Chemiluminescent Logic Gates Based on Functionalized Gold Nanoparticles/Graphene Oxide Nanocomposites

Label‐free logic gates (AND, OR, and INHIBIT) based on chemiluminescence (CL) as new optical readout signal have been developed by taking advantage of the unique CL activity of luminol‐ and lucigenin‐functionalized gold nanoparticles/graphene oxide (luminol‐lucigenin/AuNPs/GO) nanocomposites. It was found that Fe²⁺ ions could induce the CL emission of luminol‐lucigenin/AuNPs/GO nanocomposites in alkaline solution. On this basis, by using Fe²⁺ ions and NaOH as the inputs and the CL signal as the output, an AND logic gate was fabricated. When the initial reaction system contained luminol‐lucigenin/AuNPs/GO nanocomposites and NaOH, either Fe²⁺ ions or Ag⁺ ions could react with the luminol‐lucigenin/AuNPs/GO nanocomposites to produce a strong CL emission. This result was used to design an OR logic gate using Fe²⁺ ions and Ag⁺ ions as the inputs and CL signal as the output. Moreover, two INHIBIT logic gates for Fe²⁺ and Ag⁺ were also developed using by NaClO and L ‐cysteine as their CL inhibitors, respectively. Furthermore, the proposed logic gates were successfully used to detect Fe²⁺, Ag⁺, and L ‐cysteine, respectively. The developed logic gates may find future applications in sensing, clinical diagnostics, and environmental monitoring.     

Metal‐Ion‐Triggered Exonuclease III Activity for the Construction of DNA Colorimetric Logic Gates

The logic system is obtained by using a series of double‐stranded (ds) DNA templates with mismatched base pairs (T–T or C–C) and ion‐modulated exonuclease III (Exo III) activity, in which the Exo III cofactors, Hg²⁺ and Ag⁺ ions, are used as inputs for the activation of the respective scission of Exo III based on the formation of T–Hg²⁺–T or C–Ag⁺–C base pairs. Additionally, two kinds of signal probes are utilized to transduce the logic operations. One is the two split G‐rich DNA strands that are used to design the OR, AND, INHIBIT, and XOR gates, whereas the other is the self‐assembled split G‐quadruplex structure to construct NOR, NAND, IMPLICATION, and XNOR operations based on DNA hybridization and strand displacement. In the presence of hemin, the split G‐quadruplex biocatalyzes the formation of a colored product, which is an output signal for the different logic gates. Thus, we have constructed a complete set of colorimetric DNA logic gates based on the Exo III and split G‐quadruplex for the first time. In addition, we are able to effortlessly recognize the logic output signals by the naked eye and their simplicity and cost‐effective design is the most apparent feature for the logic gates developed in this work.     

Label-free sensing of pH and silver nanoparticles using an “OR” logic gate

Many natural phenomena are associated with the presence of two or more separate variables. We report here an “OR” DNA logic gate based on a luminescent platinum(II) switch-on probe for silver nanoparticles and pH, both of which may be considered putative indicators of pollution. The modulation of metal complex/double-stranded DNA complex phosphorescence by Ag⁺ and H⁺ was used to construct a simple, rapid and label-free method for the label-free detection of pH and nanomolar Ag⁺ ions and nanoparticles in aqueous solutions with high selectivity.     

Bifunctional Ion‐Selective Electrode Based on C60‐Cryptand 22 for Silver and Iodine Ions

