Tetrahedral Silver Research Articles

A novel BiOCl (110)/rGO/Ag3PO4 (111) heterostructure for efficient detoxification of 2,4-dichlorophenol

An effective method using nontoxic and efficient photocatalysts are crucial for wastewater treatment. Bismuth oxychloride (BiOCl) is considered as one of the valuable photocatalysts due to its unique layered plate like structure, however higher recombination and unsatisfied visible light absorption efficiency seriously affecting its applications. Addition of tetrahedral silver phosphate (Ag3PO4) which is known for its superior photocatalytic efficiency under visible light is believed to be the solution for the issue. Upon further adding of reduced graphene oxide (rGO) could form a bridging structure and enhance the activity. Considering the merits of these materials the BiOCl (110)/rGO/Ag3PO4 (111) heterojunction has been successfully constructed for 2,4-dichlorophenol (DCP) enhanced detoxification. The efficiency in degradation was found to be 94.8% by BiOCl/rGO/Ag3PO4 (k = 0.01879 min−1) that was greater to that of pure Ag3PO4 (∼1.9 times; k = 0.00818 min−1) and pure BiOCl (∼2.8 times; k = 0.00642 min−1) after 60 min of visible light irradiation. The mechanism of degradation was explained through the principle of heterojunction energy-band theory. Furthermore, 2,4-dichlorophenol (2,4-DCP) degradation products identification was carried out by ESI/LC-MS to propose the degradation pathway. Furthermore, the phytotoxicity of the intermediate products was investigated by estimating the germination index (GI) values on Phaseolus vulgaris (P. vulgaris) at different time intervals and the GI values were found to be 10.79% and 80.17% before and after degradation respectively. Thus, our results revealed that efficient and significant toxicity reduction was observed in this photodegradation.

Dithiophosphonate Anchored Heterometallic (Ag(I)/Fe(II)) Molecular Catalysts for Electrochemical Hydrogen Evolution Reaction.

The dichalcogenide ligated molecules in catalysis to produce molecular hydrogen through electroreduction of water are rarely explored. Here, a series of heterometallic [Ag4(S2PFc(OR)4] [where Fc = Fe(η5-C5H4)(η5-C5H5), R = Me, 1; Et, 2; nPr, 3; isoAmyl, 4] clusters were synthesized and characterized by IR, absorption spectroscopy, NMR (1H, 31P), and electrospray ionization mass spectrometry. The molecular structures of 1, 2, and 3 clusters were established by single-crystal X-ray crystallographic analysis. The structural elucidation shows that each triangular face of a tetrahedral silver(I) core is capped by a ferrocenyl dithiophosphonate ligand in a trimetallic triconnective (η3; μ2, μ1) pattern. A comparative electrocatalytic hydrogen evolution reaction of 1-5 (R = iPr, 5) was studied in order to demonstrate the potential of these clusters in water splitting activity. The experimental results reveal that catalytic performance decreases with increases in the length of the carbon chain and branching within the alkoxy (-OR) group of these clusters. Catalytic durability was found effective even after 8 h of a chronoamperometric stability test along with 1500 cycles of linear sweep voltammetry performance, and only 15 mV overpotential was increased at 5 mA/cm2 current density for cluster 1. A catalytic mechanism was proposed by applying density functional theory (DFT) on clusters 1 and 2 as a representative. Here, a μ1 coordinated S-site between Ag4 core and ligand was found a reaction center. The experimental results are also in good accordance with the DFT analysis.

