Influence of structure on electrochemical reduction of isomeric mono- and di-, nitro- or nitrosocalix[4]arenes
Abstract
A newly synthesized series of mono- and di-, nitro- or nitrosocalix[4]arenes has been investigated electrochemically. It was shown that besides the fundamental redox characterization, the electrochemical data contain also information about the space arrangement of the molecule as well as about dynamic 3D changes.
The interpretation is based on the comparison of observed electrochemical behavior of homologous couples or triads taken from the studied series of compounds. Using the nitro and nitroso group as a redox probe, it was found that unsubstituted or para-nitro-substituted cone-calixarenes are flexible, exhibiting in solution a periodic pinched cone-pinched cone interconversion, whereas the 1,3-alt conformation or any meta-substitution causes rigidity of the whole skeleton.
All aromatic nitro and nitroso groups in calixarenes appeared to be reducible at the same potential showing their electronic independency on the rest of the molecule.