Heterobimetallic Gold/Ruthenium Complexes Synthesized via Post-functionalization and Applied in Dual Photoredox Gold Catalysis

The synthesis of heterobimetallic Au^I/Ru^II complexes of the general formula syn- and anti-[{AuCl}( L1 ∩ L2 ){Ru(bpy)₂}][PF₆]₂ is reported. The ditopic bridging ligand L1 ∩ L2 refers to a P,N hybrid ligand composed of phosphine and bipyridine substructures, which was obtained via a post-functionalization strategy based on Diels-Alder reaction between a phosphole and a maleimide moiety. It was found that the stereochemistry at the phosphorus atom of the resulting 7-phosphanorbornene backbone can be controlled by executing the metal coordination and the cycloaddition reaction in a different order. All precursors, as well as the mono- and multimetallic complexes, were isolated and fully characterized by various spectroscopic methods such as NMR, IR, and UV-vis spectroscopy as well as cyclic voltammetry. Photophysical measurements show efficient phosphorescence for the investigated monometallic complex anti-[( L1 ∩ L2 ){Ru(bpy)₂}][PF₆]₂ and the bimetallic analogue syn-[{AuCl}( L1 ∩ L2 ){Ru(bpy)₂}][PF₆]₂, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic Au^I/Ru^II complexes syn- and anti-[{AuCl}( L1 ∩ L2 ){Ru(bpy)₂}][PF₆]₂ are both active catalysts in the P-arylation of aryldiazonium salts promoted by visible light with H-phosphonate affording arylphosphonates in yields of up to 91 %. Both dinuclear complexes outperform their monometallic counterparts.     

Creation of cationic iridium(III) complexes with aggregation-induced phosphorescent emission (AIPE) properties by increasing rotation groups on carbazole peripheries

Three cationic iridium complexes containing 4,7-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)-1,10-phenanthroline (L(1)) and 4,7-bis(3',6'-di-tert-butyl-6-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3,9'-bi(9H-carbazol)-9-yl)-1,10-phenanthroline (L(2)) as the ancillary ligands, namely, [Ir(ppy)(2)(L(1))]PF(6) (1), [Ir(ppy)(2)(L(2))]PF(6) (2) and [Ir(oxd)(2)(L(2))]PF(6) (3) (ppy is 2-phenylpyridine, oxd is 2,5-diphenyl-1,3,4-oxadiazole), have been designed and prepared. With more intramolecular rotational units on the ancillary ligand (L(2)), 2 and 3 possess a unique aggregation-induced phosphorescent emission (AIPE) property. This phenomenon was unprecedentedly observed in the cationic iridium(III) complexes. In order to investigate the underlying mechanism of this AIPE behavior, their photophysical, temperature-dependent aggregation properties as well as theoretical calculations, were performed. The results suggest that restricted intramolecular rotation is responsible for the AIPE of cationic complexes. Moreover, photoluminescent quantum yields in the neat film, thermal stabilities and off/on luminescence switching of 2 were investigated, revealing its potential application as a candidate for LECs and organic vapor sensing.     

A cationic iridium(III) complex showing aggregation-induced phosphorescent emission (AIPE) in the solid state: synthesis, characterization and properties

We report the synthesis and characterization of two cationic iridium(III) complexes with dendritic carbazole ligands as ancillary ligands, namely, [Ir(ppy)(2)L3]PF(6) (1) and [Ir(ppy)(2)L4]PF(6) (2), where L3 and L4 represent 3,8-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)-1,10-phenanthroline and 3,8-bis(3',6'-di-tert-butyl-6-(3,6-di-tert-butyl-9H-carbazol-9-yl)-3,9'-bi(9H-carbazol)-9-yl)-1,10-phenanthroline, respectively. Their photophysical properties have been investigated and compared. The results have shown that complex 2 is aggregation-induced phosphorescent emission (AIPE) active and exhibits the highest photoluminescent quantum yield (PLQY) of 16.2% in neat film among the reported cationic Ir(III) complexes with AIPE activity. In addition, it also enjoys redox reversibility, good film-forming ability, excellent thermal stability as well as off/on luminescence switching properties, revealing its potential application as a candidate for light-emitting electrochemical cells and organic vapor sensing. To explore applications in biology, 2 was used to image cells.     

