Tetrablock Metallopolymer Electrochromes

Abstract

Multi-block polymers are highly desirable for their addressable functions that are both unique and complementary among the blocks. With metal-containing polymers, the goal is even more challenging insofar as the metal properties may considerably extend the materials functions to sensing, catalysis, interaction with metal nanoparticles, and electro- or photochrome switching. Ring-opening metathesis polymerization (ROMP) has become available for the formation of living polymers using highly efficient initiators such as the 3rd generation Grubbs catalyst [RuCl (NHC)(=CHPh)(3-Br-C H N) ], 1. Among the 24 possibilities to introduce 4 blocks of metallopolymers into a tetrablock metallocopolymer by ROMP using the catalyst 1, two viable pathways are disclosed. The synthesis, characterization, electrochemistry, electron-transfer chemistry, and remarkable electrochromic properties of these new nanomaterials are presented.

Living ROMP Synthesis and Redox Properties of Triblock Metallocopolymers Containing Side‐Chain Iron and Cobalt Sandwich Complexes

“…Based on previous reports, the ROMP reactions of these monomers were proven to be “controlled” and “living,” which gives the opportunity to fabricate triblock copolymers containing one neural Fc (or Fc*) group and two cationic FbX and CcX redox moieties. However, to successfully carry out these syntheses, the ROMP characteristics of the intermediate homopolymers and diblock copolymers should be taken into account . In this respect, key differences were found among these routes.…”

“…These homopolymers were not quenched but retained as macromolecular initiators for further introduction of the second FbX block, with stirring for 15 h . Besides these solvent and reaction rate factors, solubility difference of the polymers is another problem that should not be neglected upon designing the synthesis route of the triblock metallocopolymers . Based on the above considerations and practical preliminary experiments, only one feasible synthetic route for each triblock copolymer was actually successfully conducted in the present study among the six possible variations of synthetic schemes (Scheme ).…”

“…The advent of the most modern metathesis catalysts, and in particular the air‐ and water‐stable Grubbs catalyst 1 of 3rd generation, has allowed living polymerization systems that are ideal for the synthesis of block copolymers ( Figure ). The resulting late‐transition metal sandwich–containing polymers and block copolymers have been the subject of excellent recent reviews, but in this series, copolymers containing more than two metalloblocks are rare …”

“…In previous reports, the ROMP technique using the catalyst 1 was used to synthesize well‐defined triblock copolymers containing two neutral Fc and pentamethylferrocene (Fc*) units and one cationic metallocene moiety (cyclopentadienyl iron hexamethylbenzene hexafluorophosphate (FbX, XPF 6 ) or cobalticenium hexafluorophosphate (CcX)). Specifically, in these papers, the cationic metallocene block was located at one end of the triblock copolymer chain as the third block and the two neutral Fc* and Fc blocks were adjacent to each other as the first and second block, respectively, or the cationic metallocene block was also embedded as the second block between two neutral Fc* and Fc blocks . Here we report the strategies of synthesis and controlled construction of two new triblock copolymers each containing three distinct late neutral and cationic metallocene units including Fc, Fc*, FbX, and CcX.…”

Ferrocenyl amphiphilic Janus dendrimers as redox‐responsive micellar carriers

“…[35,36] For example, Liu et al described a redox-controlled drug delivery system based on ferrocene (Fc)-containing amphiphilic block copolymers (PEG-b-PMAEFc) that were fabricated via atom transfer radical polymerization (ATRP) using a PEGbased macro-ATRP agent. [37][38][39][40][41][42] And notably, this redox process is attributed to the gain and loss of one electron, and the molecular structure of Fc group is not destroyed, which is a great benefit for the reversible self-assembly and disassembly of Fc-containing amphiphilic macromolecules. [37][38][39][40][41][42] And notably, this redox process is attributed to the gain and loss of one electron, and the molecular structure of Fc group is not destroyed, which is a great benefit for the reversible self-assembly and disassembly of Fc-containing amphiphilic macromolecules.…”