Novel polyfluorene polymer brushes with polymethacrylic acid side chains were obtained by atom transfer radical polymerization (ATRP) and activator generated by electron transfer (AGET) ATRP of tert-butyl methacrylate on polyfluorene multifunctional macroinitiator, followed by protonolysis of the tert-butyl groups of the side chains. Kinetics of polymerization and molecular weights were fully characterized. These polymer brushes luminesce in the blue region of the spectrum with high quantum yields (0.64–0.77). It was shown that the luminescence intensity of polymer brushes is higher than the luminescence intensity of the macroinitiator (0.61). Moreover, due to their amphiphilic nature, they can form unimolecular micelles when an alcohol solution of the polymer brush is injected into water. These properties can potentially be used in drug delivery and bioimaging.
A series of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines was synthesized for the first time by the reactions of chloroethynylphosphonates with unsubstituted and 5(6)-substituted 2-thiouracils. The reaction of chloroethynylphosphonates with 6-substituted 2-thiouracils bearing electron-donor groups (CH3, Ph) proceeded with high regioselectivity involving the cyclization through the N3-nitrogen atom to form new 3-phosphonylated thiazolo[3,2-a]-5-oxopyrimidines with good yield. In the case of unsubstituted and 5-methyl-2-thiouracils, cyclization occurred predominantly through the N1 atom and partially via the N3-nitrogen atom to form a mixture of the corresponding thiazolo[3,2-a]-7- and 5-oxopyrimidines. A dramatic change in the reaction regioselectivity was observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio.
Using palladium-catalyzed Suzuki polycondensation, we synthesized new light-emitting fluorene copolymers containing the dicyano derivatives of stilbene and phenanthrene and characterized them by gel permeation chromatography, UV-vis absorption spectroscopy, spectrofluorimetry, and cyclic voltammetry. The photoluminescence spectra of the synthesized polymers show significant energy transfer from the fluorene segments to the dicyanostilbene and 9,10-dicyanophenanthrene units, which is in agreement with the data of theoretical calculations. OLEDs based on these polymers were fabricated with an ITO/PEDOT-PSS (35 nm)/p-TPD (30 nm)/PVK (5 nm)/light emitting layer (70–75 nm)/PF-PO (20 nm)/LiF (1 nm)/Al (80 nm) configuration. Examination of their electroluminescence revealed that copolymers of fluorene with dicyanostilbene show yellow-green luminescence, while polymers with 9,10-dicyanophenanthrene have a greenish-blue emission. The 9,10-dicyanophenanthrene units have a more rigid structure compared to dicyanostilbene and, in OLEDs based on them, an increase in maximum brightness is observed with an increase in the content of the additive to the polymer chain. In particular, the device using fluorene copolymer with 9,10-dicyanophenanthrene (2.5 mol%) exhibited a maximum brightness of 9230 cd/m2 and a maximum current efficiency of 3.33 cd/A.
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