Fullerence C60‐cryptand 22 was prepared and successfully applied as the electric carrier in the PVC electrode membrane of a bifunctional ion‐selective electrode for cations, e.g., Ag⁺ ions as well as anions, e.g., I^? ions. The bifunctional ion‐selective electrode based on C60‐cryptand 22 can be applied as a Silver (Ag⁺) ion selective electrode with an internal electrode solution of 10^?3 M AgNO₃ in water (pH = 6.3), or as an Iodide (I^?) ion selective electrode with an acidic internal electrode solution of 10^?4 M KI_(aq) (pH = 2) in which the cryptand 22 is protonated, and the C60‐cryptand 22 is changed to C60‐Cryptand22–H⁺ and becomes an anionic electro‐carrier to absorb the I^? ion. The Ag⁺ ion selective electrode based on C60‐cryptand 22 gave a linear response with a near‐Nernstian slope (59.5 mV decade^?1) within the concentration range 10^?1‐10^?3 M Ag⁺_(aq). The Ag⁺ ion electrode exhibited comparatively good selectivity for silver ions, over other transition‐metal ions, alkali and alkaline earth metal ions. The Ag⁺ ion selective electrode with good stability and reproducibility was successfully used for the titration of Ag⁺_(aq) with Cl^? ions. The Iodide (I^?) Ion selective electrode based on protonated C60–cryptand22‐H⁺ also showed a linear response with a nearly Nernstian slope (58.5 mV decade^?1) within 10^?1 ‐ 10^?3 M I^? _(aq) and exhibited good selectivity for I^? ions and had small selectivity coefficients (10^?2–10^?3) for most of other anions, e.g., F^? , OH^?, CH₃COO^?, SO₄^2?, CO₃^2?, CrO₄^2?, Cr₂O₇^2? and PO₄^3? ions.     

Orthogonal Dual‐Triggered Shape‐Memory DNA‐Based Hydrogels

DNA‐based shape‐memory hydrogels revealing switchable shape recovery in the presence of two orthogonal triggers are described. In one system, a shaped DNA/acrylamide hydrogel is stabilized by duplex nucleic acids and pH‐responsive cytosine‐rich, i‐motif, bridges. Separation of the i‐motif bridges at pH 7.4 transforms the hydrogel into a quasi‐liquid, shapeless state, that includes the duplex bridges as permanent shape‐memory elements. Subjecting the quasi‐liquid state to pH 5.0 or Ag⁺ ions recovers the hydrogel shape, due to the stabilization of the hydrogel by i‐motif or C‐Ag⁺‐C bridged i‐motif. The cysteamine‐induced transformation of the duplex/C‐Ag⁺‐C bridged i‐motif hydrogel into a quasi‐liquid shapeless state results in the recovery of the shaped hydrogel in the presence of H⁺ or Ag⁺ ions as triggers. In a second system, a shaped DNA/acrylamide hydrogel is generated by DNA duplexes and bridging Pb²⁺ or Sr²⁺ ions‐stabilized G‐quadruplex subunits. Subjecting the shaped hydrogel to the DOTA or KP ligands eliminates the Pb²⁺ or Sr²⁺ ions from the respective hydrogels, leading to shapeless, memory‐containing, quasi‐liquid states that restore the original shapes with Pb²⁺ or Sr²⁺ ions.     

Molecular design of a “molecular syringe” mimic for metal cations using a 1,3‐alternate calix[4]arene cavity

The chemically switchable actions well imitate the function of a “molecular syringe,” has been studied in theory using the 1,3‐alternate calix [4]arene bearing a nitrogen‐containing crown cap at one side and a bis(ethoxyethoxy) group at another side by the π‐basic calixtube as a pipette and the crown ring as a rubber cap. The model is characterized by geometry optimization using density functional theory (DFT) at B3LYP/6‐31G level. The obtained optimized structures are used to perform natural bond orbital (NBO) and frequency analysis. The electron‐donating heteroatoms: O and N offer lone pair electrons to the contacting RY* (1‐center Rydberg) or LP* (1‐center valence antibond lone pair) orbitals of K⁺, Ag⁺. The results indicate that when the nitrogen atom in the crown ring is protonated, K⁺ and Ag⁺ will be pushed out to the bis(ethoxyethoxy) side through a π‐basic calixtube. When the nitrogen·H⁺ in the crown ring is deprotonated, K⁺ and Ag⁺ are sucked back to the crown‐capped side again. In the course of the coordination, both the intermolecular electrostatic interactions and the cation‐π interactions between the metal ion and π‐orbitals of the two pairs facing inverted benzene rings play a significant role. It is believed that this prototype of a “molecular syringe” is a novel molecular architecture for the action of metal cations. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010     

