New silver(I) coordination polymers constructed from pyrazine derivatives and aromatic carboxylic acids: Syntheses, structures and photoluminescence.

Five one-dimensional to three-dimensional coordination polymers have been synthesized by 2-chlorobenzoic acid (HL 1 ), 2-nitrobenzoic acid (HL 2 ), o-toluic acid (HL 3 ), 2,3,5-trimethylpyrazine (tpyz) and 2,3,5,6-tetramethylpyrazine (mpyz) in the presence of NH 3 ·H 2 O in mixed solvents systems, namely, {Ag 4 (tpyz) 2 (L 1 ) 4 } n ( 1 ), {Ag 2 (tpyz) (L 2 ) 2 } n ( 2 ), {Ag 2 (tpyz) (L 3 ) 2 } n ( 3 ), {Ag 2 (mpyz) (L 1 ) 2 } n ( 4 ), {Ag(mpyz) (L 2 ) (H 2 O)} n ( 5 ). All the complexes have been characterized by elemental analyses, IR spectra and X-ray diffraction. Compound 1 shows a 3D framework. The tpyz ligand links 1D chain which was connected by silver atom and L 1 anion into 3D framework. Compounds 2 and 4 possess a similar 2D network with (4, 4) topology. Complex 3 also exhibits a two-dimensional structure. There is a 1D silver chain in 3 , which is the main difference from 2 and 4 . So, 3 shows three-connected (4 8, 3) topology. For 5 , only one oxygen of L 2 coordinated to Ag(I) ions. The L 2 anions were arranged in both sides of the chain, which was connected by silver atoms and mpyz ligands. Then, the uncoordinated carboxylate oxygen with coordinated water 1 molecule oxygen through the hydrogen bond made the resultant structure to a 3D framework. Complexes 1 – 5 spanning from one-dimensional chains to three-dimensional framework suggest that carboxylates and the kinds of pyrazine derivatives play significant roles in the formation of such coordination architectures. The photoluminescence and thermogravimetric analysis (TGA) of the complexes were also investigated. [ABSTRACT FROM AUTHOR]