A Series of Cyanoacetato Copper(II) Coordination Polymers with Various N,N′-Ditopic Spacers: Structural Diversity, Supramolecular Robustness, and Magnetic Properties

Abstract

Five novel copper(II) coordination polymers containing cyanoacetate (cna) anion with various N,N'-ditopic spacers [Cu(cna) 2 (pyz)] n (1), [Cu(cna) 2 (bpy)(H 2 O) 2 ] n (2),[Cu(cna) 2 (dpe)] n (3), [Cu(cna) 2 (dpe)] n (H 2 O) n (4) and [Cu(cna) 2 (bpa)] n (5) (when pyz = pyrazine, bpy = 4,4'-bipyridyl, dpe = 1,2-di(4-pyridyl)ethylene and bpa = 1,2-di(4-pyridyl)ethane) were structurally and spectroscopically characterized. Compound 1 shows 2D sheet structure constructed from µ 2 -1,3(syn,anti) coordinative mode of cyanoacetate and µ 2 -pyz linking adjacent Cu(II) centers. Compound 2 exhibits 1D polymeric chain which is formed by µ 2 -bpy bridging between [Cu(cna) 2 (H 2 O) 2 ] units. Whereas compounds 3-5 reveal 1D ladder-like structures which are built from double-µ 2 -dpe/bpa spacers connecting neighboring Cu(II) cyanoacetate dimers.Weak interactions such as hydrogen bonding and N···π and/or C−H···π interactions join the adjacent layers of 1 or polymeric chains of 2-5 to stabilize overall supramolecular networks. The thermal stabilities of 1-5 were investigated. Interestingly, compound 2 reveals a robust supramolecular framework constructed by 1D polymeric chains during thermal dehydration and rehydration processes, that has been further verified by spectroscopic techniques, elemental analyses, TGA, and XRPD. Moreover, this behavior is not observed in the isomorphous series containing Co(II) and Ni(II) ions. The magnetic properties of 1 and 3 exhibit very weak antiferromagnetic interactions between Cu(II) centers.

Unusual crystal structure and chirality of uridine 5′-monophosphate coordination polymer

“…The Cu(II)-N and Cu(II)-O distances were similar to that of complex 1, which was normal Cu(II)-N and Cu(II)-O coordination bonding. 28 Only the distances of Cu(II)-O water (2.299(6)Å) and Cu(2)-O(22) (2.324(13)Å) were longer than the normal Cu(II)-O length, which was caused by the Jahn-Teller effect. 29 UMP and bpe act as the bridging ligands that connect the Cu(II) ions into a 2D grid with corresponding distances of 5.057(1)Å and 5.115(1)Å, 13.437(6)Å and 13.442(6)Å (Fig.…”

“…From previous studies, the coordination ratio of the auxiliary ligand going from binary to ternary in the solution could be studied by UV titration. [25][26][27][28] In order to study the interactions of bpda/bpe with Cu-UMP in an aqueous medium, UV titrations were carried out by adding an auxiliary ligand to the solution of Cu-UMP. UV absorbance was measured as a function of concentration of bpda and bpe ( Fig.…”

Optical properties of (Z)-2-(2-phenylhydrazinylidene)acenaphthen-1(2H)-one: a potential electron donor in organic solar cells

“…Computer programs: SMART (Bruker, 2008), SHELXTL (Bruker, 2008), SHELXS97 (Sheldrick, 2008) and SHELXL97 (Sheldrick, 2008). Adjacent staircases are arranged in a two-dimensional herringbone arrangement stabilized by C-HÁ Á Á interactions (Suvanvapee et al, 2015) in the bc plane ( Fig. 1b).…”