Redox Sorption and Recovery of Silver Ions as Silver Nanocrystals on Poly(aniline‐co‐5‐sulfo‐2‐anisidine) Nanosorbents

Poly[aniline(AN)‐co‐5‐sulfo‐2‐anisidine(SA)] nanograins with rough and porous structure demonstrate ultrastrong adsorption and highly efficient recovery of silver ions. The effects of five key factors—AN/SA ratio, Ag^I concentration, sorption time, ultrasonic treatment, and coexisting ions—on Ag^I adsorbability were optimized, and AN/SA (50/50) copolymer nanograins were found to exhibit much stronger Ag^I adsorption than polyaniline and all other reported sorbents. The maximal Ag^I sorption capacity of up to 2034 mg g^?1 (18.86 mmol g^?1) is the highest thus far and also much higher than the maximal Hg‐ion sorption capacity (10.28 mmol g^?1). Especially at ≤2 mM Ag^I, the nanosorbents exhibit ≥99.98 % adsorptivity, and thus achieve almost complete Ag^I sorption. The sorption fits the Langmuir isotherm well and follows pseudo‐second‐order kinetics. Studies by IR, UV/Vis, X‐ray diffraction, polarizing microscopy, centrifugation, thermogravimetry, and conductivity techniques showed that Ag^I sorption occurs by a redox mechanism mainly involving reduction of Ag^I to separable silver nanocrystals, chelation between Ag^I and ? NH? /? N?/? NH₂/ ? SO₃H/? OCH₃, and ion exchange between Ag^I and H⁺ on ? SO₃^?H⁺. Competitive sorption of Ag^I with coexisting Hg, Pb, Cu, Fe, Al, K, and Na ions was systematically investigated. In particular, the copolymer nanoparticles bearing many functional groups on their rough and porous surface can be directly used to recover and separate precious silver nanocrystals from practical Ag^I wastewaters containing Fe, Al, K, and Na ions from Kodak Studio. The nanograins have great application potential in the noble metals industry, resource reuse, wastewater treatment, and functional hybrid nanocomposites.     

Topological analysis of the three‐dimensional coordination polymer poly[(μ4‐azido)[μ4‐5‐(pyridin‐4‐yl)tetrazolido]disilver(I)]

The title compound, [Ag₂(C₆H₄N₄)(N₃₎]_n, was obtained under hydrothermal conditions at 433 K. The asymmetric unit of the orthorhombic space group (Pna2₁) consists of two Ag⁺ cations, an anionic 5‐(pyridin‐4‐yl)tetrazolide (4‐ptz⁻) ligand and an anionic azide ligand. Both Ag⁺ centres are coordinated by four N atoms, forming a distorted tetrahedral coordination environment. When all the component ions are viewed as 4‐connected nodes, the whole three‐dimensional network can be regarded topologically as a new kind of 4,4,4,4‐connected net with the Schläfli symbol (4.8⁵)(4².8⁴)(4³.8³)₂.     

A two‐dimensional network formed by self‐associating silver(I) perchlorate with 3‐[4‐(2‐thienyl)‐2H‐cyclopenta[d]pyridazin‐1‐yl]benzonitrile

