Toward Luminescence Vapochromism of Tetranuclear AuI–CuI Clusters

Reversible luminescence tuning behavior in a thermal-stimuli-responsive anthracene-based coordination polymer

A new coordination complex presented a series of structural changes accompanied by photo-fluorescence (PL) changes under different temperature stimuli.

Solid-State Structures and Photoluminescence of Lamellar Architectures of Cu(I) and Ag(I) Paddlewheel Clusters with Hydrogen-Bonded Polar Guests

Two hexanuclear paddlewheel-like clusters appending six carboxylic-acid pendants have been isolated with the inclusion of polar solvent guests: [Cu₆(Hmna)₆]·7DMF (1·7DMF) and [Ag₆(Hmna)₆]·8DMSO (2·8DMSO), where H₂mna = 2-mercaptonicotininc acid, DMF = N,N’-dimethylformamide, and DMSO = dimethyl sulfoxide. The solvated clusters, together with their fully desolvated forms 1 and 2, have been characterized by FTIR, UV–Vis diffuse reflectance spectroscopy, TG-DTA analysis, and DFT calculations. Crystal structures of two solvated clusters 1·7DMF and 2·8DMSO have been unambiguously determined by single-crystal X-ray diffraction analysis. Six carboxylic groups appended on the clusters trap solvent guests, DMF or DMSO, through H-bonds. As a result, alternately stacked lamellar architectures comprising of a paddlewheel cluster layer and H-bonded solvent layer are formed. Upon UV illumination (λ_ex = 365 nm), the solvated hexasilver(I) cluster 2·8DMSO gives intense greenish-yellow photoluminescence in the solid state (λ_PL = 545 nm, Φ_PL = 0.17 at 298 K), whereas the solvated hexacopper(I) cluster 1·7DMF displays PL in the near-IR region (λ_PL = 765 nm, Φ_PL = 0.38 at 298 K). Upon complete desolvation, a substantial bleach in the PL intensity (Φ_PL < 0.01) is observed. The desorption–sorption response was studied by the solid-state PL spectroscopy. Non-covalent interactions in the crystal including intermolecular H-bonds, CH⋯π interactions, and π⋯π stack were found to play decisive roles in the creation of the lamellar architectures, small-molecule trap-and-release behavior, and guest-induced luminescence enhancement.

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.

Tripodal gold(i) polypyridyl complexes and their Cu+ and Zn2+ heterometallic derivatives. Effects on luminescence

Three gold(i) tripodal complexes containing the tris(2-pyridylmethyl)amine (TPA) ligand coordinated to Au-PR₃ moieties (PR₃ = 1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane, PTA (1), 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane, DAPTA (2) and triphenylphosphane (3)) were prepared together with a cage-like structure containing triphosphane 1,1,1-tris(diphenylphosphinomethyl)ethane (4). The luminescence of these complexes has been studied and they show a red shift upon the formation of heterometallic complexes by reaction with Zn(NO₃)₂, CuCl and [Cu(CH₃CN)₄]BF₄. The different coordination motifs of the Zn²⁺ and Cu⁺ heterometallic species and the resulting changes in the recorded absorption, emission and NMR spectra were analysed and supported by TD-DFT calculations.

Reversible Solid-State Phase Transitions between Au-P Complexes Accompanied by Switchable Fluorescence

Six complexes {(3-bdppmapy)(AuCl)₂}_n (1-6; 3-bdppmapy = N,N'-bis(diphenylphosphanylmethyl)-3-aminopyridine and tht = tetrahydrothiophene) were simultaneously formed by the reaction of Au(tht)Cl and 3-bdppmapy in CH₂Cl₂ followed by infusion with hexane. Complexes 4-6 could be produced independently by volatilizing solvent in air, solid-state heating, or solvothermal reaction. The PPh₂-Au-Cl moieties extended in different directions, forming Au-Au and Au-Au-Au interactions. Complex 4 could be converted to 5 by heating to 130 °C, with the cleavage of one Au-Au bond, while 5 reverted back to 4 upon exposure to CH₂Cl₂ vapor over 11 h. This solid-state phase transition could be recycled and was accompanied by a change in solid-state fluorescence, without obvious intensity decay over five cycles. The reason for both the phase transition and difference in photoluminescence is related to the different numbers and strengths of aurophilic interactions in each complex that could be modeled by density functional theory calculations.