Stepwise Increase of NdIII-Based Phosphorescence by AIE-Active Sensitizer: Broadening the AIPE Family from Transition Metals to Discrete Near-Infrared Lanthanide Complexes**

We designed two near-infrared (NIR) lanthanide complexes [( L )₂-Nd(NO₃)₃] ( L =TPE₂-BPY for 1 , TPE-BPY for 2 ) by employing aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) derivatives as sensitizers, which possessed matched energy to Nd^III, prevented competitive deactivation under aggregation, even shifted the excitation window toward 600 nm by twisted intramolecular charge transfer. Furthermore, benefiting from the 4 f electron shielding effect and antenna effect, the enhanced excitation energies of the AIE-active sensitizers by structural rigidification transferred into the inert Nd^III excited state through ³LMCT, affording the first aggregation-induced phosphorescence enhancement (AIPE)-active discrete NIR-emitting lanthanide complexes. As 1 equipped with more AIE-active TPE than 2 , L →Nd energy transfer efficiency in the former was higher than that in the latter under the same conditions. Consequently, the crystal of 1 exhibited one of the longest lifetimes (9.69 μs) among Nd^III-based complexes containing C−H bonds.     

Strong Solid‐state Luminescence Enhancement in Supramolecular Assemblies of Polyoxometalate and “Aggregation‐Induced Emission”‐active Phospholium

Two new supramolecular fluorescent hybrid materials, combining for the first time [M₆O₁₉]^2? (M=Mo, W) polyoxometalates (POMs) and aggregation‐induced emission (AIE)‐active 1‐methyl‐1,2,3,4,5‐pentaphenyl‐phospholium ( 1⁺ ), were successfully synthesized. This novel molecular self‐assembling strategy allows designing efficient solid‐state emitters, such as (1)₂[W₆O₁₉] , by directing favorably the balance between the AIE and aggregation‐caused quenching (ACQ) effects using both anion‐π⁺ and H‐bonding interactions in the solid state. Combined single‐crystal X‐ray diffraction, Raman, UV‐vis and photoluminescence analyses highlighted that the nucleophilic oxygen‐enriched POM surfaces strengthened the rigidity of the phospholium via strong C?H???O contacts, thereby exalting its solid‐state luminescence. Besides, the bulky POM anions prevented π–π stacking interactions between the luminophores, blocking detrimental self‐quenching effects.     

Die Pyridinaddukte der Goldhalogenide. 2. Darstellung,Eigenschaften und Kristallstruktur von AuCl · NC5H5 und Aul · NC5H5

Pyridine Adducts of the Gold Halides. 2. Synthesis, Properties, and Crystal Structure of AuCl · NC₅H₅ and AuI · NC₅H₅ AuCl · py is formed by the reaction of AuCl · S(CH₂C₆H₅)₂ with pyridine in absolute Ethanol. AuI · py can be obtained from AuI and pyridine in toluene. Both compounds are sensitive to light and thermically instable. AuI · py decomposes already above ?30°C. AuCl · py crystallizes monoclinic with 16 formula units in the space group C2/c, AuI · py is orthorhombic with the space group Pnnm and 8 formula units per unit cell. The structures of the adducts are built up by linear Au(py)₂ and AuX₂ groups, which are linked together to tetranuclear, chainlike complexes AuX₂? Au(py)₂? Au(py)₂? AuX₂ by weak gold-gold bonds. (AuI · py)₄ forms a linear Au₄ chain and possesses nearly the symmetry D_2h. The shortest Au-Au distance being 299.0 pm. In the centrosymmetrical (AuCl · py)₄ an Au₄-zig-zag chain with Au? Au distances of 324.9 and 341.6 pm is observed. The gold-ligand bond lengths are: AuCl · py: Au? Cl = 228 pm, Au? N = 209 pm; AuI · py: Au? I = 254.4, Au? N = 202 pm. The IR spectra and the luminescence properties are discussed.     

(Benzyl isocyanide)gold(I) pyrimidine‐2‐thiolate complex: Synthesis and biological activity

