The synthesis of novel ditopic ligands for supramolecular chemistry and sensor applications

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Synthesis and X-ray structures of cadmium-containing dinuclear double helicates derived from ligands containing N-oxide units

The syntheses of two novel polydentate pyridyl-thiazolyl ligands which contain an N-oxide unit on the central pyridyl ring are reported. Reaction of either of these ligands with Cd(ClO4)2·6H2O results in the formation of a dinuclear double helicate. The solid state structures of these transition metal helicates demonstrate the ability of the N-oxide unit to partition the ligands into two separate binding domain

Synthesis of Ligands Containing N-oxide Donor Atoms and Their Assembly into Metallosupramolecular Structures.

A series of ligands that contain both N-donor and N-oxide donor atoms have been synthesised and ligands L5, L6, L7 and L8 contain, 4, 6, 5, and 6 donor atoms respectively. The smallest ligand L5 forms a mononuclear complex with Cu2+ ([Cu(L5)(ClO4)2(MeCN)]) whereas L6 and L7 form dinuclear double helicates with Ni2+ and Cu2+ respectively ([Ni2(L6)2]4+ and [Cu2(L7)2]4+ ). L8 forms a tetranuclear cyclic helicate upon reaction with Co2+ ([Co4(L8)4]8+) and in all cases the complexes are characterised by single-crystal X-ray diffraction and ESI-MS. The N-oxide units imparts flexibility in the ligand strand and where the unoxidised ligand strand forms a cyclic helicate, the incorporation of an N-oxide unit allows the formation of the dinuclear double helicate

This facile interconversion of dinuclear double helicates and side-by-side species: a reprogrammable ligand with potential sensor applications

The ligand L1 forms a dinuclear double helicate with Cu+ but upon addition of Ba2+ to the system a side-by-side species is formed both in solution and in the solid state; in the presence of Na+ both the helicate and the side-by-side species are formed in roughly equal amounts in solution

Allosteric deprogramming of a trinuclear heterometallic helicate

Two multidentate ditopic ligands L1 and L2 which contain both N-donor and crown ether units have been synthesised. The potentially octadentate ligand L1 forms a trinuclear heterometallic double helicate with Cu(I) and Zn(II) ([Zn2Cu( L1)2]5+), whereas L2 forms a tetranuclear heterometallic double helicate with the same metal ions ([Zn2Cu2( L2)2]6+). Both species have been characterised by 1H NMR, ESI-MS and single crystal X-ray crystallography. Reaction of [Zn2Cu2( L2)2]6+ with Ba2+ results in the coordination of the crown ether units giving the simple barium coordinated species [Zn2Cu2( L2)2Ba2]10+. However, reaction of [Zn2Cu( L1)2]5+ with Ba2+ deprograms the ligand and results in the formation of a mixture of species