Colin N. Warriner

Ferrocene substituted calix[4]pyrrole: a new electrochemical sensor for anions involving CH...anion hydrogen bonds

A new calix[4]pyrrole 1 containing a ferrocene moiety attached to one of the meso-positions has been synthesised by co-condensation of pyrrole, cyclohexanone and acetylferrocene. The crystal structure of 1 has been elucidated whilst 1H NMR titration studies in acetonitrile-d3/DMSO-d6 9:1 v/v have revealed that 1 binds fluoride, chloride, and dihydrogen phosphate in this solvent mixture. Electrochemical studies using cyclic voltammetric and square-wave voltammetric techniques show cathodic shifts of up to 100 mV (approx.) with dihydrogen phosphate anions.

2,5-Diamidofuran anion receptors

3,4-Diphenylfuran-2,5-dicarboxylic acid bis-N-phenylamide 1 and 3,4-biphenyl-furan-2,5-dicarboxylic acid bis-N-butylamide 2 have been synthesised and shown to act as fluoride selective anion receptors in DMSO-d6/0.5% water solution.

Pentapyrrolic calix[4]pyrroleElectronic supplementary information (ESI) available: NMR titration plots; experimental section. See http://www.rsc.org/suppdata/cc/b3/b303959e/

A new calix[4]pyrrole has been synthesised that contains a 3,4,5-trisbromopyrrole appended to a meso-position which shows enhanced anion affinity as compared to the parent meso-octamethylcalix[4]pyrrole macrocycle.

Mono- and bis-ferrocene 2,5-diamidopyrrole clefts: solid-state assembly, anion binding and electrochemical properties

Four amido-pyrrole cleft anion receptors bearing one or two ferrocene reporter groups have been synthesised and crystallographically characterised. The receptors contain either a non-conjugated (1 and 3) or conjugated (2 and 4) link between the anion binding amido-pyrrole unit and the ferrocene reporter groups. The anion binding affinities and electrochemical behaviour of the receptors in the absence and presence of anions have been studied by 1H NMR titration techniques and cyclic voltammetry using a Pt microdisc working electrode, respectively.

Crystallographic and solution anion binding studies of bis-amidofurans and thiophenes

A variety of furan and thiophene amide and thioamide cleft type anion receptors have been synthesised and crystallographically characterised. Unlike 2,5-diamidopyrrole anions, analogous 2,5-diamidofurans and thiophenes do not interlock in the solid state. The anion binding properties of these receptors have been investigated in DMSO/0.5% water solution using 1H NMR titration techniques. Solution studies and solid-state evidence suggests that the thiophene receptors may utilise a thiophene CH hydrogen atom for hydrogen bond formation to anions with a 2,4-diamidothiophene showing similar anion binding affinities to a 2,5-diamidopyrrole.

Tetra­methyl bi­phenyl-3,5,3′,5′-tetra­carboxyl­ate benzene sesquisolvate

The title structure, C20H18O8.1.5C(6)H(6), is a tetrasubstituted biphenyl which has a pseudo-inversion centre between the two halves. The benzene solvent molecules lie in special positions, one with twofold rotation symmetry and two with inversion symmetry. The tetramethyl ester molecule is twisted and forms a supramolecular assembly of stacked sheets.