Two non-interpenetrating 3D coordination networks with (3, 4)-connected topologies

Two new coordination polymers, namely [Zn₃(1,3,5-BTC)₂(L¹)₂(H₂O)₂] · 2H₂O (1) and [Cd₃(1,2,3-BTC)₂(L²)₃] · H₂O (2) (where L¹ = 1,2-bis(imidazol-1-ylmethyl)benzene, L² = 1,1′-(1,4-butanediyl)bis(imidazole), 1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid and 1,2,3-H₃BTC = 1,2,3-benzenetricarboxylic acid), were synthesized in hydrothermal conditions. In 1, each 1,3,5-BTC anion coordinates to three Zn cations, and the framework of 1 can be simplified as (6 · 8 · 10)₂(6² · 8 · 10³)(8² · 10)(6² · 10) topology. In 2, 1,2,3-BTC anions coordinate to three cadmiums, and the whole structure displays a (6² · 8⁴)₂(6⁴ · 8 · 10)(6² · 8)₂ network containing three different types of nodes. The luminescent properties for 1 and 2 are discussed.     

Synthesis,structures and electrochemical properties of two novel metal–organic coordination complexes based on trimesic acid (H3BTC) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO)

Two novel metal–organic coordination complexes [Cu(HBTC)(BPO)]·H₂O (1) and [Co₃(BTC)₂(BPO)₃(H₂O)₂]·5.25H₂O (2), have been synthesized from hydrothermal reaction of metal chloride with the mixed ligands 1,3,5-benzenetricarboxylate (H₃BTC) and bent dipyridyl based ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO), and structurally characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction analysis. The results reveal that each dinuclear Cu^II unit is bridged by two kinds of different ligands (H₃BTC and BPO) to form one-dimensional (1-D) chain structure in complex 1. The adjacent chains for 1 are further linked by π–π stacking interactions and hydrogen bonding interactions to form a three-dimensional (3-D) supramolecular framework. Complex 2 possesses a 3-D network composed of three different cobalt(II) centers [carboxylate-bridged dinuclear cobalt units and mononuclear cobalt ion] and bridging ligands BTC and BPO, which presents the first example of 3-D coordination polymer constructed from the BPO ligands simultaneously showing three different coordination modes. Moreover, the electrochemical behaviors of the two complexes bulk-modified carbon paste electrodes (1-CPE and 2-CPE) have been reported.     

Synthesis, structures, electrochemistry and electrocatalysis of two novel copper(II) complexes constructed with aromatic polycarboxylates and dipyrido[3,2-d:2′,3′-f]quinoxaline

Two novel coordination polymers [Cu₃(1,3-BDC)₄(Dpq)₂] (1) and [Cu₂(BTC)(OH)(Dpq)₂] · H₂O (2), have been hydrothermally synthesized by self-assembly of aromatic polycarboxylate ligands 1,3-H₂BDC (1,3-H₂BDC = 1,3-benzenedicarboxylate) or H₃BTC (H₃BTC = 1,3,5-benzenetricarboxylate), chelating ligand Dpq (Dpq = dipyrido[3,2-d:2′,3′-f]quinoxaline), and copper chloride. X-ray diffraction analysis reveals that each trinuclear Cu^II cluster is bridged by two coordination modes of 1,3-BDC ligands to form one-dimensional (1-D) chain structure in complex 1. Complex 2 possesses a two-dimensional (2-D) layer network composed of dinuclear [Cu₂(OH)(Dpq)₂] unit and bridging ligand BTC. The adjacent chains for 1 or the adjacent layers for 2 are further linked by π-π stacking interactions to form the three-dimensional (3-D) supramolecular frameworks. Moreover, the electrochemical properties of the two copper(II) complexes bulk-modified carbon paste electrodes (Cu-CPEs: 1-CPE and 2-CPE) have been studied, and the results indicate that both Cu-CPEs give one-electron quasi-reversible redox waves in potential range of 600 to −400 mV due to the metal copper ion Cu(II)/Cu(I). The Cu-CPEs have good electrocatalytic activities toward the reduction of nitrite and bromate in 0.1 M pH 2 phosphates buffer solution, and have remarkable long term stability and especially good surface renewability by simple mechanical polishing in the event of surface fouling, which is important for practical application.