Water-Soluble Dendronized Polyfluorenes with an Extremely High Quantum Yield in Water

Abstract

A set of water-soluble dendronized polyfluorenes bearing peripheral charged amino groups were synthesized by two steps: (1) Suzuki polycondensation of dendritic macromonomers carrying peripheral Bocprotected amino groups with 1,4-benzenediboronic acid propanediol ester; (2) the deprotection of the resulting Boc-protected dendronized polymers with aqueous HCl. All the protected dendronized polyfluorenes displayed good solubility in common organic solvents such as THF, chloroform, and methylene chloride. After deprotection, the zero generation polymers were only partially soluble in water, but the first and the second generation dendronized polymers were fully soluble in water. The optic properties of the protected and deprotected dendronized polymers were investigated. In solution, all these polymers exhibited bright blue emission. Unlike normal watersoluble conjugated polymer, the second generation deprotected dendronized polyfluorenes exhibited a quite high quantum yield (Φ F ) 94%) in water.

Dendronized Copolymers

“…Dencopols can be generated by ring-opening metathesis polymerization (ROMP) or by polycondensation of dendritic monomers and comonomers, such as Suzuki reaction [6,8]. However, the PD by polycondensation generally is low and the products are polydispersed, so the formation of dencopols with a larger l/d ratio is still difficult.…”

Design and Synthesis of Conjugated Polyelectrolytes

“…Cationic polyfluorenes with dendritic or bulky water-soluble side chains were also synthesized [36,113]. As shown in Scheme 1.25, the polymers were synthesized by coupling Boc-protected dendritic fluorene monomers (47 or 49), Boc-protected fluorene (48) with 1,4-bisphenyl-(5,5-dimethyl-1,3,2-dioxaborinane) at a feed ratio of 1 : 1 : 2 in K 2 CO 3 /Pd(dppf)Cl 2 /toluene solution, followed by trifluoroacetic acid treatment to yield P70 and P71, respectively.…”

Polyfluorenes

“…Facilitated migration of metal ions by ion-transporting ethylene oxide groups dramatically improved the device efficiency by effectively reducing the electron-injection barrier. Bo et al synthesized a series of water-soluble dendronized poly(fluorene-phenylene)s (P192-P194) carrying peripheral charged amino groups (Scheme 9.75) [222]. The introduction of lateral dendrons should not only provide the conjugated polymers with good solubility in water through the charged amino groups but also reduce the aggregation of polymers through the ''site-isolation'' effect.…”