269 research outputs found
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]
Syntheses and characterization of aryl-substituted pyrogallol[4]arenes and resorcin[4]arenes
Thirteen aryl-substituted pyrogallol[4]arene and resorcin[4]arenes structures are synthesized and characterized. The effect of the varying aryl pendent groups on π–π distance, the inward tilt of the pendent –R groups, the twist angle of the pendent –R groups, and the angle between the pendent –R groups is methodically investigated and discussed.</p
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>-butylcalixÂ[4]Âarene and salicylaldoximes.
Eight new [Mn<sup>III</sup><sub>7</sub>Mn<sup>II</sup>] 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<sup>II</sup> 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<sup>IV</sup><sub>2</sub>Mn<sup>III</sup><sub>2</sub>] 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 Mn<sub>8</sub> 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
- …