Ernest Graf

Thiacalixarenes: Synthesis and structural analysis of thiacalix[4]arene and of p-tert-butylthiacalix[4]arene

The synthesis of tetrathiacalix[4]arene was achieved by the detertiobutylation of p-tert-butyltetrathiacalix[4]arene. X-ray diffraction studies revealed that in the solid state whereas p-tert-butyltetrathiacalix[4]arene forms inclusion complexes with solvent molecules, tetrathiacalix[4]arene undergoes self-inclusion leading to trimeric units. The same behaviour in the crystalline phase was also demonstrated for calix[4]arene.

Synthesis and solid state structural analysis of conformers of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene

The role of alkaline metal cations in the synthesis and in determining the conformer distribution of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene obtained by treatment of tetrathiacalix[4]arene 1 in acetone by ethyl bromoacetate in the presence of M 2 CO 3 was systematically investigated. Among the four possible conformers, the cone, partial cone and 1,3-alternate conformers were obtained, purified and structurally characterised by X-ray analysis in the solid state. Although for Li + no tetra substituted derivative was observed, for Na + the cone conformer was exclusively formed while for both K + and Cs + a mixture of partial cone and 1,3-alternate conformers was obtained.

Tetrasulfinylcalix[4]arenes: Synthesis and solid state structural analysis

The synthesis of two tetrasulfinylcalix[4]arene was achieved by partial oxidation of tetrathiacalix[4]arene precursors. In both cases, the 1,3-alternate conformation of the calix units and the alternate orientation of the sulfoxide groups were demonstrated by X-ray diffraction studies in the solid state. In the case of tetrasulfinylcalix[4]arene, a 3-D network based on stacking interactions between the aromatic groups was observed.

Design and structural analysis of interpenetrated 3-D co-ordination networks formed by self-assembly using tetrapyridinoocyclophane and silver cations

A [1,1,1,1]metacyclophane blocked in the 1,3-alternate conformation and bearing four pyridine units leads, under self-assembly conditions in the crystalline phase, to the formation of a fourfold interpenetrated 3-D co-ordination network in the presence of silver cations; the 3-D net is generated through the bridging by linearly co-ordinated silver cations of consecutive tectons presenting a pseudo-tetrahedral arrangement of four co-ordination sites.

Molecular tectonics I: The first synthesis and X-ray analysis of a linear koilate obtained by self-assembly of linear koilands and hexadiyne

Abstract The first synthesis and X-ray analysis of a koilate, i. e. a linear array in the solid state, resulting from an iterative assembling of a koiland (hollow molecule possessing two divergent cavities based on the double fusion of two p-tert-butylcalix[4]arenes by two silicon atoms), and hexadiyne as connector, as well as two binuclear complexes formed in the solid state between the above mentioned koiland and anisol and para-xylene is described.

Synthesis and solid state structural analysis of 1,3-alternate conformer of tetrathiacalix[4]arene tetra-ester, -acid and -ether derivatives

Four new tetrathiacalix[4]arene derivatives blocked in 1,3-alternate conformation and bearing four ester, acid or ether groups were prepared and their 1,3-alternate conformation was established by X-ray diffraction methods on single-crystal.

Design and Synthesis of Sn-Porphyrin Based Molecular Gates

The design, synthesis, and structural characterization, both in solution by (1)H NMR and in the solid state by X-ray diffraction on single crystals, of a series of molecular gates based on Sn-porphyrin derivatives are presented. The molecular system is based on a porphyrin core bearing at the meso positions either phenyl or pyridyl groups as a stator, octahedral Sn(IV) cation located at the center of the porphyrin as a hinge, and different handles connected to the porphyrin through Sn-O axial bonds. The stability of the complexes in the presence of different acids is also reported.

Porphyrin-based switchable molecular turnstiles.

The design, synthesis and structural characterisation, in solution, of two new molecular turnstiles based on Sn-porphyrin derivatives are described. The system is composed of a stator (5-(4-pyridyl)-10,15,20-triphenylporphyrin), a hinge (Sn(IV)) and a rotor (handle equipped with 2,6-pyridinedicarboxamide as a tridentate coordinating site or its Pd(II) complex). The presence of interaction sites, both on the stator and the rotor, offers the possibility of switching between an open state (free rotation of the handle around the porphyrin) and a closed state (blockage of the rotation) by either establishment of hydrogen bonds between the stator and the rotor or by the simultaneous binding of Pd by both coordinating groups.

Synthesis of an exo-ditopic receptor based on calix[4]arene and catechol

Abstract The synthesis of a calix[4]arene derivative immobilised in 1,3-alternate conformation by alkylation at the lower rim and bearing four catechoylamide units at the upper rim was achieved. The chelating coordination sites were by construction oriented, in an alternating mode, below and above the main plane of the backbone, thus affording an exo-ditopic ligand.

Strapped‐Porphyrin‐Based Molecular Turnstiles

The synthesis of a series of molecular turnstiles that contained both H-bond-donor and -acceptor sites was achieved. Their structures were based on tetra-aryl X(2)Sn(IV) porphyrins (X=Cl or OH) as H-bond-acceptor sites that were equipped with a rotor that contained a pyridyldiamide moiety as a H-bond donor. In the solution phase, 1D and 2D NMR spectroscopic analysis showed that switching between the closed state, which resulted from the formation of intramolecular H-bonds, and the open state of the turnstile was achieved by using external H-bond-acceptor molecules, such as DMSO. The solid-state structure of the closed state of the turnstile was established by single-crystal X-ray diffraction.