Two aromatic hydrazide haptamers have been prepared,with both consisting of two hydrogen bonded folded segments. Compared to their fully hydrogen bonded analogues,the flexibility of their backbones increases due to lack of one or two intramolecular hydrogen bonds at the middle aromatic unit. (2D) 1H NMR,circular dichroism and fluorescent studies revealed that both oligomers moderately complex n-octyl-α-L-glucopyranoside in chloroform.
Three arylamide-bridged biscoumarin derivatives 1-3 have been designed and prepared. Compounds 1 and 2 are induced by the intramolecular N?H…O and N·H…F hydrogen bonding to possess a helical conformation,and 3 is induced to have an extended conformation. A comparison of their absorption and fluorescent spectra in a variety of solvents of a wide range of polarity with those of control compound 4 reveals that,for foldamers 1 and 2,the intramolecular hydrogen bonding and the helical conformations exist in most solvents,but do not exist or are very weak in DMF and DMSO.
LU ZhengQuanZHU YuanYuanLIN JianBinJIANG XiKuiLI ZhanTing
