A Convenient Synthetic Route to Partial-Cone p-Carboxylatocalix[4]arenes.

p-Carboxylatocalix[n]arenes have emerged as useful building blocks for the construction of a diverse range of supramolecular assemblies. A convenient route to a p-carboxylatocalix[4]arene that is locked in a partial-cone conformation is presented. The conformation gives the molecule markedly different topological directionality relative to those previously used in self- and metal-directed assembly studies

Supramolecular assemblies controlled by cucurbit[: N] uril size (n = 6, 7, 8 and 10)

This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. A benzyl substituted 4-pyrrolidinopyridinium salt (G) with multiple active sites including benzyl, pyridinium and pyrrole groups has been synthesized. The interaction between G and a series of cucurbit[n]urils (TMeQ[6], Q[7], Q[8], Q[10]), has been studied both in aqueous solution and in the solid state. The binding interaction site between G and the Q[n] can be controlled by the size of the cavity of the Q[n]s. In the case of TMeQ[6], the benzyl is accommodated within the cavity, whilst for Q[7] and Q[8], the pyrrole ring and the benzyl are accommodated within the cavity of the Q[7/8], and the latter can shuttle on the guest G in a state of dynamic equilibrium. For the larger cavity of Q[10], the entire G molecule is located within the cavity of the Q[10]

Importance of Steric Influences in the Construction of Multicomponent Hybrid Polymetallic Clusters

The straightforward room temperature synthesis of hybrid polymetallic manganese clusters is investigated, exploiting complementary ligand combinations of <i>p</i>-<i>tert</i>-butylcalix­[4]­arene and salicylaldoximes. Eight new [Mn^III₇Mn^II] clusters have been prepared wherein the simple substitution of alkyl or aryl groups at well-defined positions of the salicylaldoxime scaffold leads to two distinct structure types that, while exhibiting the same general topology, contain the unique Mn^II ion in different positions. Incorporation of a methyl, ethyl, or isopropyl group at the 3-position of the aromatic skeleton or a phenyl group at the oximic carbon gives structure type A that displays competing weak ferromagnetic and antiferromagnetic interactions. Substitution of a methyl or ethyl group at the oximic carbon atom invokes structure type B, incorporating an additional bulky chloride or nitrate into the metallic core due to the smaller steric imposition and position of the methyl or ethyl group. The distortion of the cluster core is consequently enhanced, switching the magnetic properties and resulting in single-molecule magnet behavior. The presence of <i>tert</i>-butyl groups at the 3- and 5-positions of the salicylaldoxime skeleton leads to a new [Mn^IV₂Mn^III₂] cluster that is found to be a single-molecule magnet. The bulky <i>tert</i>-butyl group in the 3-position is too large to facilitate Mn₈ cluster formation, and thus assembly occurs by an alternative pathway. Characteristic bonding modes of the constituent ligands are retained in every case, and the results presented here give insight into the potential of ligand combinations in future studies, highlighting the importance of steric factors in evaluating their relevant compatibilities