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The near-infrared (NIR) polymethine dye Styryl-13 emitting at approximately 925 nm has recently been suggested as a reference fluorophore for determining the quantum yield (QY) of the NIR photoluminescence of dispersed single-walled carbon nanotubes (SWNTs). Ju et al. reported the QY for SWNTs to be as high as 20% on the basis of 11% QY for Styryl-13 in methanol (Science 2009, 323, 1319). We directly compared the fluorescence of Styryl-13 and Styryl-20 (emitting at approximately 945 nm) with that of the standard fluorophore Rhodamine 6G using a spectrometer with a broad visible-NIR detection range. QYs of 2.0 (4.5) and 0.52 (0.80)% were determined for Styryl-13 and Styryl-20 in methanol (propylene carbonate), respectively. Correspondingly, the above-mentioned photoluminescence efficiency of SWNTs appears to be strongly overestimated. We also discuss singlet oxygen as an alternative NIR reference. A total QY of 1.4% was measured for the emission of singlet oxygen at 1275 nm, as photosensitized by C70 fullerene in air-saturated carbon tetrachloride.

Probing electrofluorochromism (EFC) at the molecular level remains challenging. Here we study the strongly charge state‐dependent photoluminescence of vanadyl phthalocyanine. We report vibrationally resolved absorption and laser‐induced fluorescence (LIF) spectra of samples comprising both the mass‐selected neutral molecule (VOPc⋅, a stable radical) and its cation produced upon electron ionization (EI) isolated in 5 K neon matrices. Ionization of the essentially non‐emissive VOPc⋅ forms a high‐spin diradical cation (VOPc+..) which shows profound photoluminescence (PL) in the NIR range. This unique phenomenon is potentially of interest for NIR‐emitting electro‐optic devices. [ABSTRACT FROM AUTHOR]

Combining phase‐dependent photoluminescence (PL) measurements and quantum chemical calculations is a powerful approach to help understand the influence of the molecular surroundings on the PL properties. Herein, a phosphine functionalized amidinate was used to synthesize a recently presented bimetallic gold complex, featuring an unusual charge separation. The latter was subsequently used as metalloligand to yield heterotetrametallic complexes with an Au‐M‐M‐Au "molecular wire" arrangement (M=Cu, Ag, Au) featuring metallophilic interactions. All compounds show bright phosphorescence in the solid state, also at ambient temperature. The effect of the molecular environment on the PL was studied in detail for these tetrametallic complexes by comparative measurements in solution, in the solid state and in the gas phase and contrasted to time‐dependent density functional theory computations. [ABSTRACT FROM AUTHOR]

The synthesis of linear symmetric ethynyl‐ and acetylide‐amidinates of the coinage metals is presented. Starting with the desilylation of the complexes [{Me3SiC≡CC(NDipp)2}2M2] (Dipp=2,6‐diisopropylphenyl) (M=Cu, Au) it is demonstrated that this compound class is suitable to serve as a versatile metalloligand. Deprotonation with n‐butyllithium and subsequent salt metathesis reactions yield symmetric tetranuclear gold(I) acetylide complexes of the form [{(PPh3)AuC≡CC(NDipp)2}2M2] (M=Cu, Au). The corresponding Ag complex [{(PPh3)AuC≡CC(NDipp)2}2Ag2] was obtained by a different route via metal rearrangement. All compounds show bright blue or blue‐green microsecond long phosphorescence in the solid state, hence their photophysical properties were thoroughly investigated in a temperature range of 20–295 K. Emission quantum yields of up to 41 % at room temperature were determined. Furthermore, similar emissions with quantum yields of 15 % were observed for the two most brightly luminescent complexes in thf solution. [ABSTRACT FROM AUTHOR]

Bis(acetylido) aurates(I) and thallium(I) trifluoromethylsulfonates were used to synthesize AuI–TlI metallopolymers, displaying novel and unusual structural motifs of the metal–metal backbones in the solid state: a discrete molecular cluster, 1D chains of interconnected dimers, tetramers, or dodecamers of Au–Tl units, and a 2D‐plane network, consisting of alternating edge‐linked (AuTl)6 and (AuTl)4 cycles. The formation of the different architectures was primarily controlled by the steric demand of the acetylide‐substituent groups. Thus, the bulkiest 2,6‐diisopropylphenyl derivative yielded a molecular cluster [Tl2Au3]. Most compounds showed bright visible photoluminescence with quantum yields of up to 25 % at ambient temperature. The color of the emitted light significantly differs with the network structure. Furthermore, theoretical studies of singlet excitations in the molecular cluster, as well as NMR and mass‐spectrometric investigations of the fragmentation of the metallopolymers in solution are described in detail. Bigger for better or worse: Luminescent AuI–TlI metallopolymers, displaying novel and unusual structural motifs of the metal–metal backbones in the solid state, are reported. [ABSTRACT FROM AUTHOR]

Bis-phenylpropynyl-functionalized imidazolium salts and their corresponding gold and copper N-heterocyclic carbene (NHC) complexes were prepared in order to investigate their potential application for the synthesis of heterometallic coinage metal compounds. By transmetalation reactions with different precious metal sources, including copper and silver phenylacetylides [MCCPh] n (M=Cu, Ag), polynuclear compounds were obtained, which were further investigated for their photoluminescence properties. Additionally, one gold NHC complex was post-functionalized by autocatalytic hydration of the alkynyl side chains. Time-dependent DFT investigations of singlet electronic excitations in representative complexes revealed excited states of diverse character, as determined by the specific complex structure and metallophilic interactions. [ABSTRACT FROM AUTHOR]

