Issue 10, 2015

Solvent- and phase-controlled photochirogenesis. Enantiodifferentiating photoisomerization of (Z)-cyclooctene sensitized by cyclic nigerosylnigerose-based nanosponges crosslinked by pyromellitate

Abstract

Cyclic nigerosylnigerose (CNN), a saucer-shaped cyclic tetrasaccharide with a shallow concave surface, was reacted with pyromellitic dianhydride in 1 : 2 and 1 : 4 ratios to give two CNN-based polymers of different degrees of crosslinking, both of which swelled upon soaking in water, acting as a ‘nanosponge’ (NS). These NSs evolved several phases from isotropic solution to flowing and rigid gels via suspension by gradually increasing the concentration in water. The CNN-NSs thus prepared effectively mediated the enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to chiral (E)-isomer (1E). The enantiomeric excess (ee) of 1E obtained was a critical function of the solvent composition and the phase evolved at different CNN-NS concentrations in water. In isotropic solution, the enantioselectivity was generally low (−4% to +6% ee) but the chiral sense of 1E was inverted by increasing the methanol content. Interestingly, the product's ee was controlled more dramatically by the phase evolved, as was the case with the cyclodextrin-based nanosponge (CD-NS) reported previously. Thus, the ee of 1E was low in solution and suspension, but suddenly leaped at the phase border of flowing gel and rigid gel to give the highest ee of 22–24%, which are much higher than those obtained with CD-NSs (6–12% ee), revealing the positive roles of the chiral void space formed upon gelation of the crosslinked saccharide polymer.

Graphical abstract: Solvent- and phase-controlled photochirogenesis. Enantiodifferentiating photoisomerization of (Z)-cyclooctene sensitized by cyclic nigerosylnigerose-based nanosponges crosslinked by pyromellitate

Supplementary files

Article information

Article type
Paper
Submitted
12 nov 2014
Accepted
22 dec 2014
First published
22 dec 2014

Org. Biomol. Chem., 2015,13, 2905-2912

Author version available

Solvent- and phase-controlled photochirogenesis. Enantiodifferentiating photoisomerization of (Z)-cyclooctene sensitized by cyclic nigerosylnigerose-based nanosponges crosslinked by pyromellitate

X. Wei, W. Liang, W. Wu, C. Yang, F. Trotta, F. Caldera, A. Mele, T. Nishimoto and Y. Inoue, Org. Biomol. Chem., 2015, 13, 2905 DOI: 10.1039/C4OB02390K

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements