Structure Determination of Alkynyl‐Protected Gold Nanocluster Au22(tBuC≡C)18 and Its Thermochromic Luminescence

An alkynyl‐protected gold nanocluster, Au₂₂(^tBuC≡C)₁₈ ( 1 ), has been synthesized and its structure has been determined by single‐crystal X‐ray diffraction. The molecular structure consists of a Au₁₃ cuboctahedron kernel and three [Au₃(^tBuC≡C)₄] trimeric staples. The cluster 1 has strong luminescence in the solid state with a 15 % quantum yield, and it displays interesting thermochromic luminescence as revealed by temperature‐dependent emission spectra. The enhanced room‐temperature emission is characterized as thermally activated delayed fluorescence.     

Structure Determination of Alkynyl-Protected Gold Nanocluster Au22(tBuC≡C)18 and Its Thermochromic Luminescence

An alkynyl-protected gold nanocluster, Au₂₂(^tBuC≡C)₁₈ ( 1 ), has been synthesized and its structure has been determined by single-crystal X-ray diffraction. The molecular structure consists of a Au₁₃ cuboctahedron kernel and three [Au₃(^tBuC≡C)₄] trimeric staples. The cluster 1 has strong luminescence in the solid state with a 15 % quantum yield, and it displays interesting thermochromic luminescence as revealed by temperature-dependent emission spectra. The enhanced room-temperature emission is characterized as thermally activated delayed fluorescence.     

Tandem Silver Cluster Isomerism and Mixed Linkers to Modulate the Photoluminescence of Cluster‐Assembled Materials

Silver chalcogenolate cluster assembled materials (SCAMs) are a category of promising light‐emitting materials the luminescence of which can be modulated by variation of their building blocks (cluster nodes and organic linkers). The transformation of a singly emissive [Ag₁₂(SBu^t)₈(CF₃COO)₄(bpy)₄]_n (Ag₁₂bpy, bpy=4,4′‐bipyridine) into a dual‐emissive [(Ag₁₂(SBu^t)₆(CF₃COO)₆(bpy)₃)]_n (Ag₁₂bpy‐2) via cluster‐node isomerization, the critical importance of which was highlighted in dictating the photoluminescence properties of SCAMs. Moreover, the newly obtained Ag₁₂bpy‐2 served to construct visual thermochromic Ag₁₂bpy‐2/NH₂ by a mixed‐linker synthesis, together with dichromatic core–shell Ag₁₂bpy‐2@Ag₁₂bpy‐NH₂‐2 via solvent‐assisted linker exchange. This work provides insight into the significance of metal arrangement on physical properties of nanoclusters.     

Anion‐, Solvent‐, Temperature‐, and Mechano‐Responsive Photoluminescence in Gold(I) Diphosphine‐Based Dimers

A series of [Au₂(nixantphos)₂](X)₂ (nixantphos=4,6‐bis(diphenylphosphino)‐phenoxazine; X=NO₃, 1 ; CF₃COO, 2 ; CF₃SO₃, 3 ; [Au(CN)₂], 4 ; and BF₄, 5 ) complexes that exhibit intriguing anion‐switchable and stimuli‐responsive luminescent photophysical properties have been synthesized and characterized. Depending on their anions, these complexes display yellow ( 3 ), orange ( 4 and 5 ), and red ( 1 and 2 ) emission colors. They exhibit reversible thermo‐, mechano‐, and vapochromic luminescence changes readily perceivable by the naked eye. Single‐crystal X‐ray studies show that the [Au₂(nixantphos)₂]²⁺ cations with short intramolecular Au ??? Au interactions are involved as donors in an infinite N?H ??? X (X=O and N) hydrogen‐bonded chain formation with CF₃COO^? ( 2 C ) and aurophilically linked [Au(CN)₂]^? counterions ( 4 C ). Both crystals show thermochromic luminescence; their room temperature red ( 2 C ) and orange ( 4 C ) emission turns into yellow upon cooling to 77 K. They also exhibit reversible mechanochromic luminescence by changing their emission color from red to dark ( 2 C ), and orange to red ( 4 C ). Compounds 1 – 5 also display reversible mechanochromic luminescence, altering their emission colors between orange ( 1 ) or red ( 2 ) to dark, as well as between yellow ( 3 ) or orange ( 4 and 5 ) to red. Detailed photophysical investigations and correlation with solid‐state structural data established the significant role of N?H ??? X interactions in the stimuli‐responsive luminescent behavior.     

A Tetradecanuclear Organometallic Copper(I)-Alkynide Cluster: Synthesis,Crystal Structure,and Luminescent Property

A novel high-nuclearity copper(I) cluster formulated as [Cu₁₄(tBuC≡C)₁₀(CH₃COO)₄] (1) was synthesized through comproportionation reaction under stirring condition. The tetradecanuclear copper(I) cluster was identified by single-crystal X-ray diffraction and characterized using UV–Vis, IR, thermogravimetric analysis, powder X-ray diffraction and elemental analyses. Interestingly, powder sample of 1 exhibits remarkable yellow luminescence at room temperature.     

A Room‐Temperature Luminescent AgCF3COO Complex Consisting of Cationic Complex Chains and Anionic Guests

Reaction of p‐phenylenediacetonitrile (p‐phda) with AgCF₃COO afforded the coordination polymer, {[Ag₂(p‐phda)₂] [Ag₄(CF₃COO)₆]}_n ( 1 ), where the 1D cationic [Ag₂(p‐phda)₂]²⁺ chain acts as host and the anionic [Ag₄(CF₃COO)₆]^2– as guest molecules occupy the channel between neighboring host chains. This is a rare crystal example of AgCF₃COO complex consisting of cationic complex chains and anionic guests. In addition, complex 1 exhibits luminescence at room temperature in solid state.     

General Assembly of Twisted Trigonal‐Prismatic Nonanuclear Silver(I) Clusters

A general class of C₃‐symmetric Ag₉ clusters, [Ag₉S(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)] ( 1 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(CF₃SO₃)₂] ? CF₃SO₃ ( 2 ), [Ag₉(tBuC₆H₄S)₆(dpph)₃(NO₃)₂] ? NO₃ ( 3 ), and [Ag₉(tBuC₆H₄S)₇(dpph)₃(Mo₂O₇)_0.5]₂ ? 2 CF₃COO ( 4 ) (dpph=1,6‐bis(diphenylphosphino)hexane), with a twisted trigonal‐prism geometry was isolated by the reaction of polymeric {(HNEt₃)₂[Ag₁₀(tBuC₆H₄S)₁₂]}_n, 1,6‐bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag₉ twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S^2? and CF₃SO₃^? for compound 1 , 2×CF₃SO₃^? for compound 2 , 2×NO₃^? for compound 3 , and tBuC₆H₄S^? and Mo₂O₇^2? for compound 4 ). This trigonal prism is bisected by another shrunken Ag₃ trigon at its waist position. Interestingly, two inversion‐related Ag₉ trigonal‐prismatic clusters are dimerized by the Mo₂O₇^2? ion in compound 4 . The twist is amplified by the bulkier thiolate, which also introduces high steric‐hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver–sulfur clusters (namely, compounds 5 – 8 ) with their nuclearity ranging from 6–10 were solely characterized by single‐crystal X‐ray diffraction to verify the above‐described synergetic effect of mixed ligands in the construction of Ag₉ twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal‐centered (MC) d¹⁰→d⁹s¹ transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180–300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion‐ and surface‐controlled redox processes were determined for compounds 1 and 3 as well as compound 4 , respectively.     

Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl‐Protected Body‐Centered Cubic Cluster [Au7Ag8(C≡CtBu)12]+

The synthesis, structure, substitution chemistry, and optical properties of the gold‐centered cubic monocationic cluster [Au@Ag₈@Au₆(C≡C^tBu)₁₂]⁺ are reported. The metal framework of this cluster can be described as a fragment of a body‐centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [M_nAg_8?nAu₇(C≡C^tBu)₁₂]⁺ clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [Cu_nAg₈Au_7?n(C≡C^tBu)₁₂]⁺ clusters (n=1–6), with the Cu atom(s) presumably occupying the capping site(s). The parent cluster exhibited strong emission in the near‐IR region (λ_max=818 nm) with a quantum yield of 2 % upon excitation at λ=482 nm. Its photoluminescence was quenched upon substitution with a Na⁺ ion. DFT calculations confirmed the superatom characteristics of the title compound and the sodium‐substituted derivatives.     

Thermochromic Luminescent Nest‐Like Silver Thiolate Cluster

A novel discrete open high‐nuclearity nest‐like silver thiolate cluster complex, [Ag₃₃S₃(StBu)₁₆(CF₃COO)₉(NO₃)(CH₃CN)₂](NO₃) ( 1 ), has been isolated with nitrate and S^2? anions acting as structure‐directing templates. Its similar nest‐like structure has been assembled into an extended layer [Ag₃₁S₃(StBu)₁₆(NO₃)₉]_n ( 2 ) by adjustment of auxiliary ligand. More interestingly, both complexes exhibit temperature‐dependent luminescence of high sensitivity with a large fluorescence enhancement (12‐fold for 1 , 21‐fold for 2 ), which can be easily recognized by the naked‐eye (dramatic red‐shift Δ=104 nm for 1 , larger Δ=113 nm for 2 at 77 K compared to those at 298 K). The correlation between luminescent thermochromism and temperature‐dependent variation of the coordination modes of template NO₃^? anion, Ag???S and Ag???Ag distances are also elucidated through variable‐temperature single‐crystal X‐ray crystal structure (VT‐SCXRD) analyses.     

Unprecedented Efficient Structure Controlled Phosphorescence of Silver(I) Clusters Stabilized by Carba‐closo‐dodecaboranylethynyl Ligands

{Ag₂(12‐C≡C‐closo‐1‐CB₁₁H₁₁)}_n and selected pyridine ligands have been used for the synthesis of photostable Ag^I clusters that, with one exception, exhibit for Ag^I compounds unusual room‐temperature phosphorescence. Extraordinarily intense phosphorescence was observed for a distorted pentagonal bipyramidal Ag^I₇ cluster that shows an unprecedented quantum yield of Φ=0.76 for Ag^I clusters. The luminescence properties correlate with the structures of the central Ag^I_n motifs as shown by comparison of the emission properties of the clusters with different numbers of Ag^I ions, different charges, and electronically different pyridine ligands.     

Extra Silver Atom Triggers Room‐Temperature Photoluminescence in Atomically Precise Radarlike Silver Clusters

Luminescent metal clusters show promise for applications in imaging and sensing. However, promoting emission from metal clusters at room temperature is a challenging task owing to the lack of an efficient approach to suppress the nonradiative decay process in metal cores. We report herein that the addition of a silver atom into a metal interstice of the radarlike thiolated silver cluster [Ag₂₇(S^tBu)₁₄(S)₂(CF₃COO)₉(DMAc)₄]?DMAc ( NC1 , DMAc=dimethylacetamide), which is non‐emissive under ambient conditions, produced another silver cluster [Ag₂₈(AdmS)₁₄(S)₂(CF₃COO)₁₀(H₂O)₄] ( NC2 ) that displayed bright green room‐temperature photoluminescence aided by the new ligand 1‐adamantanethiol (AdmSH). The 28th Ag atom, which hardly affects the geometrical and electronic structures of the Ag–S skeleton, triggered the emission of green light as a result of the rigidity of the cluster structure.     

From Cluster to Polymer: Ligand Cone Angle Controlled Syntheses and Structures of Copper(I) Alkynyl Complexes

Copper(I) alkynyl complexes have attracted tremendous attention in structural studies, as luminescent materials, and in catalysis, and homoleptic complexes have been reported to form polymers or large clusters. Herein, six unprecedented structures of Cu^I alkynyl complexes and a procedure to measure the cone angles of alkynyl ligands based on the crystal structures of these complexes are reported. An increase of the alkynyl cone angle in the complexes leads to a modulation of the structures from polymeric [((PhC≡CC≡C)Cu)₂(NH₃)]_∞, to a large cluster [(TripC≡CC≡C)Cu]₂₀(MeCN)₄, to a relatively small cluster [(TripC≡C)Cu]₈ (Trip=2,4,6‐iPr₃‐C₆H₂). The complexes exhibit yellow‐to‐red phosphorescence at ambient temperature in the solid state and the luminescence behavior of the Cu₂₀ cluster is sensitive to acetonitrile.     

Reversible Wide‐Range Tuneable Luminescence of a Dual‐Stimuli‐ Responsive Silver Cluster‐Assembled Material

Silver cluster‐assembled materials (SCAMs) are emerging multi‐functional materials and have attracted great attention recently. In this work, we have prepared a new SCAM of {[Ag₁₈(S^tBu)₁₀(CF₃COO)₂(PhPO₃)(PhPO₃H)₄(bpy‐NH₂)₂]?(PhPO₃H₂)}_n (denoted as Ag₁₈bpy‐NH₂), by a facile one‐pot method. Ag₁₈bpy‐NH₂ adopts a chain‐like structure made of Ag₁₈ clusters bridged by bipyridyl linkers. Ag₁₈bpy‐NH₂ exhibits reversible luminescent mechanochromism upon mechanical stimulation and solvent treatment. Moreover, it also displays luminescent thermochromism with a linear relationship of the temperature to the intensity ratio of the dual emissions over a wide temperature range of 83 to 303 K. This work might provide new insights into the assembly of multifunctional stimuli‐responsive SCAMs.     

Synthesis,Crystal Structure,and Visible Light Responses of Ti4Cu4-Oxo Clusters with Mixed Valence Copper Ions

Summaryof main observation and conclusion In order to extend the absorption spectrum of polyoxo-titanium clusters into the visible region,two new heterometal-oxo clusters Ti4CuII2CuI2(μ3-O)6(benzoate)10(MeCN)4(PTC-153)and Ti4CuII2CuI2(μ3-O)6(benzoate)8(CH3COO)2(MeCN)4(PTC-154)were success-fully synthesized.Single-crystal X-ray diffraction and X-ray photoelectron spectroscopy studies showed that these two heterometallic Ti4Cu4-oxo clusterspossessed Chinese knot-shape structure and mixed valence Cu^1+/2+ions.UV-visible spectroscopyanalysis demonstrated that the visible light region ab-sorption of PTC-153and PTC-154 could be significantly enhanced by doping copper.Furthermore,their visible-light driven photocurrent responses were studied by using samples of PTC-153and PTC-154as electrode precursors.     

An All‐Alkynyl Protected 74‐Nuclei Silver(I)–Copper(I)‐Oxo Nanocluster: Oxo‐Induced Hierarchical Bimetal Aggregation and Anisotropic Surface Ligand Orientation

The hardness of oxo ions (O^2?) means that coinage‐metal (Cu, Ag, Au) clusters supported by oxo ions (O^2?) are rare. Herein, a novel μ₄‐oxo supported all‐alkynyl‐protected silver(I)–copper(I) nanocluster [Ag_74?xCu_xO₁₂(PhC≡C)₅₀] ( NC‐1 , avg. x=37.9) is characterized. NC‐1 is the highest nuclearity silver–copper heterometallic cluster and contains an unprecedented twelve interstitial μ₄‐oxo ions. The oxo ions originate from the reduction of nitrate ions by NaBH₄. The oxo ions induce the hierarchical aggregation of Cu^I and Ag^I ions in the cluster, forming the unique regioselective distribution of two different metal ions. The anisotropic ligand coverage on the surface is caused by the jigsaw‐puzzle‐like cluster packing incorporating rare intermolecular C?H???metal agostic interactions and solvent molecules. This work not only reveals a new category of high‐nuclearity coinage‐metal clusters but shows the special clustering effect of oxo ions in the assembly of coinage‐metal clusters.     

Copper(II) and Sodium(I) Complexes based on 3,7‐Diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide: Synthesis,Characterization, and Catalytic Activity

The reaction of 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane (DAPTA) with metal salts of Cu^II or Na^I/Ni^II under mild conditions led to the oxidized phosphane derivative 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide (DAPTA=O) and to the first examples of metal complexes based on the DAPTA=O ligand, that is, [Cu^II(μ‐CH₃COO)₂(κO‐DAPTA=O)]₂ ( 1 ) and [Na(1κOO′;2κO‐DAPTA=O)(MeOH)]₂(BPh₄)₂ ( 2 ). The catalytic activity of 1 was tested in the Henry reaction and for the aerobic 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO)‐mediated oxidation of benzyl alcohol. Compound 1 was also evaluated as a model system for the catechol oxidase enzyme by using 3,5‐di‐tert‐butylcatechol as the substrate. The kinetic data fitted the Michaelis–Menten equation and enabled the obtainment of a rate constant for the catalytic reaction; this rate constant is among the highest obtained for this substrate with the use of dinuclear Cu^II complexes. DFT calculations discarded a bridging mode binding type of the substrate and suggested a mixed‐valence Cu^II/Cu^I complex intermediate, in which the spin electron density is mostly concentrated at one of the Cu atoms and at the organic ligand.     

Synthesis of Bimetallic Copper‐Rich Nanoclusters Encapsulating a Linear Palladium Dihydride Unit

The structurally precise Cu‐rich hydride nanoclusters [PdCu₁₄H₂(dtc/dtp)₆(C≡CPh)₆] (dtc: di‐butyldithiocarbamate ( 1 ); dtp: di‐isopropyl dithiophosphate ( 2 )) were synthesized from the reaction of polyhydrido copper clusters [Cu₂₈H₁₅(S₂CNⁿBu₂)₁₂]⁺ or [Cu₂₀H₁₁{S₂P(OⁱPr)₂}₉] with phenyl acetylene in the presence of Pd(PPh₃)₂Cl₂. Their structures and compositions were determined by single‐crystal X‐ray diffraction and the results supported by ESI‐mass spectrometry. Hydride positions in 1 were confirmed by single‐crystal neutron diffraction. Each hydride is connected to one Pd⁰ and four Cu^I atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH₂]^2? unit and its Cu₁₄ bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded.     

