title: Trinuclear Cage-Like Zn(II) Macrocyclic Complexes: Enantiomeric Recognition and Gas Adsorption Properties.
abstract: Three zinc(II) ions in combination with two units of enantiopure [3+3] triphenolic Schiff-base macrocycles 1, 2, 3, or 4 form cage-like chiral complexes. The formation of these complexes is accompanied by the enantioselective self-recognition of chiral macrocyclic units. The X-ray crystal structures of these trinuclear complexes show hollow metal-organic molecules. In some crystal forms, these barrel-shaped complexes are arranged in a window-to-window fashion, which results in the formation of 1D channels and a combination of both intrinsic and extrinsic porosity. The microporous nature of the [Zn3 12 ] complex is reflected in its N2 , Ar, H2 , and CO2 adsorption properties. The N2 and Ar adsorption isotherms show pressure-gating behavior, which is without precedent for any noncovalent porous material. A comparison of the structures of the [Zn3 12 ] and [Zn3 32 ] complexes with that of the free macrocycle H3 1 reveals a striking structural similarity. In H3 1, two macrocyclic units are stitched together by hydrogen bonds to form a cage very similar to that formed by two macrocyclic units stitched together by Zn(II) ions. This structural similarity is manifested also by the gas adsorption properties of the free H3 1 macrocycle. Recrystallization of [Zn3 12 ] in the presence of racemic 2-butanol resulted in the enantioselective binding of (S)-2-butanol inside the cage through the coordination to one of the Zn(II) ions.
authors.affiliation: Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P. O. Box 1410, 50-950 Wrocław (Poland).
authors.forename: Jan
authors.initials: J
authors.lastname: Janczak
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland).
authors.forename: Daniel
authors.initials: D
authors.lastname: Prochowicz
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland).
authors.forename: Janusz
authors.initials: J
authors.lastname: Lewiński
authors.affiliation: Department of Chemical Engineering & Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (UK).
authors.forename: David
authors.initials: D
authors.lastname: Fairen-Jimenez
authors.affiliation: Department of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław (Poland).
authors.forename: Tomasz
authors.initials: T
authors.lastname: Bereta
authors.affiliation: Department of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław (Poland). jerzy.lisowski@chem.uni.wroc.pl.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Lisowski
keywords: cage compounds; macrocycles; microporous materials; self-recognition; zinc