The effect of carboxylate and N,N′-ditopic ligand lengths on the structures of copper and zinc coordination polymers

Abstract

A series of one-dimensional coordination polymers with parallel chains has been prepared by linking together M 2 (O 2 CR) 4 paddle wheel units, where M is Cu or Zn and R is biphenyl or iodobenzoate, with pyrazine (pyz), 2-aminopyrazine (apyz) or 1,4-diazabicyclo[2.2.2]octane (dabco) bridging ligands. The longer length of the substituent in biphenyl-4-carboxylate (bpc) allows for greater separation of the chains in [Cu 2 (bpc) 4 (pyz)]•3.8BzOH 1 than has been previously observed in related benzoate compounds, leading to the formation of larger channels within the structure. In [Cu 2 (bpc) 4 (dabco)]•BzOH 2 and [Zn 2 (bpc) 4 (dabco)]•2DMF 3, neighbouring chains are offset relative to each other, enabling them to pack more efficiently and reducing the channel width from that seen in 1. For the 4-iodobenzoate (ibz) compounds [Cu 2 (ibz) 4 (pyz)] 4, [Cu 2 (ibz) 4 (apyz)]•2BzOH 5 and [Zn 2 (ibz) 4 (dabco)]•3.25DMF 6, the chains are closer together than in the bpc compounds, and again when the neighbouring chains are offset with respect to each other, they are able to pack more efficiently. When similar reactions were carried out using 4,4'-bipyridyl (4,4'-bipy) as the bridging ligand, the products were very different. [Cu(bpc) 2 (4,4'-bipy)(BzOH) 2 ]•2BzOH 7, [Zn(bpc) 2 (4,4'-bipy)] 8 and [Zn(ibz) 2 (4,4'-bipy)] 9 all have structures in which single metal centres, as opposed to M 2 (O 2 CR) 4 dimers, are bridged into chains by the ditopic linker ligand, and the chains pack efficiently without forming channels.

Zinc Dialkylhydroxybenzoates with Unusual Structures: First Example of a Discrete Three‐Blade Paddle‐Wheel and a Solvent Engulfed Coordination Polymer

“…As shown in Figure a, the lattice methanol molecules are hydrogen bonded to non‐coordinated oxygen atom of Hdiphba. As listed in Table , the Zn(1)‐O(1) (1.9651(1) Å} and Zn(1)‐N(1) (2.0687(1) Å) bond distances are typical in polymers comprise of Zn(COO) 2 knots and 4,4′‐bpy linkers . The adjacent [Zn(Hdiphba) 2 (4,4′‐bpy)] n chains in 7 are aligned in the 001 direction with a separation of 10.77 Å and are slip‐stacked.…”

“…The carboxylate group binds with zinc metal through monodentate or chelating mode of coordination and leads to the formation of a large number of discrete complexes, and metal organic frameworks, e. g. MOF‐5 . Generally, the chelation of carboxylate group leads to the formation of dinuclear tetracarboxylate [Zn 2 (μ‐O 2 CR) 4 ] paddle‐wheels, or dinuclear dicarboxylate [Zn 2 (μ‐O 2 CR) 2 ] inorganic core, while monodentate mode is found in mononuclear dicarboxylate [Zn(O 2 CR) 2 ] (Figure ) . A careful analysis of the literature of zinc carboxylates reveals that discrete triple‐blade paddle‐wheels with just three symmetrically distributed bridging carboxylates, [Zn 2 (μ‐O 2 CR) 3 ] are extremely rare .…”

Diversified architectures of one-dimensional zinc(II) and cadmium(II) coordination polymers incorporating bipyridyl ligands: Syntheses, structures, theoretical studies, fluorescent and nonlinear optical properties

“…A particularly promising class of ligands is represented by molecules containing two pyridyl donor units interconnected by chains or groups of different types. One of the most simple ligands is 4,4 0 -bipyridine, which has been used to produce a variety of fascinating architectures [34][35][36][37]. Longer bis(4-pyridyl) Table 2 Selected bonds lengths (Å) and angles (°) for CPs (1) (11) [Zn(l 2 -3,3 0 -pytz)(NO 2 ) 2 ] n (3)…”

Anion Exchange in Coordination‐Network Materials

“…In addition, anion-π [43][44][45] contacts are observed between the triflate fluorine atom F3 and two pyridine rings with anion-tocentroid distances of 3.339(3) and 3.521(3) Å (for F3···Cg2 and F3···Cg1, respectively; see Figure S2). [46][47][48][49][50] [46][47][48][49][50] …”