Silver(I) Bis(pyrazolyl)methane Complexes and Their Implementation as Precursors for Metallic Silver Deposition

Binding Interactions in Copper, Silver and Gold π-Complexes

The copper(I), silver(I), and gold(I) metals bind π-ligands by σ-bonding and π-back bonding interactions. These interactions were investigated using bidentate ancillary ligands with electron donating and withdrawing substituents. The π-ligands span from ethylene to larger terminal and internal alkenes and alkynes. Results of X-ray crystallography, NMR, and IR spectroscopy and gas phase experiments show that the binding energies increase in the order Ag Collapse

Key Words

• X-ray diffraction
• alkene ligands
• alkyne ligands
• bond energy
• mass spectrometry

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MESH Headings

• Copper/chemistry
• Crystallography, X-Ray
• Gold/chemistry
• Ligands
• Silver/chemistry

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Grants

• 682275 H2020 European Research Council
• CHE-1954456 Integrative and Collaborative Education and Research
• Y-1289 Welch Foundation
• H2020 European Research Council
• Integrative and Collaborative Education and Research
• Welch Foundation

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Affiliation(s)

Jaya Mehara Department of Spectroscopy and CatalysisInstitute for Molecules and MaterialsRadboud University NijmegenHeyendaalseweg 1356525 AJNijmegen (TheNetherlands
Brandon T. Watson Department of Chemistry and BiochemistryThe University of Texas at ArlingtonArlingtonTexas76019USA
Anurag Noonikara‐Poyil Department of Chemistry and BiochemistryThe University of Texas at ArlingtonArlingtonTexas76019USA
Adway O. Zacharias Department of Chemistry and BiochemistryThe University of Texas at ArlingtonArlingtonTexas76019USA
Jana Roithová Department of Spectroscopy and CatalysisInstitute for Molecules and MaterialsRadboud University NijmegenHeyendaalseweg 1356525 AJNijmegen (TheNetherlands
H. V. Rasika Dias Department of Chemistry and BiochemistryThe University of Texas at ArlingtonArlingtonTexas76019USA

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Synthesis, structure, fluorescence, electrochemical, and antioxidant studies of a new silver(I) complex with 2,6-bis(N-methylbenzimidazol-2-yl)pyridine

A new silver(I) complex of the type [Ag2(mbbp)2](pic)2·DMF·CH3OH [mbbp = 2,6-bis( N-methylbenzimidazol-2-yl)pyridine] is synthesized and analyzed using a range of spectroscopic and crystallographic techniques. This compound contains cationic Ag2(mbbp)2 dimers, in which the crossed eight-shaped structure is formed by two mbbp ligands bridging two silver(I) centers and Ag–Ag bonds. Two-dimensional supramolecular networks of the silver(I) complex are connected by π···π interactions and hydrogen bonds. Hirshfeld analyses are performed to support the aforementioned intermolecular interactions. The effect of π···π stacking interactions on the fluorescence properties of the complex is investigated. Cyclic voltammetry indicates two irreversible redox processes. In addition, an antioxidant assay in vitro demonstrates that the silver(I) complex displays excellent scavenging activity toward hydroxyl radicals.

Silver(i) complexes of bis- and tris-(pyrazolyl)azine derivatives - dimers, coordination polymers and a pentametallic assembly

Silver(i) complexes of 2,4,6-tri(pyrazol-1-yl)pyridine (tpp), 2,4,6-tri(pyrazol-1-yl)pyrimidine (tpym), 2,4,6-tri(pyrazol-1-yl)-1,3,5-triazine (tpt) and 2,4-di(pyrazol-1-yl)-1,3,5-triazine (bpt) are reported. Dinuclear [Ag2(μ-tpp)2(MeCN)2][BF4]2·2MeCN and [Ag2(μ-tpym)2(MeCN)2][BF4]2 are formed from approximately planar [AgL(NCMe)]+ (L = tpp or bpym) centres, which dimerise via apical interactions to the pendant pyrazolyl donor on each ligand. Two polymeric solvatomorph phases [Ag2(μ-tpp)2][BF4]2·nMeNO2 were obtained by crystallising AgBF4 and tpp from nitromethane solution. One is composed of the same dimeric [Ag2(μ-tpp)2]2+ motif as the MeCN solvates, but with semibridging pyrazolyl substitutents replacing the solvent ligands. The other form has helicate [Ag2(μ-tpp)2]2+ dimers linked into chains by unsupported AgAg interactions. In contrast, [Ag5(μ3-tpym)4][BF4]5·2MeNO2 contains discrete pentametallic assemblies, of a flattened [Ag4(μ-tpym)4]4+ molecular square centred by the fifth silver ion. Three helical or linear 1D coordination polymer topologies are described for [Ag(μ-tpt)]X (X- = BF4- or ClO4-), where ditopic tpt ligands bind one silver ion in a [2 + 1] geometry and the other in bidentate, [1 + 1] or monodentate fashion. Finally, [Ag(bpt)]BF4 is a polymer of square planar silver ions linked by bis-bidentate bpt ligands. Most of the tpt and bpt structures include short anionπ contacts to the ligand triazinyl rings. Electrospray mass spectra confirm the oligomeric nature of the Ag/tpym and tpt complexes in MeNO2 solution.

New highly fluorescent silver complexes and their thin films obtained by spin coating method

Thin, fluorescent films of novel silver(i) complexes were produced using a spin coating method.

Self-assembly of singlet-emitting double-helical silver dimers: the curious coordination chemistry and fluorescence of bisquinolylpyridone

The previously unreported ligand 2,6-bis(2-quinolyl)-4(1H)-pyridone spontaneously assembles into double helical dimers with Ag⁺ – its fluorescence is BLUESHIFTED upon complexation.

Organic-Modified Silver Nanoparticles as Lubricant Additives

Advanced lubrication is essential in human life for improving mobility, durability, and efficiency. Here we report the synthesis, characterization, and evaluation of two groups of oil-suspendable silver nanoparticles (NPs) as candidate lubricant additives. Two types of thiolated ligands, 4-(tert-butyl)benzylthiol (TBBT) and dodecanethiol (C12), were used to modify Ag NPs in two size ranges, 1-3 and 3-6 nm. The organic surface layer successfully suspended the Ag NPs in a poly-alpha-olefin (PAO) base oil with concentrations up to 0.19-0.50 wt %, depending on the particle type. Use of the Ag NPs in the base oil reduced friction by up to 35% and wear by up to 85% in boundary lubrication. The two TBBT-modified NPs produced a lower friction coefficient than the C12-modified one, while the two larger NPs (3-6 nm) had better wear protection than the smaller one (1-3 nm). Results suggested that the molecular structure of the organic ligand might have a dominant effect on the friction behavior, while the NP size could be more influential in the wear protection. No mini-ball-bearing or surface smoothening effects were observed in the Stribeck scans. Instead, the wear protection in boundary lubrication was attributed to the formation of a silver-rich 50-100 nm thick tribofilm on the worn surface, as revealed by morphology examination and composition analysis from both the top surface and cross section.