Abstract:σ-Metalation of tetracene can change the emission color of and introduce new structural dimensionality to the organic chromophore. Two synthetic entries to σ-metallotetracenes have been explored, leading to emissive mononuclear (Ph 3 PAu I )-tetracene (1) and cis-[Br(Et 3 P) 2 Pt II ]-tetracene (2) and binuclear (R 3 PAu I ) 2 -tetracenyldiacetylide (R = Ph (4), Me ( 5)) and trans-[I(Et 3 P) 2 Pt II ] 2tetracenyldiacetylide (6). Metalation can lower the emission energy of tetracene up to 0.53 eV. The X(Et 3 P)… Show more
“…In this respect, it is important to note that Ag I compounds showing TADF behaviour are not common, due to the lack of accessible MLCT states that typically results in the emission of the intraligand nature. Moreover, gold(I) ion with even higher oxidation potential than those of copper(I) and silver(I) ones predominantly serves as an external heavy atom, which promotes 3 ππ phosphorescence, dual 1 ππ/ 3 ππ emission or perturbs 1 IL fluorescence . On the other hand, intense phosphorescence emerges in the Au I aggregates, with extensive metallophilic bonding from the variety of charge transfer transitions involving Au … Au interactions .…”
Section: Resultsmentioning
confidence: 99%
“…Moreover,g old(I) ion with even higher oxidation potentialt han those of copper(I) and silver(I) ones predominantly serves as an externalh eavy atom, which promotes 3 pp phosphorescence [7c, 30] ,d ual 1 pp/ 3 pp emission [31] or perturbs 1 IL fluorescence. [32] On the other hand, intense phosphorescence emerges in the Au I aggregates,w ith extensive metallophilic bondingf rom the variety of charget ransfer transitions involving Au … Au interactions. [33] Therefore, gold(I) ions are considered asi nappropriate blocks for the design of TADF materials, though delayedf luorescence has been proposed for a[ Au(P 2 )(PS)] complex (PS = 2-diphenylphosphinobenzenethiolate) on the basis of emission characteristics measured at 298 and 77 K. [11a] Thus, to the best of our knowledge, cluster 10 is the first Au I -containing compound, for which the TADF phenomenonhas been unambiguously established.…”
Section: Photophysical Properties and Computational Studiesmentioning
The series of cyanide-bridged coordination polymers [(P )CuCN] (1), [(P )Cu{M(CN) }] (M=Cu 3, Ag 4, Au 5) and molecular tetrametallic clusters [{(P )MM'(CN)} ] (MM'=Cu 6, Ag 7, AgCu 8, AuCu 9, AuAg 10) were obtained using the bidentate P and tetradentate P phosphane ligands (P =1,2-bis(diphenylphosphino)benzene; P =tris(2-diphenylphosphinophenyl)phosphane). All title complexes were crystallographically characterized to reveal a zig-zag chain arrangement for 1 and 3-5, whereas 6-10 possess metallocyclic frameworks with different degree of metal-metal bonding. The d -d interactions were evaluated by the quantum theory of atoms in molecules (QTAIM) computational approach. The photophysical properties of 1-10 were investigated in the solid state and supported by theoretical analysis. The emission of compounds 1 and 3-5, dominated by metal-to-ligand charge transfer (MLCT) transitions located within {CuP } motifs, is compatible with thermally activated delayed fluorescence (TADF) behaviour and a small energy gap between the T and S excited states. The luminescence characteristics of 6-10 are strongly dependent on the composition of the metal core; the emission band maxima vary in the range 484-650 nm with quantum efficiency reaching 0.56 (6). The origin of the emission for 6-8 and 10 at room temperature is assigned to delayed fluorescence. AuCu cluster 9, however, exhibits only phosphorescence that corresponds to theoretically predicted large value ΔE(S -T ). DFT simulation highlights a crucial impact of metallophilic bonding on the nature and energy of the observed emission, the effect being greatly enhanced in the excited state.
