Gas-Phase Photoluminescence and Photodissociation of Silver-Capped Hexagold Clusters

Abstract

We report on the radiative and nonradiative deactivation pathways of selected charge states of the stoichiometric hexagold phosphine-stabilized ionic clusters, [(C)(AuDppy)Ag·(BF) ] with x = 2 and 3 (Dppy = diphenylphosphino-2-pyridine), combining gas-phase photoluminescence and photodissociation with quantum chemical computations. These clusters possess an identical isostructural core made of a hyper-coordinated carbon at their center octahedrally surrounded by six gold ions, and two silver ions at their apexes. Their luminescence and fragmentation behavior upon photoexcitation was investigated under mass and charge control in an ion trap. The experimental and computational results shed light on the electronic states involved in the optical transitions as well as on their core, ligand, or charge transfer character. Gas-phase results are discussed in relation with condensed phase measurements, as well as previous observations in solution and on metal-organic frameworks. The monocationic species ( x = 3) is found to be less stable than the dicationic one ( x = 2). In the luminescence spectrum of the monocationic species, a shoulder at short wavelength can be observed and is assigned to fragment emission. This fragment formation appears to be favored for the monocation by the existence of a low lying singlet state energetically overlapping with the triplet state manifold, which is populated quickly after photoexcitation.

N-Heterocyclic carbene-based C-centered Au(I)-Ag(I) clusters with intense phosphorescence and organelle-selective translocation in cells

“…The imidazolylidene and benzimidazolylidene ligand moieties are involved in the SOMO − 1 orbitals. The calculated phosphorescence energies of 3b and 3d are 2.09 and 2.08 eV (592 and 596 nm, respectively), which are in close agreement with the experimental values of 2.21 and 2.17 eV, respectively, within error 37 (Supplementary Table 21 ).

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“…The lowest peaks observed around 400 nm for 3b and 3d were considered to be transitions between MOs consisting mainly of Au I , Ag I and the central carbon. The strong absorption peaks around 330 nm for 3b and 3d are due to the MLCT transition from Au I to ligands 37 . The absorption in the high-energy region (<300 nm) is mainly due to the ππ* transition of the ligands.…”

High Precision Electronic Spectroscopy of Ligand-Protected Gold Nanoclusters: Effects of Composition, Environment, and Ligand Chemistry

“…Action spectroscopy approaches have yielded key insights in analytical biophysics, , coordination chemistry, − astrophysics, and metal cluster physics . Applications of these methods to metal clusters composed of silver, − copper, gold, − or alloys thereof have successfully elucidated the electronic and geometric structure of ligand-free and ligand-capped clusters using either electron photodetachment or photochemical fragmentation action spectroscopy. The former is suitable for anionic or neutral compounds and exclusively reports on projection into a photoionized potential energy surface, ,,− while spectra acquired by the latter subtly vary upon the photofragmentation mechanism employed.…”

Photoinitiated Charge Transfer in a Triangular Silver(I) Hydride Complex and Its Oxophilicity

“…To explore the gas‐phase reactivity of [ P ] 2+ , we applied the established mass spectrometric fragmentation techniques of 1) collisional‐induced dissociation (CID), 2) laser photodissociation (PD),– and 3) electron‐transfer dissociation (ETD)/electron‐transfer reduction (ETR), because interesting details of Ag–hydride/Ag–Ag interactions are revealed by these activations. The resulting CID, PD, and ETD mass spectra are compared in Figure a—c, and the major dissociation pathways are presented in Tables and (further details are given in the Supporting Information).…”

“…Note, that reports on ultrafast processes in transition‐metal complexes, and especially on multinuclear metal hydrides, remain rather scarce . Moreover, we will pursue the subject of silver hydride luminescence further, because it plays a major role in the design and application of atomically precise nanoclusters …”