Features of electronic circular dichroism and tips for its use in determining absolute configuration

Abstract

This review focuses on the general features of electronic circular dichroism (ECD) as applied in determining the absolute configuration of organic compounds. The high sensitivity and straightforward spectral interpretation of the exciton chirality method makes this approach very useful, and complementary to X-ray crystallography. A brief tutorial is provided on ECD, with precautions and tips for using it, especially the exciton chirality method. The spectral ECD of several examples are analyzed.

Thiahelicene-based inherently chiral films for enantioselective electroanalysis

“…[ α ] D ∼ 2990° for 7-TH 33) as well as good enantiodiscrimination ability for the circularly polarized light components in chiroptical experiments ( e.g. 7-TH 34); possible correlations have been recently discussed13 between the last feature, typical of inherently chiral electroactive oligoheterocycles,35,36 and their enantiodiscrimination ability for electroactive chiral probes in electrochemical experiments. Moreover, compared to the homologue family of carbohelicenes, consisting of all benzene rings, the thiahelicene family is electron richer, and has higher conjugation efficiency and electrochemical reactivity 30,37…”

Radiosynthesis of (R,S)‐[18F]GE387: A Potential PET Radiotracer for Imaging Translocator Protein 18 kDa (TSPO) with Low Binding Sensitivity to the Human Gene Polymorphism rs6971

“…The enantiomer of 6, which similarly exhibited am aximum positive Cotton effect at 204 nm and ac orresponding maximum negative Cotton effect at 228 nm, was in analogy assigned as the S isomer.T he other isomer showed the mirror image bisignate band in the CD spectrum and was therefore identified as R enantiomer. [21] To correlate enantiomerso btained via SFC separation to CD data, the chiral HPLC separation was performed on aW helk-O1 columnt ou nambiguously identify first eluting peak as the S enantiomer (Supporting Information).…”

“…The Et 2 Ol ayer and the dark gum were both diluted with EtOAc (200 mL) and then washed with 2 m HCl (150 mL), dried (MgSO 4 )a nd concentrated in vacuo to give ag um. This gum was purified by silica gel chromatography eluting with ag radient of 5-35 %E tOAc/petroleum ether (40-60 8C) to afford 20 as an oil 9-(2-(Benzyloxy)ethyl)-8-chloro-5-methoxy-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid (21).T ot he ester 20 (0.401 g, 0.909 mmol, 1equiv) in ethanol (12 mL) was added sodium hydroxide (0.240 g, 6.00 mmol, 6.6 equiv) in water (1 mL) and heated at 80 8Cf or 18 h. The ethanol was then removed by evaporation in vacuo and the residue partitioned between Et 2 O( 30 mL) and water (30 mL). The Et 2 Ol ayer was separated, dried (MgSO 4 )a nd concentrated in vacuo to give ag um.…”

“…Binding affinities were measured as per our published protocol. [21] Briefly,a nU ltra-Turrax homogeniser was used to prepare membranes from HEK cells stably transfected with wild-type and A147T TSPO. These cells were previously validated as an in vitro model of LABs and HABs.…”

“…These cells were previously validated as an in vitro model of LABs and HABs. [21] Membranes (20 mgp er well, diluted in 50 mm Tris·HCl, pH 7.4) were incubated with % K d concentration of [ 3 H]1 (10 nm;P erkinElmer) and test compounds (0.3 nm-10 mm)a t4 8C for 90 min. Reactions were terminated by filtration through a9 6well glass-fibre filter plate (Millipore), and washed eight times with ice-cold 50 mm Tris·HCl.…”