Łukasz Szyrwiel

One-Pot Synthesis of a New Magnetically Coupled Heterometallic Cu2Mn2 [2 × 2] Molecular Grid

The heterometallic [2 x 2] grid-type complex [Cu(2)Mn(2)(pop)(4)(OAc)(4)].7H(2)O (1) has been selectively synthesized in a targeted one-pot reaction. Single-crystal X-ray analysis shows the expected structure with identical metal ions located at diagonal vertices of the grid. Magnetochemical studies reveal that 1 has a ferrimagnetic spin ground state with some admixture of low-lying excited states.

The cyclopeptides with the multi-His motif as ligands for copper(II)

The coordination properties of cyclic octapeptides with multi-His motif: c(His-Gly-His-Xaa-His-Gly-His-Xaa) where Xaa = Asp or Lys, were investigated. The binding abilities of this peptides towards Cu(II) ions were studied by using different analytic methods as: potentiometry, spectroscopy and mass spectrometry. The obtained results show that the studied peptides in physiological related pH prefer formation of the species with the {4N(Im)} binding mode. The efficiency of Cu(II) binding depends on additional side chain groups Asp or Lys. Additionally the analysis of results for His containing cyclopeptides with different numbers of amino acid residues in cyclopeptide ring e.g. four, eight shows that in higher pH in both cases the binding by four amide nitrogens is not observed in the case of α-amino acid peptides.

The Cu2+ binding properties of branched peptides based on l -2,3-diaminopropionic acid

Three new branched peptides, namely, H-Gly-Dap(H-Gly)-Gly-NH2 (3G), H-His-Dap(H-His)-Gly-NH2 (2HG), and H-Gly-Dap(H-Gly)-His-NH2 (2GH), where Dap stands for the 2,3-diaminopropionic acid residue, were synthesized by solid phase procedures. Because of the junction at Dap these peptides have three available pending arms for metal chelation. The complex formation between these peptides and 1 equiv of Cu(2+) was investigated as a function of pH by potentiometry ultraviolet-visible absorption, circular dichroism, and X-band electron paramagnetic resonance spectroscopy in aqueous medium. Our results clearly demonstrate that cooperation between all three peptide arms essentially contributes to the stability of copper(II) complexes.

Complexes of Co(II) and Zn(II) with N-(Thio)phosphorylthioureas AdNHC(S)NHP(O)(OiPr)2 and MeNHC(S)NHP(S)(OiPr)2

The reaction of the potassium salt of the N-(thio)phosphorylated thioureas AdNHC(S)NHP(O)(OiPr)2 (HLI , Ad = Adamantyl) and MeNHC(S)NHP(S)(OiPr)2 (HLII ) with Co(II) and Zn(II) in aqueous EtOH leads to [MLI,II 2] chelate complexes. They were investigated by UV-vis, 1H and 31P NMR spectroscopy, and microanalysis. The molecular structures of [MLI 2] were elucidated by single crystal X-ray diffraction analysis. The metal centers in both complexes are found to be in a distorted-tetrahedral O2S2 environment formed by the C=S sulfur atoms and the P=O oxygen atoms of two deprotonated LI ligands. The photoluminescence properties of [ZnLII 2] are also reported.

SOD-Like Activity of Copper(II) Containing Metallopeptides Branched By 2,3-Diaminopropionic Acid: What the N-Termini Elevate, the C-Terminus Ruins

Relations between structural modifiactions and SOD-like activity of four branched CuII-metallopeptides based on l-2,3-diaminopropionic acid are reported. The IC50 values (McCord–Fridovich method) illustrate that enhanced SOD-like activity is warranted by exclusive N-terminal His localization that surmounts the driving force by the CuII/I formal potential.