New 2-D silver(I) coordination network constructed from thiomethyl group-substituted p-tert-butylthiacalix[]arene.

New ligand based on p-tertbutyltetrathiacalix[4]arene blocked in 1,3-alternate conformation, was achieved via a multistep synthesis with the introduction of thiomethylpropoxy groups on the lower rim which leads to a neutral tecton. The combination of this p-tertbutyltetrathiacalix[4]arene (p-TCA-2), in 1, 3-alternate imposed conformation, with tetrahedral Ag(I)SbF6 salt, leads to the formation of neutral, new 2-D coordination network, which was structurally investigated in the solid state by X-ray diffraction methods on a single crystal.

1-D and 2-D coordination networks based on tetrathiacalix[]arene derivative generated with mercury and cobalt salts.

The combination of four iso-nicotinate appended tetrathiacalix[4]arene (TCA-1) in 1,2-alternate imposed conformation behaving as neutral tectons with Co(II)Cl2 and Hg(II)Cl2 metallic salts, leads to the formation of neutral, new coordination networks. Indeed, the tetrasubstituted TCA-1 derivative leads to a 1D coordination polymer with Co(II)Cl2 and a 2D grid-like network with, Hg(II)Cl2. The effect of the nature of the metal used on the dimensionality was demonstrated by X-ray diffraction studies on a single crystal.

Protonation of a Spherical Macrotricyclic Tetramine: Water Inclusion, Allosteric Effect, and Cooperativity.

The spherical macrotricyclic cryptand tetramine "C24" (1) displays remarkable protonation behaviour. It undergoes protonation in four successive steps for which pKa values of 11.17±0.05, 10.28±0.04, 6.00±0.06 and 3.08±0.08 have been determined at 298 K. The unusually close values for the first two protonations provide evidence for the encapsulation of a water molecule serving as effector for the second protonation, which is consistent with earlier observations that the exchange of protons bound in the diprotonated species with solvent protons is unusually slow and that 17 O NMR spectra show the presence of an oxygen centre in the same species quite distinct from that of solvent water. Encapsulation of water is also observed in the solid state in the picrate salt of the triprotonated form of 1 and has been characterised by means of X-ray structural determination.

A platinum turnstile with a palladium lock.

An organometallic molecular turnstile composed of a stator based on an α,ω-diphosphine bearing, in a symmetric fashion, the 2,6-pyridyl diamide moiety as a central tridentate chelating unit and a rotor composed of Pt(II) equipped with two pyridyl groups in trans configuration was designed. The switching between its open and closed states using Pd(II) was investigated both in solution and in the solid state.

A platinum based organometallic turnstile.

The synthesis of an organometallic turnstile based on a Pt(II) centre as a hinge was achieved. Its dynamic behaviour in solution was investigated using 1D and 2D NMR techniques. Using Ag(I) cation as an effector, the switching between its open and closed states in solution was demonstrated.

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.

An oscillating molecular turnstile.

An oscillating molecular turnstile based on a stator composed of a porphyrin core bearing two trans coordinating pyridyl units at the meso positions and a rotor equipped with a pyridyl group was designed. Whereas, in solution, the rotor freely rotates around the stator, in the presence of a silver cation behaving as an effector, the system oscillates between two stations. The oscillatory movement may be frozen upon cooling at -70 °C generating thus the closed state of the turnstile. The switching of the system between the open and closed states may be achieved using an external stimulus such as addition of Et(4)NBr.

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.

Open and closed states of a porphyrin based molecular turnstile.

The molecular turnstile 1 composed of a stator based on an Sn(IV)-porphyrin bearing two sets of monodentate coordinating sites (pyridyl and benzonitrile) and a handle bearing a 2,6-pyridinediamide moiety as a tridentate unit was synthesised. In the absence of metal behaving as a blocking agent, the handle freely rotates around the stator (open state). In the presence of Pd(II), the closed state of the turnstile 1-Pd resulting from the simultaneous binding of the metal centre by both the dianionic tridentate site and one of the two pyridyl units is generated. The reaction of 1-Pd with the organometallic 2,6-diphenylpyridine Pt(II) complex 11 leads to the heterotrinuclear (Pt, Sn, Pd) species 13, resulting from the binding of the platinum complex by 1-Pd.

Porphyrin based molecular turnstiles.

Molecular turnstiles, based on a hinge composed of a Sn-porphyrin bearing coordinating sites at the meso positions and a handle, equipped with a tridentate coordinating pole or its Pd(ii) complex, connected to the porphyrin through Sn-O bonds, offering open (free rotation of the handle around the hinge) and close states (blockage of rotation through binding of Pd(ii)) were designed, prepared and studied both in solution and in the solid state.

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.

A molecular gate based on a porphyrin and a silver lock.

A Sn(IV) metallaporphyrin bearing a 4-pyridyl group on one meso position and a handle equipped also with a pyridyl unit functions in solution as a molecular gate in the presence of silver cation: the complexation-decomplexation of Ag(I) corresponds to the opening and closing motions of the gate.

Koilands from thiophiles: mercury(II) clusters from thiacalixarenes.

Tetra- and hexa-nuclear mercury(II) complexes have been obtained from tetrathiacalix[4]arene and tetramercaptotetrathiacalix[4]arene, respectively, and structurally characterised in the solid state; the complexes provide new digonal and trigonal receptors of the koiland type.