Unique topological motifs in two Cd(ii)-coordination polymers: mutual-embedded 2D bilayers, 3D polythreaded structures, self-penetrated networks and 2D → 2D interpenetrated homochiral bilayers

Abstract

Two unique entangled Cd(II) coordination polymers, {[Cd₂(m-pdoa)₂(dpa)₃(H₂O)]}_n (1) and {[Cd(m-pdoa)(bpp) (H₂O)]·2H₂O}_n (2) (m-H₂pdoa = 1,3-phenylenedioxy diacetic acid, dpa = 4,4′-dipyridylamine; bpp = 1,3-di(4-pyridyl)propane), have been modulated using flexible/semi-rigid mixed aromatic carboxylate and pyridine derivative ligands and characterized using elemental analysis, infrared spectra (IR), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 shows the first topological motifs of mutual-embedded bilayers originating from two reverse 2D 4⁴-sql layers with 1D single side arms in an alternating fashion, and thus affording a 3D polythreaded structure featuring poly-pseudo-rotaxane that exhibits a new 3D (3,3,3,3,3,5,5,5)-connected self-penetrated H-bonding net. Whereas 2 displays rare 2D → 2D homochiral interpenetrated layers propagating from 4⁴-sql chiral layers. Additionally, thermal stabilities and luminescent properties for 1 and 2 were also discussed.