In the organometallic silver(I) supramolecular complex poly[[silver(I)‐μ₃‐3‐[4‐(2‐thienyl)‐2H‐cyclopenta[d]pyridazin‐1‐yl]benzonitrile] perchlorate methanol solvate], {[Ag(C₁₈H₁₁N₃S)](ClO₄)·CH₃OH}_n, there is only one type of Ag^I center, which lies in an {AgN₂Sπ} coordination environment. Two unsymmetric multidentate 3‐[4‐(2‐thienyl)‐2H‐cyclopenta[d]pyridazin‐1‐yl]benzonitrile (L) ligands link two Ag^I atoms through π–Ag^I interactions into an organometallic box‐like unit, from which two 3‐cyanobenzoyl arms stretch out in opposite directions and bind two Ag^I atoms from neighboring box‐like building blocks. This results in a novel two‐dimensional network extending in the crystallographic bc plane. These two‐dimensional sheets stack together along the crystallographic a axis to generate parallelogram‐like channels. The methanol solvent molecules and the perchlorate counter‐ions are located in the channels, where they are fixed by intermolecular hydrogen‐bonding interactions. This architecture may provide opportunities for host–guest chemistry, such as guest molecule loss and absorption or ion exchange. The new fulvene‐type multidentate ligand L is a good candidate for the preparation of Cp–Ag^I‐containing (Cp is cyclopentadienyl) organometallic coordination polymers or supramolecular complexes.     

Poly[μ2‐(N‐hydroxypyridine‐2‐carboxamidine)‐μ2‐nitrato‐silver(I)]

In the title complex, [Ag(NO₃)(C₆H₇N₃O)]_n or [Ag(NO₃)(pyaoxH₂)] (pyaoxH₂ is N‐hydroxypyridine‐2‐carboxamidine), the Ag⁺ ion is bridged by the pyaoxH₂ ligands and nitrate anions, giving rise to a two‐dimensional molecular structure. Each pyaoxH₂ ligand coordinates to two Ag⁺ ions using its pyridyl and carboxamidine N atoms, and the OH and the NH₂ groups are uncoordinated. Each nitrate anion uses two O atoms to coordinate to two Ag⁺ ions. The Ag...Ag separation via the pyaoxH₂ bridge is 2.869 (1) Å, markedly shorter than that of 6.452 (1) Åvia the nitrate bridge. The two‐dimensional structure is fishscale‐like, and can be described as pyaoxH₂‐bridged Ag₂ nodes that are further linked by nitrate anions. Hydrogen bonding between the amidine groups and the nitrate O atoms connects adjacent layers into a three‐dimensional network.     

[N⋅⋅⋅I+⋅⋅⋅N] Halogen‐Bonded Dimeric Capsules from Tetrakis(3‐pyridyl)ethylene Cavitands

Two [N???I⁺???N] halogen‐bonded dimeric capsules using tetrakis(3‐pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I⁺) as the main connecting module are characterized by ¹H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI‐MS), and ion mobility‐mass spectrometry (TW‐IMS) experiments. The synthesis and effective halogen‐bonded dimerization proceeds through analogous dimeric capsules with [N???Ag⁺???N] binding motifs as the intermediates as evidenced by the X‐ray structures of (CH₂Cl₂)₂@[ 3 a ₂?Ag₄?(H₂O)₂?OTs₄] and (CH₂Cl₂)₂@[ 3 a ₂?Ag₄?(H₂O)₄?OTs₄], two structurally different capsules.     

Time‐Resolved Assembly of Cluster‐in‐Cluster {Ag12}‐in‐{W76} Polyoxometalates under Supramolecular Control

We report the time‐resolved supramolecular assembly of a series of nanoscale polyoxometalate clusters (from the same one‐pot reaction) of the form: [H_(10+m)Ag₁₈Cl(Te₃W₃₈O₁₃₄)₂]_n, where n=1 and m=0 for compound 1 (after 4 days), n=2 and m=3 for compound 2 (after 10 days), and n=∞ and m=5 for compound 3 (after 14 days). The reaction is based upon the self‐organization of two {Te₃W₃₈} units around a single chloride template and the formation of a {Ag₁₂} cluster, giving a {Ag₁₂}‐in‐{W₇₆} cluster‐in‐cluster in compound 1 , which further aggregates to cluster compounds 2 and 3 by supramolecular Ag‐POM interactions. The proposed mechanism for the formation of the clusters has been studied by ESI‐MS. Further, control experiments demonstrate the crucial role that TeO₃^2?, Cl^?, and Ag⁺ play in the self‐assembly of compounds 1 – 3 .     

