Abstract
A one-dimensional chain-type dicopper(II) coordination polymer with 1,4-di(4-pyridyl)-benzene (dpybz), [Cu2(O2C-tBu)4(dpybz)] (1), is synthesized and characterized by single crystal X-ray diffraction, infrared spectroscopy, and CHN elemental analysis. Single crystal X-ray diffraction confirms that the one-dimensional chains of 1 are assembled with CH···π interactions at the dpybz moieties to form a brick-like porous network structure. Magnetic susceptibility measurement and broken-symmetry density functional theory (BS-DFT) calculations indicate that (i) antiferromagnetic interactions are present between two copper ions through the bridging carboxylate ligands; the observed exchange integral value (J) of 1 is −175.3 cm−1, which is consistent with the DFT-calculated value for 1 (−174.5 cm−1), and (ii) the magnetic interaction between two Cu2 units through the dpybz ligand is negligible. N2 adsorption measurements indicate that the porous structure of 1 is retained even after evacuation of the guest solvents from the pores of 1, and 1 adsorbs N2 molecules into its pores (the Langmuir surface area of 1 is estimated as 538.0 m2/g).
Highlights
A paddlewheel-type dicopper (Cu2) unit bridged by four carboxylate (−O2C-R) ligands, [Cu2(O2C-R)4], is well known as an important molecular skeleton in the area of coordination chemistry [1,2,3,4], because it has been widely utilized as a secondary building block (SBU) for supra-molecular cages [5], coordination polymers (CPs) [6,7] and metal–organic frameworks (MOFs) [8,9]
Results of Theoretical Calculations To investigate the thermodynamically favorable spin states, electronic structures, spin density distributions and magnetic properties of 1, broken-symmetry density functional theory (BS-DFT) calculations were performed on model structures of 1, which were obtained from crystal structures of 1
The calculated results are summarized: (i) an antiferromagnetic interaction occurred in 1 between unpaired electrons residing in dx2-y2 orbitals of Cu ions via a super-exchange mechanism through four bridging carboxylate ligands, and (ii) the magnetic interaction between two Cu2 units through the dpybz ligand was negligible
Summary
A paddlewheel-type dicopper (Cu2) unit bridged by four carboxylate (−O2C-R) ligands, [Cu2(O2C-R)4], is well known as an important molecular skeleton in the area of coordination chemistry [1,2,3,4], because it has been widely utilized as a secondary building block (SBU) for supra-molecular cages [5], coordination polymers (CPs) [6,7] and metal–organic frameworks (MOFs) [8,9]. In 1995, Mikuriya et al reported the synthesis and characterization of one-dimensional CPs [Cu2(O2C-tBu)4(N~N)], in which [Cu2(O2C-tBu)4] SBUs were linked by 1,4-diazabicyclo[2.2.2]octane (DABCO), pyrazine (pyz), and 4,4 -bipyridine (bpy) ligands [12]. These CPs are robust in air and occur in the crystalline state.
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