Four novel coordination polymers of transition metals built using a semi rigid oxygen donor ligand: Crystal structures, novel topology and emission studies

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• 作者：Rupali Mishra^a ; Musheer Ahmad^b ; Madhav Ram Tripathi^a ; ^{madhavramtripathi@gmail.com} ; Ray J. Butcher^c
• 关键词：Coordination polymer ; Transition metal ions ; Crystal structure ; Homometallic clusters ; Thermogravimetric analyses (TGA) ; Photoluminescence studies
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：13 February, 2013
• 年：2013
• 卷：50
• 期：1
• 页码：169-178
• 全文大小：3205 K

文摘

Four new coordination polymers namely, [Cd₃(L₁)₂(DMA)₄]_n (1), [Mn(HL₁)(H₂O)₃]_n (2), [Mn(H₂L₂)]_n (3) and {[Co₂(HL₂)(L₂)]¡¤(Et₄N)¡¤(1.5H₂O)}_n (4) have been synthesized with semi-rigid ether bridged tricarboxylic acid ligands H₃L₁ and H₃L₂ [H₃L₁ = 5-(4-carboxy-phenoxy)-isophthalic acid and H₃L₂ = 5-(2-carboxy-phenoxy)-isophthalic acid] with various transition metal ions using hydro(solvo)thermal techniques. All the coordination polymers have been structurally characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and X-ray single crystallography. Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric to trimeric units except 2 which is a linear monomeric. On reacting para-isomer of the ligand H₃L₁ with metal ions, 2D and 3D supramolecular structures have been obtained while with the ortho-isomer H₃L₂ dimeric 2D and 3D framework were obtained. Topological analysis reveals that 1 and 3 are binodal (3,6)-connected kgd net, 2 is also a binodal (3,3)-connected honey-comb type hcb net, while 4 shows unprecedented (3,3,6)-connected pkb5 topological trinodal-network. Interestingly, 3 and 4 exhibits unusual coordination modes involving one of carbonyl O atom of an acid functional group. Moreover, in 4 ethereal O atom is also coordinated to one of the metal center. All complexes show high thermal stability, thus losing coordinated and lattice solvent molecules in the range, ¡«100-200 ¡ãC. Upon excitation at 325 nm, compounds 1-4 exhibit solid-state luminescences at room temperature.