Three novel 3D (3,8)-connected metal–organic frameworks constructed from flexible-rigid mixed ligands

Abstract

Three novel 3D (3,8)-connected networks, namely [Cd₂(L1)₂(1,3-bdc)] 1, [Cd₂(L2)₂(1,4-bdc)]·3H₂O 2 and [Cd₃(L3)₂(1,3-bdc)₂] 3, where L1 = 3,5-bis(pyridin-4-ylmethoxy)benzoic acid, L2 = 3,4-bis(pyridin-4-ylmethoxy)benzoic acid, L3 = 3,5-bis(pyridin-3-ylmethoxy)benzoic acid, bdc = benzenedicarboxylate, have been synthesized hydrothermally and characterized. Complex 1 exhibits a twofold interpenetrating network constructed from Cd₂-based secondary building units (SBUs) [Cd₂(CO₂)₂O₂N₄] with (4²·6)₂(4⁴·6²²·8²) topology. Complex 2 is constructed from Cd₂-based SBUs [Cd₂(CO₂)₄N₄] with (4³)₂(4⁶·6¹⁸·8⁴) topology. The structure of 3 is based on linear Cd₃-based SBUs [Cd₃(CO₂)₆N₂] with a Schläfli symbol (4²·5)₂(4⁴·5⁶·6¹⁰·7⁵·8²·9). In addition, X-ray powder diffraction (XRPD) and luminescent properties of 1–3 were also investigated in detail.