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The present work represents new facile route for synthesis of luminescent hydrophilic core-shell colloids, where the luminescence results from Au(I) complex (AuCl)2L with cyclic PNNP ligand (L). The synthesis is based on solvent mediated aggregation of (AuCl)2L in aqueous organic solutions. Instability of (AuCl)2L in aqueous organic solutions was minimized by specific hydrophilic shell deposition arisen from electrostatically driven adsorption of polyethylenimine onto (AuCl)2L-based cores. Luminescence of the colloids is stable for week at least due to restricted degradation of the luminescent complex at the interface and high positive exterior charge of the colloids. The sensing properties of the colloids towards thiols results from their complex formation with Au+ ions. The thiol-induced stripping of Au+ ions from the colloids quenches the luminescence. The optimal conditions for fluorescent recognition of cysteine, homocysteine and glutathione with lower detection limits about 1 μM are highlighted in the work.

A series of multinuclear Cu(I) complexes (CuI)xLy, namely the previously reported (CuI)6L2 and (CuI)2L′ and novel (CuI)2L2, where L and L′ are 1,5-di(R)-3,7-bis(2-pyridine-2′-yl)ethyl-1,5-diaza-3,7-diphosphacyclooctanes are introduced. Both dissociative and oxidative behavior of the complexes in DMSO and DMF solutions are correlated with the time-dependent changes in their phosphorescence originated from 3(X + M)LCT transitions. The instability of butterfly-like (CuI)2L′ resulting in its oxidative degradation in DMSO and transformation into (CuI)L′2 in DMF solutions differentiates it from more stable linear complexes (CuI)6L2 and (CuI)2L2. The complexes (CuI)2L2 and (CuI)L2 produced by the dissociation of (CuI)6L2.in DMSO and DMF solutions are regarded as structural motifs responsible for both reversible blue-shifting by 10 nm of the emission band and the decrease in the excited states lifetime values upon the heating of the solutions within 293–333 K. This temperature-induced behavior along with the phosphorescence character of the emission of both complexes points to thermally activated delayed fluorescence as the reason for the reversible temperature-induced spectral changes of hexanuclear (CuI)6L2. Smaller nuclearity of (CuI)2L2 is the reason for partial reversibility of the spectral changes.