We report a simple synthesis of silver:glutathione (Ag:SG) clusters using a cyclic reduction under oxidative conditions. Two syntheses are described which lead to solutions containing well-defined Ag₃₁(SG)₁₉ and Ag₁₅(SG)₁₁ clusters that have been characterized by mass spectrometry. The optical properties of silver:glutathione (Ag:SG) cluster solutions have been investigated experimentally. In particular, the solution containing Ag₁₅(SG)₁₁ clusters shows a bright and photostable emission. For Ag₃₁(SG)₁₉ and Ag₁₅(SG)₁₁ clusters, the comparison of experimental findings with DFT and TDDFT calculations allowed us to reveal the structural and electronic properties of such low nuclearity liganded silver clusters.

For the rational design of new fluorophores, reliable predictions of fluorescence quantum yields from first principles would be of great help. However, efficient computational approaches for predicting transition rates usually assume that the vibrational structure is harmonic. While the harmonic approximation has been used successfully to predict vibrationally resolved spectra and radiative rates, its reliability for non-radiative rates is much more questionable. Since non-adiabatic transitions convert large amounts of electronic energy into vibrational energy, the highly excited final vibrational states deviate greatly from harmonic oscillator eigenfunctions. We employ a time-dependent formalism to compute radiative and non-radiative rates for transitions and study the dependence on model parameters. For several coumarin dyes, we compare different adiabatic and vertical harmonic models (AS, ASF, AH, VG, VGF, and VH), in order to dissect the importance of displacements, frequency changes, and Duschinsky rotations. In addition, we analyze the effect of different broadening functions (Gaussian, Lorentzian, or Voigt). Moreover, to assess the qualitative influence of anharmonicity on the internal conversion rate, we develop a simplified anharmonic model. We address the reliability of these models considering the potential errors introduced by the harmonic approximation and the phenomenological width of the broadening function.

Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg₂(H)]⁺by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO₂CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag₂(H)]⁺and [Ph₃PAg₂(H)]⁺react with formic acid yielding Lewis adducts, while [(Ph₃P)₂Ag₂(H)]⁺is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag₂(H)⁺scaffold, triggering reactivity towards formic acid, to produce [dppmAg₂(O₂CH)]⁺and H₂. Decarboxylation of [dppmAg₂(O₂CH)]⁺via CID regenerates [dppmAg₂(H)]⁺. These gas-phase insights inspired variable temperature NMR studies that show CO₂and H₂production at 70 °C from solutions containing dppm, AgBF₄, NaO₂CH and HO₂CH.

Ligated silver and gold nanoclusters belonging to a non-scalable size regime with molecular-like discrete electronic states represent an emerging class of extremely interesting optical materials.