Probing the dynamic environment-associated conformational conversion from secondary to supersecondary structures in oligo(phenanthroline dicarboxamide)s.
The special structural features of the oligo(phenanthroline dicarboxamide)s and their dynamic environment-associated conformational conversion from secondary helical structure to supersecondary helix-turn structure, owing to the conversion of the CONH bond from s-cis form to s-trans form, have been experimentally and theoretically characterized by X-ray crystallographic, variable-temperature (1)H NMR, variable-temperature circular dichroism techniques, and computational studies. It has been demonstrated that the solvent effects together with intramolecular hydrogen bonds and pi-pi stacking play a key role in stabilizing both the secondary and supersecondary structures. Furthermore, by introducing the intramolecular F...H-N hydrogen bond to restrict the rotation about the CONH-aryl bonds, the oligomers 6 and 7 have been synthesized, which showed well-defined and predictable secondary helical conformations in solution and in the solid state.
Hu
Hai-Yu
HY
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Xue
Wei
W
Hu
Zhi-Qiang
ZQ
Xiang
Jun-Feng
JF
Chen
Chuan-Feng
CF
He
Sheng-Gui
SG