A novel tetrahedral silver complex of (z)-o-methyl s-hydrogen tosylcarbonimidothioate: DFT supported crystallographic and spectroscopic study

This article aims to discuss the synthesis and DFT-experimental formulation of a tetrahedral silver complex of (z)-o-methyl s-hydrogen tosylcarbonimidothioate. Spectroscopic and other analytical data reveal that the ligand behaves as monobasic unidentate ligand and reacts with Ag(I) core in 1:1 ratio to give diamagnetic complex of the general composition [Ag(L)(PPh3)3], where LH denotes the ligand. The complex has been characterized using FT-IR, UV–Visible, mass spectral analyses and single X-ray crystallography in addition to other preliminary non-instrumental techniques. Also, the optimized framework of the proposed geometry has been confirmed from DFT calculations at LANL2DZ/B3LYP level of theory. The vibrational frequencies of the complex the corresponding normal modes were evaluated at the optimized geometry using the same basis sets followed by other required spectroscopic computation. From the results it is evident that the complex bears tetrahedral geometry with the tosyl ligand binding through S-anionic site.

Insertion of a Hydride Ion Into a Tetrasilver(I) Cluster Covered by S-Donating Rhodium(III) Metalloligands.

Here, we report a tetrahedral silver(I) cluster of {Ag4}4+ covered by Δ-[Rh(l-cys)3]3- (l-H2cys = l-cysteine), which is converted to an {Ag4H}3+ cluster via the inclusion of a H- ion. The 1:1 reaction of Δ-[Rh(l-cys)3]3- with Ag+ gave a sulfur-bridged AgI4RhIII4 octanuclear structure in [Ag4{Rh(l-cys)3}4]8- ([1]8-), in which a tetrahedral {Ag4}4+ core is bound by four Δ-[Rh(l-cys)3]3- units through thiolato groups. DFT calculations revealed that a superatomic orbital exists in {Ag4}4+ as the lowest unoccupied molecular orbital, contributing to the appearance of a characteristic charge-transfer transition in the visible region for [1]8-. Treatment of [1]8- with NaBH4 led to the insertion of a H- ion to generate [Ag4H{Rh(l-cys)3}4]9- ([2]9-) with an {Ag4H}3+ core, accompanied by the disappearance of the visible band for [1]8-. The presence of a H- ion in the center of [2]9- was established by the 1H NMR spectrum, which reveals a unique quintuple-quintet signal from the H- ion surrounded by four AgI atoms. [2]9- was considerably stable in aqueous media, which is ascribed to a chemical bond between the unoccupied superatomic orbital of {Ag4}4+ and the occupied orbital of H- in the {Ag4H}3+ core.

МОНЕТНО-РЕЧОВИЙ СКАРБ ПЕРШОЇ ПОЛОВИНИ ІХ СТОЛІТТЯ З ЧЕРКАСЬКОЇ ОБЛАСТІ

У статті зроблено опис нумізматичної частини монетно-речового скарбу, знайденого біля хутора Кобеляки Звенигородського району Черкаської області, а саме куфічних дирхемів, карбованих у період династії Аббасидів, кількістю 64 шт. Розглянуто можливі причини та шляхи потрапляння даного скарбу на територію Черкащини.Визначені дирхеми походять із семи регіонів ісламського світу:1) Магріб – 32 шт.; 2) Ірак – 14 шт.; 3) Джібал – 8 шт.; 4) Кавказ – 5 шт.; 5) Хорасан – 2 шт.; 6) Мавераннахр – 2 шт.; 7) Кірман – 1 шт. Найпізніші дати на монетах дають можливість віднести знайдений скарб, з урахуванням ще певного часу для його надходження на землі Середнього Подніпров’я, до першої половини-середини ІХ століття, що відповідає періоду існування Луки-Райковецької культури на Правобережжі Дніпра. Науковці вважають, що саме уличі, одне з «літописних племен», які згадуються у «Повісті времяних літ», залишили нам археологічні пам’ятки типу луки-райковецьких.Даний скарб унікальний для Черкаської області як за набором, так і за кількістю знайдених куфічних монет. На території області від періоду посилення слов’янських племен та формування Київської Русі більше знаходять візантійських монет, тоді як куфічні монети трапляються значно рідше. Знахідка даного монетно-речового скарбу може вказувати на шляхи поширення та використання куфічних монет. Дати карбування дирхемів, які були у скарбі, свідчать про їх надходження на Середнє Подніпров’я у першій половині-середині ІХ ст., ще до утворення давньоруської держави, центром якої стало місто Київ. Якщо на Лівобережжі торговельні шляхи, починаючи від VIII-IХ ст., на сьогодні визначені краще, то даний скарб разом з іншими знахідками куфічних монет на Черкащині та на теренах більш західних областей України може допомогти у визначенні таких торговельних шляхів і на Правобережжі та в Західній Україні.

