A new Ag(i) metal–organic framework (Ag-MOF) [Ag(p-OH-C₆H₄COOH)₂(NO₃)]_n [Ag(PHBA)₂(NO₃)]_n, (1) (PHBA: C₈H₆O₄ {p-hydroxybenzoic acid}) was synthesized using two different methods; the laying method (single crystal) and sonochemical irradiation (nanostructures).

Four Pb(II) complexes of (iso)nicotinohydrazide-based ligands and different anionic coligands (azide, nitrate, acetate and iodide) have been synthesized and characterized by structural, analytical and spectroscopic methods. The mono-deprotonated or neutral forms of the ligands coordinate in a tridentate fashion via two nitrogen and one oxygen donor atoms to the Pb. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending upon the anion coordinated to the metal centre. In all four complexes the lead center is hemidirectionally coordinated and, consequently, it is sterically ideal for establishing tetrel bonding interactions. In the crystal structures of all complexes, the lead atoms participate in short contacts with nitrogen atoms. These contacts are shorter than the sums of the van der Waals radii and larger than the sums of the covalent radii. The tetrel bonding interactions interconnect the covalently bonded units (monomers or dimers) into supramolecular assemblies (chains and 3D structures). We have analysed the interesting supramolecular assemblies observed in the solid state of all four complexes by means of DFT calculations.

A series of new mercury(II)–organic polymeric complexes generated from 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpo) as an angular dipyridyl derivative ligand, [Hg(bpo)_nX₂]: X = SCN⁻ (1), I⁻ (2), Br⁻ (3), NO₂ ⁻ (4) and N₃ ⁻ (5), was prepared from reactions of the ligand bpo with different mercury(II) salts. All these compounds were characterized by elemental analysis, IR-, ¹H NMR-, and ¹³C NMR spectroscopies and structurally determined by X-ray single-crystal diffraction. The thermal stabilities of compounds 1–5 and also the reported compound, [Hg(μ-bpo)I₂]·CH₃CN (6), were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Solid-state luminescent spectra of the compounds 1–6 indicate intense fluorescent emissions at ca. 470 nm. The results show the influence of the counter-ions on the coordination mode of the bpo ligand in the mercury ion as a soft acid that is capable of forming compounds with four-, five- and six coordination numbers and, consequently, acting in different forms of coordination polymers, containing both discrete and divergent (from one-dimensional, 1-D to two-dimensional, 2-D) coordination frameworks.

A series of new polymeric mercury(II) complexes, [Hg(4-bpdb)(SCN)₂]_n (1), [Hg(3-bpdb)(SCN)₂]_n (2), [Hg(4-bpdb)Br₂]_n (3), [Hg(3-bpdb)Br₂]_n (4) and [Hg₂(2-bpdb)Br₄]_n (5) {4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and 2-bpdb = 1,4-bis(2-pyridyl)-2,3-diaza-1,3-butadiene} was prepared from reactions of mercury(II) thiocyanate or bromide with three organic nitrogen donor-based ligands under thermal gradient conditions using the branched tube method. All these compounds were structurally characterized by single-crystal X-ray diffraction. The thermal stabilities of compounds 1–5 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA).

The cooperative action of multiple non-covalent interactions allowed for the assembly of a new series of Pb ^II coordination compounds.