The reaction of [(Me₂S)AuCl] with an equimolar amount of benzyl isocyanide (PhCH₂NC) ligand led to the formation of complex [(PhCH₂NC)AuCl] ( 1 ). The solid‐state structure of 1 was determined using the X‐ray diffraction method. Through a salt metathesis reaction, the chloride ligand in 1 was replaced by pyrimidine‐2‐thiolate (SpyN^?) to afford the complex [(PhCH₂NC)Au(η¹‐S‐Spy)] ( 2 ), which was characterized spectroscopically. The cytotoxic activities of 1 and 2 were evaluated against three human cancer cell lines: ovarian carcinoma (SKOV3), lung carcinoma (A549) and breast carcinoma (MCF‐7). Complex 2 showed higher cytotoxicity than cisplatin against SKOV3 and MCF‐7 cancer cell lines. It showed a strong anti‐proliferative activity with IC₅₀ of 7.80, 6.26 and 6.14 μM, compared with that measured for cisplatin which was 7.62, 12.36 and 11.47 μM, against A549, SKOV3 and MCF‐7 cell lines, respectively. The induction of cellular apoptosis by 2 was also studied on MCF‐7 cell line. Our results indicated that 2 could induce apoptosis in cancerous cells in a dose‐dependent manner.     

Synthese und Struktur von K[Au(AuCl)(AuPPh3)8)](PF6)2

Synthesis and Structure of K[Au(AuCl)(AuPPh₃)₈)](PF₆)₂ Photolysis of a mixture of Ph₃PAuCl and Ph₃PAuN₃ (1 : 3) in toluene/THF yields in the presence of Na₂[(C₅H₅)V(CO)₃] the new cluster cation [Au(AuCl)(AuPPh₃)₈]⁺. It crystallizes from CH₂Cl₂ after addition of KPF₆ as K[Au(AuCl)(AuPPh₃)₈](PF₆)₂ · 4 CH₂Cl₂. The compound forms a tetragonal structure with the space group P4/n and a = 2552.6(3), c = 1401.1(1) pm, Z = 2. The cluster cations with a spheroidal topology are built up of a centered Au₈ crown whose central gold atom in addition binds a AuCl group. The cluster occupies with its center and AuCl group a fourfold axis of the space group. The radial bonds between the central and the peripheral Au atoms are in the range of 263.7 to 268.4 pm, while the distances between the peripheral atoms are longer with 291.7 to 350.9 pm.     

Medium-Ring Strategy Enables Multiple Resonance Emitters with Twisted Geometry and Fast Spin-Flip to Suppress Efficiency Roll-Off

Suppressing aggregation-caused quenching (ACQ) effect and reducing device efficiency roll-off are both crucial yet challenging for multi-resonance (MR) emitters. Herein, we put forward a medium-ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR-emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin-orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium-ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 10⁸ s⁻¹ and RISC rate as fast as 10⁶ s⁻¹. Accordingly, DTBA-B2N3 enables to assemble high-performance blue organic light-emitting diodes (OLEDs) with maximum external quantum efficiency (EQE_max) of 30.9 % and alleviated efficiency roll-off (EQE₁₀₀₀: 20.5 %).     

Two-Step Dielectric Responsive Organic-Inorganic Hybrid Material with Mid-Band Light Emission

Hybrid organic-inorganic perovskite (HOIP) have received tremendous scientific attention because of the phase transition and photovoltaic properties. However, achieving the special perovskite structure with both two-step dielectric response and luminescence characteristics is rarely reported. Herein, we report an organic-inorganic hybrid perovskite, [(BA)₂ ⋅ PbI₄] (Compound 1, BA=n-butylamine) by introducing flexible organic cations (HBA⁺), with direct mid-band gap as 2.28 eV. Interestingly, this material exhibits two-step reversible dielectric response at 350 K and 460 K (in heating process), respectively. Besides, the photoluminescence was found: it emits charming green light under 365 nm lamp (Photoluminescence quantum yield is 9.52 %). The outstanding two-step dielectric response and luminescence characteristics of this compound might pave the way for the application of dielectric and ferroelectric functional materials in temperature sensors and mechanical switches.     

Unexpected Isomerization of Hexa-tert-butyl-octaphosphane

Octaphosphane {cyclo-(P₄tBu₃)}₂ ( 1 ) undergoes an unexpected isomerization reaction to the constitutional isomer 2,2′,2′′,2′′′,3,3′-hexa-tert-butyl-bicyclo[3.3.0]octaphosphane ( 2 ) in the presence of Lewis acidic metal salts. The mechanism of this reaction is discussed and elucidated with DFT calculations. The results underline the fascinating similarity between phosphorus-rich and isolobal carbon compounds. The new bicyclic octaphosphane 2 shows a dynamic behavior in solution and reacts with [AuCl(tht)] (tht=tetrahydrothiophene) to give a mono- ([AuCl( 2 -κP³)], 3 ) and a dinuclear complex ([(AuCl)₂( 2 -κP³,κP^3′)], 4 ). With cis-[PdCl₂(cod)] (cod=1,5-cyclooctadiene), the chelate complex ([PdCl₂( 2 -κ²P²,P^2′)], 5 ) with a different coordination mode of the ligand was obtained.     

