Design and synthesis of core and peripherally functionalized with 1,8-naphthalimide units fluorescent PAMAM dendron as light harvesting antenna

This paper reports on the design, synthesis and spectral characteristics of a novel PAMAM dendron (7), core and peripherally functionalized with 1,8-naphthalimide fluorophores. The novel compound 7 was configured as light harvesting antenna where the system surface is functionalized with “donor” dyes (blue emitting 1,8-naphthalimides) that are capable of absorbing light and efficiently transferring the energy to a single “acceptor” dye (yellow-green emitting 1,8-naphthalimide) in the focal point of the dendron. The overlap between the emission of the donor and the absorbance of the acceptor was more than 95%. As a result of the energy transfer, the blue emission intensity of the periphery in the donor–acceptor system was decreased with 93%, while the yellow-green core fluorescence enhancement (λ_ex = 360 nm) of the system was more than 26 times with respect to the fluorescence intensity of the comparative yellow-green emitting 1,8-naphthalimide. This indicates efficient energy transfer between the donor and acceptor dye fragments and that the novel compound 7 would be able to act as a highly efficient light harvesting antenna.     

新型三嗪桥连的双1,8-萘酰亚胺衍生物的合成及其光物理行为

以1,8-萘酰亚胺和三聚氯氰为主要原料, 合成了两种由三嗪环桥连的双1,8-萘酰亚胺化合物3 和5. 采用紫外-可见光谱和荧光光谱等手段考察了两种化合物在不同溶剂中的光物理行为. 与参比化合物N-丁基-1,8-萘酰亚胺相比, 在二氯甲烷、三氯甲烷和甲醇等极性溶剂中, 化合物3和5除了在短波区(λ<400 nm)存在1,8-萘酰亚胺的特征荧光发射峰外, 在长波区(>450 nm)均产生一个较强的新荧光发射峰, 表现出分子内激基缔合物的光物理行为. 与化合物5相比, 由于化合物3特殊的构象异构, 其荧光强度发生严重的猝灭. 在非极性溶剂甲基环己烷中, 化合物5 由于存在较强的分子间氢键作用而聚集, 受激后形成了较稳定的分子间激基缔合物, 但未观察到明显的分子内激基缔合物的形成. 在甲苯溶剂中, 化合物3和5与甲苯分子形成了激基复合物, 并未形成分子内激基缔合物. 进一步研究3和5的固态激发态性质, 发现化合物3和5的固体薄膜受激后分别在465和469 nm处出现激基缔合物的特征荧光发射峰.     

Synthesis and characterization of novel germanium‐containing poly(p‐phenylenevinylene) derivatives

Novel blue‐emitting germanium‐containing poly(p‐phenylenevinylene) (PPV) derivatives with well‐defined conjugation lengths were synthesized via Wittig‐condensation polymerizations. The polymers can be color‐tuned by the introduction of various chromophores into the PPV‐based polymer backbones. The photoluminescence (PL) spectra of the polymers, GePVK (containing carbazole moieties), GeMEH (containing dialkoxybenzene moieties), and GePTH (containing phenothiazine moieties), were found to exhibit blue, greenish blue, and green emissions, respectively. GePTH produces more red‐shifted emission than GeMEH and GEPVK, resulting in green emission, and the solution and solid state PL spectra of GePVK consist of almost blue emission. The electroluminescence spectra of GeMEH and GePTH contain yellowy green and yellow colors, respectively. Interestingly, GePVK exhibits white emission with CIE coordinates of (0.33, 0.37) due to electroplex emission in the light‐emitting diodes. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 979–988, 2008     

Synthesis and photo- and electroluminescent properties of copolyfluorenes with nile red fragments in side chains

