Towards the design of ionic traps incorporating thermolabile units: structural characterization of copper(II), palladium(II) and rhodium(II) complexes with the aminoalcohol ligand 2-(pyridin-2-ylamino)ethanol

Aminoalcohol-based ligands incorporating heteroaromatic moieties, such as 2- (pyridin-2-ylamino) ethanol (L1), are of particular interest in coordination chemistry due to their dual donor character and conformational adaptability. A series of L1-based transition-metal complexes, namely, diacetatobis2- (pyridin-2-ylamino) ethanolpalladium (II), Pd (C2H3O2) 2 (C7H10N2O) 2 or PdL12 (OAc) 2 (1), and the copper (II) analogue (4), tetra-μ-acetato-bis2- (pyridin-2-ylamino) ethanolrhodium (II), Rh2 (C2H3O2) 4 (C7H10N2O) 2 or Rh2L12 (OAc) 4 (2), and the copper (II) analogue (3), and the nitrate salt 2- (2-hydroxyethyl) aminopyridinium nitrate, C7H11N2O+·NO3- or L1·NO3 (5), were structurally characterized using single-crystal X-ray diffraction (SCXRD). Crystallographic analyses revealed well-defined coordination modes and distinct supramolecular architectures influenced by the nature of the metal centre. These findings demonstrate the ability of the L1 ligand to form well-defined crystalline complexes with Cu, Pd and Rh ions, providing valuable crystallographic benchmarks for understanding the coordination preferences and crystal packing effects in pyridyl-aminoalcohol systems. The presented results provide a foundation for the further design of ionic traps involving thermolabile moieties.