Synthesis of Platinum(II)-Containing Block Copolymers: Luminescence Enhancement and Controllable Self-Assembly

Abstract

In this work, a novel class of diblock polymer ligands, poly­(ethylene oxide)-block-polystyrenes end-functionalized with 2,6-bis­(benzimidazol-2′-yl)­pyridine (bzimpy), have been synthesized and their coordination reactions with K2PtCl4 have created platinum­(II)-containing diblock copolymers. They emit red phosphorescence in both THF-water and 1,4-dioxane-n-hexane mixed solvents, arising from Pt­(II)···Pt­(II) and/or π–π stacking interactions between the planar [Pt­(bzimpy)­Cl]+ units. Correspondingly, the block copolymers demonstrate a solvent-tunable self-assembly behavior to controllably generate vesicles and worms with core–shell–corona architectures. In these hierarchical nanostructures, the planar [Pt­(bzimpy)­Cl]+ blocks are associated together to form cores driven by Pt­(II)···Pt­(II) and/or π–π stacking interactions. Such cores are completely isolated by PS shells, which are further encapsulated by PEO coronas. It should be highlighted here that diblock polymers as polymeric ligands are coupled with phosphorescence platinum­(II) complexes, representing a novel approach to create functional metal-containing polymer materials with hierarchical architectures.

Investigating the Impact of Packing and Environmental Factors on the Luminescence of Pt(N^N^N) Chromophores

“…The research on metal-containing polymers and, in particular, metallopolymers, refer to a fascinating category of functional soft materials, in the field of polymer and materials science. These systems are composed of polymeric chains, metal centers, and/or metal-related segments − with specific roles suitable to provide a new dimension in several fields such as emissive materials, photovoltaics, electrochromic devices, sensors, nanowires, memory devices, catalysts, or memory and data storage. − The presence of metal centers into the metallopolymers is particularly relevant to attain phosphorescent materials for a variety of photonic applications. − …”

“…The design and synthesis of coordination polymers, where the metal centers coordinated to specific ligands in a polymeric chain (being the metal part of the polymeric structure), has been extensively explored. − , Nevertheless, the introduction of metallic chromophores as side pending chains within an organic polymer is less explored and even less, the particular use of metal centers suitable to establish metal···metal interactions, playing particular roles in the 2D and 3D structure of metallopolymers or metal coordinating polymers and also in the resulting emissive properties. Regarding this, poly­(4-vinylpyridine), PV, is a very good option due to the presence of pyridyl pending groups, suitable for coordination to a large number of metals and for this reason, it has been used as support of metal-containing polymers, metal nanoparticles, or metal films with several applications such as (photo)­sensing or catalysis. − Nevertheless, the coordination of specific metals well-known to establish metallophilic contacts is scarcely explored. − The use of these metals is of great importance regarding the development of luminescent materials since the resulting photophysical properties are strongly affected by the interplay of different noncovalent interactions such as M···M but also hydrogen bonding, π–π stacking or halogen bonding, among others. − Platinum­(II), with d 8 configuration, is one of the most studied metals suitable for metallophilic contacts and with relevant emissive properties.…”

Asymmetric Cyclodextrin-Dimer-Involved Nanoassemblies by Selective Host–Guest Interactions: Concentration-Dependent Morphology Evolution and Light-Regulated Biomedical Applications

“…Polymeric assemblies including spherical, star-like, or worm-like nanoparticles, vesicles, or other complex structures could perform numerous applications in drug carriers or nanoreactors because of their unique characteristics and stability in a water environment. − The self-assembly of amphiphilic copolymers with both hydrophilic and hydrophobic building blocks have been studied extensively, and several ripe experiences have been summarized. However, besides amphiphilic copolymers, covalently linked organic–inorganic hybrid materials bearing organic polymer chains and inorganic units, such as carbon or metal nanoparticles, have attracted a lot of research interest. − Among inorganic nanobuilding blocks, polymer chain-modified fullerene C 60 has been widely investigated. − As one of the typical examples, a series of supramolecular nanoassemblies, including the core–shell structure, spherical nanoparticles (SNPs), and nanonetwork architectures could be constructed from isotactic (it-) and syndiotactic (st-) C 60 -end-capped poly­(methyl methacrylate)­s through adjusting the types of solvents and block ratios …”