Search

The novel photoswitchable ligand 3,3'-Azobenz(metPA) 2 (1) is used to prepare a [Cu 2 (1) 2 ](BF 4 ) 2 metallocycle (2), whose photoisomerization was characterized using static and time-resolved spectroscopic methods. Optical studies demonstrate the highly quantitative and reproducible photoinduced cyclic E/Z switching without decay of the complex. Accordingly and best to our knowledge, [Cu 2 (1) 2 ](BF 4 ) 2 constitutes the first reversibly photoswitchable (3d)-metallocycle based on azobenzene. The photoinduced multiexponential dynamics in the sub-picosecond to few picosecond time domain of 1 and 2 have been assessed. These ultrafast dynamics as well as the yield of the respective photostationary state (PSS Z = 65 %) resemble the behavior of archetypical azobenzene. Also, the innovative pump-probe laser technique of gas phase transient photodissociation (τ-PD) in a mass spectrometric ion trap was used to determine the intrinsic relaxation dynamics for the isolated complex. These results are consistent with the results from femtosecond UV/Vis transient absorption (fs-TA) in solution, emphasizing the azobenzene-like dynamics of 2. This unique combination of fs-TA and τ-PD enables valuable insights into the prevailing interplay of dynamics and solvation. Both analyses (in solution and gas phase) and quantum chemical calculations reveal a negligible effect of the metal coordination on the switching mechanism and electronic pathway, which suggests a non-cooperative isomerization process., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The modular synthesis of Au(I)/Ru(II) decorated mono- and heterobimetallic complexes with π-conjugated [2.2]paracyclophane is described. [2.2]Paracyclophane serves as a rigid spacer which holds the metal centers in precise spatial orientations and allows metal-to-metal distance modulation. A broad set of architectural arrangements of pseudo -geminal, -ortho, -meta, and -para substitution patterns were employed. Metal-to-metal distance modulation of Au(I)/Ru(II) heterobimetallic complexes and the innate transannular π-communication of the cyclophanyl scaffold provides a promising platform for the investigations of structure-activity relationship and cooperative effects. The Au(I)/Ru(II) heterobimetallic cyclophanyl complexes are stable, easily accessible, and exhibit promising catalytic activity in the visible-light promoted arylative Meyer-Schuster rearrangement., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

We report the binding geometries of the isomers that are formed when the hydrogen oxalate ((CO 2 ) 2 H=HOx) anion attaches to dinuclear coinage metal phosphine complexes of the form [M 1 M 2 dcpm 2 (HOx)] + with M=Cu, Ag and dcpm=bis(dicyclohexylphosphino)methane, abbreviated [MM] + . These structures are established by comparison of isomer-selective experimental vibrational band patterns displayed by the cryogenically cooled and N 2 -tagged cations with DFT calculations of the predicted spectra for various local minima. Two isomeric classes are identified that feature either attachment of the carboxylate oxygen atoms to the two metal centers (end-on docking) or attachment of oxygen atoms on different carbon atoms asymmetrically to the metal ions (side-on docking). Within each class, there are additional isomeric variations according to the orientation of the OH group. This behavior indicates that HOx undergoes strong and directional coordination to [CuCu] + but adopts a more flexible coordination to [AgAg] + . Infrared spectra of the bare ions, fragmentation thresholds and ion mobility measurements are reported to explore the behaviors of the complexes at ambient temperature., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Chemical and spectroscopic characterization of the mononuclear photosensitizers [(DPEPhos)Cu(I)(MPyrT)] 0/+ (CuL, CuLH) and their dinuclear analogues (Cu 2 L', Cu 2 L'H 2 ), backed by (TD)DFT and high-level GW-Bethe-Salpeter equation calculations, exemplifies the complex influence of charge, nuclearity and structural flexibility on UV-induced photophysical pathways. Ultrafast transient absorption and step-scan FTIR spectroscopy reveal flattening distortion in the triplet state of CuLH as controlled by charge, which also appears to have a large impact on the symmetry of the long-lived triplet states in Cu 2 L' and Cu 2 L'H 2 . Time-resolved luminescence spectroscopy (solid state), supported by transient photodissociation spectroscopy (gas phase), confirm a lifetime of some tens of μs for the respective triplet states, as well as the energetics of thermally activated delayed luminescence, both being essential parameters for application of these materials based on earth-abundant copper in photocatalysis and luminescent devices., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The photoexcitation of a triangular silver(I) hydride complex, [Ag 3 (μ 3 -H)(μ 2 -dcpm) 3 ](PF 6 ) 2 ([P](PF 6 ) 2 , dcpm=bis(dicyclohexylphosphino)methane), designed with "UV-silent" bis-phosphine ligands, provokes hydride-to-Ag 3 single and double electron transfer. The nature of the electronic transitions has been authenticated by absorption and photodissociation spectroscopy in parallel with high-level quantum-chemical computations utilizing the GW method and Bethe-Salpeter equation (GW-BSE). Specific photofragments of mass-selected [P] 2+ ions testify to charge transfer and competing pathways resulting from the unique [Ag 3 (μ 3 -H)] 2+ scaffold. This structural motif of [P](PF 6 ) 2 has been unequivocally verified by 1 H NMR spectroscopy in concert with DFT and X-ray diffraction structural analysis, which revealed short equilateral Ag-Ag distances (d AgAg =3.08 Å) within the range of argentophilic interactions. The reduced radical cation [P] . + exhibits strong oxophilicity, forming [P+O 2 ] .+ ,which is a model intermediate for silver oxidation catalysis., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The hybrid ligand 3-(2,2'-bipyridine-6-ylmethyl)-1-mesityl-1H-imidazolylidene (NHC Bipy ) featuring both carbene and N-donor sites, was selectively complexed with various d 10 metal cations in order to examine its coordination behavior with regard to homo and heterometallic structures. Respective silver complexes can be obtained by the silver oxide route and are suitable transmetallation reagents for the synthesis of gold(I) compounds. Starting from the mononuclear complexes [(NHC Bipy )AuCl], [(NHC Bipy )Au(C 6 F 5 )] and [(NHC Bipy ) 2 Au][ClO 4 ], open-chain as well as cyclic heterobimetallic complexes containing Cu + , Ag + , Zn 2+ , Cd 2+ , and Hg 2+ were synthesized. Furthermore, the homobimetallic species [(NHC Bipy ) 2 M 2 ][ClO 4 ] 2 (M=Cu, Ag) were obtained. All bimetallic compounds were fully characterized including single-crystal X-ray analysis. Their photoluminescence (PL) properties were investigated in the solid state at temperatures between 15 and 295 K and compared with those of the mononuclear species. There is a clear difference in PL properties between the open chain and the cyclic heterobimetallic complexes. The latter species show different PL properties, depending on the metals involved. In addition, collision-induced dissociation (CID) experiments were performed on electrosprayed cations of the cyclic heterobimetallic compounds, to compare the metal binding at the carbene and N-donor sites., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)