Pargyline-phosphine copper(I) clusters with tunable emission for light-emitting devices

Three pargyline-phosphine copper(I) clusters, [Cu4(CC-C9H12N)3(PPh3)4](PF6) (1) and [Cu6(CC-C9H12N)4(dppy)4](X)2 (dppy = diphenyl-2-pyridylphosphine; X = PF6 for 2 and X = ClO4 for 3), were synthesized. Their structures were fully characterized using various spectroscopic methods and X-ray crystallography, which showed that the stoichiometry and nature of pargyline and phosphine ligands play an important role in tuning the structure and photophysical features of Cu(I) clusters. Interestingly, clusters 1, 2 and 3 exhibited red, orange and yellow phosphorescence with high quantum yields of 88.5%, 22.0% and 40.2%, respectively, at room temperature. Moreover, clusters 1-3 show distinct temperature-dependent emissions. The excellent luminescence performance of 1 and 3 was designed and employed for the construction of monochrome and white light-emitting devices (LEDs).

From Mono- to Polynuclear 2-(Diphenylphosphino)pyridine-Based Cu(I) and Ag(I) Complexes: Synthesis, Structural Characterization, and DFT Calculations

A series of monometallic Ag(I) and Cu(I) halide complexes bearing 2-(diphenylphosphino)pyridine (PyrPhos, L) as a ligand were synthesized and spectroscopically characterized. The structure of most of the derivatives was unambiguously established by X-ray diffraction analysis, revealing the formation of mono-, di-, and tetranuclear complexes having general formulas MXL3 (M = Cu, X = Cl, Br; M = Ag, X = Cl, Br, I), Ag2X2L3 (X = Cl, Br), and Ag4X4L4 (X = Cl, Br, I). The Ag(I) species were compared to the corresponding Cu(I) analogues from a structural point of view. The formation of Cu(I)/Ag(I) heterobimetallic complexes MM'X2L3 (M/M' = Cu, Ag; X = Cl, Br, I) was also investigated. The X-ray structure of the bromo-derivatives revealed the formation of two possible MM'Br2L3 complexes with Cu/Ag ratios, respectively, of 7:1 and 1:7. The ratio between Cu and Ag was studied by scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX) measurements. The structure of the binuclear homo- and heterometallic derivatives was investigated using density functional theory (DFT) calculations, revealing the tendency of the PyrPhos ligands not to maintain the bridging motif in the presence of Ag(I) as the metal center.

Bright near-infrared circularly polarized electrochemiluminescence from Au9Ag4 nanoclusters

Metal nanoclusters are excellent electrochemiluminescent luminophores owing to their rich electrochemical and optical properties. However, the optical activity of their electrochemiluminescence (ECL) is unknown. Herein, we achieved, for the first time, the integration of optical activity and ECL, i.e., circularly polarized electrochemiluminescence (CPECL), in a pair of chiral Au₉Ag₄ metal nanocluster enantiomers. Chiral ligand induction and alloying were employed to endow the racemic nanoclusters with chirality and photoelectrochemical reactivity. S-Au₉Ag₄ and R-Au₉Ag₄ exhibited chirality and bright-red emission (quantum yield = 4.2%) in the ground and excited states. The enantiomers showed mirror-imaged CPECL signals at 805 nm owing to their highly intense and stable ECL emission in the presence of tripropylamine as a co-reactant. The ECL dissymmetry factor of the enantiomers at 805 nm was calculated to be ±3 × 10^-3, which is comparable with that obtained from their photoluminescence. The obtained nanocluster CPECL platform shows the discrimination of chiral 2-chloropropionic acid. The integration of optical activity and ECL in metal nanoclusters provides the opportunity to achieve enantiomer discrimination and local chirality detection with high sensitivity and contrast.

Heterometallic Au(I)-Cu(I) Clusters: Luminescence Studies and 1O2 Production

Two different organometallic gold(I) compounds containing naphthalene and phenanthrene as fluorophores and 2-pyridyldiphenylphosphane as the ancillary ligand were synthesized (compounds 1 with naphthalene and 2 with phenanthrene). They were reacted with three different copper(I) salts with different counterions (PF₆^-, OTf^-, and BF₄^-; OTf = triflate) to obtain six Au(I)/Cu(I) heterometallic clusters (compounds 1a-c for naphthalene derivatives and 2a-c for phenanthrene derivatives). The heterometallic compounds present red pure room-temperature phosphorescence in both solution, the solid state, and air-equilibrated samples, as a difference with the dual emission recorded for the gold(I) precursors 1 and 2. The presence of Au(I)-Cu(I) metallophilic contacts has been identified using single-crystal X-ray diffraction structure resolution of two of the compounds, which play a direct role in the resulting red-shifted emission with respect to the gold(I) homometallic precursors. Polystyrene (PS) and poly(methyl methacrylate) (PMMA) polymeric matrices were doped with our luminescent compounds, and the resulting changes in their emissive properties were analyzed and compared with those previously recorded in the solution and the solid state. All complexes were tested to analyze their ability to produce ¹O₂ and present very good values of Φ_Δ up to 50%.