New copolyfluorenes containing units of 4,7-dibromo-2,1,3-benzothiadiazole (green luminophore) and 3,6- or 2,7-dibromocarbazole derivatives with side-chain fragments of green (4-pyrrolidinyl-1,8-naphthalimide) and red (Nile red) luminophores and additional carbazole or diphenyloxadiazole groups are synthesized via the Suzuki copolycondensation reaction. The structure of the polymers is modified via insertion of triphenylamine, aryloxadiazole, and quinoxaline units in the backbone of copolyfluorenes and via introduction of triphenylamine, fluorene, and benzene terminal groups. The molecular-weight characteristics of the polycondensation products and the specific features of the transfer of polyfluorene emission energy to the indicated luminophores in solutions and films are studied. Coating the emissive copolyfluorene layer with electron-conducting and hole-blocking layers of poly[9,9-bis(6′-diethoxyphosphorylhexyl)fluorene] makes it possible to increase the brightness of light-emitting diodes (to 2380–3900 cd/m²) and their current and luminance efficiencies.     

新型双发色团固体激光染料薄膜的光稳定性研究

利用UV-Vis吸收光谱仪和光化学反应器研究了新型双发色团固体激光染料薄膜的光降解动力学.研究结果表明:双发色团固体激光染料薄膜的光褪色反应遵循假一级动力学衰减.在PRNAM系列共聚物(N-烯丙基-若丹明1、N-[(2-丙烯酸基)乙基]-1,8-萘酰亚胺和甲基丙烯酸甲酯的共聚物)中萘酰亚胺基团通过聚合物碳链与若丹明基团的氮原子相连;而在PRNM系列共聚物(若丹明1的烯丙基酯、N-[(2-丙烯酸基)乙基]-1,8-萘酰亚胺和甲基丙烯酸甲酯的共聚物)中则是与若丹明基团的酯基相连.PRNAM系列共聚物的光稳定性优于PRNM和PRM(若丹明1的烯丙基酯和甲基丙烯酸甲酯的共聚物)系列的光稳定性.     

氧化偶联共聚合制备主链含β-萘烷基醚的红色发光聚合物

用氧化偶联聚合法合成了主链上含β-萘烷基醚和吡啶、二烷基芴、二苯乙烯和均四甲苯的聚合物.用FT-IR和1H NMR表征了聚合物的结构.广角X射线衍射表明共聚物的结构都是非晶态的.用UV-V is表征了共聚物的吸收特征.聚合物的荧光光谱表明,含有β-萘烷基醚和吡啶的聚合物在溶液中表现为红光发射材料.含有β-萘甲醚和二苯乙烯的共聚物为黄橙光发射,通过改变单体含量也可实现红光发射.含有β-萘甲醚和二烷基芴的聚合物固体有望成为白光发射材料.     

Full color light‐emitting electrospun nanofibers prepared from PFO/MEH‐PPV/PMMA ternary blends

In this study, luminescence electrospun (ES) nanofibers based on ternary blends of poly(9,9‐dioctylfluoreny‐2,7‐diyl) (PFO)/poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV)/poly(methyl methacrylate) (PMMA) were prepared from chloroform solutions using a single capillary spinneret. Effects of PFO/MEH‐PPV ratio on the morphology and photophysical properties were studied while the PMMA weight percentage was fixed at 90 wt %. The morphologies of the prepared ES fibers were characterized by FE‐SEM and fluorescence microscopy. The obtained fibers had diameters around a few hundred nm and pore sizes in the range of 30–35 nm. The emission colors of the PFO/MEH‐PPV/PMMA blend ES fibers changed from blue, white, yellowish‐green, greenish‐yellow, orange, to yellow, as the MEH‐PPV composition increased. In contrast, the emission colors of the corresponding spin‐coated films were blue, orange, pink‐red, red, and deep‐red. Based on the values of solubility parameters, the PFO and MEH‐PPV are miscible to each other and trapped in the PMMA matrix. Hence, energy transfer between these two polymers is possible. The smaller aggregated domains in the ES fiber compared to those of spin‐coated films possibly reduce the efficiency of energy transfer, leading to different emission colors. Also, the prepared ES fibers had higher photoluminescence efficiencies than those of the spin‐coated films. Pure white light‐emitting fibers prepared from the PFO/MEH‐PPV/PMMA blend ratio of 9.5/0.5/90 had the Commission Internationale de L'Eclairage (CIE) coordinate of (0.33, 0.31). Our results showed that different color light‐emitting ES fibers were produced through optimizing the composition of semiconducting polymer in the transparent polymer matrix. This type of ES fibers could have potential applications as new light sources or sensory materials for smart textiles. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 463–470, 2009     

