Reversible Transformation Of Two Different Foldamers Under Redox Conditions

This dissertation is focused on the construction of two novel foldamers fabricated from radical-radical dimerization and donor-acceptor interactions,respectively,and the reversible transformation behavior between these two foldameric architectures are revealed.It mainly includes the following two parts:In the first section,we have prepared two flexible linear TTF oligomers Me-2TTF and Me-4TTF by connecting the TTF units with glycol chains.The folding behaviors of these TTF oligomers driven by the intramolecular radical-radical dimerization of TTF + subunits were investigated in the presence of Fe(ClO4)3 as oxidant,evidenced by the UV-visible and electron paramagnetic resonance(EPR)spectroscopic investigations.On the other hand,folded donor-acceptor[3]pseudorotaxane can be fabricated when Me-4TTF is interlocked with 2.0 equivalent of CBPQT4+ macrocycles in the neutral condition which is proven by the 1H NMR,UV-Visible spectroscopic studies as well as DFT calculation.In particular,reversible transformation conversion between the pleated radical foldamer and the folded donor-acceptor[3]pseudorotaxane,can be achieved under the alternative regulation of the redox states of TTF units.In the second part,we design another interconversional foldameric systems under redox conditions between an oligomeric viologen-based radical foldamer and the folded donor-acceptor[3]pseudorotaxane fabricated from the corresponding viologen oligomer and TTF or DNP macrocycles.Currently,we have finished the synthesis of the TTF and DNP macrocycles,the synthesis of the viologen oligomer and the construction and characterization of these two foldamers,as well as the reversible transformation behavior between them are underway.