Novel tetrahedral Ag3PO4@N-rGO for photocatalytic detoxification of sulfamethoxazole: Process optimization, transformation pathways and biotoxicity assessment

Global spreading of antibiotic resistant microorganisms and genes calls for the development of effective strategy to eliminate antibiotic pollution from the environment. Tetrahedral silver phosphate (Ag3PO4) is one of the master visible light photocatalysts but encountered the drawback of low stability due to photocorrosion. Integration of Ag3PO4 with N-doped reduced graphene oxide (N-rGO) that has large specific surface area, ample functional groups and hetero atoms doping is anticipated to overcome the problem. Thus, the present study prepared high stability Ag3PO4@N-rGO hybrid catalysts and applied for detoxification of sulfamethoxazole (SMX). Further, the operational parameters towards the photocatalytic degradation was systematically optimized to maximize the efficiency through response surface methodology (RSM) based on central composite design (CCD). The parameters that influenced the SMX degradation efficiency was as follows: pH > N-content > catalyst dosage. Under the optimal conditions (catalyst dosage = 0.2 g/L, pH = 5.8, and N-content of 5.14%), 93.8% of SMX degradation was obtained within 60 min. The plausible degradation products generation during the photocatalytic degradation of SMX was analyzed by LC-ESI/MS and the degradation pathway was proposed. In addition, the toxicity of the degradation products was investigated through Escherichia coli colony forming unit assay and a substantial biotoxicity reduction by this photodegradation was observed.

Enhanced discretization of surface integral equations for resonant scattering analysis of sharp-edged plasmonic nanoparticles

The surface integral equation (SIE) method, discretized with the method of moments, is a well-established methodology for the scattering analysis of subwavelength plasmonic nanoparticles. SIEs are usually discretized with low-order basis functions that preserve the normal continuity of the surface currents across the edges arising in the meshed boundary, such as Rao-Wilton-Glisson (RWG) functions. However, the plasmonic enhancement modeling on sharp-edged particles is an extremely challenging task, especially due to the singular fields exerted at sharp corners, exposing a slow (or no) convergence in the computation of the scattering and absorption spectra. In this paper, we propose an alternative discretization strategy based on a discontinuous basis function set in conjunction with a volumetric-tetrahedral testing scheme. We demonstrate the potential of the proposed discretization scheme by studying scattering and absorption spectra of three canonical plasmonic polyhedra, i.e., a hexahedral, an octahedral, and a tetrahedral silver inclusion. The results expose an improved accuracy and faster convergence in both far-field and near-field regions when compared to the standard RWG implementation. The proposed discretization scheme can offer faster and more accurate routes towards the exploration and design of the plasmonic resonant spectrum of sharp-edged nanoparticles and nanoantennas.

Ag7(H){S2CC(CN)2}6]6−: An Anionic Heptanuclear Silver Hydride Cluster Compound Stabilized by Dithiolate Ligands

In our attempts to identify probable intermediates in the preparation of anionic silver hydride cluster [Ag8(H){S2CC(CN)2}6]5− under the condition of excess NaBH4, we isolated and analyzed a new cluster compound, namely, [Bu4N]6[Ag7(H){S2CC(CN)2}6]. We report here the synthesis, crystal structure, characterizations by various spectroscopic (UV–Vis, IR, multinuclear NMR, elemental analyses) techniques and the luminescent properties of this cluster. Its X-ray crystal structure reveals that the cluster contains a distorted; tricapped tetrahedral silver core enclosed an interstitial hydride anion and is surrounded by six 1,1-dicyanoethylene-2,2-dithiolate ([S2CC(CN)2]2−, i-MNT) ligands. The presence of hydride inside the heptanuclear silver cluster is unequivocally certified by both 1H and 109Ag NMR spectroscopies. The title compound represents the first atomic precisely anionic Ag7-H skeleton with a non-disordered, tricapped tetrahedral silver framework.

