Efficient structural modification of electron-withdrawing substituents on Pt(II) complexes for red emitters: A theoretical study

In this study, the electronic structures and optical properties of a cyclometalated Pt(II) complex (M1) and a series of derivatives (M1–F, M1–CF₃, and M1–CN) with electron-withdrawing substituents (–F, –CF₃, and –CN) at the carbazole moiety were theoretically investigated by density functional theory and time-dependent density functional theory. The calculation results reveal that these Pt complexes display deep red phosphorescence emission above Λ = 640 nm. When the ³MLCT/π → π* to triplet metal-centered ³MC/d–d state decay mechanism is taken into consideration, the nonradiative decay rate constant (k_nr) decreased in the order M1 > M1–CF₃ > M1–F > M1–CN. The <T₁|H_SOC|S_m> and kr values of M1-F are similar with those of M1, however the Knr rate ofM1-F is larger than that of M1. M1–F is expected to have improved quantum yields. Moreover, through the analyses of the HOMO/LUMO level and triplet energy, it is found that the introduction of –F and –CN substituents in M1 results in efficient energy transfer from the host material 4,4′-N,N′-dicarbazole-biphenyl to these complexes. In view of the electroluminescent applications in organic light-emitting diodes, M1–F can serve as efficient deep-red guest materials with improved electron injection and transport ability.     

高分子自组装ZnO纳米带合成过程的研究

ZnO nanobelts were synthesized from zinc acetate (Zn(CH₃COO)₂) and polyvinyl alcohol(PVA) at about 300 ℃, 400 ℃, and 550 ℃. The products were characterized by scanning electron microscope(SEM) and transmission electron microscope(TEM). The ZnO nanobelts were typically 10～30 μm in length and 30～8 000 nm in width. The results show that the ZnO Y-nanobelts were formed owing to dislocation structure. The thermal treatment of 120 ℃ and enough time for growth of the crystal are essential to ZnO nanobelts synthesis.     

沉积温度对Cu_2O薄膜生长过程及光电性能的影响(英文)

以硫酸铜为铜源,采用一步化学浴沉积法制备出了晶粒尺寸可调的纳米晶Cu2O薄膜。通过X射线衍射、扫描电镜和紫外可见分光光度法研究了沉积温度对薄膜晶体结构、成核密度、晶粒尺寸、薄膜厚度和光电性能的影响。结果表明,当在60~90℃范围内调节温度时,能够很好地控制晶粒尺寸、薄膜厚度,并将禁带宽度控制在33~51 nm、392~556 nm和2.47~2.61 eV范围内;随着晶粒尺寸的减小,紫外可见光谱的吸收边有明显的蓝移。此外还对薄膜的生长过程,成核密度和颗粒尺寸变化的机理进行了讨论。     

Catalytic asymmetric synthesis of quaternary trifluoromethyl α- to ε-amino acid derivatives via umpolung allylation/2-aza-Cope rearrangement

In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and ε-amino acid derivatives.

In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement for the preparation of a variety of quaternary trifluoromethyl α-ε-amino acids in high yields with excellent enantioselectivities.     

镉配位聚合物的合成及其染料吸附性能研究综合实验*

介绍了一个研究型综合实验,涉及镉配位聚合物的合成及其染料吸附性能研究。该实验使用常见有机配体丁二酸、1,4-二(1-咪唑)苯与硝酸镉四水合物,在溶剂热条件下进行反应得到一例镉配位聚合物。利用X射线单晶衍射、X射线粉末衍射、热重分析、红外光谱对配位聚合物进行结构表征,并对其染料吸附性能进行研究。该实验将科学研究热点融入基础实验教学,既巩固了学生的基础理论知识,提高了实验技能,又拓展了学生的科学视野,加强了他们独立分析问题、解决问题的能力,有利于培养学生的创新精神和实践能力。     

硅胶整体柱芯的制备方法研究

目前,新型色谱填充材料发展很快,但传统的高效液相色谱(HPLC)颗粒型填充柱存在缺陷,难以实现既高效又快速的分离,Minakuchi等制备了连续的硅胶整体柱,该柱同时具有通孔和中孔双孔结构,孔容量大大高于填充柱,因此,该柱具有高速、低压、高效、适于溶剂及流速梯度洗脱等优点,适合高通量分析和快速分离,     

Gold nanoparticles-enhanced bisphenol A electrochemical biosensor based on tyrosinase immobilized onto self-assembled monolayers-modified gold electrode

A novel electrochemical sensor based on the immobilization of tyrosinase(tyr) onto gold nanoparticles(nano-Au) and thioctic acid amide(T-NH2) self-assembled monolayers(SAMs)-modified gold electrode has been developed for the determination of bisphenol A(BPA).It was found that the nano-Au could significantly enhance the electrochemical response of tyr/nano-Au/T-NH2/Au electrode to BPA,and the enhancement effect of nano-Au on the current response was also related to the enzyme.The results indicated that the biosensor could be used as a detector for BPA determination with a linear range from3.99 ×10-7mol/L to 2.34 ×10-4mol/L and a detection limit of 1.33×10-7mol/L.In addition,this biosensor showed good reproducibility.     

Li+，Na+//CO32-，B4O72--H2O交互四元体系273 K介稳相平衡研究

我国青藏高原由于特殊的地理气候特点而盐湖众多,西藏境内的扎布耶盐湖卤水中锂、硼、钾浓度之高,在世界盐湖中也非常罕见[1-3].     

含腺嘌呤的杯芳烃衍生物的合成、表征及其对核苷碱基的分子识别性质

设计合成了一种新型含腺嘌呤基的杯芳烃衍生物(AC)5,11,17,23-四叔丁基-25, 27-二羟基-26-[1-(9-腺嘌呤)-丙氧基]-28-溴丙氧基杯芳烃, 通过红外光谱、元素分析、核磁共振谱和电喷雾质谱等手段对其进行了表征,确认为目标产物; 并采用紫外分光光度法研究了AC的分子识别作用, 通过测定AC与不同浓度、不同组分的核苷、碱基混合体系的吸光度, 证明了AC对尿嘧啶、尿苷具有分子识别作用, 能从其它核苷或碱基共存的体系中将尿苷或尿嘧啶识别出来.     

用人工神经网络处理谷物成分分析

本文用人工神经网络处理谷物的付立叶变换近红外漫反射光谱,对谷物中含量在10~(-1)～10~(-3)的蛋白质、脂肪和6种人体必需氨基酸定量分析数据进行了解析,分析结果与经典化学方法没有系统偏差,且优于逐步回归分析法的结果。