Papers by Keyword: Fluorene

Abstract: Electrochemical copolymerization of 2,5-bis[4-(p-aminophenoxy)phenylene]-1,3,4-oxadiazole (Ox) with fluorene (Fl) was carried out via consecutive multisweep cyclic voltammetry. The electrogrowth process was conducted in the potential range between 0 and 1.8 V, at a scan rate of 50 mV/s. The FTIR spectroscopy was used to solve the issues concerning the way of monomers linkage in the copolymer structure. A deep investigation of the electrogenerated copolymer film characteristics was performed by scanning electron microscopy, UV-Vis and fluorescence spectroscopy, and cyclic voltammetry.

Abstract: Novel donor-acceptor conjugated organic molecules composed of central fluorene and phenothiazine units and aldehyde terminal groups have been designed and constructed via the Vilsmeier-Haack reaction. Optical properties of the resulting molecules were examined by UV-vis and fluorescence spectroscopies. The fluorescence spectra of the molecules in the solid state show strong emission peaks in the violet, blue, cyan and green light regions. Thus, the molecules are expected to be promising light-emitting materials for organic light-emitting diodes applications.

Abstract:

Two iridium complexes, orange emitter bis[2-(9, 9-diethylfluoren-2-yl)-5-trifluoromethyl- pyridinto-C³, N] iridium (acetylacetonate) ((fl-5CF₃-py)₂Ir(acac)) and blue emitter bis(4,6-difluoro- phenylpyridine)(picolinate) iridium(III) (FIrPic), were used. As a single emitting layer at the constant emitting concentration of 8 wt %, EL spectra of the device containing the emitting layer PVK: PBD: (fl-5CF₃-py)₂Ir(acac) (8 wt %) peaked at 588 nm, the device having the emitting layer PVK: PBD: (fl-5CF₃-py)₂Ir(acac) (2 wt %): FIrPic (6 wt %) showed the main peak at 588 nm and the weak shoulder peaks at 472 and 500 nm, the device containing the emitting layer PVK: PBD: (fl-5CF₃-py)₂Ir(acac) (0.2 wt %): FIrPic (7.8 wt %) exhibited the main peak at 580 nm and slightly higher shoulder peaks at 472 and 500 nm. The device having the double emitting layers CBP: (fl-5CF₃-py)₂Ir(acac) (5 wt %) by spin-coating method and mCP: FIrPic (8 wt %) by vacuum deposition showed the main peaks at 472 and 500 nm, and shoulder peak at 580 nm. Maximum luminances of devices were found to be 14582 cd/m² (at 16 V), 12497 cd/m² (at 17 V), 1061 cd/m² (at 23 V), and 5396 cd/m² (at 25 V), respectively. The absence of host PVK, PBD, mCP or CBP emission in these devices indicated an efficient energy transfer from the host to the guest complex. Holes and electrons were efficiently recombined in the double emitting layers and an important approach for making WOLEDs was provided in the future.

Abstract: The work introduces the spectra of fluorescent derivatives which have been annealed. It’s usually unstable when heated or electrified, showing the red-shift and emerging new emission peak. We analyze the connection between emission peak and temperature. OF3R4, OF3R6, OF4R4, which are characterized by NMR. By contract, different temperatures and materials have similar phenomenon.

Abstract: Fluorene is a basic chemical raw material, which has wide applications.This paper introduces the current fluorene technology of extration and purification from wash oil. Use the after-cut of wash oil as raw material, get fluorene by distillation and solvent crystallization. The content of fluorene is higher than 97%.The total yield is 72.24%, which is higher than current domestic production levels.

Abstract: A donor-acceptor organic molecule based on fluorene unit as an electron donor and aldehyde group as an electron acceptor has been demonstrated in high yields over four steps. This approach offers a much milder and more efficient route to synthesize the target compound via the Vilsmeier-Haack reaction. Optical spectra show that the electron-accepting groups induce an intermolecular charge transfer, resulting in a shift of the absorbance maximum toward longer wavelength. Such D-A type intermediate compounds as organic molecules display a significantly improved property profile in photoelectrical materials for applications in organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic field-effect transistors (OFETs).

Abstract: Three isomers, [4'-(bisphenylamino)[1,1']biphen-2-yl]methylenefluorene (BAB2MF), [4'-(bisphenylamino)[1,1']biphen-3-yl]methylenefluorene (BAB3MF) and [4'-(bisphenylamino)[1,1']biphen-4-yl]methylenefluorene (BAB4MF), were synthesized through Suzuki coupling. The substitution pattern exerts a dramatic influence on the optical property. BAB3MF and BAB4MF are hardly emissive either in the solution or as solid state. On the contrary, BAB2MF emits strongly, especially in the aggregate state with a high fluorescent quantum yield of 69%. Furthermore, BAB2MF shows an aggregation-induced enhanced emission behavior. BAB2MF solid emits at 488 nm, about 60 nm blue-shifted from its solution.

Abstract: A new unsymmetrical photochromic diarylethene compound was synthesized and its photochemical, fluorescence properties were investigated in detail in solution. The results showed that the compound exhibited remarkable photochromism and the emission intensity was quenched 87% at the photostationary state in solution. When the concentration arrived at 2 × 10^-5 mol L^-1, the fluorescence peak of the diarylethene had the maximum.

Abstract: Emission spectrum of Iridium complex bis [2-(9, 9-diethylfluoren-2-yl)-5-trifluoromethyl-pyridinto-C³, iridium (acetylacetonate) (fl-5CF₃-py)₂Ir (acac) in THF was 589 nm. Two weak UV absorption bands can be assigned to spin-allowed singlet metal-to-ligand charge transfer (¹MLCT) and spin-forbidden ³MLCT transitions. The organic light-emitting devices A ITO/PEDOT: PSS/PBD: PVK: (fl-5CF₃-py)₂Ir (acac) (8 %) /LiF/Al and B ITO/PEDOT:PSS/PBD: PVK: (fl-5CF₃-py)₂Ir (acac) (8 %) /TPBi/LiF/Al were fabricated using iridium complex as emitter dopant with electro-luminescent spectra at 592 and 588 nm at the bias voltages of 9, 11 and 13V. Devices A and B exhibited luminance of 5265 (at 15 V) and 4098 cd/m² with Commission International de LEclairage (CIE) coordinates of (0.5805, 0.4185) and (0.5815, 0.4176), respectively. Device B (with TPBi) emitted orange light more efficiently than Device A (without TPBi).

Abstract: A compound of 9,9-dipropionitrilefluorene (C₁₉H₁₆N₂, Mr=272.34) was synthesized via nucleophilic addition reaction under microwave irradiation (500 w) within short reaction time (8 min), giving high yield of product (87%). Its structure was determined IR, ¹H NMR, MS, elemental analysis and X-ray diffraction. The crystal belongs to monoclinic, space group P2(1)/c with a = 21.8358(16),b = 8.9457(7), c = 15.9895(12) Å, β = 105.078(2)^o, V= 3015.8(4) Å3, Z=8, Dc= 1.200 g/cm3,μ=0.071 mm-1, F(000)=1152, R=0.0629 and wR = 0.0881 for 3155 observed reflection with I>2σ (I). X-ray analysis reveals that the three fused rings of the fluorene system are almost coplanar and the two propionitrile groups are completely perpendicular to the fused-ring system, the molecular is symmetrical.