Photophysics of a mono-nuclear tetrahedral silver(I)N4 core and its copper(I) analog

A neutral ligand L is prepared by condensation of benzil dihydrazone and acetone in 1:2 mol ratio and used for the syntheses of [CuL2]ClO4, [CuL2]PF6, [AgL2]ClO4 and [AgL2]PF6. The X-ray crystal structures of L and the two perchlorate salts have been determined. The metal complexes are found to be mononuclear containing tetrahedral N4 coordination spheres for Cu(I) and Ag(I). Cyclic voltammetrically, the Cu(II/I) and Ag(II/I) potentials are 1.23 and 0.76 V vs NHE respectively in CH2Cl2 at a Pt electrode. The reason for the such a low Ag(II/I) potential is that the silver(I) complex is adsorbed on the electrode surface with a free energy of adsorption of ∼ −14.99 kcal mol−1. DFT calculations at the BP86/LanL2DZ level show that the HOMO’s in [CuL2]ClO4 and [AgL2]ClO4 are both metal based and the LUMO’s have no contribution from the metals. Both complexes show weak emissions from the MLCT states upon excitation at 270 nm in ethanol solution at room temperature. Changing the counterion to PF6− leads to higher quantum yields for these processes. It is consistent with the general observation that ClO4− being more coordinating than PF6−, it binds the metals in the MLCT state to form exciplexes leading to a lower ϕ or total quenching. At 77 K in ethanol glass, L, [CuL2]+ and [AgL2]+ show ligand centered (LC) emissions. Thus the MLCT and LC states are thermally equilibrated in the silver(I) and copper(I) complexes. In keeping with this, a mixture of the two processes, MLCT and LC emissions, is observed at room temperature for [AgL2]ClO4 and [CuL2]ClO4 when they are incorporated in a rigid polymethyl methacrylate matrix.

Tetrahedral Silver Phosphate/Graphene Oxide Hybrids as Highly Efficient Visible Light Photocatalysts with Excellent Cyclic Stability

The degradation efficiency and recyclability of photocatalysts are the key for their practical applications. Tetrahedral silver phosphate (Ag3PO4) is a superior visible-light photocatalyst, while graphene oxide (GO) sheets with high specific surface area and abundant functional groups are expected to further enhance the photocatalytic efficiency and improve the recyclability of Ag3PO4. Herein, we demonstrate an eco-friendly and kinetically controlled approach to synthesize Ag3PO4/GO hybrids. Tetrahedral Ag3PO4 are grown in situ on the GO sheets in mixed solvents, and their microstructures are controlled by the slow dissolution and ionization of H3PO4 and the adjustment of the volume ratios of ethanol/water solvents. The hybrid with 5 wt % of GO exhibits an extraordinary photocatalytic efficiency and satisfactory recyclability for the degradation of organic dyes. Approximately 99% of methylene blue could be degraded in 4 min, and the degradation percentage is still as high as 97% even after 5 cycles of pho...

Acylchalcogenourea Complexes of Silver(I)

Acylthio‐ or acylselenoureas react with silver(I) oxide to form tetranuclear silver(I) complexes containing the deprotonated acylchalcogenourea ligands bound to the silver atoms through the chalcogen and oxygen atoms. These tetrasilver(I) species react with either 4 or 8 equiv. of a phosphine to afford either dinuclear silver(I) phosphine complexes or tetrahedral silver diphosphine complexes. In these compounds, the acylchalcogenourea ligands form six‐membered rings by coordinating to the metal atom through the chalcogen and oxygen atoms. In one case, we observed a very rare example of an acylthiourea ligand coordinated through the nitrogen and sulfur atoms to form a four‐membered ring. A silver(I) complex containing a deprotonated acylselenourea and an N‐heterocyclic carbene ligand is also reported. This was prepared from the corresponding acetate derivative and the acylselenourea; in this case, the acetate acts as the base. All of the reported compounds were characterized by spectroscopic techniques, and many were also studied by single‐crystal X‐ray diffraction.

