52 research outputs found

    Near-Infrared Luminescence in Trinuclear Mixed-Metal Chalcogenolate Complexes of the Types [M2_{2}Ti(EPh)6_{6}(PPh3_{3})2_{2}] (M = Cu, Ag; E = S, Se) and [Na(thf)3_{3}]2_{2}[Ti(SPh)6_{6}]

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    The optical properties of four new trinuclear chalcogenolato bridged metal complexes [Ag2_{2}Ti(SPh)6_{6}(PPh3_{3})2_{2}], [Na(thf)3_{3}]2_{2}[Ti(SPh)6_{6}], [Cu2_{2}Ti(SePh)6_{6}(PPh3_{3})2_{2}], and [Ag2_{2}Ti(SePh)6_{6}(PPh3_{3})2_{2}] have been investigated by absorption and photoluminescence spectroscopy as well as time-dependent density functional theory (TDDFT) calculations and compared to the results published recently for [Cu2_{2}Ti(SPh)6_{6}(PPh3_{3})2_{2}]. All of these compounds are distinguished by efficient near-infrared luminescence at ∼880–1200 nm in the solid state at low temperatures, which remains quite intense for the copper–titanium complexes at ambient temperature with PL quantum yields of 9.5 and 4.8% at λPL = 1090 and 1240 nm for [Cu2_{2}Ti(EPh)6_{6}(PPh3_{3})2_{2}], E = S, Se, respectively. According to the calculations, a peculiar feature of the lowest-energy electronic transitions in these complexes is their high localization on the metal and chalcogen atoms, with negligible contributions of the “external” ligand groups. Correspondingly, the type of atoms in the M2_{2}TiE6_{6} (M = Cu, Ag, Na) core structure determines optical properties such as the absorption and emission wavelengths and PL lifetime

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

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    The synthesis of heterobimetallic AuI/RuII complexes of the general formula syn- and anti-[{AuCl}(L1∩L2){Ru(bpy)2_{2}}][PF6_{6}]2_{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_{2}}][PF6_{6}]2_{2} and the bimetallic analogue syn-[{AuCl}(L1∩L2){Ru(bpy)2_{2}}][PF6_{6}]2_{2}, thus indicating a small influence of the {AuCl} fragment on the photoluminescence properties. The heterobimetallic AuI^{I}/RuII^{II} complexes syn- and anti-[{AuCl}(L1∩L2){Ru(bpy)2_{2}}][PF6_{6}]2_{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

    Triggering near‐infrared luminescence of vanadyl phthalocyanine by charging

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    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

    Bi- and trinuclear coinage metal complexes of a PNNP ligand featuring metallophilic interactions and an unusual charge separation

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    A selective synthesis of bi- and trinuclear complexes featuring a tetradentate monoanionic PNNP ligand is presented. The binuclear coinage metal complexes show a typical fourfold coordination for Cu and Ag, which changes to a bifold coordination for Au. The latter is accompanied by an unusual charge separation. Optical properties are investigated using photoluminescence spectroscopy and complemented by time-dependent density-functional-theory calculations. All compounds demonstrate clearly distinguished features dependent on the metals chosen and differences in the complex scaffold

    Alkynyl-functionalized gold NHC complexes and their coinage metal clusters

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    Phenylpropynyl-functionalized imidazolium salts, as well as their gold complexes, were prepared in excellent yields affording suitable starting materials for metal cluster synthesis. The reactions of these gold complexes with coinage metal phenylacetylides [M(CCPh)]x (M = Cu, Ag) resulted in the formation of novel heterometallic hexanuclear clusters which exhibit mixed metallophillic interactions and intense white photoluminescence at low temperature

    Tetra- And hexanuclear string complexes of the coinage metals

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    Reaction of the PNNP ligand system N,N′-bis[(2-diphenylphosphino)phenyl]formamidinate (dpfam) featuring different coordination compartments with [AuCl(tht)], [CuMes]5_{5}, [AgMes]4_{4}, or [AuC6_{6}F5_{5}(tht)] (tht = tetrahydrothiophene) resulted in tetranuclear homo- and heterometallic coinage metal complexes, as well as a hexanuclear gold complex. All of them feature a metal string conformation. Photophysical investigation revealed a significant dependence of the photoluminescence properties on the metal composition. Below 100 K, the PL efficiency of three compounds approaches nearly 100%

    Versatile Heteroleptic Cu(I) Complexes Based on Quino(xa)-line-Triazole Ligands: from Visible-Light Absorption and Cooperativity to Luminescence and Photoredox Catalysis

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    Four new heteroleptic Cu(I) complexes based on 1, 2, 3-triazolyl-quinoline or quinoxaline and a chelating diphosphine were prepared and fully characterised. The mononuclear derivatives absorb in the visible region, up to 600 nm, while the dinuclear complex has a long-tail absorption up to 800 nm, showing an additional electronic state corroborated by theoretical calculations. Although a methylene group between the triazole and the quino(xa)line moiety increases the bite angle and decreases the luminescence in solution, all complexes emit brightly in the solid-state. Their redox properties in the excited state were determined, proving their ability in serving as photoredox catalysts in atom transfer radical addition successfully

    Novel Cofacial Porphyrin-Based Homo- and Heterotrimetallic Complexes of Transition Metals

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    We present a straightforward and generally applicable synthesis route for cofacially linked homo- and heterotrimetallic trisporphyin complexes. The protocol encompasses synthesising the first aryl-based, trans-o-phenylene trisporphyrin starting from pyrrole and benzaldehyde with an overall yield of 3.6 %. It also allows investigating the respective cis-isomer as the first conformationally restricted planar-chiral trisporphyrin. The free-base ligand was used in subsequent metalation reactions to afford the corresponding homotrimetallic Mn(III)-, Fe(III)-, Ni(II)-, Cu(II)-, Zn(II)- and Pd(II) complexes – additionally, a small adaptation of the protocol resulted in the defined Ni(II)Fe(III)Ni(II) complex in a total yield of 2.3 %. By monitoring Ni(II) insertion into the empty trimeric ligands, we affirmed that the outer porphyrin rings are filled before the internal ring. The molecular species were characterised by 1^{1}H NMR, UV-Vis, photoluminescence, IR, MS, CID, and high-resolution IMS measurements
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