845622-19-7Relevant academic research and scientific papers
Syntheses and characterizations of metal-organic frameworks with unusual topologies derived from flexible dipyridyl ligands
Wang, Ruihu,Han, Lei,Xu, Lijin,Gong, Yaqiong,Zhou, Youfu,Hong, Maochun,Chan, Albert S. C.
, p. 3751 - 3763 (2004)
Two flexible exo-bidentate ligands, 2,2′-bis(3-pyridylmethyleneoxy)- 1,1′-biphenylene (3,3′-bpp) and 2,2′-bis(4-pyridyl- methyleneoxy)-1,1′-biphenylene (4,4′-bpp), were synthesized and employed for the preparation of coordination polymers. Seven metal-organic complexes, [Zn2(3,3′-bpp)2Cl4] (1), [Zn2(3,3′-bpp)2Br4] (2), [Zn(4,4′-bpp)Cl2]n (3), [Zn(4,4′-bpp)Br 2]n (4), [Co(4,4′-bpp)2(SCN) 2]n (5), {[Cd(4,4′- bpp)2(SCN) 2]·2H2O}n (6) and [Cd(4,4′-bpp) (dca)2]n (7) (dca- = dicyanamide), have been obtained through self-assembly reactions of 3,3′-bpp or 4,4′-bpp with the divalent metal ions ZnII, CoII and Cd II. Crystal structure analyses reveal that 1 and 2 are dinuclear metallomacrocycles, are isomorphous and possess a layer network built from metallomacrocycles through π-π interactions. In drastic contrast, 3 and 4 exhibit a three-dimensional structure consisting of one-dimensional polymeric chains held together through π-π interactions between adjacent pyridyl rings. The metal-organic frameworks of 5, 6, and 7 possess unusual topologies: Complex 5 is a two-dimensional polymer based on folded rectangular boxes and zigzag chains, whereas 6 is a polycatenated species consisting of inclined interpenetrating two-dimensional layers, and each layer is constructed by the alternating assembly of left-hand (M) and right-hand (P) cylindrical 2j helices. In 7, dca- connects CdII centers forming a two-dimensional {Cd(dca)2}n layer, which is fused with (M)- and (P)-Cd-(4,4′-bpp) helical chains into a three-dimensional structure. The results suggest that the nature of organic ligands and the coordination preferences of transitional metal ions have a great influence on the structures of metal-organic complexes. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
