynamics (MD) simulation. Results show that excellent ET properties can be attributed to the Ag and ZGNR interaction. In addition, due to the unceasing lattice vibration of the Ag/ZGNR, the ET changes. Knowledge about the quantum of vibration at temperature T is quite important to elucidate its role governing the resulting ET. As the phonon having shorter wave length significantly increases at elevated temperatures, the corresponding forward bias voltage across the Ag/ZGNR increases. There is an increase in the conductance of vibrating Ag/ZGNR at elevated temperatures. A single-gated field effect transistor based on Ag-adsorbed ZGNR can act as a potential semiconductor for modern electronic applications.

Comparative Study of the Adsorption of Thiol and Isocyanide Molecules on a Silver Surface by in Situ Surface-Enhanced Raman Scattering

We report an investigation of the adsorption of thiol and isocyanide molecules on colloidal Ag nanocubes through surface-enhanced Raman scattering (SERS). Specifically, we collect SERS spectra in situ at different time points from a mixture of Ag nanocubes and ligand molecules at a specific concentration. We demonstrate that 4-nitrothiophenol could readily bind to the Ag surface through strong thiol–Ag interaction. We also observe red shifts for the SERS peaks as the concentration decreases, suggesting a change to the molecular orientation relative to the surface. Likewise, 4-aminothiophenol also adsorbs onto Ag quickly, but gives much weaker SERS signals relative to 4-nitrothiophenol because the electron-donating amine group would retard the chemical enhancement of SERS. Different from thiols, 1,4-phenylene diisocyanide binds to Ag surface through a relatively weak, σ-donation bond. With an increase in concentration, molecules tend to adsorb on the nanocubes with the benzene ring tilting away from the su...

Argentophilic Interactions in Two AgI Complexes of 3-(2-(Pyridin-4-yl)ethyl)pentane-2,4-dione, a Promising Ditopic Ligand

Reactions of 3-(2-(pyridin-4-yl)ethyl)pentane-2,4-dione (HacacPyen) with AgPF6 and AgBF4 afforded cationic silver complexes [Ag(HacacPyen)2]+ with essentially linear coordination of the Ag I cation by two pyridine N atoms. Rather unexpectedly, the HacacPyen ligands in the PF6- salt 1 adopt the diketo form, in contrast to the uncoordinated HacacPyen molecule, whereas the corresponding BF4- salt 2 and the majority of 3-substituted acetylacetones crystallizes as the enol tautomer. In both compounds 1 and 2, complex cations aggregate via short Ag...Ag interactions to pairs. These contacts amount to 3 . 21 Å in 1 and 3 . 26 Å or 3 . 31 Å in 2. As they are unsupported by any additional bridging ligands and correspond to the closest interionic interactions between neighbouring complex cations, they may be addressed as argentophilic interactions. The PF6- anions in 1 and the BF4- counter ions in 2 are involved in long and presumably electrostatic Ag...F contacts of ca. 2 . 9 Å. Additional coordination between Ag I and keto O atoms of symmetry-equivalent ligands occurs in 1 and leads to an extended two-periodic supramolecular structure.

Systematic Design of Crystal Structure for Hofmann-Like Spin Crossover Fe(L)2[Ag(CN)2]2 Complexes

The synthesis, crystal structures, and magnetic properties of a new two-dimensional (2D) Hofmann-like series, FeII(L)2[AgI(CN)2]2 (L = 3-cyano-4-methylpyridine (1), allyl isonicotinate (2), phenyl-isonicotinate (3), and benzyl nicotinate (4)) were studied. These compounds have a 2D sheet structure because of their strongly determinate self-assembly process. An octahedral FeII ion is coordinated with the nitrogen atoms of[AgI(CN)2 linear units at equatorial positions and monodentate pyridine derivatives at the axial position. The layers construct a parallel stacking array. Compounds 1–3 show pairs of layers constructed by intermetallic Ag···Ag interactions. Compound 4 shows a mono-layer structure. The substituent bulk of the ligands affects the interlayer space. Compounds 1–4 undergo a 100% spin transition. However, compound 1, incorporating a smaller group, has a relatively lower critical temperature (Tc = 182 K (1), Tc = 221 K (2), Tc = 227 (3) and Tc1 = 236 K, Tc2 = 215 K (4)). We investigated the correlations between our systematic crystal design, substituent size, and the spin crossover profiles.

Through-Space Spin Coupling in a Silver(II) Porphyrin Dimer upon Stepwise Oxidations: AgII ⋅⋅⋅AgII , AgII ⋅⋅⋅AgIII , and AgIII ⋅⋅⋅AgIII Metallophilic Interactions.

