Microporous Nanotubular Self-Assembly of a Molecular Chair

A M6L6 type molecular chair, [(Zn6(μ-L4)6Cl12)·X] 4 (X = disordered lattice included solvents), has been isolated by reacting N,N′-bis-(4-pyridyl)amido-2-oxo-imidizolidine (L4) with ZnCl2, and characterized by single crystal X-ray diffraction. The structure of 4 revealed a microporous nanotubular self-assembly having a pore size as large as zeolites. The robustness and microporosity of 4 was evident from thermogravimetric and X-ray powder diffraction experiments. Isolation of 4 was a consequence of the exploratory studies on the effect of the hydrogen bonding backbone, ligating topologies of the ligands on the supramolecular structures of the resulting compounds derived from various pyridyl based ditopic ligands, namely, N,N′-bis-(3-pyridyl)ethylene-bis-urea (L1), N,N′-bis-(4-pyridyl)ethylene-bis-urea (L2), and their corresponding 2-oxoimidazolidine derivatives, namely, N,N′-bis-(3-pyridyl)amido-2-oxo-imidizolidine (L3) and N,N′-bis-(4-pyridyl)amido-2-oxo-imidizolidine (L4). Single crystal structures of [(Zn(μ-L1)Cl2)·2MeOH]n (1), [(Zn(μ-L2)Cl2)·X]n (2) (X = disordered lattice included solvents), and [((L3)(Cl)2Zn(μ-L3)Zn(L3)(Cl)2] (3) are also discussed in this context.