Dependence of Plasmon Energies on the Acoustic Normal Modes of Agn (n = 20, 84, and 120) Clusters

The vibrational and optical properties of Ag20, Ag84, and Ag120 closed-shell clusters are investigated through a combination of continuum mechanics and density functional theory approaches. The acoustic vibrational frequencies associated with these tetrahedral silver clusters are found to be in close correspondence for the two theories, demonstrating the ability of finite-element calculations to reproduce first-principles computational results, even down to few-atom structures. TDDFT calculations of the absorption spectra of these clusters indicate a strong plasmon-like mode both for equilibrium structures of the clusters and for structures where the acoustic breathing mode is excited by amounts that are accessible to ultrafast experiments. The plasmon-like mode energy is found to vary linearly with the acoustic mode displacement (for small displacements), with a slope that increases with increasing cluster size. For larger clusters, the TDDFT slope is larger than the FDTD slope, which indicates that ther...

Absolute asymmetric synthesis of a tetrahedral silver complex.

Even though the isolation of tetrahedral stereoisomers usually presents a synthetic challenge, a highly enantioenriched tetrahedral silver complex could be easily accessed by either crystallization or Viedma ripening. The overall preparation may be regarded as an example of absolute asymmetric synthesis. Experimental results indicate that both crystallization and Viedma ripening follow a similar cluster-controlled mechanism.

Aryl-BIAN-ligated silver(I) trifluoromethoxide complex.

A reaction of acetonitrile-solvated AgOCF3 with 1 equiv. of Aryl-BIAN ligand in THF at room-temperature afforded the silver(i) complex (Aryl-BIAN)AgOCF3 (1) in 75% yield. The crystal structure of this silver(i) trifluoromethoxide was determined by single-crystal X-ray crystallography. The molecular structure of 1 shows the metal centre bound to one molecule of BIAN, one trifluoromethoxide and one THF solvate, resulting in a distorted tetrahedral silver. Density functional theory (DFT) calculations and the natural bond orbital (NBO) analysis were conducted to give insights into the electronic structure of 1 and the bonding characters of the OCF3 group. The reactivity of 1 towards trifluoromethoxylation of organic halides was also examined; a reaction with benzyl bromides gave the desired products of benzyl trifluoromethyl ethers in good to excellent yields.

Ag7(H){E2P(OR)2}6] (E = Se, S): Precursors for the Fabrication of Silver Nanoparticles

Reactions of Ag(I) salt, NH(4)(E(2)P(OR)(2)) (R = (i)Pr, Et; E = Se, S), and NaBH(4) in a 7:6:1 ratio in CH(2)Cl(2) at room temperature, led to the formation of hydride-centered heptanuclear silver clusters, [Ag(7)(H){E(2)P(OR)(2)}(6)] (R = (i)Pr, E = Se (3): R = Et; E = S(4). The reaction of [Ag(10)(E){E(2)P(OR)(2)}(8)] with NaBH(4) in CH(2)Cl(2) produced [Ag(8)(H){E(2)P(OR)(2)}(6)](PF(6)) (R = (i)Pr, E = Se (1): R = Et; E = S(2)), which can be converted to clusters 3 and 4, respectively, via the addition of 1 equiv of borohydride. Intriguingly clusters 1 and 2 can be regenerated via adding 1 equiv of Ag(CH(3)CN)(4)PF(6) to the solution of compounds 3 and 4, respectively. All complexes have been fully characterized by NMR ((1)H, (77)Se, (109)Ag) spectroscopy, UV-vis, electrospray ionization mass spectrometry (ESI-MS), FT-IR, thermogravimetric analysis (TGA), and elemental analysis, and molecular structures of 3(H) and 4(H) were clearly established by single crystal X-ray diffraction. Both 3(H) and 4(H) exhibit a tricapped tetrahedral Ag(7) skeleton, which is inscribed within an E(12) icosahedron constituted by six dialkyl dichalcogenophosphate ligands in a tetrametallic-tetraconnective (μ(2), μ(2)) bonding mode. Density functional theory (DFT) calculations on the models [Ag(7)(H)(E(2)PH(2))(6)] (E = Se: 3'; E = S: 4') yielded to a tricapped, slightly elongated tetrahedral silver skeleton, and time-dependent DFT (TDDFT) calculations reproduce satisfyingly the UV-vis spectrum with computed transitions at 452 and 423 nm for 3' and 378 nm for 4'. Intriguingly further reactions of [Ag(7)(H){E(2)P(OR)(2)}(6)] with 8-fold excess amounts of NaBH(4) produced monodisperse silver nanoparticles with an averaged particle size of 30 nm, which are characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and UV-vis absorption spectrum.

