Foldamer organogels: a circular dichroism study of glucose-mediated dynamic helicity induction and amplification.
This paper reports a systematic study of the dynamic process for the self-assembly of chiral organogels from achiral hydrogen bonded hydrazide foldamers by induction of chiral glucose. Six foldamers incorporated with six decyl chains and two benzene, naphthalene, anthracene, or pyrene units at the ends are revealed to strongly gelate apolar and polar solvents, including alkanes, arenes, esters, alcohols, and 1,4-dioxane. The gels are characterized by UV-vis, fluorescent, XRD, SEM, and AFM methods, based on which a dislocated "tail-to-tail" stacking pattern is proposed. Addition of octylated glucose considerably enhances the capacity of the foldamers to gelate apolar solvents due to strong complexation. The complexation also causes unique dynamic helicity induction in the gels, which is studied systematically by circular dichroism. The results are treated with the Avrami theory according to a reported method (J. Am. Chem. Soc. 2005, 127, 4336), which suggests that the gelation involves a nucleation-elongation mechanism. In addition, the "Sergeants and Soldiers" effect in the gel phase is also revealed.
Cai
Wei
W
State Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
Wang
Gui-Tao
GT
Du
Ping
P
Wang
Ren-Xiao
RX
Jiang
Xi-Kui
XK
Li
Zhan-Ting
ZT
D002725:Chloroform / Q000737:chemistry; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D005780:Gelatin / Q000737:chemistry; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D015394:Molecular Structure; D055601:Organic Chemistry Phenomena; D013053:Spectrophotometry
D005782:Gels; D002725:Chloroform; D005780:Gelatin; D005947:Glucose