Photo- and Metallo-responsive N-Alkyl α-Bisimines as Orthogonally Addressable Main-Chain Functional Groups in Metathesis Polymers

Abstract

N-alkyl α-bisimines were employed as main-chain functional groups in acyclic diene metathesis (ADMET)-polymers, conferring dual responsiveness for the controlled switching of the polymeric particle shape with light and metal ions. Photochemical Z/E-isomerization leads to a significant and reversible change in hydrodynamic volume, thus introducing simple imines as novel photoswitches for light-responsive materials. Mild imine-directed CH activation by Pd(OAc)2 is demonstrated as a new single-chain nanoparticle (SCNP) folding process, enabling a controlled atom- and step-economic SCNP synthesis. The combination of light- and metallo-responsiveness in the same polymer provides the ability for orthogonal switching, a valuable tool for advanced functional material design.

Platinum(II)‐Crosslinked Single‐Chain Nanoparticles: An Approach towards Recyclable Homogeneous Catalysts

“…[5][6][7] In the past, bioinspired SCNPs have been typically synthesized via hydrogen-or covalent bonding in order to mimic biomacromolecules. [10][11][12][13] While metal complexes,i nt he first place, operate as triggers for the chain-collapse,t heir embedding into the SCNP-structure additionally allows them to function, for example,a sc atalytic centers. [10][11][12][13] While metal complexes,i nt he first place, operate as triggers for the chain-collapse,t heir embedding into the SCNP-structure additionally allows them to function, for example,a sc atalytic centers.…”

Internal C–C Bond Rotation in Photoisomers of α‐Bisimines: a Light‐Responsive Two‐Step Molecular Speed Regulator Based on Double Imine Photoswitching

“…The described dynamic and structural features may serve as a starting point towards more advanced molecular machines based on imines. Moreover, the structural and dynamic behavior of α‐bisimines could also serve as a guideline in the investigation of the conformational preference and dynamic/motional features of polyisocyanides,17 as well as for the installation of oligo/poly‐imine groups into materials (polymeric chains or particles) 18…”

Macromolecular Superstructures: A Future Beyond Single Chain Nanoparticles

“…While light gated folding and unfolding of SCNPs remains unachieved until today, the groups of Barner-Kowollik and Lehn recently developed a strategy to remotely control conformations of SCNPs with light. [117] Acyclic diene metathesis (ADMET) polymerization of N-alkyl α-bisimine dienes enabled the synthesis of polymer containing dual reactive moieties embedded into their backbones. The imine containing polymer could be folded into an SCNP upon addition metal ions inducing metal-ligand interactions.…”