The unprecedented role of a Cu<Superscript>II</Superscript> cryptand in the luminescence properties of a Eu<Superscript>III</Superscript> cryptate complex

Abstract  A Eu^III cryptate complex constructed from a Cu^II cryptand with an L ^tBu ligand, [Eu^IIICu₂^II(L ^tBu)₂(NO₃)₃(MeOH)], and the corresponding Ca^II and Na^I cryptates, [Ca^IICu₂^II(L ^tBu)₂(NO₃)₂(MeOH)₂] and [Na^ICu₂^II(L ^tBu)₂(Me₂CO)](BPh₄), have been synthesized and characterized in order to shed light on the essential role of Cu^II in the luminescence of a Eu^III cryptate. The unprecedented role of a Cu^II cryptand makes it possible to produce lanthanide luminescence in a Eu^III cryptate complex and is successfully elucidated by comparison with the corresponding Ca^II and Na^I cryptates. Graphical abstract   Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A three‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from biphenyl‐3,4′,5‐tricarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands

Coordination polymers (CPs) built by coordination bonds between metal ions/clusters and multidentate organic ligands exhibit fascinating structural topologies and potential applications as functional solid materials. The title coordination polymer, poly[diaquabis(μ₄‐biphenyl‐3,4′,5‐tricarboxylato‐κ⁴O³:O^3′:O^4′:O⁵)tris[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]dicopper(II)dicopper(I)], [Cu^II₂Cu^I₂(C₁₅H₇O₆)₂(C₁₂H₁₀N₄)₃(H₂O)₂]_n, was crystallized from a mixture of biphenyl‐3,4′,5‐tricarboxylic acid (H₃bpt), 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐bib) and copper(II) chloride in a water–CH₃CN mixture under solvothermal reaction conditions. The asymmetric unit consists of two crystallographically independent Cu atoms, one of which is Cu^II, while the other has been reduced to the Cu^I ion. The Cu^II centre is pentacoordinated by three O atoms from three bpt³⁻ ligands, one N atom from a 1,4‐bib ligand and one O atom from a coordinated water molecule, and the coordination geometry can be described as distorted trigonal bipyramidal. The Cu^I atom exhibits a T‐shaped geometry (CuN₂O) coordinated by one O atom from a bpt³⁻ ligand and two N atoms from two 1,4‐bib ligands. The Cu^II atoms are extended by bpt³⁻ and 1,4‐bib linkers to generate a two‐dimensional network, while the Cu^I atoms are linked by 1,4‐bib ligands, forming one‐dimensional chains along the [20] direction. In addition, the completely deprotonated μ₄‐η¹:η¹:η¹:η¹ bpt³⁻ ligands bridge one Cu^I and three Cu^II cations along the a (or [100]) direction to form a three‐dimensional framework with a (10³)₂(10)₂(4².6.10².12)₂(4².6.8².10)₂(8) topology via a 2,2,3,4,4‐connected net. An investigation of the magnetic properties indicated a very weak ferromagnetic behaviour.     

Copper(I) π‐Complexes with 2‐Butyne‐1,4‐diol. Synthesis and Crystal Structure of Na[CuCl2(HOCH2C≡CCH2OH)]·2H2O

Crystals of anionic Na[CuCl₂(HOCH₂C≡CCH₂OH)]·2H₂O π‐complex have been synthesized by interaction of 2‐butyne‐1,4‐diol with CuCl in a concentrated aqueous NaCl solution and characterized by X‐ray diffraction at 100 K. The crystals are triclinic: space group , a = 7.142(3), b = 7.703(3), c = 10.425(4) Å, α = 105.60(3), β = 99.49(3), γ = 110.43(3)°, V = 495.9(4) ų, Z = 2, R = 0.0203 for 3496 reflections. The structure is built of discrete [CuCl₂(HOCH₂C≡CCH₂OH)]^? anionic stacks and polymeric cations among the stacks. The Cu^I atom adopts trigonal planar coordination of two Cl^? anions and the C≡C bond of 2‐butyne‐1,4‐diol, Cu–(C≡C) distance is equal to 1.903(3) Å. Na⁺ cations environment is octahedral and consists of O and Cl atoms. The crystal packing is governed by strong hydrogen bonds of O–H···Cl and O–H···O types.