Synthesis,crystal structures and luminescent properties of an isotypic series of rare-earths complexes with a dialdehyde ligand

A series of mononuclear complexes based on lanthanide ions has been synthesized and X-ray characterized. The compounds [Ln^IIIL₂(NO₃)₃(H₂O)₂] (Ln = La, Ce, Pr, Nd, Sm, Gd and Tm; L = 2,6-bis(2-formylphenoxymethyl)pyridine) are found to be isomorphous and isostructural. Ligand L systematically coordinates through one carbonyl functionality, and the resulting complexes are placed on a twofold axis in crystals belonging to C2/c space-group. Emission spectra for Ln = La, Pr, Nd revealed a correlation between the Ln–O coordination bond length and the photoluminescent properties of the complexes, in line with a Förster–Dexter mechanism for intramolecular energy transfer. Ligand L is therefore a suitable sensitizer for lanthanide ions.     

Synthesis, crystal structure and photoluminescence of 2,6-dimethylanthracene and its pseudo-triptycene derivatives

A simple one-step synthesis of 2,6-dimethylanthracene, 1, in high yield is reported utilizing the easily accessible benzyl alcohol as the starting material. Based on 2,6-dimethylanthracene, two pseudo-triptycene compounds, cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinic anhydride, 2, and cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinyl amine, 3, are firstly synthesized in high yield and they are characterized by single crystal X-ray diffraction. Compound 2 crystallizes in triclinic space group and compound 3 crystallizes in monoclinic P2₁/c space group. Both compound 2 and 3 exhibit cis-configurations and endo-conformations. Compound 1 exhibits very intense photoluminescence property due to the delocalized electron in the whole molecule, whereas fluorescence quench happens to some extents due to the destruction of the conjugated structure in compound 2.     

Synthesis and structure of dinuclear dimethylene- or 1,4-phenylene-linked bis(decamethyltitanoceneoxide) (Ti) complexes

The singly tucked-in titanocene [Ti(η⁵-C₅Me₅)(η⁵:η¹-C₅Me₄CH₂)] (1) reacts smoothly with ethylene glycol or hydroquinone to give bis(titanoceneoxide) (Ti^III) complexes [CH₂OTi(η⁵-C₅Me₅)₂]₂ (2) and [(η⁵-C₅Me₅)₂TiOC₆H₄OTi(η⁵-C₅Me₅)₂] (3) containing dimethylene and 1,4-phenylene link, respectively. EPR spectra of 2 in 2-methyltetrahydrofuran glass and 3 in toluene glass revealed that the unpaired d¹ electrons are in interaction to form triplet state molecules. The Ti-Ti distance derived from the zero-field splittings D for the two conformations of 2 (7.42 Å and 7.66 Å) are in good agreement with the Ti-Ti distance of 7.2430(7) Å from the X-ray diffraction single-crystal analysis. For 3, however, the Ti-Ti distance derived from D (7.65 Å) is by 1.47 Å shorter than the crystallographic distance of 9.1230(8) Å that indicates an enhancement of the through-space dipole-dipole interaction due to the presence of a conjugated quinonide link.     

Pure red electrophosphorescence from polymer light-emitting diodes doped with highly emissive bis-cyclometalated iridium(III) complexes

In order to develop highly emissive red phosphorescent materials for OLED application, novel bis-cyclometalated iridium(III) complexes were developed using the 1-(dibenzo[b,d]furan-4-yl)isoquinolinato-N,C^3′ (dbfiq) cyclometalating ligand. When 1,3-bis(3,4-dibutoxyphenyl)propane-1,3-dionate (bdbp) is employed as an ancillary ligand, Ir(dbfiq)₂(bdbp) 1 exhibits red photoluminescence (PL) at 640 nm with a quantum yield (Φ_PL) of 0.61 (in toluene, 298 K). Replacement of bdbp to dipivaloylmethanate (dpm) and acetylacetonate (acac) (Ir(dbfiq)₂(dpm) 2 and Ir(dbfiq)₂(acac) 3, respectively) does not affect the PL spectrum, but reduces Φ_PL to 0.55 and 0.49 for 2 and 3, respectively. Similar tendency is also found in the doped poly(methyl methacrylate) (PMMA) film, and 1 is more emissive (Φ_PL = 0.17) than 2 and 3 (Φ_PL = 0.08 and 0.06, respectively). Using 1 as a phosphorescent dopant, polymer light-emitting diodes (PLEDs) were fabricated, of which structure was ITO/PEDOT:PSS (40 nm)/PVCz:1:PBD (100 nm)/CsF (1 nm)/Al (250 nm). Pure red electroluminescence (EL) is obtained from the fabricated PLEDs, affording a CIE chromaticity coordinate of (0.68, 0.31). When 0.51 mol% of 1 is incorporated in the PVCz-based emitting layer, the PLED shows maximum luminance of 7270 cd m⁻² at 16.5 V, power efficiency of 1.4 lm W⁻¹ at 7.5 V, and external quantum efficiency of 6.4% at 9.0 V. PLEDs with the same structure and components were also fabricated using 2 and 3, and their device characteristics were investigated. In proportion to the PL quantum yields, 1 affords better device performance than 2 and 3. Owing to four butoxy groups introduced to the bdbp ligand, 1 exhibits high solubility in organic solvents such as chloroform and toluene, and thus, is an excellent red phosphorescent dopant for solution-processed OLEDs.     

