Temporal switching of an amphiphilic self-assembly by a chemical fuel-driven conformational response

A unique redox active amphiphilic foldamer that undergoes transient conformation changes that amplify into observable morphology changes in its self-assembly.


S3
Protocol for transient conformational change: All the measurements were done at pH 7 aqueous buffer unless mentioned otherwise. All the UV-Vis spectroscopic measurements were done in uncapped quartz cuvette (except when stated) for equilibration of O2 in solution and at continuous stirring condition for homogeneity. Freshly prepared sodium dithionite (SDT) stock was used for each measurement as it is unstable in water. Stock solutions were prepared such that there is minimum dilution.
1. For non-enzymatic conformational change: Measurements were done at room temperature.
In a cuvette, a solution of 10 -4 M PN-VN was taken, required amount SDT was added and measurements were done.
2. For enzymatic conformational change: Temperature was maintained at 35°C for better enzymatic activity.
In a cuvette, a solution of 10 -4 M PN-VN with required amount of glucose and Gox were taken, to it appropriate amount of SDT was added and measurements were done immediately.

Calculation of the CT association constant of the PN-VN foldamer:
As the CT absorbance of PN-VN involves scattering above CAC, the association constant could not be calculated with relaibility. We further attempted to calculate the intramolecular CT association constant of PN-VN using concentration dependent spectroscopic measurements and isothermal titration calorimetry (ITC), however due to difficulties no reliable value was obtained and hence we restrict ourselves to obtain a lower limit of association constant (KPN-VN ~10 5 ) using model compounds PN-TEG and DMV that undergo intermolecular charge transfer (vide infra). Further, the concentration dependent emission studies ( Figure S2b) of PN-VN foldamer shows a linear dependence till the low concentration of 6x10 -6 M reiterating the lower limit of association constant of the order of 10 5 . Moreover, the study presented here doesn't rely on absolute values of association constants, thus doesn't affect the quality of study.
The association constants of the PN-TEG and DMV intermolecular CT pair was calculated using the following two methods.

Method 2.
The intermolecular association constant of the PN-TEG and DMV CT pair was also calculated by using another equation with the fitting of same fluorescence titration data shown below.

S13
The calculation using above equation suggest an intermolecular CT of order 10 4 -10 5 in consistence with reported value for pyranine-viologen. S10 Hence, we believe that the intramolecular association constant of PN-VN foldamer would be greater than 10 5 due to high local concentration compared to intermolecular system.        k [a] s -1 τ1 [b] s τ2 [c]