Anion-Templated Rotaxane Formation

Abstract

The development of an acyclic chloride anion template in which the chloride anion is coordinatively unsaturated and available for subsequent complexation to various hydrogen bond donating components is described. This template orients a neutral hydrogen bond donating ligand and a pyridinium cation orthogonally to one another. Incorporation of second-sphere interactions between the ligand and the pyridinium cation improved the efficacy of the chloride template. These results were exploited in the construction of a chloride anion-templated [2]rotaxane which, after anion template removal, was studied with regards to its anion recognition properties. Encirclement of the neutral macrocycle around the dumbbell-shaped pyridinium cation in the [2]rotaxane produced a dramatic increase in its selectivity for chloride anions as compared to the noninterlocked cation. This is interpreted as a function of the anion template used to create the [2]rotaxane superstructure.

Mechanostereochemistry and the mechanical bond

“…Subsequently, Beer and co-workers have used the tetrahedral geometry arranged around a chloride anion-acting as an external template-by an isophthalimide and a pyridinium based diamide, each providing (figure 11) two N-H hydrogen-bond donors, as a crossing point or node in a manner similar to that of the archetypal bis-phenanthrolino copper(I) synthon. When a dumbbell with bulky stoppers and a pyridinium diamido binding station is combined (Wisner et al 2002) with an isophthalimido derivative terminated with alkene functions and one equivalent of chloride, the 1 : 1 : 1 complex 53 that is formed can be converted (figure 11a) to a [2]rotaxane 54 by ring-closing alkene metathesis. Similarly, when the dumbbell is replaced (Sambrook et al 2004) by a macrocycle, thus resulting in the complex 55, a chloride-templated [2]catenane 56 can be synthesized (figure 11b).…”

Homochiral metal-organic framework [Zn2(d-Cam)2(4,4′-bpy)]nfor high-resolution gas chromatographic separations

“…Chiral metal-organic frameworks (MOFs) have fascinating structures (such as cage [2,3], honeycomb [4,5], herringbone [6,7], and catenanes [8,9]) and potential applications in many areas (such as gas storage, separation, ion exchange, electrical conductivity, and photochemistry [10][11][12][13][14][15][16][17][18][19][20][21][22]), which have attracted a growing number of researchers. To date, a large number of chiral MOFs have been synthesized [23][24][25][26][27][28][29][30][31][32][33], which can be suitable as chiral stationary phases (CSPs) because of its excellent chiral recognition ability and thermal and mechanical stability [34,35].…”

An Introduction to the Mechanical Bond

“…In Figure 1.16, we simply present a few examples that we find noteworthy. [134][135][136][137][138][139] In Section 1.3, see Figures 1.25, 1.27, and 1.29, as well as Scheme 1.3 to find more beautiful mechanically interlocked crystal structures.…”