外电场对2-氟-5-溴吡啶分子结构与电子光谱影响的研究

采用密度泛函B3LYP方法,在6-311++g(3df,3pd)基组水平上优化了不同外电场下2-氟-5-溴吡啶分子的基态稳定构型、电偶极矩和分子的总能量,在此基础上利用杂化CIS方法研究了外电场下2-氟-5-溴吡啶分子的前9个激发态的激发能、波长和振子强度受外电场的影响规律.结果表明:5C-9Br和3C-10F间键长受到X轴向外场影响最大,随着外电场的继续增加,可能最先趋于断裂;在外电场F=-0.05 a.u.时总能量达到最大,而偶极矩达到最小;LUMO能级受外场影响较大,HOMO能级受外电场影响较小;激发波长、振子强度也受外电场影响,但随电场变化比较复杂.

分子结拉伸与界面识别:破解4,4′-二吡啶分子结拉伸过程中高低电导之谜

4,4′-二吡啶分子结在拉伸过程中呈现出独特的高低电导现象,是分子电子学近十几年研究中的未解之谜.根据实验测量过程以及所采用的技术手段,发展了基于第一性原理计算的分子结绝热拉伸模拟方法,对4,4′-二吡啶分子结的拉伸过程进行了模拟计算.并利用一维透射结合三维修正近似(OTCTCA)方法计算了拉伸过程中体系电导的变化,成功破解了4,4′-二吡啶分子结在拉伸过程中的高低电导之谜.结果显示,在4,4′-二吡啶分子结的拉伸过程中,分子末端的氮原子很容易吸附到探针电极的第二层金原子上,并且导致分子对尖端金原子产生特有的侧向推动作用,将探针尖端金原子推向一侧,从而在拉伸过程中出现高电导平台.进一步拉伸分子结,分子上端氮原子移动并吸附到探针尖端金原子上,同时尖端金原子重新回到原来的晶格位置上.体系电导也因此降低大约5—8倍,形成低电导平台.根据计算结果,4,4′-二吡啶分子结双电导平台的出现同时表明基底电极很容易存在表面金原子,且只有分子吸附到表面金原子上才会出现高低电导现象.可见,利用分子结拉伸过程中测量到的电导曲线并借助理论计算可以有效识别分子结界面结构.另外,对4,4′-二吡啶分子结高低电导现象物理过程和内在物理机制的破译,为更好利用含吡啶末端分子构建分子开关、分子存储器、分子传感器等功能分子器件提供了重要技术信息与依据.

气相吡啶分子S_1态的(2+3)偏振共振多光子电离谱研究

利用气相吡啶分子分别在圆偏振光激发和线偏振光激发下的 (2 +3)偏振共振多光子电离(PRMPI)谱 ,对其第一激发态 (S1)上的振转结构进行了研究。在谱中观察到了呈双峰结构的电子振转跃迁谱带。分析表明 ,所有振动谱带均为 S1态上ν6a、ν10 a、ν12 、ν16b和ν17a以及基态上ν9a的混合频率谱带。指认吡啶ν17a 的 S1态频率为 6 70 cm-1,并认为在 S1态上ν17a 频率降低的原因与ν10 a 类似。

金电极与吡啶末端连接界面结构的力学变化过程理论研究

利用基于第一性原理的绝热拉伸模拟方法计算了4,4’-二吡啶分子与不同构型金电极之间的作用过程,研究了分子在外力作用下逐渐远离金电极过程中分子与电极间界面结构特有的演化过程以及体系能量与作用力的变化特征.结果显示,分子在远离锥形电极过程中很容易出现近于垂直地连接到锥形电极第二层金原子上的特有连接构型,同时由于吡啶末端的排斥作用,电极尖端的金原子偏向一侧.分子从第二层金原子上断开并连接到尖端金原子上需要1.3—1.5 nN的拉力作用,明显大于分子从尖端电极上断开所需要的0.8—1.0 nN的作用力,从而揭示了实验中二吡啶分子结在形成过程中作用力与界面构型变化之间的对应关系.4,4’-二吡啶分子与平面金电极的作用较弱,只需要不到0.5 nN的作用力就可断开,而当分子连接到吸附在平面电极表面的孤立金原子上时,可以承受约1.7 nN的作用力.以上研究表明基于第一性原理的绝热拉伸模拟方法不仅可以揭示分子与电极之间的界面结构演化过程,而且通过作用力的计算可以很好地识别实验中分子与电极间的特有界面结构.

水溶性聚吡啶树枝状分子的合成

以草酸二乙酯、丙酮为原料,运用收敛法合成了聚吡啶树枝状分子[(EtO_2C)_4-Py_3-OCH_2Ph],在此基础之上,通过对树枝状分子外围及核进行化学改性,制备出一种新型的水溶性聚吡啶树枝状分子(HOH_2C)_4-Py_3-OH.利用核磁氢谱、核磁碳谱、红外光谱以及 DSC 对部分中间产物和最终产物进行表征.