Synthesis and characterization of Ru/Au,Pd/Au,Pd/2Au,Pt/2Au and Cu/2Au heterometallic complexes of cyclodiphosphazane cis-{(o-MeOC6H4O)P(μ-NBu)}2

Mononuclear complexes of cyclodiphosphazane with an uncoordinated phosphorus centre [RuCl₂(η⁶-cymene){l-κP}] (1a) (L = cis-{(o-MeOC₆H₄O)P(μ-N^tBu)}₂) and [PdCl₂(PEt₃){l-κP}] (1b) react with 1 equiv. of [AuCl(SMe₂)] to afford Ru^II/Au^I and Pd^II/Au^I heterodinuclear complexes [RuCl₂(η⁶-cymene){μ-l-κP,κP}AuCl] (2) and [PdCl₂(PEt₃){μ-l-κP,κP}AuCl] (3), respectively. Heterotrinuclear complexes [PdCl₂{μ-l-κP,κP}₂(AuCl)₂] (4), [PtCl₂{μ-l-κP,κP}₂(AuCl)₂] (5) and [CuI{μ-l-κP,κP}₂(AuCl)₂] (6) containing Pd^II/2Au^I, Pt^II/2Au^I and Cu^I/2Au^I metal centers have been synthesized from the reactions of trans-[PdCl₂{l-κP}₂] (1c), cis-[PtCl₂{l-κP}₂] (1d) and [CuI{{l-κP}₂] (1f) respectively, with 2 equiv. of [AuCl(SMe₂)]. Molecular structures of complexes 2, 3 and 4 were established by single crystal X-ray diffraction studies.     

Unprecedented Sensitization of Visible and Near‐Infrared Lanthanide Luminescence by Using a Tetrathiafulvalene‐Based Chromophore

Ligand L was synthesized and then coordinated to [Ln(hfac)₃] ? 2 H₂O (Ln^III=Tb, Dy, Er; hfac^?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion) and [Ln(tta)₃]?2 H₂O (Ln^III=Eu, Gd, Tb, Dy, Er, Yb; tta^?=2‐thenoyltrifluoroacetonate) to give two families of dinuclear complexes [Ln₂(hfac)₆( L )] ? C₆H₁₄ and [Ln₂(tta)₆( L )] ? 2 CH₂Cl₂. Irradiation of the ligand at 37 040 cm^?1 and 29 410 cm^?1 leads to tetrathiafulvalene‐centered and 2,6‐di(pyrazol‐1‐yl)‐4‐pyridine‐centered fluorescence, respectively. The ligand acts as an organic chromophore for the sensitization of the infrared Er^III (6535 cm^?1) and Yb^III (10 200 cm^?1) luminescence. The energies of the singlet and triplet states of L are high enough to guarantee an efficient sensitization of the visible Eu^III luminescence (17 300–14 100 cm^?1). The Eu^III luminescence decay can be nicely fitted by a monoexponential function that allows a lifetime estimation of (0.49±0.01) ms. Finally, the magnetic and luminescence properties of [Yb₂(hfac)₆( L )] ? C₆H₁₄ were correlated, which allowed the determination of the crystal field splitting of the ²F_7/2 multiplet state with M_J=±1/2 as ground states.     

Matrix Coordination Induced Emission in a Three-Dimensional Silver Cluster-Assembled Material

Developing highly luminescent and extensively stable silver cluster-assembled materials (SCAMs) from the inferior luminogens and unstable silver cluster is an important and challenging issue. Herein, a new luminescent three-dimensional SCAM ( Ag₁₂CPPP , [Ag₁₂(StBu)₆(CF₃COO)₆(CPPP)₂(DMAc)₁₂]_n; CPPP=2,5-bis(4-cyanophenyl)-1,4-bis(4-(pyridine-4-yl)-phenyl)-1,4-dihydropyrrolo[3,2-b]pyrrole, DMAc=dimethylacetamide) was designed and synthesized with a quadridentate rigid emission ligand ( CPPP ) and a silver–chalcogenolate cluster (SCC) containing 12 Ag^I atoms. The luminescence study indicates that CPPP is an aggregation-caused quenching (ACQ) molecule with twisted intramolecular charge transfer (TICT) character. Benefiting from the strong immobilization effect in the robust framework, the quantum yield of CPPP is greatly enhanced in Ag₁₂CPPP compared with that of CPPP in solution or in the solid state. As a result, Ag₁₂CPPP exhibits typical matrix coordination induced emission (MCIE) effect. Such efficient rigidifying methodology provides a promising approach for enhancing luminescence of ACQ molecules in an aggregated state and strengthening the silver cluster in an unstable state.     

