Redox‐Robust Pentamethylferrocene Polymers and Supramolecular Polymers, and Controlled Self‐Assembly of Pentamethylferricenium Polymer‐Embedded Ag, AgI, and Au Nanoparticles

Abstract

We report the first pentamethylferrocene (PMF) polymers and the redox chemistry of their robust polycationic pentamethylferricenium (PMFium) analogues. The PMF polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a PMF-containing norbornene derivative by using the third-generation Grubbs ruthenium metathesis catalyst. Cyclic voltammetry studies allowed us to determine confidently the number of monomer units in the polymers through the Bard-Anson method. Stoichiometric oxidation by using ferricenium hexafluorophosphate quantitatively and instantaneously provided fully stable (even in aerobic solutions) blue d(5) Fe(III) metallopolymers. Alternatively, oxidation of the PMF-containing polymers was conducted by reactions with Ag(I) or Au(III) , to give PMFium polymer-embedded Ag and Au nanoparticles (NPs). In the presence of I2 , oxidation by using Ag(I) gave polymer-embedded Ag/AgI NPs and AgNPs at the surface of AgI NPs. Oxidation by using Au(III) also produced an Au(I) intermediate that was trapped and characterized. Engineered single-electron transfer reactions of these redox-robust nanomaterial precursors appear to be a new way to control their formation, size, and environment in a supramolecular way.

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

“…Two norbornene amino derivatives, N ‐[11‐amine‐3′,6′,9′‐trioxahendecyl]‐ cis ‐5‐norbornene‐ exo ‐2,3‐dicarboximide ( 15 ) and N ‐(2‐aminoethyl)‐ cis ‐5‐norbornene‐ exo ‐2,3‐dicarboximide ( 16 ) were used for the syntheses of the functional organometallic monomers 2 , 3 , 4, and 5 according to the published procedures . The monoamine 15 served as a precursor for the syntheses of the norbornene derivatives of the monomers containing either Fc or Fc* group, respectively, 2 and 3 , whereas the monoamine 16 was used for the synthesis of the monomers bearing either the mixed iron‐sandwich complex (FbX) or cobalticenium hexafluorophosphate (CcX), respectively, 4 and 5 . These amidation reactions were conducted upon reaction with the known chlorocarbonyl iron or cobalt sandwich derivatives (Scheme S1, Supporting Information).…”

“…These amidation reactions were conducted upon reaction with the known chlorocarbonyl iron or cobalt sandwich derivatives (Scheme S1, Supporting Information). 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 .…”

“…For example, CH 2 Cl 2 is a perfect solvent for the ROMP of neutral monomers 2 and 3 , whereas DMF is the only choice for polymerization of the cationic monomers 4 and 5 . At the feed molar ratio [monomer]:[catalyst 1 ] of 25:1, it takes 15 min to finish the ROMP of Fc monomer 2 , whereas ROMP of the Fc* monomer 3 is completed in 10 min, with nearly 100% conversion . The slowest rate was observed for the ROMP of monomers 4 and 5 in DMF, in which 30 min (at least) is required to achieve 100% conversion .…”

“…Cis ‐5‐norbornene‐ exo ‐2,3‐dicarboxylic anhydride (95%), tetraethylene glycol, ethanediamine, ethyl vinyl ether (EVE, 99%), and Grubbs 2nd generation catalyst were purchased from Aldrich and used directly. Grubbs 3rd generation catalyst 1 , Fc‐containing monomer 2 , Fc*‐containing monomer 3 , the cationic FbX‐containing monomer 4 , and the cationic CcX‐containing monomer 5 were synthesized following the procedures reported in the literature. All the other chemicals were from commercial sources and used as received.…”

“…Substituted cobalticenium salts have distinct basic chemical properties from those of ferrocene due to the charge difference and also allow easy incorporation into polymers via carbonyl chloride or ethynyl side groups . On the other hand, permethylated ring sandwich complexes such as 1,2,3,4,5‐pentamethylferrocenyl (Fc*) and cationic organoiron complex [Fe(η 5 ‐C 5 H 4 ‐)(η 6 ‐C 6 Me 6 )][PF 6 ] (FbX) have seldom been incorporated into organic polymeric frameworks owing to the challenge in their synthesis, although Abd‐El‐Aziz has already thoroughly investigated metallomacromolecules containing [Fe(η 5 ‐C 5 H 5 )(η 6 ‐arene)][PF 6 ] units with p ‐substituted arenes.…”