两种双吡啶盐在盐酸中对A3钢的缓蚀性能

用静态失重法测定了两种gemini型化合物溴化1,4-二(α-癸基吡啶)丁烷(Gp3)和1,6-二(α-癸基吡啶)己烷(Gp4)在含有1.0g/LNaCl的10%盐酸中对A3钢的缓蚀性能。25℃时Gp3在加量10mg/L时的缓蚀率即高达99.85%,加量逐步增加到500mg/L时大体上维持此高缓蚀率。90℃时,在加量20,200,800mg/L时的缓蚀率,Gp3分别为63.17%,90.62%,89.91%,Gp4分别为75.80%,92.97%,93.37%,而四川广汉油田目前使用的缓蚀剂WD-11分别为10.57%,36.95%,88.87%。两种双吡啶盐是成膜型缓蚀剂,在盐酸中对A3碳钢的缓蚀效率高而用量低。表1参7。

新型吡啶鎓盐分子的合成及其对Fe^(3+)的检测

针对水中铁离子(Fe^(3+))检测存在使用有毒溶剂、对设备要求较高、检测限高等缺点,以四联吡啶和5-溴甲基-间苯二甲酸二甲酯为原料,以N,N-二甲基甲酰胺为溶剂,通过亲核取代和水解反应制备出一种新型的铁离子检测探针——吡啶鎓盐分子。运用一系列的表征技术分析了吡啶鎓盐分子的性质,并通过实验探察了共存离子、Fe^(3+)的浓度等对吡啶鎓盐分子识别Fe^(3+)的影响。表征实验结果表明,吡啶鎓盐分子结构具有三齿吡啶氮和羧基,使其与Fe^(3+)之间具有很高的亲和力,可以与Fe^(3+)配位形成金属络合物。识别实验结果表明,吡啶鎓盐分子对Fe^(3+)的络合显色实现了对Fe^(3+)的专一性检测,其检测限为4.8×10^(−7)mol·L^(−1);在Cd^(2+)、Zn^(2+)、Mn^(2+)、Ni^(2+)、Cu^(2+)、Fe^(2+)和K^(+)等多种干扰离子存在条件下,对Fe^(3+)仍具有良好的识别效果,体现出较强的抗干扰性能。综上所述,新型吡啶鎓盐分子结构中具有三齿吡啶氮和羧基,使其对水中Fe^(3+)具有易识别、灵敏度高、选择性好等优点。

A Ternary Ruthenium（II） 2,2′ ：6′,2″-Terpyridine Complex Having Intramolecular Tr-Tr Stacking Interaction with Ancillary Benzyl Groups of the Mixed Ligand

A new ruthenium（II） complex with two different types oftridentate ligands was synthesized, 2,2′：6′,2″-terpyridine （tpy） and 2,6-Bis（（N-benzyl）aminomethyl）pyridine （bbap）： [Ru（tpy）（bbap）]2＋ （1）. This compound was designed to form intramolecular π-π stacking interaction between tpy and substituted benzyl groups of bbap. The single-crystal X-ray diffraction analysis revealed that 1 crystallized with orthorhombic space group Aea2 and the ruthenium center has a distorted octahedral coordination geometry with fully chelated tpy and bbap ligands. Simultaneously, in the crystal structure of 1, the central part of ligating tpy was stacked and sandwiched with a pair of capped benzyl substituent groups of bbap, the nearest atomic distance being N...C = 3.28 A.

水溶性吡啶萘酰亚胺-聚酰胺-胺荧光树形分子的合成、聚集诱导荧光增强及细胞成像

将具有聚集诱导荧光的4-(2-吡啶乙烯基)-1,8-萘酰亚胺单元通过酰胺化反应连接到聚酰胺-胺(PAMAM)树形分子上,制备了一种水溶性吡啶萘酰亚胺-聚酰胺-胺荧光树形分子PN-PAMAM.结构经核磁共振氢谱、核磁共振碳谱、红外及高分辨质谱表征.吡啶萘酰亚胺-聚酰胺-胺树形分子PN-PAMAM具有明显的聚集诱导荧光增强(AIEE)特性.在固体态时的最大荧光发射波长为532 nm,紫外灯下发出黄绿色荧光.在纯水中的最大荧光发射波长为494 nm,荧光量子产率为4.42%.在水含量为60%的水/四氢呋喃混合溶液中,其荧光强度达到最大,荧光发射波长为485 nm,荧光量子产率增大到17.54%.制备了一种负载聚集诱导荧光染料PN-PAMAM的二氧化硅纳米粒子PN-PAMAM/Si O_2,测得该纳米粒子的荧光发射波长为473 nm,粒径约为40 nm.测定了水溶液中树形分子PN-PAMAM与乳腺癌细胞MCF-7共同孵化后的共聚焦荧光成像,得到清晰的蓝场荧光照片.研究表明,吡啶萘酰亚胺-聚酰胺-胺树形分子PN-PAMAM是一种水溶性荧光分子,具有明显的聚集诱导荧光增强特性,可广泛应用于肿瘤定位、生物追踪及纳米材料等重要领域.