Luminescent silver nitrate complexes of bis[2-(diphenylphosphano)phenyl]ether (DPEphos): Crystal structure of [Ag(DPEphos)(py2SH) 2]NO 3

Heteroleptic silver(I) nitrate complexes containing the bis[2-(diphenylphosphano)phenyl]ether (DPEphos) ligand and the heterocyclic thioamides pyridine-2(1H)-thione (py2SH), pyrimidine-2(1H)-thione (pymtH), 4,6-dimethylpyrimidine-2(1H)-thione (dmpymtH), 1,4,5,6-tetrahydropyrimidine-2-thione (thpymtH) or 1,3-imidazolidine-2-thione (imtH 2) have been synthesized and characterized by IR and UV–Vis spectroscopy, elemental analyses and melting point determinations. The complexes can be obtained by the addition of the thioamide ligand to an AgNO 3–diphosphane adduct in dichloromethane/ethanol solution. The molecular structure of [Ag(DPEphos)(py2SH) 2]NO 3 complex has been established by single-crystal X-ray diffraction. The structure features a tetrahedral silver(I) center with two phosphorus atoms from the chelating diphos ligand, and the exocyclic sulfur atom of two heterocyclic thioamide units. Intense blue-green emission is observed in the region 470–483 nm for all the complexes in the solid state and in solution at ambient temperature.

Silver coordination networks and cages based on a semi-rigid bis(isoxazolyl) ligand

The semi-rigid ligand 1,4-bis((3,5-dimethylisoxazol-4-yl)methyl)benzene (bisox) reacts with a range of silver(i) salts to give products in which the anions dictate the structure. The reactions with AgNO(3) and AgO(2)CCF(3) both lead to compounds in which the anions are coordinated to the silver centres. Thus, the structure of [Ag(2)(NO(3))(2)(bisox)] 1 contains helical silver-nitrate chains that are linked into sheets by bridging bisox ligands, whereas the structures of [Ag(O(2)CCF(3))(bisox)]·0.5X (2a, X = MeOH; 2b, X = MeCN) consist of sheets in which Ag(2)(μ-O(2)CCF(3))(2) dimers act as 4-connecting nodes. In these structures bisox adopts the S-conformation, with the nitrogen donor atoms anti to each other. The reactions of bisox with AgClO(4) and AgBF(4) in methanol give the compounds [Ag(2)(bisox)(3)]X(2) (3, X = ClO(4); 5, X = BF(4)), the structures of which contain triply-interpenetrated sheets with Borromean links and ligands in the S-conformation. Recrystallisation of these compounds from acetonitrile-diethyl ether gives [Ag(2)(bisox)(3)]X(2)·xEt(2)O (4, X = ClO(4), x = 1; 6, X = BF(4), x = 1.2). The structures of 4 and 6 contain similar triply-interpenetrated sheets to those in 3 and 5, though these are sandwiched between sheets of discrete Ag(2)(bisox)(3) cages, in which the bisox ligands are in the C-conformation, with the nitrogen donor atoms syn to each other. Diethyl ether molecules project through the faces of the cages and template cage formation. Both 4 and 6 lose diethyl ether on heating in vacuum, and convert into 3 and 5, respectively. This solid state transformation requires a change in conformation of half the bisox ligands, with conversion of 6 into 5 occurring more readily than conversion of 4 into 3. The reactions of bisox with AgPF(6) and AgSbF(6) in methanol give mixtures of products from which [Ag(bisox)(2)]X·0.5bisox (7, X = PF(6); 8, X = SbF(6)) can be isolated. Both 7 and 8 have structures containing one-dimensional chains, in which the bisox ligands adopt C-conformations and interconnect distorted tetrahedral silver centres in a pairwise manner generating macrocycles. Additional uncoordinated bisox molecules lie within half of these macrocyclic rings. Recrystallisation of the crude AgSbF(6)/bisox reaction mixture from acetonitrile-diethyl ether gives [Ag(bisox)(2)]SbF(6)9, the structure of which consists of a triply-interpenetrated flattened diamondoid network. A similar structure was observed for [Ag(bisox)(2)]CF(3)SO(3)10, which is formed from the reaction of AgO(3)SCF(3) and bisox in methanol.

