One-step synthesis of Ling's tetrol and its conversion into A,D-di-allo-α-cyclodextrin derivatives.

2A-F,3B,C,E,F,6B,C,E,F-Tetradeca-O-benzyl-α-cyclodextrin or Ling's tetrol is a unique α-cyclodextrin derivative that is partially protected with specific access points on both rims of the cyclodextrin structure. Ling's tetrol is therefore potentially useful for the synthesis of more complex and sophisticated enzyme models and supramolecular structures. However, the original synthesis gave only 10% yield after a reaction time of 4 days, and a recent improvement that gave 52% yield required two steps and a reaction time in one step of 6 days. Here, a single-step synthesis is reported where Ling's tetrol is obtained in a yield of 59% with a reaction time of 40 hours. 2A-F,3B,C,E,F,6B,C,E,F-Tetradeca-O-benzyl-α-cyclodextrin was subsequently converted into 6A,D-dicarboxy-3A,D-diepi-α-cyclodextrin, 3A,D-dioxo-α-cyclodextrin and 3A,D-diamino-3A,D-dideoxy-3A,D-diepi-α-cyclodextrin. The binding of these compounds to CH4 and CO2 was determined.

CO2 complexation with cyclodextrins.

Carbon dioxide (CO2) emissions from industrial processes, power generation, and transportation contribute significantly to global warming and climate change. Carbon capture and storage (CCS) technologies are essential to reduce these emissions and mitigate the effects of climate change. Cyclodextrins (CDs), cyclic oligosaccharides, are studied as potential CO2 capture agents due to their unique molecular structures and high selectivity towards CO2. In this paper we have investigated binding efficiency of a number of cyclodextrins towards CO2. It is found that the crystal structure of α-cyclodextrin with CO2 has a 1:1 stoichioimetry and that a number of simple and modified cyclodextrins bind CO2 in water with a Kg of 0.18-1.2 bar-1 (7-35 M-1) with per-O-methyl α-cyclodextrin having the highest CO2 affinity.

Galectin-Glycan Interactions: Guidelines for Monitoring by 77 Se NMR Spectroscopy, and Solvent (H2 O/D2 O) Impact on Binding.

Functional pairing between cellular glycoconjugates and tissue lectins like galectins has wide (patho)physiological significance. Their study is facilitated by nonhydrolysable derivatives of the natural O-glycans, such as S- and Se-glycosides. The latter enable extensive analyses by specific 77 Se NMR spectroscopy, but still remain underexplored. By using the example of selenodigalactoside (SeDG) and the human galectin-1 and -3, we have evaluated diverse 77 Se NMR detection methods and propose selective 1 H,77 Se heteronuclear Hartmann-Hahn transfer for efficient use in competitive NMR screening against a selenoglycoside spy ligand. By fluorescence anisotropy, circular dichroism, and isothermal titration calorimetry (ITC), we show that the affinity and thermodynamics of SeDG binding by galectins are similar to thiodigalactoside (TDG) and N-acetyllactosamine (LacNAc), confirming that Se substitution has no major impact. ITC data in D2 O versus H2 O are similar for TDG and LacNAc binding by both galectins, but a solvent effect, indicating solvent rearrangement at the binding site, is hinted at for SeDG and clearly observed for LacNAc dimers with extended chain length.

Iridium catalysis: reductive conversion of glucan to xylan.

By using iridium catalysed dehydrogenative decarbonylation, we converted a partly protected cellobioside into a fully protected xylobioside. We demonstrate good yields with two different aromatic ester protecting groups. The resulting xylobioside was directly used as glycosyl donor in further synthesis of a xylooctaose.