Dynamic Supramolecular Ruthenium-Based Gels Responsive to Visible/NIR Light and Heat.

Ian Teasdale,Aitziber Iturmendi,Uwe Monkowius,Philipp Mayrhofer,Moritz Strobel,Sabrina Theis,Sabine Hild,Jaroslaw Jacak

doi:10.1002/chem.201902088

Abstract

A simple supramolecular crosslinked gel is reported with a photosensitive ruthenium bipyridine complex functioning as a crosslinker and poly(4‐vinylpyridine) (P4VP) as a macromolecular ligand. Irradiation of the organogels in H2O/MeOH with visible and NIR light (in a multiphoton process) leads to cleavage of pyridine moieties from the ruthenium complex breaking the cross‐links and causing degelation and hence solubilization of the P4VP chains. Real‐time (RT) photorheology experiments of thin films showed a rapid degelation in several seconds, whereas larger bulk samples could also be photocleaved. Furthermore, the gels could be reformed or healed by simple heating of the system and restoration of the metal–ligand crosslinks. The relatively simple dynamic system with a high sensitivity towards light in the visible and NIR region make them interesting positive photoresists for nano/micropatterning applications, as was demonstrated by writing, erasing, and rewriting of the gels by single‐ and multiphoton lithography.

Highlights

A simple supramolecular crosslinked gel is reported with a photosensitive ruthenium bipyridine complex functioning as a crosslinker and poly(4-vinylpyridine) (P4VP) as a macromolecular ligand
While materials responsive to UV-light have long been established, there has been a recent shift in the field towards the use of photochemical processes, which respond in the visible and NIR region[13,11a] due to the poor penetration of highenergy UV-light as well as its incompatibility with biological environments.[14]
Light-sensitive ruthenium-based complexes have been shown to be responsive to light with long wavelengths,[15] for example, for photodynamic therapy with deep-tissue penetration

Summary

Introduction

A simple supramolecular crosslinked gel is reported with a photosensitive ruthenium bipyridine complex functioning as a crosslinker and poly(4-vinylpyridine) (P4VP) as a macromolecular ligand. Iturmendi Institute of Polymer Chemistry, Johannes Kepler University Linz Altenberger Straße 69, 4040 Theis Institute of Inorganic Chemistry, Johannes Kepler University Linz Altenberger Straße 69, 4040

Results

Conclusion