{[3,5-(CF₃)₂Pz]Ag}₃ (1) films exhibit selective/reversible sensing of small-organic-molecule (SAM) vapors, which readily switch-on bright-green (benzene or toluene) or bright-blue (mesitylene) luminescence that switches-off upon vapor removal. Vapors of electron-deficient SAMs or non-aromatic solvents did not attain luminescence switching and were not adsorbed.

The structure and luminescence properties of a well-known trinuclear Au(I) imidazolate complex are determined for the first time along with its interaction with the organic π acid perfluoronaphthalene in the solid state and solution.

Trinuclear coinage metal metallacycles are obtained when two-coordinate metals are bonded to C, N or N, N anionic ligands of the proper symmetry to form cycles where metals alternate with bridging ligands. Cyclotrimers often exhibit semiplanar structures and mostly columnar or finite stacking in the solid state by means of metallophilic interactions. They show some peculiar properties with an impact on many different fields such as supramolecular architectures, luminescence, molecular recognition, host-guest chemistry, and acid-base chemistry. The comprehensive evaluation of the data shows that, depending on the nature of the central metal and bridging ligand, there is a fine balance of the energy involved in the inter-trimer bond cleavages and the energy gained from the formation of new intermolecular electrostatic interactions, proceeding occasionally to the chemical extreme of redox processes. In this review, a number of important developments are highlighted and systematically analyzed along with structural and computational data and chemical properties to rationalize and build a unifying leitmotif for this chemistry; the focus is made on the authors’ contributions in these areas.