Multifunctional Polythreading Coordination Polymers: Spontaneous Resolution, Nonlinear-Optic, and Ferroelectric Properties



The reactions of methylenediisophthalic acid (H4L) and N-auxiliary ligands (1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethane) with transition-metal centers (Co2+/Mn2+) have given rise to four unprecedented polythreading coordination polymers. Single-crystal X-ray diffraction analyses revealed that the compounds can be described as 3D2−⊂2[1D2+]+2D6− for 1, 3D4−⊂1D2++1D6− for 2, and 2D4−⊂0D2++2[1D3−] for 3 and 4. All the polymers are formed through the assembly of two kinds of motifs with opposite charges. Noncentrosymmetric structures and multifunctionality in 24 are established by varying ligands and metal centers. Spontaneous resolution upon crystallization occurred in compounds 3 and 4 in the absence of any chiral source. The enantiomers of 3 and 4 consist of three chiral building blocks of L4−/HL3− and Mn2+ centers. In the solid state, polar compounds 24 exhibit nonlinear-optic (NLO) and ferroelectric properties at room temperature. The assembly of two kinds of motifs with opposite charges provides a useful method for the preparation of multifunctional compounds.