通过氢键和烷基长链的稳定化作用构筑联吡啶衍生物二元共混体系的二维纳米结构

利用扫描隧道显微镜观测了4,4′-二壬基-2,2′-联吡啶分子及其与硬脂酸共吸附在石墨表面的自组装结构.实验结果表明,在两种情况下4,4′-二壬基-2,2′-联吡啶分子均形成平面反式构型,并且共吸附后,4,4′-二壬基-2,2′-联吡啶分子与硬脂酸通过氢键形成了规则有序的二维纳米结构.

Theoretical studies on high energetic density nitramine explosives containing pyridine

The insensitive property of explosives containing pyfidine is combined with the high energy of nitramine explosives, and the concept of new nitramine explosives containing pyridine is proposed, into which nitramine group with N-N bonds is intro- duced as much as possible. Based on molecular structures of nitramine compounds containing pyridine, density functional the- ory （DFT） calculation method was applied to study designed molecules at B3LYP/6-31＋G（d） level. The geometric and elec- tronic structures, density, heats of formation （HOF）, detonation performance and bond dissociation energies （BDE） were investigated and comparable to 1,3,5-trinitro-l,3,5-triazinane （RDX） and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane （HMX）. The simulation results reveal that molecules B and D perform similarly to traditionally used RDX. Molecule E outperform RDX, with performance that approach that of HMX and may be considered as potential candidate of high energy density compound （HEDC）. These results provide basic information for molecular design of novel high energetic density compounds.

Polymer light-emitting devices based on europium(Ⅲ) complex with 11-bromo-dipyrido[3,2-a:2′,3′-c]phenazine

Polymer light-emitting diodes(PLEDs) containing Eu(DBM)3(Br DPPz)(DBM is dibenzoylmethane, and Br DPPz is 11- bromo-dipyrido[3,2-a:2′,3′-c]phenazine) doped in a blend of poly(9,9-dioctylfluorene)(PFO) and 2-tert-butylphenyl-5- biphenyl-1,3,4-oxadiazole(PBD) as the host matrix were reported. Eu(DBM)3(Br DPPz) exhibited high thermal stability and intense UV-Vis absorption. Narrow-bandwidth red emission at 612 nm with a full width at half-maximum(FWHM) of 14.0 nm was observed from Eu(DBM)3(Br DPPz) in these double-layered PLEDs at dopant concentrations from 1 wt% to 8 wt%. For the PLED containing 1 wt% Eu(DBM)3(Br DPPz), a maximum luminance of 829 cd/m2 at 153.5 m A/cm2, highest external quantum efficiency of 1.70% at 2.1 m A/cm2 and maximum luminance of 0.74 cd/A at 4.31 m A/cm2 were obtained.

Supramolecular PS-P4VP diblock copolymer thin films slowly dip-coated from chloroform solutions

This contribution shows the strong influence of using chloroform instead of THF on the characteristics of thin films of supramolecular block copolymers of poly(styrene-b-4-vinyl pyridine) dip-coated in the so-called "capillarity" regime from solutions containing 1-naphthol or 1-naphthoic acid.The small molecule content in the dip-coated films was investigated by infrared spectroscopy and the film morphology by atomic force microscopy.It was found that the small molecule content in the films is constant with dip-coating rate in the range investigated,but it is higher for 1-naphthoic acid than for 1-naphthol.The main morphology observed was in the form of "islands" and "holes",which is typical of flat-on lamellae.These findings are related to hydrogen-bonding between the small molecule and pyridine being conserved in chloroform and to the good solubility of both blocks in this solvent,with differences between the two small molecules related to their differing H-bond strengths.These findings contrast strongly with what was observed previously using THF as a solvent,for which the SM content increases with dip-coating rate and the morphologies are mainly spherical and cylindrical in the same parameter range.

Quantum chemical study on excited states and charge transfer of oxazolo[4,5-b]-pyridine derivatives

The excitedstate intramolecular charge transfer of four oxazolo[4,5-b]pyridine derivatives with different electron donating and electron withdrawing groups was investigated using the time-dependent density functional theory. The vertical excitation energies and the electronic structures were explored. Their distinct properties of absorption and fluorescence spectra in solvent phase were explained according to the electronic coupling matrix elements calculated by the Mulliken-Hush theory. The sub-stituent on the oxazolo[4,5-b]pyridines will remarkably change their spectra properties and increase the first excited-state dipole moments. The effect of protonation on the absorption and fluorescence spectra was also investigated systematically. Our study suggests that the present method is feasible to explain charge transfer excitation and predict the properties of absorption and emission spectra in the studied systems.