Novel chiral dinuclear Co (II)-salen catalysts self-assembled through the pyridone/ aminopyridine hydrogen-bonding pair have been developed. The self-assembled dinuclear Co (II)-Salen catalyst results in significant rate acceleration (48 times faster rate) as well as excellent enantioselectivity (96% ee vs 55% ee) in a nitro-aldol reaction, compared to the corresponding monomeric catalyst. A bimetallic mechanism is suggested by the kinetic ...