Syntheses, structural characterization, and thermal behaviour of metal complexes with 3-aminopyridine as co-ligands

Abstract

Six mixed metal complexes with 3-aminopyridine (3-ampy) as a co-ligand have been synthesized: catena-{[M(μ2-3-ampy)(H2O)4]SO4·H2O} (M=Ni (1) and Co (2)), [Co(3-ampy)4(NCS)2] (3), [Co(3-ampy)2(NCS)2] (4), [Co(3-ampy)4(N3)2] (5) and mer-[Co(3-ampy)3(N3)3] (6), (NCS−=isothiocyanate ion, N3− azide ion), and characterized by physio-chemical and spectroscopic methods as well as single crystal X-ray and powder diffraction. In the isostructural complexes 1 and 2 single μ2-3-ampy links the Ni(II) and Co(II) centers into polymeric chains. The mononuclear Co(II) and Co(III) pseudohalide complexes 3–6 reveal only terminal 3-ampy ligands. The 3-ampy ligands form supramolecular hydrogen bonded systems via their NH2-groups and non-covalent π-π ring-ring interactions via their pyridine moieties. Thermoanalytical properties were investigated for 1–3.

Graphic abstract

Structural Insights into Influence of Isomerism on Properties of Open Shell Cobalt Coordination System

The two coordination compounds of cobalt were designed and synthesized. The substrates were carefully selected to allow gentle tuning of the molecular structure of the designed compounds. The crystal, molecular and supramolecular structure of studied compounds has been determined and discussed. The spectroscopic and thermal properties of designed coordination compounds have been studied and their application as precursors for the synthesis of cobalt oxide nanoparticles has been demonstrated. It was proven that not only are parameters of conversion of the precursor to nanoparticles important, but also small changes in molecular structure can considerably affect the size of formed particles. For unambiguous determination of the influence of compounds structure on their UV-Vis radiation absorption, density functional theory and time-dependent density functions theory calculations have been performed. The complexity of the correct ab-initio reflection of the open shell molecular system was outlined and discussed. The results obtained from density functional theory (DFT) calculations have been also employed for discussion of the bonding properties.

Effect of Charge on the Structures of Zn(II) Coordination Polymers with Triazole-carboxylate Ligands: Syntheses, Structures, and Luminescent Properties

Three new Zn(II) coordination polymers, {[Zn(L1)2(H2O)2]·4H2O}n (1), {[Zn(L2)(H2O)2]·0.5H2O}n (2), and {[Zn1.5(L1)(o-bdc)(H2O)]·0.5H2O}n (3) (HL1 = 3,5-di(1,2,4-triazol-1-yl)benzoic acid, H2L2 = 5-(triazol-1-yl)isophthalic acid, o-H2bdc = 1,2-benzenedicarboxylic acid), were successfully synthesized and characterized. Compound 1 exhibits 1D chain structure containing [Zn(L1)2] unit. Compound 2 shows a 2D plane with the ratio of Zn:L2 was 1:1 since L2 can match the positive charge of Zn(II). When L1 and o-bdc2– were presented together, Zn(II) centers are linked by L1 to form 2D double layers, then o-bdc2– further connected the adjacent layers to generate final 3D framework of 3. The ligand charges may play key roles in tuning the frameworks of compounds 1–3. The solid state luminescence of compounds 1–3 and all ligands have been investigated here.