“…In this respect, it is important to note that Ag I compounds showing TADF behaviour are not common, due to the lack of accessible MLCT states that typically results in the emission of the intraligand nature. Moreover, gold(I) ion with even higher oxidation potential than those of copper(I) and silver(I) ones predominantly serves as an external heavy atom, which promotes 3 ππ phosphorescence, dual 1 ππ/ 3 ππ emission or perturbs 1 IL fluorescence . On the other hand, intense phosphorescence emerges in the Au I aggregates, with extensive metallophilic bonding from the variety of charge transfer transitions involving Au … Au interactions .…”
Section: Resultsmentioning
confidence: 99%
“…Moreover,g old(I) ion with even higher oxidation potentialt han those of copper(I) and silver(I) ones predominantly serves as an externalh eavy atom, which promotes 3 pp phosphorescence [7c, 30] ,d ual 1 pp/ 3 pp emission [31] or perturbs 1 IL fluorescence. [32] On the other hand, intense phosphorescence emerges in the Au I aggregates,w ith extensive metallophilic bondingf rom the variety of charget ransfer transitions involving Au … Au interactions. [33] Therefore, gold(I) ions are considered asi nappropriate blocks for the design of TADF materials, though delayedf luorescence has been proposed for a[ Au(P 2 )(PS)] complex (PS = 2-diphenylphosphinobenzenethiolate) on the basis of emission characteristics measured at 298 and 77 K. [11a] Thus, to the best of our knowledge, cluster 10 is the first Au I -containing compound, for which the TADF phenomenonhas been unambiguously established.…”
Section: Photophysical Properties and Computational Studiesmentioning
The series of cyanide-bridged coordination polymers [(P )CuCN] (1), [(P )Cu{M(CN) }] (M=Cu 3, Ag 4, Au 5) and molecular tetrametallic clusters [{(P )MM'(CN)} ] (MM'=Cu 6, Ag 7, AgCu 8, AuCu 9, AuAg 10) were obtained using the bidentate P and tetradentate P phosphane ligands (P =1,2-bis(diphenylphosphino)benzene; P =tris(2-diphenylphosphinophenyl)phosphane). All title complexes were crystallographically characterized to reveal a zig-zag chain arrangement for 1 and 3-5, whereas 6-10 possess metallocyclic frameworks with different degree of metal-metal bonding. The d -d interactions were evaluated by the quantum theory of atoms in molecules (QTAIM) computational approach. The photophysical properties of 1-10 were investigated in the solid state and supported by theoretical analysis. The emission of compounds 1 and 3-5, dominated by metal-to-ligand charge transfer (MLCT) transitions located within {CuP } motifs, is compatible with thermally activated delayed fluorescence (TADF) behaviour and a small energy gap between the T and S excited states. The luminescence characteristics of 6-10 are strongly dependent on the composition of the metal core; the emission band maxima vary in the range 484-650 nm with quantum efficiency reaching 0.56 (6). The origin of the emission for 6-8 and 10 at room temperature is assigned to delayed fluorescence. AuCu cluster 9, however, exhibits only phosphorescence that corresponds to theoretically predicted large value ΔE(S -T ). DFT simulation highlights a crucial impact of metallophilic bonding on the nature and energy of the observed emission, the effect being greatly enhanced in the excited state.