Metallophilic interactions between closed-shell metal ions are becoming a popular tool for a variety of applications related to high-end materials. Heavier d8 transition-metal ions are also considered to have a closed shell and can be involved in such interactions. There is no systematic investigation so far to estimate the structure and energy characteristics of metallophilic interactions in AgII /AgII (d9 /d9 ), AgIII /AgIII (d8 /d8 ), and mixed-valent AgII /AgIII (d9 /d8 ) complexes, which have been demonstrated in the present study. Both interporphyrinic and intermetallic interactions were investigated on stepwise oxidation by using a rigid ethene-bridged cis silver(II) porphyrin dimer and the results compared with those for highly flexible ethane-bridged analogues. By controlling the nature of chemical oxidants and their stoichiometry, both 1e and 2e oxidations were done stepwise to generate AgII /AgIII mixed-valent and AgIII /AgIII porphyrin dimers, respectively. Unlike all other ethene-bridged metalloporphyrin dimers reported earlier, in which 2e oxidation stabilizes only the trans form, such an oxidation of silver(II) porphyrin dimer stabilizes only the cis form because of the metallophilic interaction. Besides silver(II)⋅⋅⋅silver(II) interactions in cis silver(II) porphyrin dimer, stepwise oxidations also enabled us to achieve various hitherto-unknown silver(II)⋅⋅⋅silver(III) and silver(III)⋅⋅⋅silver(III) interactions, which thereby allow significant modulation of their structure and properties. The strength of Ag⋅⋅⋅Ag interaction follows the order AgII /AgII (d9 /d9 )<AgII /AgIII (d9 /d8 )<AgIII /AgIII (d8 /d8 ). Single-crystal XRD, X-ray photoelectron spectroscopy (XPS), 1 H NMR and EPR spectroscopy, and variable-temperature magnetic investigations revealed various oxidation states of silver and metallophilic interactions, which are also well supported by computational analysis.

Polyamic acid (PAA) immobilized on glassy carbon electrode (GCE) as an electrochemical platform for the sensing of tuberculosis (TB) antibodies and hydrogen peroxide determination

Tuberculosis (TB) is a chronic infectious disease that usually affects the pulmonary region of human beings. It remains critically important to develop cost effective methods for TB detection, especially since impoverished communities are often the target population. Immunological assays are commonly used for the detection of TB and are typically based on selected antibody (Ab) antigen (Ag) interactions as measured by the enzyme-linked immunosorbent assay (ELISA). It is also common to have tagged antibody/antigen binding pairs where the signaling is produced by the tag as is the case with the indirect tuberculosis IgG ELISA Kit, where a horseradish peroxidase (HRP) tag on the antibody is responsible for the analytical signal. Mycobacterium tuberculosis (MTB), recombinant protein antigen 85B (Ag85B), is the most abundant protein exposed by Mycobacterium tuberculosis acting as a potent immuno-protective antigen. In this work, both Ag85B and antibody-HRP (Ab-HRP) were immobilized on a semi-conductive polyamic acid (PAA) electrochemical interface towards the design of new electrochemical sensors. In a first approach, the antigen, Ag85B, was employed as the bioreceptor to afford label-free TB signaling through antibody detection and the obtained limit of detection was 8 μg/mL of antibody. The response was evaluated by voltammetric methods and electron impedance spectroscopy (EIS). Cyclic voltammetry (CV) and EIS were used to characterize the charge transfer and capacitive behavior of the label-free sensor. In a second approach, the HRP tagged antibody was used for the design of a stable hydrogen peroxide (H2O2) sensor with very good analytical performance with a limit of detection equal to 1.3 μM. Even though we developed an ultrasensitive H2O2 sensor, no further development of TB antigen detection was possible in this work.

Synthesis, crystal structure and studies on the interaction with albumin of a new silver(I) complex based on 2-(4-nitrobenzenesulfonamido)benzoic acid.

In the present work, the two-dimensional (2D) polymer poly[[μ4-2-(4-nitrobenzenesulfonamido)benzoato-κ4O1:O1:O1':N6]silver(I)] (AgL), [Ag(C13H9N2O6S)]n, was obtained from 2-(4-nitrobenzenesulfonamido)benzoic acid (HL), C13H10N2O6S. FT-IR, 1H and 13C{1H} NMR spectroscopic analyses were used to characterize both compounds. The crystal structures of HL and AgL were determined by single-crystal X-ray diffraction. In the structure of HL, O-H...O hydrogen bonds between neighbouring molecules result in the formation of dimers, while the silver(I) complex shows polymerization associated with the O atoms of three distinct deprotonated ligands (L-). Thus, the structure of the Ag complex can be considered as a coordination polymer consisting of a one-dimensional linear chain, constructed by carboxylate bridging groups, running parallel to the b axis. Neighbouring polymeric chains are further bridged by Ag-C monohapto contacts, resulting in a 2D framework. Fingerprint analysis of the Hirshfeld surfaces show that O...H/H...O hydrogen bonds are responsible for the most significant contacts in the crystal packing of HL and AgL, followed by the H...H and O...C/C...O interactions. The Ag...Ag, Ag...O/O...Ag and Ag...C/C...Ag interactions in the Hirshfeld surface represent 12.1% of the total interactions in the crystal packing. Studies of the interactions of the compounds with human serum albumin (HSA) indicated that both HL and AgL interact with HSA.