C3‐Symmetric Assemblies from Trigonal Polycarbene Ligands and MI Ions for the Synthesis of Three‐Dimensional Polyimidazolium Cations

Metallosupramolecular poly‐NHC‐metal assemblies were prepared from trigonal hexakis (H₆‐ 1 a (PF₆)₆ and H₆‐ 1 b (PF₆)₆) or nonakis (H₉‐ 3 (BF₄)₉) imidazolium salts and Ag₂O. Complexes [Ag₆( 1 a )₂](PF₆)₆ and [Ag₆( 1 b )₂](PF₆)₆ are built from six Ag⁺ ions sandwiched between two trigonal hexacarbene ligands with an inner and an outer NHC donor in each of the three ligand arms. The metal atoms are arranged in two triangles. The hexakis‐NHC ligands bear cinnamic ester groups at the outlying NHC donors, used in postsynthetic [2+2] cycloaddition reactions linking two hexakis‐NHC ligands by three cyclobutane units to give complexes [Ag₆( 2 a )](PF₆)₆ and [Ag₆( 2 b )](PF₆)₆ bearing a dodecacarbene ligand. From the related nonakisimidazolium salt H₉‐ 3 (BF₄)₉, complex [Ag₉( 4 )](BF₄)₉ bearing an octadecacarbene ligand was obtained. Removal of the template metals yielded very large, stable, polyimidazolium cations with 12 or 18 internal imidazolium groups.     

catena‐Poly[bis[silver(I)‐μ2‐4,4′‐bipyridine‐κ2N:N′] naphthalene‐2,6‐dicarboxylate tetrahydrate]: self‐assembly of a supramolecular framework via coordination bonds and supramolecular interactions

The ultrasonic reaction of AgNO₃, 4,4′‐bipyridine (bipy) and naphthalene‐2,6‐dicarboxylic acid (H₂NDC) gives rise to the title compound, {[Ag₂(C₁₀H₈N₂)₂](C₁₂H₆O₄)·4H₂O}_n. The NDC dianion is located on an inversion centre. The Ag^I centre is coordinated in a linear manner by two N atoms from two bipy ligands. The crystal structure consists of one‐dimensional Ag^I–bipy cationic chains and two‐dimensional NDC–H₂O anionic sheets, constructed by coordination bonds and supramolecular interactions, respectively.     

Two New Silver(I) Ammine Complexes by Displacement Reaction Between [Ag(NH3)2]+ Ions and Different Pyridine‐4,5‐Imidazoledicarboxylic Acids

[Ag(NH₃)₂]⁺ ions are chosen as an initial reaction precursor because of its simple displacement reaction and intrinsic arrangement as well as specific coordination directionality. Two new silver(I) ammine complexes, Ag₂(NH₃)HL² ( 2 ) and Ag₂(NH₃)₂HL³ ( 3 ), were obtained by a simple substitution reaction between [Ag(NH₃)₂]⁺ ions and pyridine‐4,5‐imidazoledicarboxylic acid [H₃L² = 2‐(3′‐pyridyl) 4,5‐imidazoledicarboxylic acid and H₃L³ = 2‐(4′‐pyridyl) 4,5‐imidazoledicarboxylic acid]. Silver dimers are connected into a 2D layer and 1D chain in complexes 2 and 3 , respectively. In complex 2 two kinds of displacement reactions (mono‐substituting and bis‐substituting) occurred between the ammine molecules in [Ag(NH₃)₂]⁺ ions and H₃L², however, only the mono‐substituting reaction occurs in complex 3 .     

