Several 1,3-diphenyl-substituted silafluorene compounds were synthesized and characterized as potential fluorescent materials for OLED fabrication and bioimaging. Introducing phenyl groups into the silafluorene ring at the 1and 3-positions led to a red shift in the emission, resulting in blue light emitting compounds (λ max 368−375 nm in solution; λ max 362−371 and 482 nm in the solid state), and improved the quantum yield efficiency both in solution and as solids. Aggregation enhanced emission of the silafluorenes (AEE) was also investigated. Theoretical MO calculations were carried out to aid in understanding the optical properties of these molecules. Since these compounds might be useful in bioimaging, their toxicity was also investigated in skin fibroblast cells. All compounds were found to be nontoxic to the investigated cell cultures.
Two
novel highly fluorescent blue light emitting compounds were synthesized:
9,9-bis(diquinaldinatoalumino)-1,3-diphenyl-9-silafluorene (4) and 9,9-bis(diquinaldinatoalumino)-9-silafluorene (7). Combining silafluorene and quinaldinate aluminum moieties
resulted in molecules with high quantum yield efficiency both in solution
(31–34%) and in the solid state (79–92%). 4 showed intense electroluminescence, 4090 cd/m2 at 15
V, and the mechanochromism of 7 was revealed.
Two‐in‐one fluorescent compounds: Blending the strong emitter, diquinaldinato aluminum, and the good electron transporter, tetraphenyl silole, resulted in highly fluorescent compounds that are promising candidates for light‐emitting devices without the need of dopants (see figure).
Abstract. Poly(siloxane-urethane) (PSiU) networks based on a bis(hydroxyorgano) disiloxane chain extender, a trifunctional polyether polyol as a cross-linker, methylene-diphenyl diisocyanate and #,$-hydroxyethoxyethyl polydimethylsiloxane were synthesized in butyl acetate solution. The effect of the chain extenders and the cross-link density was investigated by using thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), swelling, hardness and tensile strength measurements. Isotherm thermogravimetric analyses were carried out for selected polymer compositions at 120 and 170°C and also the changes in tensile strength were followed. The different chain extenders have a strong effect on the hard segment structure, thus on the thermal and mechanical behaviour. The phase separation of the soft and hard segments was indicated by the two or three well distinguished tan% peaks, the maxima of which range within wide intervals depending on the polymer composition. The polymers of high cross-link density showed a very good thermal stability, high tensile strength (up to 68.7 MPa) and hardness (80-95 Shore A) even of high 13-36% dimethyl siloxane content. Changing the siloxane soft segment ratio and the cross-link density the physical properties can be adjusted.
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