Facile Synthesis of a Polycatenane Compound Based on Ag-triazole Complexes and Phosphomolybdic Acid for the Catalytic Epoxidation of Olefins with Molecular Oxygen

A simple and efficient approach was developed for synthesizing a metal-organic polycatenated compound composed of Ag-triazole complexes and phosphomolybdic acid (PMA) clusters. The hybrid compound, namely {[Ag2(trz)2] [Ag24(trz)18]}[PMo12O40]2 (1) (trz = 1,2,4-triazole), showed high catalytic activity, selectivity and recyclability for the epoxidation of olefins with molecular oxygen as the oxidant and isobutyraldehyde as the co-reagent, and could even work well under ambient conditions. The special polycatenane framework, formed by interlocking [Ag24(trz)18]6+ nanocages, provides suitable space for filling the PMA clusters. The existence of multi-interactions, including π-π stacking, Ag-Ag interactions, and electrostatic interactions, should play a determinative role in fabricating the catalytically active and stable PMA-based polycatenane catalyst for aerobic epoxidation of olefins.

Mechanism of the Palladium-Catalyzed C(sp3)–H Arylation of Aliphatic Amines: Unraveling the Crucial Role of Silver(I) Additives

DFT calculations have been combined with experiments to study the mechanism of γ-C(sp3)–H arylation of aliphatic amines promoted by palladium–glyoxylic acid cooperative catalysis, with a focus on the role of silver(I) additives. Glyoxylic acid (the cocatalyst) uses its aldehyde functionality to react with the amine substrate to form an iminoacetic acid. This acid acts as a transient directing reagent and metathesizes with Pd(OAc)2 (the precatalyst) to give a Pd(II)–diiminoacetate five-membered chelate, which has been shown computationally as the catalyst resting state and which has been experimentally synthesized and characterized. C(sp3)–H activation from the Pd(II)–diiminoacetate complex or its mononuclear derivatives would face a high kinetic barrier (>30 kcal/mol) arising mainly from breaking a stable five-membered N,O-chelate ring. The crucial role of the silver(I) carboxylate additive is in reacting with the Pd(II)–diiminoacetate complex to provide a heterodimeric Pd(II)–Ag(I) complex supported by bridging chelators and intermetallic Pd–Ag interaction, which would lead to a C(sp3)–H activation transition state with a considerably lower barrier (∼25 kcal/mol). The Pd(II)–Ag(I) complex has been detected by mass spectrometry, which provides the first experimental evidence of a Pd–Ag-containing active species in Pd-catalyzed C–H activation reactions using Ag(I) additives. After C(sp3)–H activation, the reaction proceeds through oxidative addition of Pd(II) and reductive elimination from Pd(IV) completing C–C formation, followed by ligand exchange to regenerate the catalyst resting state and release the arylated iminoacetic acid which continues on hydrolysis to give the final amine product and regenerate the glyoxylic acid cocatalyst. The computational and experimental findings taken together provide new mechanistic insight into the broad range of palladium-catalyzed C–H activation reactions that use silver(I) additives.

Electronic properties of OH–CNT–Ag composite: a combined first-principles and experimental study

Carbon nanotube-based silver (CNT–Ag) composite has recently proved to be a sensing material due to the excellent electrical characteristics and is being considered as one of the promising sensing material candidates for flexible strain sensors. However, understanding the effect of interaction ways between Ag and CNT on conductivity is limited. Based on first-principles calculations, it was studied and compared that whether the presence of hydroxyl group affects the electronic properties of CNT–Ag for the first time. The results give an explanation for that the hydroxyl group increases the interaction of Ag and CNT, which makes conductivity better while silver clusters are often formed stably with even-number atoms. The corresponding experiment further demonstrates that silver nanoparticles (Ag NPs) are relatively dispersed uniformly and bind to CNT tightly in hydroxyl-functionalized CNT (OH–CNT). Meanwhile, the conductivity of the CNT–Ag composite improves by 95.81% with OH–CNT compared to that without OH–CNT, which confirms the calculated results. The present work provides a theoretical guide for preparing highly conductive CNT–Ag composite and would promote the application of functionalized CNT in the field of sensors’ sensing materials.

A 3D inorganic-organic hybrid constructed from Strandberg-type polyoxometalates and silver complexes: Synthesis, structure and properties

A 3D Strandberg-type polyoxometalate-based inorganic-organic hybrid, [Ag4(H3L)2(P2Mo5O23)]·H2O (1) (H2L = 2,6-dimethyl-3,5-bis(pyrazol-3-yl)pyridine), has been synthesized under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction, elemental analysis, IR, TG and powder X-ray diffraction. In compound 1, the adjacent [P2Mo5O23]6− clusters are linked by Ag1 into a 2D layer with left- and right-handed helical chains. And the layers are further linked together through organic ligands H2L and Ag⋯Ag interactions into a 3D framework with 1D channels extended along c axis. The luminescence, electrochemical properties and photocatalytic activities of compound 1 have also been investigated.