Self‐Assembled Triple‐Stranded Lanthanide Dimetallic Helicates with a Ditopic Ligand Derived from Bis(benzimidazole)pyridine and Featuring an (4‐Isothiocyanatophenyl)ethynyl Substituent

Bis(2‐{6‐(diethylcarbamoyl)‐4‐[(4‐isothiocyanatophenyl)ethynyl]pyridin‐2′‐yl}‐1‐ethylbenzimidazol‐5‐yl)methane ( L ^G ) reacts with trivalent lanthanide ions in acetonitrile to yield triple‐stranded dimetallic helicates [Ln₂( L ^G )₃]⁶⁺. ¹H‐NMR Data point to the helicates being the only species formed under stoichiometric conditions and having a time‐averaged D₃ symmetry on the NMR time scale. The photophysical properties of L ^G and its helicates are discussed with respect to the closely related ligands L ^B , L ^E , and their complexes, two ligands devoid of the isothiocyanatophenylethynyl substituent. The quantum yield of the ligand fluorescence is three times smaller compared to L ^E , while that of the Eu^III‐centered luminescence (1.1%) is three times larger. On the other hand, the luminescence of Tb^III is not sensitized by L ^G . This is explained in terms of energy differences between the singlet and triplet states on one hand, and between the 0‐phonon transition of the triplet state and the excited metal ion states on the other. This work demonstrates that bulky substituents in the 4‐position of the pyridine ring do not prevent the formation of triple‐stranded helicates, opening the way for luminescent probes that can easily be coupled to biological materials.     

N‐Heterocyclic Carbenes and Imidazole‐2‐thiones as Ligands for the Gold(I)‐Catalysed Hydroamination of Phenylacetylene

Gold(I) complexes of 1‐[1‐(2,6‐dimethylphenylimino)alkyl]‐3‐(mesityl)imidazol‐2‐ylidene (C^Imine_R), 1,3‐dimesitylimidazol‐2‐ylidene (IMes) and of the corresponding thione derivatives (S^Imine_R and IMesS) were prepared and structurally characterised. The solid‐state structure of the C^Imine_R and S^Imine_R gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^Imine_tBu with [AuCl(SMe₂)] led to the formation of [(C^Imine_tBu)AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^Imine_tBu)₂Au]⁺, with AuCl₂^? as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^Imine_tBu)AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.     

Intramolecular d10–d10 interactions in neutral,dinuclear Au(I) complexes supported by amino-thiazoline- and -thiazole-based P,N-phosphine ligands

The ligands N-(diphenylphosphino)-thiazoline-2-amine (1), N-(diphenylphosphino)thiazol-2-amine (2) and N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine 3, readily reacted with [AuCl(THT)] in dichloromethane to form the linearly coordinated complexes [AuCl(1-κP)] (5), [AuCl(2-κP)] (6) and [AuCl(3-κP)] (7), respectively. Facile deprotonation with t-BuOK or Na₂CO₃ of 5–7 afforded the stable, neutral dinuclear complexes [AuCl(1_—H-κP,κN)]₂ (8), [AuCl(2_—H-κP,κN)]₂ (9) and [AuCl(3_—H-κP,κN)]₂ (10), respectively. The crystal structures of the mononuclear complexes 5, 6 and 7 and of the dinuclear complexes 8, 9 and 10 have been determined by X-ray diffraction. The latter represent rare examples of neutral complexes supported by bridging P,N-ligands which display intramolecular Au(I)···Au(I) d¹⁰–d¹⁰ interactions, in the range 2.8592(4)–2.8831(4) Å.     