Design,synthesis, photophysical,and electrochemical properties of DCM‐based conjugated polymers for light‐emitting devices

A series of conjugated hyperbranched polymers, hyperbranched copolymers, and linear polymers containing 2‐pyran‐4‐ylidenemalononitrile (acceptor) and triphenylamine/fluorene (donor) units were synthesized and characterized by FTIR, ¹H NMR, thermogravimetric analyses, differential scanning calorimetry, gel permeation chromatography, UV–visible, photoluminescence, and cyclic voltammetry measurements. All the polymers show red‐light emission in the range of 566–656 nm both in solution and in solid state. The quantum efficiency of the polymers was in the range of 56–82%. Among the six polymers synthesized, only polymers containing fluorene units show T_g and polymers based on triphenylamine not exhibit T_g. The band gap of these polymers were found to be reasonably low; hyperbranched copolymer containing fluorene unit shows lowest band gap of 2.18 eV due to the stabilization of LUMO energy level by the electron withdrawing ? CN groups. The thermal and solubility behavior of the polymers were found to be good. All the EL spectra of the devices (indium‐tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)/polymer/2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline/tris(8‐hydroxyquinoline)aluminum)/LiF/Al) show red‐light emission, and the device fabricated with P3 and P4 shows maximum luminance and luminous efficiency of 4104 cd m^?2 and 0.55 cd Å^?1 and 3696 cd m^?2 and 0.47 cd Å^?1, respectively, indicates that they had the best carrier balance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Photostability of novel copolymers functionalized with laser dyes based on modified rhodamine 6G and 1,8-naphthalimide

Modified rhodamine 6G molecules (Rh-Al or Rh-Aln) with polymerizable double bonds had been copolymerized with 1,8-naphthalimide derivatives. In copolymers PRNAM, naphthalimide moieties are connected to rhodamine moieties at nitrogen atom of rhodamine moiety, and in copolymers PRNM naphthalimide moieties are connected to rhodamine moieties at ester group of rhodamine moiety. We report on their photostability in liquid solution and in solid film. The photodegradation kinetics of novel copolymers functionalized with laser dyes based on modified rhodamine 6G and 1,8-naphthalimide has been studied by UV-VIS absorption spectroscopy. The results show that the rates of the photofading reactions of these novel copolymers follow quasi-first-order. The photostability of the copolymers functionalized with laser dyes in solid films is better than that in solutions. The different type of the copolymer shows the different photostability.     

Pure white‐light‐emitting diodes from phosphorescent single polymer systems

New white polymeric light‐emitting diodes from phosphorescent single polymer systems have been developed using a blue‐light‐emitting fluorene monomer copolymerized with a red‐light‐emitting phosphorescent dye, and end‐capped with a green‐light‐emission dye. All of the copolymers have good thermal stability with 5% weight loss temperatures at 380–413 °C and glass transition temperatures at 75–137 °C. We obtained white‐light‐emission devices by adjusting the molar ratio of the comonomers with a structure of indium tin oxide/poly(3,4‐ethylenedioxythiophene): poly(styrene sulfonic acid)/polyvinylcarbazole (PVK)/emission layer/Ca/Ag. The highest brightness in such a device configuration is 300 cd/m² at a current density of 2900 A/m² with high white color quality (Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.34)). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 464–472, 2008