Functionalization of polymers with phosphorescent iridium complexes via click chemistry

Abstract

We report a simple yet highly efficient route to prepare polymers with a variety of pendant iridium complexes as potential materials in organic light-emitting diodes by employing click chemistry.

Recent Developments in the Application of Phosphorescent Iridium(III) Complex Systems

“…I) In order to ''decorate'' (co)polymers with complexes, suitable combinations of functionalities attached to the (co)polymer and the complex, respectively, are utilized. [25,58,59,116,117] Weck and co-workers reacted aldehyde-functionalized heteroleptic triscyclometallated Ir III complexes with amino-group bearing styrene units, copolymerized with N-vinylcarbazole or styrene, forming Schiff's bases, which were further on reduced to chemically more inert amines. [58] In another approach, they used a so-called ''click'' reaction to attach heteroleptic tris-cyclometallated Ir III complexes equipped with a terminal C C bond to azide-functionalized N-vinylcarbazole (Scheme 4) and styrene copolymers.…”

“…[58] In another approach, they used a so-called ''click'' reaction to attach heteroleptic tris-cyclometallated Ir III complexes equipped with a terminal C C bond to azide-functionalized N-vinylcarbazole (Scheme 4) and styrene copolymers. [59] Since polyvinylcarbazole (PVK) is a well-known hole transporter and is widely used as a polymeric host for phosphors, the N-vinylcarbazole copolymers appear highly promising as emissive materials in PLEDs. By reacting bis-cyclometallated Ir III complexes bearing a vinyl group at the ancillary ligand (i.e., pyridine or acetoacetate) and hydride-terminated poly(dimethylsiloxane) (PDMS) via hydrosilylation, DeRosa and Köse et al obtained PDMS systems with complexes as endgroups.…”

“…[43] A general protocol for the synthesis of Ir(ppy) 3 in high yields, starting from Ir(acac) 3 and Hppy, was described by the same group in 1991. [30] Since then, numerous variations of the basic Ir(ppy) 3 structure (e.g., introduction of electronwithdrawing or electron-donating substituents; [44][45][46][47][48][49] extension of the p-conjugated system; [50][51][52][53][54][55][56] replacement of the pyridine ring by other N-heteroaromatic rings; [26,57] or lateral functional groups for post-complexation modifications [58,59] ) have been reported (Scheme 1). The outstanding role of tris-cyclometallated Ir III complexes (both homoleptic and heteroleptic) based on phenylpyridine-type derivatives as ligands is underlined by the tremendous number of scientific publications and patents dealing with the synthesis and/or application of the respective complexes (June 2009: nearly 2000 hits in SciFinder).…”

Click Chemistry: Versatility and Control in the Hands of Materials Scientists

“…Specifically, for the synthesis of multi-functional materials with a range of different, possibly competing functional side groups, the extraordinary control offered by click reactions has produced a series of novel materials with, in some cases, unique properties. To illustrate this point, a few examples are given on how click chemistry can be used for the application-driven design of functional materials with interesting properties: i) Complete functionalization of alkyne-appended poly(p-phenyleneethynylene) [68] followed by quantitative attachment of phosphorescent iridium complexes [109] and flavin [110] to azido-functionalized polystyrene copolymers has been achieved via click chemistry (Huisgen cycloaddition). The incorporation of iridium complexes resulted in functional polymeric materials with potential applications in OLEDs, while the incorporation of flavin led to the formation of redox-active polymers that are potentially useful in electrochemically controlled molecular sensing and surface modification.…”

Synthesis of an ABCD 4-Miktoarm Star Quaterpolymer Through a Diels–Alder Click Reaction

“…The click chemistry using Cu(I)-catalyzed Huisgen and Diels-Alder reactions for the preparation of polymers with different composition and topology, ranging from linear (telechelic [29,30], macromonomer [31,32] and block co-polymer [33][34][35][36][37][38][39][40]), to non-linear macromolecular structures (graft [41][42][43][44][45][46][47][48][49][50], star [51][52][53][54], miktoarm star [55][56][57][58][59], H-type [60,61], dendrimer [62][63][64][65][66][67], dendronized linear polymer [68], macrocyclic polymer [69] and network system [70][71][72]) has been receiving increasing interest nowadays due to its described advantages previously.…”