Structural features and dynamical behaviour of the copper(II) bis-complexes with glycine, D-alanine, D-valine, L-serine, L-aspartic acid, L-glutamic acid, L-lysine, L-proline, and sarcosine were studied by combined EPR and NMR relaxation methods. The cis and trans isomers were unambiguously assigned and characterized by EPR data. It was found that addition of a salt background has an influence on the cis–trans isomer equilibrium in favour of the formation of the cis isomer. By comparison of NMRD, DFT computations, and structural data it was shown that only one water molecule is coordinated in the axial position of these complexes. The increased exchange rates of this molecule found for Cu(L-Asp)₂ ²⁻, Cu(L-Glu)₂ ²⁻, Cu(L-LysH)₂ ²⁺, and Cu(L-Pro)₂ were attributed to its pushing out by side chain groups of the ligands. By simulation of NMRD profiles an increase of lifetimes of the copper(II) 2nd coordination sphere water molecules was revealed in the presence of additional carboxylic, alcoholic, or ammonium groups of the ligands, as well as the pyrrolidine ring of proline. The very short lifetimes of the 2nd coordination sphere water molecules (4–13 ps at 298 K) were explained in terms of the Frank–Wen structural model by the existence of cavities which draw in quickly enough water molecules from the 2nd coordination sphere.

Crystals of four new copper(II) complexes have been grown from copper(II) acetate/chloride–1-ethyl-3-methylimidazolium acetate/chloride–water systems and characterized by X-ray analysis. The first complex, bis(1-ethyl-3-methylimidazolium) tetra-μ-acetato-bis[chloridocuprate(II)], [Emim]₂[Cu₂(C₂H₃O₂)₄Cl₂] (1) (Emim is 1-ethyl-3-methylimidazolium, C₆H₁₁N₂), contains [Cu₂(C₂H₃O₂)₄Cl₂]²⁻ coordination anions with a paddle-wheel structure and ionic liquid cations. Two of the synthesized complexes are one-dimensional polymers, namely catena-poly[1-ethyl-3-methylimidazolium [[tetra-μ-acetato-dicuprate(II)]-μ-chlorido] monohydrate], {[Emim][Cu₂(C₂H₃O₂)₄Cl]·H₂O} _n (2), and catena-poly[1-ethyl-3-methylimidazolium [[tetra-μ-acetato-dicuprate(II)]-μ-acetato]], {[Emim][Cu₂(C₂H₃O₂)₅]} _n (3). In these compounds, the Cu₂(C₂H₃O₂)₄ units with a paddle-wheel structure are connected to each other through chloride (in 2) or acetate (in 3) anions to form parallel chains, between which cations of ionic liquid are situated. The last compound, bis(1-ethyl-3-methylimidazolium) tetra-μ-acetato-bis[aquacopper(II)] tetra-μ-acetato-bis[acetatocuprate(II)] dihydrate, [Emim]₂[Cu₂(C₂H₃O₂)₄(H₂O)₂][Cu₂(C₂H₃O₂)₆]·2H₂O (4), contains two different binuclear coordination units (neutral and anionic), connected through hydrogen bonds between water molecules and acetate ions.

Ionic liquid (1-ethyl-3-methylimidazolium acetate, [C₂C₁im][AcO])–copper(II) diacetate monohydrate–water–air (O₂) systems have been investigated by ¹³C NMR, EPR, spectrophotometry, HPLC, and synthetic chemistry methods at different temperatures. The C–H bond activation of [C₂C₁im]⁺ with the formation of the unusual dication 1,1′-diethyl-3,3′-dimethyl-2,2′-biimidazolium ([(C₂C₁im)₂]²⁺) at 50 °C and 1-ethyl-3-methyl-1H-imidazol-2(3H)-one (C₂C₁imO) at 50–85 °C was revealed. Two new complexes with the above compounds, [(C₂C₁im)₂][Cu(AcO)₄] and Cu₂(AcO)₄(C₂C₁imO)₂, were isolated from the systems and characterized by X-ray structural analysis. Catalytic cycles with the participation of copper(II) acetate and dioxygen and the production of [(C₂C₁im)₂]²⁺ and C₂C₁imO have been proposed. The catalysis presumably includes the formation of the Cu^II(O₂)Cu^II active centre with μ–η²:η²-peroxide bridging in analogy with tyrosinase and catechol oxidase activity.

The critical micelle concentration (CMC) is a fundamental physicochemical property of surfactants with significant implications across multiple industries. This paper presents an uncertainty-aware graph neural network (GNN) that integrates molecular structure and temperature to simultaneously predict CMC values and prediction uncertainties. Trained on a curated dataset of 2133 CMC values with temperature annotations, our GNN achieves comparatively similar performance on two external test sets from similar works. The model provides adequately calibrated uncertainty estimates that reliably quantify prediction confidence. This dual-output approach enables reliable CMC prediction with quantifiable confidence intervals, addressing a practical need for safety-critical applications where underestimation of uncertainty could have serious consequences.