Chlorometallate-Pyridinium Boronic Acid Salts for Crystal Engineering: Synthesis of One‑, Two‑, and Three-Dimensional Hydrogen Bond Networks

A series of new crystal structures of salts containing 3- and 4-pyridineboronic acid (3- and 4-pba) with chlorometallate have been prepared: [4-pbaH]­[MnCl₂] (<b>1</b>), [4-pbaH]­[CdCl₂], (<b>2</b>), [4-pbaH]₂[CuCl₄] (<b>3</b>), [4-pbaH]₂[PdCl₄] (<b>4</b>), [3-pbaH]₂[CdCl₄] (<b>5</b>), [3-pbaH]­[CuCl₃(OH₂)] (<b>6</b>), and [3-pbaH]­[PdCl₂] (<b>7</b>). In these salts five structural forms for the chlorometallate species are observed: mononuclear square planar [M = Pd (<b>4</b> and <b>7</b>)], dimeric square-pyramidal [M = Cu (<b>3</b>)], polymeric square-pyramidal [M = Cu (<b>6</b>)], polymeric <i>trans</i>-edge-sharing octahedral [M = Mn (<b>1</b>), Cd (<b>2</b>)], and polymeric <i>cis</i>-edge-sharing octahedral [M = Cd (<b>5</b>)]. The cyclic R2,2(8) boronic acid dimer is formed in the salt of <b>1</b>–<b>5</b>. NH···Cl₂M synthons <b>A</b> have been exploited in <b>1</b>–<b>4</b>, <b>6</b>, and <b>7</b>. Both NH···Cl₂M (sythons <b>A</b>) and B­(OH)₂···Cl₂M (sythons <b>B</b>) interactions give rise to a synthon of form <b>I</b> in <b>6</b>. The uncommon folded conformation of the NH···Cl₂M (synthons <b>A</b>) are formed in <b>7</b>. The NH or OH donors and consequent branching of the NH···Cl hydrogen-bond network leads to one-, two-, and three-dimensional structures. These structures are further stabilized by CH···O and CH···Cl and π···π stacking interactions

Magnetic properties and sensitized visible and NIR luminescence of Dy^III and Eu^III coordination polymers by energy transfer antenna ligands

<p>Two coordination polymers, {[Ln(2-stp)(4,4′-bipy)(H₂O)].(H₂O)}, [Ln = Dy (<b>1</b>) and Eu (<b>2</b>), 2-stp = 2-sulfoterephthalate and 4,4′-bipy = 4,4′-bipyridine] have been characterized by solid state UV-vis, FTIR spectra, X-ray single crystal diffraction and solid state photoluminescence. Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field is also studied for both complexes. After ligand-mediated excitation, both complexes show the characteristic visible and NIR luminescence of the corresponding Ln^III ions (Ln = Dy, Eu) which is due to efficient energy transfer from the ligands to the central Ln^III ions <i>via</i> an antenna effect. The indirect energy transfer in both complexes has been investigated and discussed in detail.</p