Pairwise selection of guests in a cylindrical molecular capsule of nanometre dimensions

Abstract

Nature © Macmillan Publishers Ltd 19988 does not suf®ce. These observations indicate that many-body states due to signi®cant electron±electron correlations beyond exchangetype correlations have to be taken into account to describe the lowenergy transport properties of carbon nanotubes.M

A family of double-bowl pseudo metallocalix[6]arene discs

“…This is achieved via careful structural manipulation 25 of these molecules (and molecular assemblies) giving rise to complex molecular architectures possessing targeted synergic chemical and physical properties. Although supramolecular host-guest chemistry has been readily exhibited and widely reported with a vast array of organic receptor moieties, 5 the 30 engagement of magnetically interesting inorganic host units is still relatively rare. 6 The complementarity which has long existed between the fields of supramolecular chemistry and molecular magnetism has fascinated scientists for many years.…”

“…The six singly deprotonated (at the phenolate site) L 1¯ ligands bridge the peripheral Ni II centres via a µ 2 -η 1 :η 2 :η 1 coordination mode. These ligands are situated alternately above and below the [Ni 7 ] plane which gives rise to a double-bowl conformation in which the [Ni 7 ] core is the basal plane, reminiscent of a metallocalix [6]arene 5 concave unit (Fig. 1).…”

“…Efforts to encapsulate MeCN and MeNO 2 solvent guests inside the cavities of 2 and 4, respectively, were unsuccessful. 5 These findings suggest that guest molecules can only be placed within such cavities if and when they are able to orientate themselves into certain topologies comprising symmetry elements compatible with their host lattices. This hypothesis is supported by the formation of complex 3 in 10 which three MeOH guests, linked via a three-fold rotation axis, are accommodated inside the trigonal P-3c1 cell whereas attempts at producing a MeOH guest analogue to 4 (in a monoclinic C2/c cell) remain fruitless.…”

“…When small molecules are located within such highly symmetrical molecular cavities, it is common to observe crystallographic disorder and the MeOH guest molecules in 2 are no exception. 5 The first disordered MeOH guest (atoms C20-O10) has only 1/6 th occupancy and thus periodically occupies positions in between the NO 3¯ counter anions (which form the aforementioned zig-zag belt) and partakes in H-bonding interactions (O4…O10 = 2.86 Å). The second MeOH guest 10 (C21-O9) lies within the molecular cavity in 2 at the midpoint between the two [Ni 7 ] planes (possessing a two-fold axis along the C-O vertex) where it is also disordered over three sites with respect to the three fold rotation axis inherent to the cell (Fig.…”

Chemical amplification with encapsulated reagents

“…Specifically, deuterated mesitylene is appropriate for most guests and provides a convenient solvent for NMR spectroscopy of the encapsulation complexes. The capsule distinguishes shape and size in the molecular recognition of potential guests (10,11). For example, trans stilbene 2 is encapsulated but cis stilbene 3 is not (Eq.…”