Solvent-controlled self-assembly of tetrapodal [4 + 4] phosphate organic molecular cage.

Two flexible subcomponents, namely tris(4-formylphenyl)phosphate and tris(2-aminoethyl)amine, are assembled into a tetrapodal [4 + 4] cage depending on the solvent effect. Single-crystal structure analysis reveals that the caivity is surrounded by four phosphate uints. Good selectivity of CO2 adsorption over CH4 is demonstrated by the gas adsorption experiment.

Construction of Chiral [4 + 4] and [2 + 2] Schiff-Base Macrocyclic Zinc(II) Complexes Influenced by Counterions and Pendant Arms.

Chiral and racemic 68-membered [4 + 4] tetranuclear and 34-membered [2 + 2] dinuclear Schiff-base macrocyclic zinc(II) complexes 1-10 can be selectively synthesized based on the secondary template effects of counterions and pendant arms, when [(S,S), (R,R), (±)]-1,2-diaminocyclohexane precursors are first used to react with a pair of extended dialdehydes with different pendant arms via zinc(II) ion template-assisted imine condensation.

Two Types of Anion-Induced Reconstruction of Schiff-Base Macrocyclic Zinc Complexes: Ring-Contraction and Self-Assembly of a Molecular Box.

Two 46-membered [2 + 2] Schiff-base macrocyclic dinuclear Zn(II) complexes (1a and 1b) were investigated deeply by the postmodification strategy, and two types of supramolecular processes (ring-contraction and self-assembly) have been achieved after the addition of specific anions as stimulus for the equilibrium of Schiff-base macrocyclic complexes. Namely, in the presence of linear three-atom SCN(-), 1a was degraded into two 23-membered [1 + 1] Schiff-base macrocyclic complexes simultaneously (mononuclear Zn(II) complex 2 and dinuclear Zn(II) complex 3). In contrast, 1b was only transformed into the macrocyclic mononuclear complex 5. More interestingly, in the case of pseudolinear five-atom N(CN)2(-), supramolecular self-assembly took place instead of the above-mentioned ring-contraction. Finally, 1a was assembled into a unique molecular box 4 with two 46-membered [2 + 2] Schiff-base macrocyclic heteronuclear Zn4Na4 substrates and double µ2-N(CN)2(-) bridges, while no similar assembly process was observed for 1b. The geometry of anions and pH values slightly adjusted by the pendant arms on the macrocyclic skeletons are believed to be the critical factors for the different supramolecular processes originating from the dynamic covalent chemistry of Schiff-base imine bonds.