A Multifunctional, Charge-Neutral, Chiral Octahedral M12 L12 Cage.

peer reviewedA chiral, octahedral M12 L12 cage, which is charge neutral and contains an internal void of about 2000 Å3 , is reported. The cage was synthesised as an enantiopure complex by virtue of amino-acid-based dicarboxylate ligands, which assemble around copper paddlewheels at the vertices of the octahedron. The cage persists in solution with retention of the fluorescence properties of the parent acid. The solid-state structure contains large pores both within and between the cages, and displays permanent porosity for the sorption of gases with retention of crystallinity. Initial tests show some enantioselectivity of the cage towards guests in solution

Crystallographic studies on a series of salts of 2,3,7-trihydroxy-9-phenyl-fluorone

2,3,7-Trihydroxy-9-phenyl-fluorone (hereafter H3Z) has been synthesised in its H4Z+, H3Z, H2Z- and Z3- protonation states. X-ray crystal structure determinations have been carried out for (H4Z)(HSO4), H3Z, [EtiPr2NH]H2Z, solvated (PPh4)H2Z and solvated K3Z. In each of these salts the 9-phenyl group adopts a different orientation so as to be involved in intermolecular aromatic interactions. The 3- and 6-phenolic carbon-oxygen bond lengths show that double bond character can be delocalised from the ketone to the deprotonated phenoxide across the conjugated π system of the fluorone.</p

Synthesis, structure and magnetic properties of a novel Tb4 spin cluster and synthesis of a Tb chain

The syntheses of two new polynuclear TbIII compounds are reported. A tetranuclear complex [Tb4(H2L)2(H4L)2(OAc)8] (1), with H4L=2-((2-hydroxy-benzylidene)-amino)-2-hydroxy-methyl-propane-1,3-diol, has a butterfly-type structure, while [Tb(OAc)3MeOH]∞ (2) is a linear chain. A novel binding mode for H2L2− is observed in 1, with two alkoxides each bridging three TbIII ions. The magnetic properties of 1 are determined by the superposition of the ligand field split 7F6 states of TbIII single-ions located on two crystallographically distinct sites. Weak antiferromagnetic exchange interactions possibly contribute to the lowering of the magnetic moment at the lowest temperatures. © 2007, Elsevier Ltd

Coordination polymers of 2,5-dihydroxybenzoquinone and chloranilic acid with the (10,3)- A topology

Crystalline compounds of general composition (NBu4) 2[MII2(dhbq)3] (where M = Mn, Fe, Co, Ni, Zn, and Cd and dhbq2- is the dianion of 2,5- dihydroxybenzoquinone) are obtained by reaction of the divalent metal acetate (or the sulfate in the case of Fe) with 2,5-diaminobenzoquinone and an excess of NBu4Br in aqueous solution at 115 °C in sealed tubes. The dhbq2- ligand is generated in situ by hydrolysis of the 2,5-diaminobenzoquinone. We have been unable to obtain these compounds in a crystalline form suitable for single crystal X-ray diffraction studies directly from H2dhbq itself. A structural feature common to this series is the presence of two interpenetrating [MII2(dhbq) 3]2- coordination networks, each with the chiral (10,3)-a topology, with the two independent nets being of opposite hand - unprecedented circumstances for dhbq-based coordination polymers. Crystals of the same zinc compound as that obtained above from 2,5-diaminobenzoquinone can alternatively be obtained by in situ aerial oxidation of 1,2,4,5-tetrahydroxybenzene in the presence of Zn(OAc)2 and NBu4Br in aqueous methanol at room temperature. Analogous in situ aerial oxidation of 1,2,4,5-tetrahydroxy-3, 6-dichlorobenzene in the presence of Mn(OAc)2 and NBu4Br affords crystalline samples of the chloranilate (NBu4) 2[MnII2(can)3], which contains two interpenetrating (10,3)-a [MnII2(can)3] 2- networks of opposite hand.</p