Syntheses and Structures of Silver(I) and Palladium(II) Complexes with Ferrocenyl-phosphonodithiolate Ligands

Coordinative interaction of [Ag(PPh3)2NO3] or [Pd(MeCN)2Cl2] with in situ-prepared Na[FcP- (OR)S2] afforded 1 : 1 products [FcP(OR)S2Ag(PPh3)2] (R = Me 1, n-Pr 2) or the 1 : 2 product [{FcP(OMe)S2}2Pd] (3). Complexes 1 - 3 were characterized by elemental analysis, mass spectrometry, NMR (1H, 31P) and IR spectroscopy, as well as by X-ray crystallography. The distorted tetrahedral silver(I) coordination led to non-planar and distorted four-membered AgS2P rings in 1 and 2, whereas the square-planar palladium(II) coordination resulted in four-membered co-planar PdS2P rings in 3

2-D Coordination Polymers of Hexa(4-cyanophenyl)[3]-radialene and Silver(I): Anion···π-Interactions and Radialene C−H···Anion Hydrogen Bonds in the Solid-State Interactions of Hexaaryl[3]-radialenes with Anions

As part of our studies of ligands containing an electron-deficient [3]-radialene core we discovered that the hexadentate ligand hexa(4-cyanophenyl)[3]-radialene 1 forms 6,3-connected 2-D coordination polymers on reaction with silver(I). Compounds {[Ag(1)](PF6)·2(CH3NO2)}n 2 and {[Ag(1)](ClO4)·2(CH3NO2)}n 3, which are the first coordination polymers of 1, readily crystallize from solutions of the silver salt and 1 in noncoordinating nitromethane solvent and were characterized by X-ray crystallography. In these structures the ligand is hypodentate, coordinating only through four nitrile N-donors to act as a 3-connecting center. The distorted tetrahedral silver also acts as a 3-connecting center. In the extended structure the anions lie in pockets above and below the [3]-radialene core of the ligands, forming moderate and weak hydrogen bonds with four different molecules of 1. The anions are in close proximity to the electron-deficient [3]-radialene core of 1, forming weak anion−π interactions.

Growth of Tetrahedral Silver Nanocrystals in Aqueous Solution and Their SERS Enhancement

Silver nanocrystals with tetrahedral shapes and {111} faces have been synthesized by the light-driven growth method in an aqueous solution. The nanocrystals of T(d) symmetry were formed under the effect of tartrate and citrate as the structural-directing reagents at the appropriate stages of reaction. Further, the nanocrystals may be assembled through electrostatic interaction to develop large-scale particle surfaces with sharp vertexes, which can generate strong localized electromagnetic field for surface-enhanced Raman scattering (SERS) studies. Benzenethiol was used as the probe to evaluate their SERS enhancement, and enhancement factors of up to 10(6) are reached. As a kind of promising material, these novel nanocrystals will be applied in surface enhanced spectroscopy and plasmonics field.