OH functionalized triarylphosphines were used to assemble zirconocene-based metalloligands with phosphine donor sites in varying positions. These complexes were subsequently treated with different gold precursors to obtain early-late heterometallic compounds in which the metal atoms exhibit different intermetallic distances. All compounds were fully investigated by spectroscopic techniques, photoluminescence measurements and single crystal X-ray diffraction. Quantum chemical calculations were also performed. Some compounds show bright emission even at room temperature with quantum yields of up to 19 % (excitation at 350 nm). Furthermore, the reactivity of dimethyl zirconocene derivatives towards gold complexes was investigated, revealing simultaneous ligand exchange and transmetallation reactions. [ABSTRACT FROM AUTHOR]

Diphenylphosphinoethyl-functionalised imidazolium salts and their silver-carbene complexes were used to synthesise a series of di- and trinuclear gold complexes through ligand exchange and transmetallation, respectively. Besides a few positively charged macrocyclic compounds with different anions (both with and without activation of the carbene function), we were able to obtain neutral polynuclear complexes by varying the gold precursor. The synthesised gold complexes show a variety of photophysical properties, including bright white photoluminescence at ambient temperature. [ABSTRACT FROM AUTHOR]

We have prepared digold(I) complexes with the rigid-backbone diphosphane ligands PhanePhos, xyl-PhanePhos, and Ph2-GemPhos. All complexes were characterized by single-crystal X-ray diffraction, NMR, IR, Raman, and photoluminescence (PL) spectroscopy. [PhanePhos(AuCl)2] and [GemPhos(AuCl)2] show a very similar ligand scaffold, but different (aurophilic vs. nonaurophilic) intramolecular Au-Au distances. Absorption and PL spectra of both compounds are quite similar. Theoretical investigations reveal that the excited states are of different character (i.e., influenced by the Au-Au contacts). The respective transition energies, however, lie close to each other, thus resulting in similar experimental spectra. The gold atoms appear to produce a significant heavy-atom effect in the electronic relaxation dynamics. Thus, [PhanePhos(AuCl)2] and [GemPhos(AuCl)2] both show bright-green millisecond-long phosphorescence at low temperatures, although the latter is quenched at ambient temperature. [PhanePhos(AuCl)2] and [GemPhos(AuCl)2] were also used as catalysts in the intra- and intermolecular hydroamination of alkynes. Good to quantitative conversions on a reasonable time scale were observed. The overall performance of these catalysts in the studied reactions was similar, showing that Au-Au contacts do not have a major influence on the catalytic performance. [ABSTRACT FROM AUTHOR]

Cover Feature: Efficient Blue Phosphorescence in Gold(I)-Acetylide Functionalized Coinage Metal Bis(amidinate) Complexes (Chem. Eur. J. 70/2020) Keywords: acetylide; amidinate; desilylation; gold; luminescence EN acetylide amidinate desilylation gold luminescence 16564 16564 1 12/18/20 20201215 NES 201215 B The synthesis of linear symmetric ethynyl- and acetylide- amidinates b of the coinage metals is presented. Acetylide, amidinate, desilylation, gold, luminescence. [Extracted from the article]

A novel and neutral trinuclear gold complex ligated by a phosphinoethyl functionalised NHC is highlighted in the middle of the picture. The complex is carried and lifted by three laborious golden bears. Furthermore, the molecule is surrounded by the terms “aurophilicity” and “photoluminescence”: both of these very interesting characteristics were unified and studied in the compounds reported in the Full Paper by P. W. Roesky et al. on page 601 ff. [ABSTRACT FROM AUTHOR]

Abstract: Two new ligands with {(Ph2P)2N} functions have been synthesized and introduced into the chemistry of gold(I). The first ligand N,N-bis(diphenylphosphanyl)-4-(phenyldiazenyl)aniline (DPPPA) is a derivative of an azo dye. Reaction of DPPPA with [(tht)AuCl] (tht = tetrahydrothiophene) in CH2Cl2 gave the dye functionalized bimetallic gold(I) complex [DPPPA(AuCl)2] (1). The second ligand, m-N,N,N′,N′-tetrakis(diphenylphosphanyl)xylylenediamine, (DPPXA), has two {(Ph2P)2N} functional groups in a xylylenediamine backbone. DPPXA was reacted with [(tht)AuCl] to give the tetrametallic gold complex [DPPXA(AuCl)4] (2). Reaction of DPPXA with [(COD)MCl2] (M = Pd, Pt) (COD = 1,5-cyclooctadiene) in DMSO resulted in the bimetallic palladium and platinum complexes [DPPXA(MCl2)2] (M = Pd (3), Pt (4)). DPPPA and all metal complexes were characterized by single crystal X-ray diffraction. The complexes demonstrate quite different photophysical properties. Whereas no photoluminescence (PL) was detected for 1 and 4, complex 2 shows red PL in methylene chloride solution as well as in the solid state. Near-infrared emission at ∼800 nm was observed for complex 3 at temperatures below ∼50 K. [Copyright &y& Elsevier]

The reaction of [(AuCI)2dppm] (dppm = Ph2PCH2PPh2) with PhP(SiMe3)2 and P(SiMe3)3 leads to the formation of the gold cluster compound [Au18(P)2(PPh)4(PHPh)(dppm)6]Cl3 (1). The crystal structure investigation shows a central Au7P2 unit formed by two P centered gold tetrahedra sharing the central gold corner. This central unit is surrounded by a 10-membered Au5P5 ring which, together with the remaining six gold atoms, builds two Au4P rectangular and two Au3P trigonal pyramids. The different structure motifs are connected by the phosphine ligands. The compound has been characterized using microanalysis, IR spectroscopy, ESI-MS, and 31P NMR techniques. Luminescence measurements have also been carried out. [ABSTRACT FROM AUTHOR]