A one‐dimensional silver(I) coordination polymer based on 5‐methyl‐1,3,4‐thiadiazol‐2‐amine and pyridine‐2,3‐dicarboxylate

The bifunctional pyridine‐2,3‐dicarboxylic acid (H₂pdc) ligand has one N atom and four O atoms, which could bind more than one Ag^I centre with diverse binding modes. A novel infinite one‐dimensional Ag^I coordination polymer, namely catena‐poly[[silver(I)‐(μ₂‐pyridine‐2,3‐dicarboxylato‐κ²N :O ³)‐silver(I)‐tris(μ₂‐5‐methyl‐1,3,4‐thiodiazol‐2‐amine‐κ²N :N ′)] monohydrate ethanol monosolvate], {[Ag₂(C₇H₃NO₄)(C₃H₅N₃S)₃]·H₂O·C₂H₅OH}_n , has been synthesized using H₂pdc and 5‐methyl‐1,3,4‐thiadiazol‐2‐amine (tda), and characterized by single‐crystal X‐ray diffraction. One Ag^I atom is located in a four‐coordinated AgN₄ tetrahedral geometry and the other Ag^I atom is in a tetrahedral AgN₃O geometry. A dinuclear Ag^I cluster formed by three tda ligands with a paddelwheel configuration is bridged by the dianionic pdc²⁻ ligand into a one‐dimensional coordination polymer. Interchain N—H…O hydrogen bonds extend the one‐dimensional chains into an undulating two‐dimensional sheet. The sheets are further packed into a three‐dimensional supramolecular framework by interchain N—H…O hydrogen bonds.     

Counter‐anion role in the formation of two supramolecular complexes: [Ag2(DPP)2](ClO4)2·CH3CN and [Ag2(DPP)2(NO3)2] {DPP is N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine}

The title compounds, bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}disilver bis(perchlorate) acetonitrile monosolvate, [Ag₂(C₁₈H₁₇N₂P)₂](ClO₄)₂·CH₃CN, (1), and bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}bis[(nitrato‐κ²O,O)silver], [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂], (2), each contain disilver macrocyclic [Ag₂(C₁₈H₁₇N₂P)₂]²⁺ cations lying about inversion centres. The cations are constructed by two N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine (DPP) ligands linking two Ag⁺ cations in a head‐to‐tail fashion. In (1), the unique Ag⁺ cation has a near‐linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. Two ClO₄⁻ anions doubly bridge two metallomacrocycles through Ag...O and N—H...O weak interactions to form a chain extending in the c direction. The half‐occupancy acetonitrile molecule lies with its methyl C atom on a twofold axis and makes a weak N...Ag contact. In (2), there are two independent [Ag(C₁₈H₁₇N₂P)]⁺ cations. The nitrate anions weakly chelate to each Ag⁺ cation, leading to each Ag⁺ cation having a distorted tetrahedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms. Each dinuclear [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂] molecule acts as a four‐node to bridge four adjacent equivalent molecules through N—H...O interactions, forming a two‐dimensional sheet parallel to the bc plane. Each sheet contains dinuclear molecules involving just Ag1 or Ag2 and these two types of sheet are stacked in an alternating fashion. The sheets containing Ag1 all lie near x = , , etc, while those containing Ag2 all lie near x = 0, 1, 2 etc. Thus, the two independent sheets are arranged in an alternating sequence at x = 0, , 1, etc. These two different supramolecular structures result from the different geometric conformations of the templating anions which direct the self‐assembly of the cations and anions.     

