Charged Metallopolymers as Universal Precursors for Versatile Cobalt Materials

Abstract

Inorganic metal-based materials have been widely utilized in catalytic chemistry, life sciences, and engineering. [1] Cobaltrelated materials, including metallic cobalt, [2] cobalt oxide, [3] cobalt alloy, [4] and cobalt phosphide, [5] have been used in magnetic materials, aerospace engineering, and energy storage. With the development of modern nanoelectronic technology and the increasing demand for nanostructured materials, [6] the preparation of nanostructured inorganic cobaltcontaining materials has become a crucial technological challenge. Various methods have been developed to prepare nanoscale inorganic cobalt-containing materials, including electrodeposition, [7] polymeric precursor synthesis, [8] solvothermal/hydrothermal methods, [5b, 9] and sol-gel precipitation. [10] Among them, the utilization of metal-containing polymer precursors to prepare nanostructured cobalt-based materials has been used in particular, for such reasons as controlled molecular weight and architectures offered by well-established controlled/living synthetic methods, various morphologies from polymer self-assembly, [11] and facile manipulation of polymers. [12] As a result, a myriad of metalcontaining polymer precursors in the form of thin films, micelles, or fibers have been designed and utilized for preparation of functional inorganic materials. [8] However, metal-containing polyelectrolytes or charged metallopolymers have been much less studied as precursors to prepare inorganic metal-based materials. [13] Compared with neutral metal-containing polymers, the existence of counterions in charged metallopolymers has several advantages as novel precursors, such as ion-dependent solubility [14] and ioninduced self-assembly. [15] Thus these polyelectrolytes could be universal precursors for access to multifunctional inorganic materials. Unfortunately, it is challenging to perform facile exchange of counterions for charged metallopolymers. Most studies have been limited to specific systems (usually small molecules [16] or super-macromolecules [17] ), thus severely restricting the diversity of charged metallopolymers.Phase transfer has been applied in various organic reactions [18] and utilized in applications such as ionic selfassembly, [19] heterogeneous catalysts, [18,20] and ionic liquids. [21] However, the utilization of phase transfer to tune metalassociated counterions for charged metallopolymers is much less explored. [15, 19b] We have recently demonstrated ion exchange between hexafluorophosphate (PF 6 À ) and tetraphenyl borate (BPh 4 À ) ions in cationic cobaltocenium-containing monomers/polymers, which was clearly a phase transfer-driven reaction. [14b, 22] But this specific reaction was only limited for BPh 4 À anions. It is still challenging to apply a powerful technique to access other types of counterions for cobaltocenium-containing polymers.Herein, we report a facile phase-transfer ion-exchange method to prepare cationic cobaltocenium-containing polyelectrolytes with diverse counterions by the use of tetrabutylam...

Nanostructured Bimetallic Block Copolymers as Precursors to Magnetic FePt Nanoparticles

“…The development of metal-containing polymers has rapidly expanded over the past two decades, [1][2][3][4][5][6] and they have been successfully utilized, for example, as stimuli-responsive materials, [7][8][9] in energy conversion and storage [10][11][12] and as precursors of nanomaterials. [13][14][15][16][17] To enrich the potential functions of metallopolymers, nanostructured materials are under intensive investigation for various applications. [18][19][20][21][22] In general, a top-down approach is the most direct method to transfer patterns to the underlying polymers by masks or molds.…”

“…35 Cobalt-based nanomaterials have also been accessed using BCPs with cobalt-carbonyl clusters attached to ethynyl units [36][37][38] or half-sandwich cobaltocenium/ (η 5 -cyclopentadienyl)(η 4 -cyclobutadiene)cobalt moieties. 16,[39][40] Nanostructuring of the BCP through cylindrical domain formation has been shown to alter the magnetic properties of the resulting cobalt NPs. 38 In addition, Pd-pincer complexes have been introduced to poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) via either coordination or through stacking interactions leading to morphological transitions 41 and the formation of disk-shaped Pd NP aggregates organized into ordered hierarchical arrays.…”

Anion-induced self-assembly of positively charged polycyclic aromatic hydrocarbons towards nanostructures with controllable two-dimensional morphologies

“…The ionic complexes of PQPC 6 -M (PQPC 6 -PtCl 4 , PQPC 6 -PdCl 6 and PQPC 6 -AuCl 4 , Scheme 1) were prepared from PQPC 6 -BF 4 with potassium tetrachloroplatinate (K 2 PtCl 4 ), potassium hexachloropalladate (K 2 PdCl 6 ) and potassium tetrachloroaurate (KAuCl 4 ) in a one-to-one charge ratio via a facile ion-exchange procedure. 10 Typically, PQPC 6 -BF 4 was first dissolved in a binary solvent system (DMF/MeOH 1 : 7) and the aqueous solution containing the potassium salts of the corresponding anions was then added drop-wise (see the ESI †). Due to the amphiphilic nature of the ionic complex, aggregates with an ordered packing in such a mixed solvent were obtained as direct precipitate from the solution.…”

Anion-Responsive Metallopolymer Hydrogels for Healthcare Applications

“…The combination of organometallics and polymer gels not only maintains attributes from polymeric networks, but also develops inherent functionalities from organometallic molecules as unique building blocks 20 26 28 29 30 . Metallocene-containing polymeric materials have been demonstrated for a variety of applications in the areas of biomedicines, energy storage, catalysts, templating precursors, and magnetic materials 13 31 32 33 34 35 36 . Given its signature redox chemistry, ferrocene has been used in hydrogels 9 17 29 , although the hydrophobicity and stability of ferrocene has limited its role mostly as an auxiliary building block for fabricating environmentally-compatible materials 33 36 .…”

“…According to recent work 34 40 , cobaltocenium-containing polymers are ion-responsive materials. With different counterions, their corresponding polymers show drastic difference in hydrophobicity.…”