“…These results suggest some gold participation in the excited states of geminally diaurated aryls, whereas phosphorescence of normal gold(I) aryls and alkynyls is ligand-centered. [25][26][27][28][29][31][32][33] The available crystal structures suggest disrupted aromaticity, as do the optimized geometries. Perturbations of carbon-carbon bond lengths decrease with distance from the dimetallation site.…”
Gold catalysts and catalyst precursors have commanded attention for more than a decade. Several reviews [1][2][3][4][5][6][7][8] highlight the utility of gold in organic transformations. Recent efforts have succeeded in isolating putative intermediates of alkene and alkyne transformations. In 2008, Hammond and coworkers generated aurated g-lactone complexes from allenes. [9] Later, Bertrand, Hashmi, and their respective coworkers independently reported vinylgold(I) species derived from alkynes. [10] GagnØ and co-workers first implicated geminally diaurated species as resting states in catalytic cycles of gold by reacting vinylgold(I) species with one equivalent of gold(I) cation. [11] Fürstner and co-workers later showed that transmetalation from boron using the Gagosz complex [12] ([Ph 3 PAu]NTf 2 , Tf= trifluoromethanesulfonyl) gave only geminally diaurated species regardless of the number of equivalents used. [13] Such species are not recent discoveries. Work by Nesmeyanov and co-workers in the 1970s produced the first geminally diaurated aromatic ring systems, bis(triphenylphosphine)gold(I) complexes of ferrocene. [14] The work was soon expanded to include adducts of heteroarenes. [15] Schmidbaur and co-workers have reported geminally diaurated diketones and disulfones, [16] as well as arenes, although with lithiated reagents. [17] Most recently, Hashizume et al. generated a gemdiaurated 2-naphthyl species by protonation with perchloric acid of mono-gold complexes, with subsequent capture of the released cationic gold fragment. [18] In contrast to the recent development of diaurated vinyl complexes, the frontier of arene gem-diauration remains relatively quiet. A very recent report by GagnØ and co-workers disclosed a preparation of several diaurated species from parent monoaurated arenes. [19] Such species deserve further investigation.Due to the isolobality of the proton and the LAu + fragment (L = phosphine, carbene, and others), [20,21] diaurated arenes are analogues of Wheland intermediates in electrophilic aromatic substitutions (Scheme 1). However, future studies would benefit from mild methods of generating these complexes. All established routes require hazardous reagents, or they entail the loss of one half equivalent of aryl liganda costly issue in the case of value-added organic ligands. Here, we disclose syntheses of geminally diaurated arenes from arylboronic acids [22] without the need for activating silver salts, Brønsted acids, or Grignard reagents. The reactions are mild, quick, and high-yielding. In most cases the isolated solids are pure. No air-or moisture-free techniques were employed. All products are fully characterized by 1 H and 31 P NMR spectroscopy and elemental analysis, unless otherwise noted; 13 C NMR data are not reported because attempts to detect the bridging, ipso-carbon were unsuccessful. [23] For several of the products, crystals suitable for X-ray diffraction analysis were grown.Reaction of one-half equivalent of arylboronic acid with [Ph 3 PAu]NTf 2 in diethyl ether led t...
“…2a ). According to the previous literatures 55 – 57 , the intense vibronic band at 250–310 nm, together with the moderately intense band at 400–525 nm ( λ max = 454 and 484 nm for the two absorption maxima), are assigned to 1 L b and 1 L a bands of anthracene unit, respectively. In addition, the broad and intense band locating at 310–395 nm ( λ max = 331 nm) belongs to π–π* transition of platinum acetylide (–C≡C–Pt–C≡C–) segment, which is absent for the counterpart compound 4 (see the structure in Fig.…”
Section: Resultsmentioning
confidence: 65%
“…2a, b ). Such phenomena are primarily ascribed to the overlapping between Pt d -orbitals and anthracene p -orbitals, resulting in the enhancement of π-electron delocalization 45 , 55 – 57 . Fig.…”
Innovative technologies are highly pursued for the detection and avoidance of counterfeiting in modern information society. Herein, we report the construction of photo-responsive supramolecular polymers toward fluorescent anti-counterfeit applications, by taking advantage of multicycle anthracene‒endoperoxide switching properties. Due to σ-metalation effect, photo-oxygenation of anthracene to endoperoxide is proceeded under the mild visible light irradiation conditions, while the backward conversion occurs spontaneously at room temperature. Supramolecular polymers are formed with cooperative nucleation‒elongation mechanism, which facilitate fluorescence resonance energy transfer process via two-component co-assembly strategy. Fluorescence resonance energy transfer efficiency is delicately regulated by either light-triggered anthracene‒endoperoxide conversion or vapor-induced monomer–polymer transition, leading to high-contrast fluorescent changes among three different states. On this basis, dual-mode anti-counterfeiting patterns have been successfully fabricated via inkjet printing techniques. Hence, cooperative supramolecular polymerization of photo-fluorochromic molecules represents an efficient approach toward high-performance anti-counterfeit materials with enhanced security reliability, fast response, and ease of operation.
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