Rational design of two bpy-bridged 3D and 2D Co(II) open frameworks with similar amino-acid-based Schiff bases.
Two novel bpy-bridged Co(II) Schiff base complexes have been synthesized by the hydro(solvo)thermal reactions of corresponding amino-acid-based Schiff bases, bpy and Co(NO(3))(2)·6H(2)O. The following formulae identify the two complexes: {[Co(napala)(bpy)(0.5)]·H(2)O}(n) (1) and [Co(napgly)(bpy)(0.5)](n) (2) [H(2)napala = N-(2-hydroxy-1-naphthylmethylidene)-D/L-alanine, H(2)napgly = N-(2-hydroxy-1-naphthylmethylidene)-glycine and bpy = 4,4'-bipyridine]. These two compounds have been characterized using single-crystal X-ray diffraction, infrared, powder X-ray diffraction, thermogravimetric analysis, optical spectra analysis, and magnetic measurement. Complex 1 features an unprecedented threefold interpenetrated diamond network based on the fan-shaped Co(II)(4)(μ(2)-napala)(4) molecular square node and bpy linker, which represents the first example of 3D framework among the amino-acid-based Schiff base complexes with salicylaldehyde or its derivatives. In 2, adjacent Co(II) ions are bridged by μ(2)-napgly(2-) to form left- and right-handed [Co(II)(μ(2)-napgly)](n) helical chains. These two types of helical chains are sustained alternately by a symmetrical bpy co-ligand into a 2D grid-based layer. The solid-state fluorescence of complexes 1 and 2 are quenched almost completely compared with free mixed-ligands at room temperature. Moreover, magnetic studies show the dominant antiferromagnetic coupling between the Co(II) centers mediated by the syn-anti-COO(-)-bridges in both complexes.
Department of Chemistry, Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, Yunnan University, Kunming, 650091, PR China.
Zong-Ze
ZZ
Li
Lin
L
Du
Jie
J
Zhou
Ming-Rong
MR
Zhu
Fen-Hua
FH
Qian
Jing
J
Liu
Peng
P
Chen
Qi-Hua
QH
Zhao
D000596:Amino Acids / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D011725:Pyridines / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*
D000596:Amino Acids; D011725:Pyridines; D012545:Schiff Bases; D003035:Cobalt; C034306:4,4'-bipyridyl