Introduction of axial chirality in a planar aromatic ligand results in chiral recognition with DNA.

Dimerization of a hydroxycarbazole produces an axially chiral biaryl, BICOL (2). One enantiomer (R)-2, is capable of enantioselective binding to different polymorphs of DNA. The biaryl (R)-2 was shown by fluorescence and circular dichroism to induce a shift of Z-DNA to B-DNA. The opposite enantiomer (S)-2 shows no specific binding. The significant difference in behaviour between the two enantiomers (S)-2 and (R)-2 is in line with molecular modelling studies which show two very different binding geometries between the enantiomers with each polymorph of DNA.

Enantioselective synthesis of [7]helicene: dramatic effects of olefin additives and aromatic solvents in asymmetric olefin metathesis.

The asymmetric synthesis of [7]helicene was accomplished in good ee (80%) by kinetic resolution by means of asymmetric olefin metathesis. Three key factors contributed to the success of the kinetic resolution: the use of new Ru-based olefin metathesis catalysts bearing C1-symmetric N-heterocyclic carbene ligands, simple olefins as additives to control the nature of the propagating alkylidene and hexafluorobenzene as a solvent.

Mechanistically inspired catalysts for enantioselective desymmetrizations by olefin metathesis.

In asymmetric olefin metathesis reactions, the addition of halide additives is often required to augment enantioselectivities, despite the fact that the additives result in catalysts with diminished reactivities. The preparation of new chiral Ru-based catalysts was accomplished by exploiting previously reported mechanistic studies. The catalysts possess a high level of reactivity and successfully induce high levels of asymmetry in desymmetrization reactions without the use of halide additives.

Synthesis and characterization of dimaleimide fluorogens designed for specific labeling of proteins.

A series of aromatic compounds were prepared bearing two maleimide groups attached directly to the fluorescent cores. The resulting derivatives do not fluoresce until the maleimide groups undergo their typical thiol addition reaction, thus removing their ability to quench fluorescence, as shown by kinetic and spectral characterization studies. In this way, the title compounds serve as fluorogens capable of detection of small thiols or appropriately sized dithiols. Recombinant alpha-helical proteins were then designed to bear two cysteine residues capable of regioselective dithiol addition reaction with the dimaleimide fluorogens, thus acting as spatially encoded substrates that form specifically labeled covalent complexes. The efficiency of this in vitro fluorescent protein-labeling reaction demonstrates the feasibility of the development of a method for the fluorescent labeling of specific recombinant proteins.