Gold(I) complexes containing ionic phosphine ligands with a cobaltocenium backbone

The reaction of [(η⁵-R₂PC₅H₄)₂Co][PF₆] with (Me₂S)AuCl (1:2) resulted in {[(η⁵-R₂PC₅H₄)₂Co](AuCl)₂}[PF₆] (R = Ph, Cy, or ⁱ Pr). With a 1:1 ratio of [(η⁵-R₂PC₅H₄)Co(η⁵-C₅H₅)][PF₆] to (Me₂S)AuCl, yellow crystalline {[(η⁵-R₂PC₅H₄)Co(η⁵-C₅H₅)](AuCl)}[PF₆] was produced. The reaction of {[(η⁵-Cy₂PC₅H₄)Co(η⁵-C₅H₅)](AuCl)}[PF₆] with phenyl acetylene gave {[(η⁵-Cy₂PC₅H₄)Co(η⁵-C₅H₅)][Au(C≡C–Ph)]}[PF₆], while the reaction of {[(η⁵-Cy₂PC₅H₄)₂Co](AuCl)₂}[PF₆] with phenyl acetylene produced the unusual ionic complex {[(η⁵-Cy₂PC₅H₄)₂Co][Au(C≡C–Ph)]₂}[Au(C≡C–Ph)₂]. The structure of this complex has been characterized by X-ray crystallography, and a possible pathway for its formation is suggested. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Acridine N-Heterocyclic Carbene Gold(I) Compounds: Tuning from Yellow to Blue Luminescence

The synthesis and the luminescence features of three gold(I)-N-heterocyclic carbene (NHC) complexes are presented to study how the n-alkyl group can influence the luminescence properties in the crystalline state. The mononuclear gold(I)-NHC complexes, [( L¹ )Au(Cl)] ( 1 ), [( L² )Au(Cl)] ( 2 ), and [( L³ )Au(Cl)] ( 3 ) were isolated from the reactions between [(tht)AuCl] and corresponding NHC ligand precursors, [N-(9-acridinyl)-N’-(n-butyl)-imidazolium chloride, ( L¹ .HCl)], [N-(9-acridinyl)-N’-(n-pentyl)-imidazolium chloride, ( L² .HCl)] and [N-(9-acridinyl)-N’-(n-hexyl)-imidazolium chloride, ( L³ .HCl)]. Their single-crystal X-ray analysis reveals the influence of the n-alkyl groups on solid-state packing. A comparison of the luminescence features of 1 – 3 with n-alkyl substituents is explored. The molecules 1 – 3 depicted blue emission in the solution state, while the yellow emission (for 1 ), greenish-yellow emission (for 2 ), and blue emission (for 3 ) in the crystalline phase. This paradigm emission shift arises from n-butyl to n-pentyl and n-hexyl in the crystalline state due to the carbon-carbon rotation of the n-alkyl group, which tends to promote unusual solid packing. Hence n-alkyl group adds a novel emission property in the crystalline state. Density Functional Theory and Time-Dependent Density Functional Theory calculations were carried out for monomeric complex, N-(9-acridinyl)-N’-(n-heptyl)imidazole-2-ylidene gold(I) chloride and dimeric complex, N-(9-acridinyl)-N’-(n-heptyl)imidazole-2-ylidene gold(I) chloride to understand the structural and electronic properties.     

Adduct effects on structure and luminescence in a series of new dithiocarbamatogold(I) complexes

Reaction of [AuCl(SMe₂)] with NaL·H₂O (L = ethyl(pyridine-4-yl methyl)dithiocarbamate (epdtc) or methyl(2-(pyridin-2-yl)ethyl)dithiocarbamate (mpdtc)) affords a series of neutral dinuclear gold(I) complexes bridged by each dithiocarbamate ligand, [Au(L)]₂. The successive reaction of [Au(L)]₂ with organic acids such as isophthalic acid (m-pa) and maleic acid (ma) produces 1:1 adducts, [Au(L)]₂·(organic acid). The crystal structure of [Au(L)]₂·(m-pa) is a 1D polymer formed via hydrogen bonds between the free pyridyl and the carboxylic acid moiety. For the dinuclear moiety, strong intradinuclear aurophilic interactions (Au(I)–Au(I) = 2.7783(8) Å and 2.7525(7) Å) exist, but interdinuclear interactions are weak (3.2551(8)–3.2733(8) Å). The dinuclear gold(I) complexes, [Au(epdtc)]₂ and [Au(mpdtc)]₂, show a bright luminescence at 562.5 and 552.0 nm in solid state, respectively, but their organic acid adducts, [Au(L)]₂·(organic acid), have no luminescent properties. This dramatic difference in properties between the gold(I) complexes and their adducts may be ascribed to the weakness of the internuclear Au(I)–Au(I) interaction including crystal packing.