The fluorinated phenylene unit is used as a building block for an all-conjugated fluorene-based alternating copolymer (PFO-TFP). The synthesis, carried out by an optimized Suzuki cross-coupling, produces an extremely high purity compound with a series of intriguing properties. Firstly, a blue-shift of the absorption and emission spectra with respect to the parent polymer is achieved. Secondly, the photoluminescence (PL) quantum yields (QYs) of the solution, as high as 68%, are surprisingly retained in the solid-state. Finally, an improved colour stability of the film with respect to unsubstituted polymers, investigated by means of cyclic voltammetry and exposure to ultraviolet radiation, is observed.The PFO-TFP tested as an undoped active layer in a polymer light-emitting diode (PLED) shows a highly desirable pure deep blue 405 nm electroluminescence, CIE ¼ (0.17; 0.06) and a remarkable 5.03% external quantum efficiency, thus fulfilling the requirements for both full-colour displays and biomedical applications. To date, fluorine atom incorporation has been successfully employed in the synthesis of high-performing polymers for organic field-effect transistors and photovoltaics. We give the first unambiguous proof of its efficacy in achieving pure deep blue electroluminescence in a highly efficient and stable PLED, which is competitive with the best reported conjugated oligomer-based devices. † Electronic supplementary information (ESI) available: 1 H, 13 C-NMR, DSC analysis, positive ion MALDI-TOF mass spectroscopy optical data of PFO-TFP, electroluminescence spectra, current-voltage-light curves, PL-EL microscopy, AFM images and photostability of reference compounds. See
Two novel benzofulvene monomers bearing propargyl or allyl groups have been synthesized by means of readily accessible reactions, and were found to polymerize spontaneously by solvent removal, in the apparent absence of catalysts or initiators, to give the corresponding polybenzofulvene derivatives bearing clickable propargyl or allyl moieties. The clickable propargyl and allyl groups were exploited in appropriate click reactions to develop a powerful and versatile "grafting onto" synthetic methodology for obtaining tailored polymer brushes.
Hyaluronic acid (HA) forms pericellular coats in many cell types that are involved in the early stages of cell adhesion by interacting with the CD44 receptor. Based on the largely recognized overexpression of the CD44 receptor in tumor tissues, a polybenzofulvene molecular brush has been enveloped into hyaluronan shells to obtain a tri-component polymer brush (TCPB) composed of intrinsically fluorescent backbones bearing nona(ethylene glycol) arms terminated with low molecular weight HA macromolecules. The nanoaggregates obtained in TCPB water dispersions were characterized on the basis of dimensions, zeta potential, and in vitro cell toxicity. This biomimetic multifunctional material bearing HA on the surface of its cylindrical brush architecture showed promising prerequisites for the preparation of nanostructured drug delivery systems
Four new benzofulvene derivatives bearing bithiophene chromophores in two different key positions of the phenylindene scaffold were prepared in order to evaluate the role of different chromophores in the optoelectronic features of polybenzofulvene derivatives. The results of the photophysical studies showed that the optical properties of the newly-synthesized bithiophenefunctionalized polymers were affected by both the polymer enchainment and the substitution topology of the monomeric units. On the other hand, the hole-mobility appeared to be affected to a lower extent, but the best performances were obtained in poly-6-HBT-BF3k showing the strongest bithiophene side chain packing. This work demonstrates that the optoelectronic properties of polybenzofulvene derivatives can be optimized by a targeted chemical design such as side chain engineering. 5 different key positions (6 and 4') of the phenylindene scaffold that were found to retain the spontaneous polymerization mechanism. By means of spectroscopic and electrical characterizations, we show that the bithiophene chromophore substitution induces in the polybenzofulvene derivatives a quenching of the emission combined with an improvement of the hole-transporting features. 14 Figure 2. SEC-MALS signals (DRI = concentration detector, MALS 90° = MALS photodiode at 90°) recorded for the first run sample (MA-1) obtained by the dehydration of indenol 3a by Method A.Moreover, the SEC-MALDI analysis of the second run sample (MA-2) showed an analogous composition ( Figure 3).
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