Cupriphication of gold to sensitize d10–d10 metal–metal bonds and near-unity phosphorescence quantum yields

Outer-shell s0/p0 orbital mixing with d10 orbitals and symmetry reductionuponcupriphicationofcyclic trinucleartrigonal-planargold(I) complexes are found to sensitize ground-state Cu(I)–Au(I) covalent bonds and near-unity phosphorescence quantum yields. Heterobimetallic Au4Cu2 {[Au4(μ-C2,N3-EtIm)4Cu2(μ-3,5-(CF3)2Pz)2], (4a)}, Au2Cu {[Au2(μ-C2,N3-BzIm)2Cu(μ-3,5-(CF3)2Pz)], (1) and [Au2(μ-C2, N3-MeIm)2Cu(μ-3,5-(CF3)2Pz)], (3a)}, AuCu2 {[Au(μ-C2,N3-MeIm)Cu2(μ3,5-(CF3)2Pz)2], (3b) and [Au(μ-C2,N3-EtIm)Cu2(μ-3,5-(CF3)2Pz)2], (4b)} and stacked Au3/Cu3 {[Au(μ-C2,N3-BzIm)]3[Cu(μ-3,5-(CF3)2Pz)]3, (2)} formuponreactingAu3 {[Au(μ-C2,N3-(N-R)Im)]3 ((N-R)Im = imidazolate; R =benzyl/methyl/ethyl =BzIm/MeIm/EtIm)} with Cu3 {[Cu(μ-3,5(CF3)2Pz)]3 (3,5-(CF3)2Pz = 3,5-bis(trifluoromethyl)pyrazolate)}. The crystal structures of 1 and 3a reveal stair-step infinite chains whereby adjacent dimer-of-trimer units are noncovalently packed via twoAu(I)⋯Cu(I)metallophilicinteractions,whereas 4a exhibitsa hexanuclear cluster structure wherein two monomer-of-trimer units are linked by a genuine d10–d10 polar-covalent bond with ligandunassisted Cu(I)–Au(I) distances of 2.8750(8) Å each—the shortest such an intermolecular distance ever reported between any two d10 centers so as to deem it a “metal–metal bond” vis-à-vis “metallophilic interaction.” Density-functional calculations estimate 35– 43kcal/molbindingenergy,akintotypicalM–Msingle-bondenergies. Congruently, FTIR spectra of4a showmultiple far-IR bands within 65– 200 cm−1, assignable to vCu-Au as validated by both the Harvey–Gray method of crystallographic-distance-to-force-constant correlation and dispersive density functional theory computations. Notably, the heterobimetallic complexes herein exhibit photophysical properties that are favorable to those for their homometallic congeners, due to threefold-to-twofold symmetry reduction, resulting in cuprophilicsensitizationinextinctioncoefficientandsolid-state photoluminescence quantum yields approaching unity (ΦPL = 0.90–0.97 vs. 0–0.83 for Au3 and Cu3 precursors), which bodes well for potential future utilization in inorganic and/or organic LED applications

Photochemical and Photophysical Properties of Mononuclear and Multinuclear Closed Shell D10 Coinage Metal Complexes and Their Metallo-organometallic Adducts

This dissertation covers the studies of two major topics: the photochemistry of mononuclear and multinuclear gold(I) complexes and synthetic approaches to tailor photophysical properties of cyclic trinuclear d10 complexes. First a detailed photochemical examination into the photoreactivity of neutral mononuclear and multinuclear gold(I) complexes is discussed, with the aim of gold nanoparticle size and shape control for biomedical and catalysis applications. Next is a comprehensive systematic synthetic approach to tailor the photophysical properties of cyclic trinuclear d10 complexes. This synthetic approach includes an investigation of structure-luminescence relationships between cyclic trinuclear complexes, an examination into their π-acid/π-base reactivity with heavy metal cations and an exploration into the photophysical properties of new heterobimetallic cyclic trinuclear complexes. These photophysical properties inspections are used to screen materials for their employment in molecular electronic devices such as organic light-emitting diodes (OLEDs) and thin film transistors (OTFTs)

Eutectoid flux growth and physical properties of single crystal Ln117Ni54-ySn112-z (Ln = Gd-Dy)