吡喃并[4,3-b]吡喃衍生物与牛血清白蛋白作用的荧光光谱

用荧光光谱法分析了在生理条件下一种吡喃并[4,3-b]吡喃衍生物—2-氨基-7-甲基-4-(4-硝基苯)-5-氧代-4H,5H-吡喃并[4,3-b]吡喃-3-腈与牛血清白蛋白的作用机制。求得不同温度下二者的结合常数和结合位点数,探讨了微量金属离子对实验体系结合常数的影响,并根据热力学参数确定了这种吡喃并[4,3-b]吡喃衍生物与牛血清白蛋白之间的作用力类型。根据Frster非辐射能量转移机理,测定了这种吡喃并[4,3-b]吡喃衍生物与牛血清白蛋白相互结合时,能量给体-受体间的作用距离和能量转移效率,并用同步和三维荧光技术讨论了其衍生物对牛血清白蛋白构象的影响。结果表明,吡喃并[4,3-b]吡喃衍生物主要以静态猝灭方式使牛血清白蛋白荧光强度显著降低,二者主要凭借氢键和范德华力结合。     

螺二芴基可溶性共聚物的合成及发光性能

以9,9'-螺二芴和不同链长的二烷氧基苯为单体, 以FeCl3为催化剂, 采用化学氧化法合成了一系列聚合物发光材料. 溶解度测试表明, 共聚物在二氯甲烷、四氢呋喃(THF)、氯仿等极性溶剂中具有良好的溶解性. 利用核磁共振氢谱(1H NMR)、傅里叶变换红外(FT-IR)光谱、紫外-可见(UV-Vis)光谱和荧光(PL)光谱研究了共聚物的化学结构和发光性能, 结果表明共聚物在二甲基亚砜(DMSO)中均发射蓝色荧光, 最大吸收和荧光发射峰分别为356和413 nm. 以硫酸奎宁溶液作为参比, 测得共聚物的荧光量子效率为0.69至0.77. 通过循环伏安法(CV)测得所合成的三种共聚物的最高占有分子轨道(HOMO)能级均位于-5.85至-5.69 eV之间.     

草酸铕颗粒微米层状颗粒的合成及其光学性能

在室温条件下, 以柠檬酸钠为辅助剂, 通过简单沉淀法合成了草酸铕Eu₂(C₂O₄)₃·10H₂O微米层状颗粒. 应用X射线衍射、X射线电子能谱、场发射扫描电子显微镜、光致发光光谱对Eu₂(C₂O₄)₃·10H₂O结构与性能进行了表征. 讨论了草酸铕微米层状颗粒可能的形成机理.     

半径位置微扰对形状不同的空气孔结构二维光子晶体波导透射的影响

分析了不同空气孔形状的光子晶体受位置和半径微扰对于透射的影响,包括圆形,方形与椭圆形.仿真结果发现及形状相同微扰程度下,通过比较透射平坦带宽部分的分析得到透射率对位置微扰更加敏感.慢光区域正方形空气孔对于位置微扰表现较好,圆形空气孔对于半径微扰更稳健.由于不同形状的空气孔光子晶体波导结构有各自的优势,因此研究微扰对透射...     

高温高压固态复分解反应法生长氮化镓的应变性质研究

本文采用高温高压下固态复分解反应法生长氮化镓.用X射线衍射仪、扫描电子显微镜、激光拉曼光谱仪对其进行分析,结果表明生成了六角纤锌矿结构的氮化镓晶体.该样品在宏观上受到了张应力的作用,退火后,宏观的应变状态由张应变向压应变转变;晶体微观应力减小,晶粒尺寸变大,晶体质量变好.     

超二代微光像增强器Na2KSb(Cs)多碱光电阴极荧光谱研究

利用785 nm波长激光作为激发源,测量了超二代微光像增强器Na2 KSb (Cs)多碱光电阴极的荧光谱.试验中发现该荧光谱不是一条光滑的高斯型曲线,而是一条在高斯型荧光谱上叠加了一定频率间隔小锯齿峰的曲线.经实验验证和理论分析证明该荧光谱上的小锯齿峰是一种干涉条纹,与超二代微光像增强器的结构有关.干涉条纹之间的间距与...