Coordination Polymers Based on Rhenium Octahedral Chalcocyanide Cluster Anions and Ag+ Cations with Bipyridine Analogs

A series of six coordination polymers based on octahedral cluster anions [Re₆Q₈(CN)₆]^4- (Q = S or Se) and Ag⁺ cations coordinated by bipyridine analogs were synthesized under solvothermal conditions. Their structures have been characterized by single crystal X-ray diffraction. Compounds 1 and 2 described by the general formula [{Ag(phen)}₄Re₆Q₈(CN)₆] (Q = Se (1), S (2); phen = 1,10-phenanthroline) exhibit layered structures assembled into a supramolecular network by CH…π contacts. At the same time, compounds [{Ag(bipym)}₂Ag₂Re₆Se₈(CN)₆] (bipym = 2,2'-bipyrimidine) (3), [{Ag₂(bipy)}Ag₂Re₆Se₈(CN)₆]·CH₃CN (bipy = 4,4'-bipyridine) (4) and [{Ag(dpbp)}₄Re₆Q₈(CN)₆]·2H₂O·2CH₃CN (Q = Se (5), S (6); dpbp = 4,4'-Di(4-pyridyl)biphenyl)) evince framework structures. In 1, 2, 5 and 6 weak Ag⋯Ag interactions are observed. All the compounds show luminescence in the red region. The luminescence quantum yields and lifetimes were found to be notably higher than those for most of the coordination polymers based on the octahedral rhenium cluster complexes.

Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

Focused electron beam induced deposition (FEBID) is a versatile tool to produce nanostructures through electron-induced decomposition of metal-containing precursor molecules. However, the metal content of the resulting materials is often low. Using different Ag(I) complexes, this study shows that the precursor performance depends critically on the molecular structure. This includes Ag(I) 2,2-dimethylbutanoate, which yields high Ag contents in FEBID, as well as similar aliphatic Ag(I) carboxylates, aromatic Ag(I) benzoate, and the acetylide Ag(I) 3,3-dimethylbutynyl. The compounds were sublimated on inert surfaces and their electron-induced decomposition was monitored by electron-stimulated desorption (ESD) experiments in ultrahigh vacuum and by reflection-absorption infrared spectroscopy (RAIRS). The results reveal that Ag(I) carboxylates with aliphatic side chains are particularly favourable for FEBID. Following electron impact ionization, they fragment by loss of volatile CO2. The remaining alkyl radical converts to a stable and equally volatile alkene. The lower decomposition efficiency of Ag(I) benzoate and Ag(I) 3,3-dimethylbutynyl is explained by calculated average local ionization energies (ALIE) which reveal that ionization from the unsaturated carbon units competes with ionization from the coordinate bond to Ag. This can stabilise the ionized complex with respect to fragmentation. This insight provides guidance with respect to the design of novel FEBID precursors.

First-principles exploration of the versatile configurations at an alkynyl-protected coinage metal(111) interface

Alkynyl groups (R-C[triple bond, length as m-dash]C-) have attracted intense interest recently as alternative ligands to thiolates to protect atomically precise coinage metal nanoclusters, and more than two dozen compositions have been structurally resolved. However, structure determinations indicated that the interface shows strong metal sensitivity, where a staple motif is the common structural feature at the interface of Au-alkynyl nanoclusters, while the bridging motif dominates at the RC[triple bond, length as m-dash]C-/Ag and RC[triple bond, length as m-dash]C-/Cu interface. To understand their interfacial differences, we employed density functional theory (DFT) calculations to examine the versatile interfacial structures between CH3C[triple bond, length as m-dash]C- and the coinage metal surface; both the (111) surface as well as a surface with a metal adatom are investigated. We find that the alkynyl/gold(111) interface does prefer to form the staple motifs, and a linear flat-lying staple motif is preferred. The adatom occupies the bridge position and two CH3C[triple bond, length as m-dash]C- ligands lie diagonally at the fcc hollow sites with the C[triple bond, length as m-dash]C bond interacting with the surface Au by both σ- and π-coordination modes. In contrast, the bridging motif is energetically more favored on Ag(111) and Cu(111). The alkynyl carbons form strong σ, π- or σ-only bonds with the surface Ag/Cu, forming μ3-bridge coordination over the fcc hollow site. The binding strengths have the order of Cu(111) > Ag(111) > Au(111). The difference in structural preference is attributed to the intrinsic metal attributes with the different gaps of energetic penalty for surface energy, adatom creation and vacancy formation. The other two reasons are the differences of alkynyl-metal bond character and vdW interaction. We further show that this structure preference is also the preferred bonding mode of CH3C[triple bond, length as m-dash]C- on M55 clusters and the CH3S-/M(111) interface. Our insights greatly facilitate the structural elucidation and provide useful guidelines for future structure predictions in alkynyl-protected metal nanosystems.

The Self-Assembly of [{Ag3(C≡CtBu)2}n]n+ Building Units into a Template-Free Cuboctahedron and Anion-Encapsulating Silver Cages

We describe the controlled synthesis of silver acetylide clusters based on a simple polymeric [Ag₃L₂]⁺ (L = -C≡C^tBu) building block. A linear one-dimensional polymeric structure shows alternating pyramidal motifs and is the basic repeating unit forming discrete molecular cages (pentamers [X⊂Ag₁₅L₁₀]⁴⁺ and hexamers [PF₆⊂Ag₁₈L₁₂]⁵⁺) obtained by incorporating suitable templates. These motifs and a rare template-free cuboctahedral [Ag₁₂L₈]⁴⁺ cluster (tetramer) were crystallographically characterized.

Silver ethynide clusters constructed with fluorinated β-diketonate ligands

Phosphonate can act as the intermediate connector to link two silver ethynide clusters functionalized by hfac ligands together to enlarge the silver cluster.

Solvent and anion effects on the organization of a luminescent [2 + 2] BODIPY/Ag(i) metallamacrocycle in the crystalline state

The assembly of a novel BODIPY bearing peripheral vinyl–benzonitrile groups with AgX salts (X⁻ = AsF₆⁻, BF₄⁻, ClO₄⁻) leads to the recurrent formation of a [2 + 2] [Ag₂(BODIPY)₂]²⁺ type metallamacrocycle featuring emission in the crystalline state.

Highly sensitive and selective fluorescent probes for Hg2+ in Ag(i)/Cu(ii) 3D supramolecular architectures based on noncovalent interactions

Three novel Ag(i)/Cu(ii) metal–organic assemblies displayed 3D supramolecular architectures with the help of noncovalent interactions. 1 performs as a highly sensitive and selective fluorescent probe for Hg²⁺, and 2 shows a unique semiconductive nature.