A Reusable DNA Single‐Walled Carbon‐Nanotube‐Based Fluorescent Sensor for Highly Sensitive and Selective Detection of Ag+ and Cysteine in Aqueous Solutions

Here we report a reusable DNA single‐walled carbon nanotube (SWNT)‐based fluorescent sensor for highly sensitive and selective detection of Ag⁺ and cysteine (Cys) in aqueous solution. SWNTs can effectively quench the fluorescence of dye‐labeled single‐stranded DNA due to their strong π–π stacking interactions. However, upon incubation with Ag⁺, Ag⁺ can induce stable duplex formation mediated by C–Ag⁺–C (C=cytosine) coordination chemistry, which has been further confirmed by DNA melting studies. This weakens the interactions between DNA and SWNTs, and thus activates the sensor fluorescence. On the other hand, because Cys is a strong Ag⁺ binder, it can remove Ag⁺ from C–Ag⁺–C base pairs and deactivates the sensor fluorescence by rewrapping the dye‐labeled oligonucleotides around the SWNT. In this way, the fluorescence signal‐on and signal‐off of a DNA/SWNT sensor can be used to detect aqueous Ag⁺ and Cys, respectively. This sensing platform exhibits high sensitivity and selectivity toward Ag⁺ and Cys versus other metal ions and the other 19 natural amino acids, with a limit of detection of 1 nM for Ag⁺ and 9.5 nM for Cys. Based on these results, we have constructed a reusable fluorescent sensor by using the covalent‐linked SWNT–DNA conjugates according to the same sensing mechanism. There is no report on the use of SWNT–DNA assays for the detection of Ag⁺ and Cys. This assay is simple, effective, and reusable, and can in principle be used to detect other metal ions by substituting C–C base pairs with other native or artificial bases that selectively bind to other metal ions.     

Formation and Characterisation of the Silver Hydride Nanocluster Cation [Ag3H2((Ph2P)2CH2)]+ and Its Release of Hydrogen

Multistage mass spectrometry and density functional theory (DFT) were used to characterise the small silver hydride nanocluster, [Ag₃H₂L]⁺ (where L=(Ph₂P)₂CH₂) and its gas‐phase unimolecular chemistry. Collision‐induced dissociation (CID) yields [Ag₂HL]⁺ as the major product while laser‐induced dissociation (LID) proceeds via H₂ formation and subsequent release from [Ag₃H₂L]⁺, giving rise to [Ag₃L]⁺ as the major product. Deuterium labelling studies on [Ag₃D₂L]⁺ prove that the source of H₂ is from the hydrides and not from the ligand. Comparison of TD‐DFT absorption patterns obtained for the optimised structures with action spectroscopy results, allows assignment of the measured features to structures of precursors and products. Molecular dynamics “on the fly” reveal that AgH loss is favoured in the ground state, but H₂ formation and loss is preferred in the first excited state S₁, in agreement with CID and LID experimental findings. This indicates favourable photo‐induced formation of H₂ and subsequent release from [Ag₃H₂L]⁺, an important finding in context of metal hydrides as a hydrogen storage medium, which can subsequently be released by heating or irradiation with light.     

catena‐Poly[[silver(I)‐μ‐1,3‐bis(4‐pyridyl)propane] hemi(naphthalene‐1,5‐disulfonate) dihydrate]: a three‐dimensional metallo‐supramolecular sandwich lamellar network

The title compound, {[Ag(C₁₃H₁₄N₂)](C₁₀H₆O₆S₂)_0.5·2H₂O}_n, (I), features a three‐dimensional supramolecular sandwich architecture that consists of two‐dimensional cationic layers composed of polymeric chains of silver(I) ions and 1,3‐bis(4‐pyridyl)propane (bpp) ligands, linked by Ag...Ag and π–π interactions, alternating with anionic layers in which uncoordinated naphthalene‐1,5‐disulfonate (nds²⁻) anions and solvent water molecules form a hydrogen‐bonded network. The asymmetric unit consists of one Ag^I cation linearly coordinated by N atoms from two bpp ligands, one bpp ligand, one half of an nds²⁻ anion lying on a centre of inversion and two solvent water molecules. The two‐dimensional {[Ag(bpp)]⁺}_n cationic and {[(nds)·2H₂O]²⁻}_n anionic layers are assembled into a three‐dimensional supramolecular framework through long secondary coordination Ag...O interactions between the sulfonate O atoms and Ag^I centres and through nonclassical C—H...O hydrogen bonds.