Vapochromic crystals: understanding vapochromism from the perspective of crystal engineering

Vapochromic materials, which undergo colour and/or emission changes upon exposure to certain vapours or gases, have received increasing attention recently because of their wide range of applications in, e.g., chemical sensors, light-emitting diodes, and environmental monitors. Vapochromic crystals, as a specific kind of vapochromic materials, can be investigated from the perspective of crystal engineering to understand the mechanism of vapochromism. Moreover, understanding the vapochromism mechanism will be beneficial to design and prepare task-specific vapochromic crystals as one kind of low-cost 'electronic nose' to detect toxic gases or volatile organic compounds. This review provides important information in a broad scientific context to develop new vapochromic materials, which covers organometallic or coordination complexes and organic crystals, as well as the different mechanisms of the related vapochromic behaviour. In addition, recent examples of supramolecular vapochromic crystals and metal-organic-framework (MOFs) vapochromic crystals are introduced.

Pyridylphosphine supported Ag(i) and Cu(i) complexes for detection of alcohols and nitriles via structural transformations from 1D to 0D

One-dimensional chain Ag(i) and Cu(i) complexes exhibit vapochromic luminescence for the detection of alcohols and nitriles via structural transformations from 1D to 0D.

Sky-blue thermally activated delayed fluorescence (TADF) based on Ag(i) complexes: strong solvation-induced emission enhancement

Remarkable solvation-induced emission enhancement is discovered on a new Ag(i) complex showing sky-blue thermally activated delayed fluorescence (TADF).

The first representatives of tetranuclear gold(i) complexes of P,N-containing cyclophanes

The first representatives of the tetranuclear gold(i) complexes of P,N-containing cyclophanes with two 1,5-diaza-3,7-diphosphacyclooctane rings incorporated into the macrocyclic core have been obtained. The complexation leads to a change in ligand conformations so that the diazadiphosphacyclooctane fragments of the complexes adopt twist-chair conformations, and two of the four gold(i) ions are located over and under the partially collapsed macrocyclic cavity. The complexes demonstrate moderate solid-state green emission.

Synthesis, photophysical properties and cation-binding studies of bipyridine-functionalized gold(i) complexes

A new family of Au(i) complexes equipped with bipyridine function demonstrate bright luminescence response to M(ii) cations in solution.

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.

“Host–guest” binding of a luminescent dinuclear Au(i) complex based on cyclic diphosphine with organic substrates as a reason for luminescence tuneability

A dinuclear Au(i) complex with cyclic diphosphine is a versatile platform for different luminescence responses to nucleophilic and electrophilic molecules in solutions.

Adjustable coordination of a hybrid phosphine–phosphine oxide ligand in luminescent Cu, Ag and Au complexes

The mixed-donor ligand shows variable binding ability with respect to d¹⁰ metal ions to afford a series of mono- and dinuclear complexes with tunable photophysical characteristics.

Neutral copper(i) complexes featuring phosphinesulfonate chelates

The reaction of diphenylphosphinobenzenesulfonic acid with copper(i) oxide resulted in the formation of the new neutral dimeric copper(i) complex {Cu₂(DPPBS)₂·(MeOH)₂}.

Mechano-induced reversible colour and luminescence switching of a gold(i)–diphosphine complex

A gold(i)–diphosphine exhibits an intriguing dual-response (mechanochromism and mechanochromic luminescence) to mechanical stress as a consequence of the reversible neutral-to-ionic phase transition.

Photoluminescent AuCu bimetallic nanoclusters as pH sensors and catalysts

A facile and one-pot approach to the preparation of gold (Au) and copper (Cu) bimetallic nanoclusters (NCs) is unveiled. AuCu NCs reveal features of orange photoluminescence (PL), reversible pH-dependent PL properties, and efficient catalytic activity for degradation of methylene blue (MB).