Redox Inversion of Helicity in Propeller-Shaped Molecules Derived from S-Methyl Cysteine and Methioninol

Abstract

One-electron reduction inverts the helicity of copper complexes formed from derivatives of S-methylcysteine and methioninol. The change in conformation of the organic ligand is followed in the exciton-coupled circular dichroism (ECCD) spectra of the complexes.

Chiral nanotechnology

“…In one system, a synthetic derivative of the amino acid methionine presents carboxylic and sulfur groups near the a-carbon chiral center, either of which can coordinate to Cu(I) or Cu(II). 28,29 As shown in Figure 4a, the oxidation state of the copper determines which heteroatom will be bound, providing control of the orientation of the two chromophores which constitute two of the three blades of a propeller. Excitoncoupled circular dichroism (ECCD) spectra provide a convenient and unique spectroscopic handle by which to observe these phenomena.…”

Multimode selective detection of mercury by chiroptical fluorescent sensors based on methionine/cysteine

“…of 2‐bromomethylquinoline and 1 equiv. of (L)‐methionine methyl ester or ( L )‐S‐methyl cysteine methyl ester followed by hydrolysis 38, 40. In these sensors, we incorporated pyridine/quinoline‐based binding sites, which have been reported to selectively recognize relevant heavy metals41 such as Hg 2+ 26.…”

“…The two sensors reported here (Scheme ), ( S )‐ N , N ‐bis(2‐quinolylmethyl)methionine (L‐MethBQA) and ( R )‐ N , N ‐bis(2‐quinolylmethyl)‐ S ‐methyl cysteine (L‐CysBQA), were either a gift from Prof. Canary of NYU or synthesized following published protocols 38, 39. Analytical grade HgCl 2 , CuCl 2 , ZnCl 2 , Cu(ClO 4 ) 2 , Zn(ClO 4 ) 2 , Ni(ClO 4 ) 2 , Pb(ClO 4 ) 2 , and other reagents were obtained from commercial sources and used as received unless noted otherwise.…”

Transition metal-based chiroptical switches for nanoscale electronics and sensors

“…21, gives inversion of ECCD upon reduction with thiosulfate ion or ascorbate [78]. However, the Cu(I)/Cu(II) complexes of other tripodal ligands also give inversion of the ECCD spectrum including derivatives of methioninol and S-methylcysteine [79].…”