Ln117Ni53-ySn112-z (Ln = Gd-Dy) have been grown via the eutectoid flux growth method, characterized using single crystal X-ray diffraction, and determined to have a face centered cubic unit cell with lattice parameters of a = 30.070(4), 29.862(5), and 29.823(4) Å for the Gd, Dy, and Tb analogues. The compounds contain over 1100 atoms per unit cell with a complex bonding network and multiple magnetic sublattices. In addition, disorder is prevalent throughout the structure. These physical characteristics are ideal when searching for ultralow thermal conductivity materials. Magnetic susceptibility and electrical properties are presented, and all analogues exhibit positive Curie-Weiss constants, suggesting ferromagnetic interactions in each compound, in addition to a spin-glass component to the magnetic behavior

Soft metal cations trigger sandwich-cluster luminescence of a new Au(I)-vinylimidazolate cyclic trinuclear complex

The formation of heterobimetallic complexes from parent cyclic trinuclear complexes (CTCs) of gold(I) has become straightforward in recent years with this team and others showing that the strategy leads to strengthened Au-M’ bonding and optoelectronic properties. A new gold(I)-vinylimidazolate CTC, 1, was prepared and the formation of highly-emissive sandwich adducts with the soft metal cations Cu+, Ag+, and Tl+, 2 – 4, respectively, was investigated. Compound 1 does not exhibit peculiar emissive properties at room or cryogenic temperatures as the adducts do. Its unit cell packing displays an unprecedented collection of repeating units for CTCs. While the intermolecular Au…Au distances are versatile (3.470, 3.673, and 4.045 Å), they connect only single Au centres from adjacent CTCs and form extended circular networks. Hirshfeld surface analyses mapped the new CTC contours underlining the possible cooperative effects of not only metallophilic interactions but also C-H…π and hydrogen bonding in the packing of 1 (as opposed to the dominance of the former in most other reported CTCs). DFT calculations validate the formation of sandwich-like structures for compounds 2 - 4 with averaged Au–M distances of 2.665 Å, 2.802 Å, and 3.036 Å, respectively, close by to experimental crystal data obtained for similar sandwich compounds

Putting ScTGa₅ (T = Fe, Co, Ni) on the Map: How Electron Counts and Chemical Pressure Shape the Stability Range of the HoCoGa₅ Type

We explore the factors stabilizing one member of the diverse structures encountered in Ln–T–E systems (Ln = lanthanide or similar early d-block element, T = transition metal, E = p-block element): the HoCoGa₅ type, an arrangement of atoms associated with unconventional superconductivity. We first probe the boundaries of its stability range through the growth and characterization of ScTGa₅ crystals (T = Fe, Co, Ni). After confirming that these compounds adopt the HoCoGa₅ type, we analyze their electronic structure using density functional theory (DFT) and DFT-calibrated Hückel calculations. The observed valence electron count range of the HoCoGa₅ type is explained in terms of the 18-<i>n</i> rule, with <i>n</i> = 6 for the Ln atoms and <i>n</i> = 2 for the T sites. The role of atomic sizes is investigated with DFT-chemical pressure (DFT-CP) analysis of ScNiGa₅, which reveals negative pressures within the Ga sublattice as it stretches to accommodate the Sc and T atoms. This CP scheme is consistent with HoCoGa₅-type gallides only being observed for relatively small Ln and T atoms. These conclusions account for the relative positions of the HoCoGa₅, BaMg₄Si₃, and Ce₂NiGa₁₀ types in a structure map, demonstrating how combining the 18-<i>n</i> and CP schemes can guide our understanding of Ln–T–E systems

Polymorphic, Porous, and Host–Guest Nanostructures Directed by Monolayer–Substrate Interactions: Epitaxial Self-Assembly Study of Cyclic Trinuclear Au(I) Complexes on HOPG at the Solution–Solid Interface