A novel heterometallic platinum(ii)–silver(i) alkynyl complex [PtAg(dppm)2(CCC6H4COOCH3-4)2Cl] with two crystal morphologies exhibiting morphology-dependent photoluminescence

A novel complex [PtAg(dppm)2(CCC6H4COOCH3-4)2Cl] with two crystal morphologies as rod-like and prism was separately obtained by manipulating the recrystallization solvents. They exhibit glamorous morphology-dependent photoluminescence.

A Photoluminescent Ag10 Cu6 Cluster Stablized by a PNNP Ligand and Phenylacetylides Selectively and Reversibly Senses Ammonia in Air and Water

A photoluminescent bimetallic cluster [Ag₁₀ Cu₆ (bdppthi)₂ (C≡CPh)₁₂ (MeOH)₂ (H₂ O)](ClO₄ )₄ (1, bdppthi=N,N'-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH₃ in air or water. The sensing of NH₃ was rapid and recoverable, with detection limits of 53 ppm (v/v) in N₂ and 21 μmol/L (0.36 ppm, w/w) for NH₃  ⋅ H₂ O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water.

Copper(I) Alkynyl Clusters with Crystallization-Induced Emission Enhancement

Four copper(I) alkynyl complexes incorporating phosphate ligands, namely, [Cu₁₆(^tBuC≡C)₁₂(PhOPO₃)₂]_n (1; PhOPO₃ = phenyl phosphate), [Cu₁₆(^tBuC≡C)₁₂(1-NaphOPO₃)₂]_n (2; 1-NaphOPO₃ = 1-naphthyl phosphate), [VO₄@Cu₂₅(^tBuC≡C)₁₉(1-NaphOPO₃)](PF₆)_0.5(F)_0.5 (3), and [PO₄@Cu₂₅(^tBuC≡C)₁₉(1-NaphOPO₃)](PF₆)_0.5(F)_0.5 (4), were solvothermally synthesized and well-characterized by IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray analysis revealed that the Cu₁₆ cluster-based coordination chain polymers 1 and 2 are formed by assembly during crystallization, while 3 and 4 contain high-nuclearity copper(I) composite clusters enclosing orthovanadate and phosphate template ions, respectively, that are supported by ROPO₃^2- ligands. Complexes 1-4 exhibit crystallization-induced emission enhancement. Their crystalline state shows strong luminescence, in striking contrast to the weak emission of the amorphous state and solution phase. A detailed investigation of the crystal structure suggests that well-arranged C-H···π and π···π interactions between the ligands are the major factors for this enhanced emission. Clusters 3 and 4 also exhibit photocurrent responses upon visible-light illumination.

Progress in electrochemiluminescence of nanoclusters: how to improve the quantum yield of nanoclusters

Classification of nanoclusters and methods to improve their quantum yield and applications.

Keep it tight: a crucial role of bridging phosphine ligands in the design and optical properties of multinuclear coinage metal complexes

Copper subgroup metal ions in the +1 oxidation state are classical candidates for aggregation via non-covalent metal-metal interactions, which are supported by a number of bridging ligands. The bridging phosphines, soft donors with a relatively labile coordination to coinage metals, serve as convenient and essential components of the ligand environment that allow for efficient self-assembly of discrete polynuclear aggregates. Simultaneously, accessible and rich modification of the organic spacer of such P-donors has been used to generate many fascinating structures with attractive photoluminescent behavior. In this work we consider the development of di- and polynuclear complexes of M(i) (M = Cu, Ag, Au) and their photophysical properties, focusing on the effect of phosphine bridging ligands, their flexibility and denticity.

Novel luminescent homo/heterometallic platinum(ii) alkynyl complexes based on Y-shaped pyridyl diphosphines

A series of dinuclear platinum(ii) alkynyl complexes [Pt2L2(C[triple bond, length as m-dash]CC6H4R-4)4] (R = H 1, CH32, But3) and unusual tetranuclear Pt(ii)-Ag(i) clusters [Pt2Ag2L(C[triple bond, length as m-dash]CC6H4R-4)6] (R = H, 4; CH3, 5; But, 6), together with novel polymer crystals [Pt2Ag2L(C[triple bond, length as m-dash]CC6H5)6]∞ ([4]∞), were synthesized by a self-assembly reaction between [NBu4]2[Pt(C[triple bond, length as m-dash]CC6H4-R-4)4] and [Ag6L6]6+ (L = 4-(3,5-(diphenylphosphine)phenyl)pyridine). These complexes were characterized by using a range of spectroscopic techniques and complexes 1, 3, 5, and [4]∞ were analysed by X-ray crystallography. Each platinum atom of the Pt(ii)-Ag(i) clusters shows an unusual asymmetric distorted square planar geometry with three alkynyl groups and one bridging L phosphorus atom. Dinuclear complexes 1-3 demonstrate solid-state weak blue luminescence, while tetranuclear Pt(ii)-Ag(i) clusters 4-6 show intense blue-green or yellow-green emission. Furthermore, the crystalline samples of polymer [4]∞ display bright yellow emission (518 nm) that is significantly red-shifted as compared to monomer crystal 4.

Alkynyl bridged cyclometalated Ir2M2 clusters: impact of the heterometal in the photo- and electro-luminescence properties

The distinct photo- and electro-luminescence properties of clusters [Ir₂M₂(ppy)₄(μ-CCC₆H₄-OMe₃)₄] (M = Ag, Cu) provide an example of the role of the CCR groups in modulating metallophillic bonding in the T₁ state.