Abstract
Integrating stimulus-responsive components into macromolecular architectures is a versatile strategy to create smart materials that can be controlled by external stimuli and even adapt to their environment. Helical foldamers, which are omnipresent in Nature and display well-defined yet dynamic structures, serve as an ideal platform to integrate photoswitches to modulate their conformations by light. This feature article summarizes the development of photoswitchable foldamers, focussing on various design approaches that incorporate the photoswitches either at the side chains, as tethered loops, or directly in the main chain. Based on the emerging insight into the folding-switching relationship more advanced molecular designs should enable the development of photoresponsive foldamers with high sensitivity to control and power functional macromolecular and supramolecular systems.
Highlights
IntroductionPhotoresponsive molecular systems, allowing for an external control of their structures and resulting properties by light, will be one of the key elements for creating ‘‘smart’’ materials with broad applications ranging from nanotechnology to pharmacology.[1,2,3] Over the past two decades, photochromic moieties[4,5,6] have been
Considering the three tetradecamers 144, 145, and 147, which only vary in the number and relative orientation of azobenzenes within the helix, we found that an increasing azobenzene content leads to both slower photoisomerization and unfolding, yet more complete denaturation according to the circular dichroism (CD) spectra upon UV-irradiation (Fig. 15)
We detail the development of the photoswitchable foldamers with particular emphasis on the different design approaches for incorporating the photoswitches into the backbones
Summary
Photoresponsive molecular systems, allowing for an external control of their structures and resulting properties by light, will be one of the key elements for creating ‘‘smart’’ materials with broad applications ranging from nanotechnology to pharmacology.[1,2,3] Over the past two decades, photochromic moieties[4,5,6] have been. The light-induced conversion of charge-neutral spiropyrans to their zwitterionic merocyanine form[51] has been used to locally enhance polarity and stabilize or destabilize helical structures.[52] far, three types of design approaches have been followed by integrating the photoswitches into the helical systems either (i) as side chains linked in a more or less flexible fashion to the main chain, or (ii) as tethered loops giving rise to constrained macrocyclic architectures, or (iii) directly into the helical backbone (Fig. 1, right) In this feature article, we summarize the development of photoswitchable helical foldamers composed of various oligomeric/polymeric backbones and highlight their resulting lightinduced (un)folding behavior in relation to the specific location of the photoswitches within the chain. Throughout we focus on the underlying design principle of the photoresponsive helices, following either side chain, loop, or backbone approaches, and the resulting relationship between local photoswitching and global foldamer conformation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