Synthesis, crystallographic characterization, and molecular self-assembly of two novel cyclotrimeric gold­(I) complexes, Au₃[3,5-(COOEt)₂Pz]₃ (Au₃Pz₃) and Au₃[(<i>n</i>-Pr–O)­CN­(Me)]₃ (Au₃Cb₃) was studied. Single crystal X-ray crystallography data reveal that both gold­(I) complexes have one-dimensional stacking patterns caused by intermolecular Au­(I)···Au­(I) aurophilic interactions. The Au₃Pz₃ trimer units stack with two alternate and symmetrical Au­(I)···Au­(I) interactions while the Au₃Cb₃ units have three alternating and nonsymmetrical Au­(I)···Au­(I) interactions. Molecular self-assembly of the gold­(I) complexes on the 1-phenyloctane/highly ordered pyrolytic graphite (HOPG) (0001) solution–solid interface is studied with scanning tunneling microscopy (STM). The gold­(I) cyclotrimers form epitaxial nanostructures on the HOPG surface. At a concentration of ∼1 × 10^–4 M, Au₃Pz₃ complexes exhibit a single morphology, while Au₃Cb₃ complexes exhibit polymorphology. Two polymorphs, one nonporous and the other porous, are observed at 22.0 ± 2.0 °C for Au₃Cb₃ complexes. A nonporous, low-surface-density (0.82 molecules/nm²) Au₃Cb₃ nanostructure forms first and then transforms into a high-density (1.43 molecules/nm²) porous nanostructure. This is the first time any porous surface nanostructure is reported for an organometallic system. The porous structure is thought to be stabilized by a combination of hydrogen bonding and monolayer–substrate interactions. These pores are utilized to incorporate pyrene into the film, rendering this the first organometallic host–guest system imaged at the solid–solution interface. Molecular and periodic density functional theory (DFT) calculations shed light on the two-dimensional topography and polymorphic self-assembly revealed by STM; these calculations suggest significant electronic hybridization of the Au₃ trimer orbitals and HOPG. The multiple-technique approach used herein provides insights concerning molecule–substrate and molecule–molecule interactions

Eutectoid Flux Growth and Physical Properties of Single Crystal Ln₁₁₇Ni_{54–<i>y</i>}Sn_{112–<i>z</i>} (Ln = Gd–Dy)

Ln₁₁₇Ni_{53–<i>y</i>}Sn_{112–<i>z</i>} (Ln = Gd–Dy) have been grown via the eutectoid flux growth method, characterized using single crystal X-ray diffraction, and determined to have a face centered cubic unit cell with lattice parameters of <i>a</i> = 30.070(4), 29.862(5), and 29.823(4) Å for the Gd, Dy, and Tb analogues. The compounds contain over 1100 atoms per unit cell with a complex bonding network and multiple magnetic sublattices. In addition, disorder is prevalent throughout the structure. These physical characteristics are ideal when searching for ultralow thermal conductivity materials. Magnetic susceptibility and electrical properties are presented, and all analogues exhibit positive Curie–Weiss constants, suggesting ferromagnetic interactions in each compound, in addition to a spin-glass component to the magnetic behavior

Eutectoid Flux Growth and Physical Properties of Single Crystal Ln₁₁₇Ni_{54–<i>y</i>}Sn_{112–<i>z</i>} (Ln = Gd–Dy)

Ln₁₁₇Ni_{53–<i>y</i>}Sn_{112–<i>z</i>} (Ln = Gd–Dy) have been grown via the eutectoid flux growth method, characterized using single crystal X-ray diffraction, and determined to have a face centered cubic unit cell with lattice parameters of <i>a</i> = 30.070(4), 29.862(5), and 29.823(4) Å for the Gd, Dy, and Tb analogues. The compounds contain over 1100 atoms per unit cell with a complex bonding network and multiple magnetic sublattices. In addition, disorder is prevalent throughout the structure. These physical characteristics are ideal when searching for ultralow thermal conductivity materials. Magnetic susceptibility and electrical properties are presented, and all analogues exhibit positive Curie–Weiss constants, suggesting ferromagnetic interactions in each compound, in addition to a spin-glass component to the magnetic behavior

Molecular and Electronic Structure of Cyclic Trinuclear Gold(I) Carbeniate Complexes: Insights for Structure/Luminescence/Conductivity Relationships

An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold­(I) carbeniates, [Au₃(RNCOR′)₃] (R, R′ = H, Me, ⁿBu, or ^cPe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au₃(MeNCOⁿBu)₃], [Au₃(ⁿBuNCOMe)₃], [Au₃(ⁿBuNCOⁿBu)₃], and [Au₃(^cPeNCOMe)₃] are presented. Changes in R and R′ lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au₃(RNCOR′)₃] was investigated via molecular and solid-state simulations. Calculations on [Au₃(HNCOH)₃] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au--Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (λ). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimerdoped within a poly­(9-vinylcarbazole) hostproduced a colossal increase in current density from ∼1 to ∼1000 mA/cm². Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold­(I) carbeniates