Cd(II) coordination polymers based on expanded N,N′-heteroaromatic donor ligands

Abstract

The isomeric N donor linkers bis(pyridin-4-ylmethylene)naphthalene-1,5-diamine (L1) and bis(pyridin-3-ylmethylene)naphthalene-1,5-diamine (L2) have been used with acetate and iodide as co-ligands to generate four new cadmium(II) coordination polymers. [CdL1(OAc) 2 ] n (1), [CdL1(I) 2 ] n (2), [CdL2(OAc) 2 ] n (3) and [CdL2(I) 2 ] n (4) were characterized by elemental analysis, X-ray powder diffraction, IR spectroscopy, thermal analysis and single crystal X-ray diffraction. In line with the concept of crystal engineering, their structures share common motifs: the heteroaromatic linkers generate chains, subtending CdÁ Á ÁCd distances consistent with their N donor arrangement. The co-ligands control the coordination number of the Cd(II) cations and interchain connectivity: The acetate moieties either adopt bridging and chelating or exclusively bridging modes and crosslink essentially linear chains based on octahedral metal centers; in the former case, the ladder-like one-dimensional ribbon 1 is generated, whereas the latter connectivity results in the two-dimensional layer structure 3. In contrast, iodide acts as terminal ligand towards tetrahedral Cd(II), and hence 2 and 4 are single-stranded 1D zig-zag polymers. In comparison to the uncoordinated heteroaromatic L1 and L2, the Cd coordination polymers show slightly red-shifted luminescence spectra of significantly higher intensity due to the more rigid arrangement of the p systems.

A Discrete Molecule and a 1D Coordination Polymer of Cadmium(II): Preparation, Structures, and Properties of [Cd(L1)2(NO3)2(CH3OH)] and {[Cd(L2)(CH3COO)2]·(CH3OH)}∞ (L1 = (4‐Py)–CH=N–C10H6–NH2; L2 = (3‐Py)–CH=N–C10H6–N=CH–(3‐Py))

“…It was very recently reported the ligand L 2 (in THF) reacts cadmium acetate (in a 1:1 mixture of MeOH and THF) under layer‐diffusion conditions to produce a 2D CP with a layer structure, [Cd(L 2 )(CH 3 COO) 2 ] ∞ , which does not possess lattice solvent molecules . Compound 2 and the CP [Cd(L 2 )(CH 3 COO) 2 ] ∞ show a good example in which different solvent compositions can induce a great change in structures of the resulting CPs.…”

A series of 1-D zinc(II) coordination polymers with 3-D supramolecular networks: synthesis, structural investigation, and NBO analysis

“…Li et al introduced 1-D and 2-D structures in which L is coordinated to Fe(II) cations [14]. Previous systematic work from our group on the synthesis of coordination polymers containing this dipyridyl ligand is documented [15][16][17].…”