Synthesis and electro‐optical properties of polyfluorene modified with randomly distributed electron‐donor and rotaxane electron‐acceptor structural units in the main chain

Abstract

Polyfluorene PF center dot CD rotaxane copolymer, composed of randomly distributed 9,9-dioctylfluorene, methyltriphenylamine (electron-donating) and 9-dicyanomethylenefluorene complexed with -cyclodextrin (CD) (electron-accepting) structural units, has been synthesized by Suzuki cross-coupling reaction. The chemical structures were proved by FTIR and 1H NMR spectroscopy. The surface morphology, thermal, optical, electrochemical behavior, and adhesion characteristics of the obtained rotaxane copolymer have been investigated and compared with those of the nonrotaxane counterpart (PF). Relatively high fluorescence efficiency, almost identical normalized absorbance maximum in solution and solid-state of PF center dot CD rotaxane copolymer, and a more uniform and smoother surface with lower adhesion forces provides the role of CD encapsulation on the lower aggregation propensity. PF center dot CD and PF copolymers exhibit n- and p-doping processes and blue-light emission in the film state. The optical and electrochemical band gaps (Eg), as well as the highest occupied molecular orbital/lowest unoccupied molecular orbital positions in an energetic diagram indicate that both copolymers are promising blue-emitting electroluminescent materials

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

“…The DCM solution of 4a and 4b copolymers suggested no improvements of Φ compared with previously reported results [13], which restrict us to point out a distinctive effect of the rotaxane formation with TMS-β-CD and TMS-γ-CD macrocycles. To further understand Φ results, we also carried out fluorescence intensity decay.…”

“…h The optical gap, E opt , estimated from the onset of absorption ( E opt = 1240/λ onset) . i Data taken from [13]. …”

Effect of permodified β-cyclodextrin on the photophysical properties of poly[2,7-(9,9-dioctylfluorene)-alt-(5,5′-bithiophene)] main chain polyrotaxanes

“…PFBTh as a reference compound was also prepared in similar experimental conditions with those of polyrotaxanes. The reactions were performed in toluene compared with native CDs where a mixture of polar/non‐polar solvents were employed . The chemical structure of the copolymers was proved by IR and NMR spectroscopy.…”

“…This possibility represents an attractive approach to achieve control over molecular rigidity, prevention of aggregation, improved PLQE, and surface‐morphological characteristics of the resulting conjugated polyrotaxanes. Macrocyclic encapsulation of conjugated monomers into native cyclodextrins (CDs), as macrocycle host molecules followed by polymerization has been employed as an alternative supramolecular approach to achieve an “insulation” of the individual molecular wires . Such threading of macrocycles onto the conjugated chains does not disrupt the π‐conjugation and can additionally improve the solubility as well as the morphological characteristics of the resulting polymers.…”

Radical-radical rotaxanes with tetracationic cyclophane ring, and quaternary azaaromatic rotaxanes with cage macrocycles

“…Growing attention is paid today to cyclodextrin-based rotaxanes, 86,87 and especially to cyclodextrin-based polyrotaxanes, [88][89][90][91][92][93][94][95] interesting for their valuable properties. Another class is the calixarene-based rotaxanes.…”