Metal–Organic Nanotube with Helical and Propeller-Chiral Motifs Composed of a <i>C</i><sub>10</sub>-Symmetric Double-Decker Nanoring
2015-06-24T00:00:00Z (GMT) by
Coassembly of an achiral ferrocene-cored tetratopic pyridyl ligand (<b>FcL</b>) with AgBF<sub>4</sub> in CH<sub>2</sub>Cl<sub>2</sub>/MeCN (7:3 v/v) containing chiral Bu<sub>4</sub>N<sup>+</sup> (+)- or (−)-menthylsulfate (MS*<sup>–</sup>) results in the formation of an “optically active” metal–organic nanotube (<b>FcNT</b>) composed of a <i>C</i><sub>10</sub>-symmetric double-decker nanoring featuring 10 <b>FcL</b> units and 20 Ag<sup>+</sup> ions. The circular dichroism spectrum of <b>FcNT</b> along with its 2D X-ray diffraction (2D XRD) pattern indicates that the constituent metal–organic nanorings in <b>FcNT</b> stack one-handed helically on top of each other. A crystal structure of the dimeric double-decker model complex (Ag<sub>2</sub>(<b>FcL</b>′)<sub>2</sub>) from a ditopic ferrocene ligand (<b>FcL</b>′) and AgBF<sub>4</sub> allowed for confirming the binding of MS*<sup>–</sup> onto the Ag<sup>+</sup> center of the complex. The results of detailed spectroscopic studies indicate that in its double-decker aromatic arrays, <b>FcNT</b> possibly possesses propeller-chiral twists in addition to the helically chiral structure, where the former is considerably more dynamic than the latter. Notably, both chiral structural motifs responded nonlinearly to an enantiomeric excess of MS*<sup>–</sup> (majority rule) though with no stereochemical influence on one another.