光异构化反应的研究——水杨醛缩芳胺席夫碱的吸收光谱与分子结构的关系

<正> 具有光致变色现象的席夫碱在过去几十年里一直为人们所感兴趣。一般认为,水杨醛上的邻羟基是这类席夫碱发生光致变色的必要条件。光致变色的过程就是邻羟基的质子转移到亚氨基的氮原子上,随后发生分子内的几何异构,但对此机理仍存在争执。本文主要报道一些席夫碱的电子吸收光谱与分子结构的关系,以及溶剂对电子吸收光谱的影响。     

含席夫碱基团的光致变色螺吡喃化合物的光谱性能和与DNA作用研究

本文合成6种带有席夫碱基团的螺吡喃光致变色化合物,并利用电子吸收光谱、荧光光谱研究了它们的光谱性质以及与DNA的相互作用,考察了不同基团对其作用的影响,对同一化合物研究了在不同pH值、不同离子强度条件下的作用情况,初步探讨了它们与DNA的作用方式.     

取代芳香醛缩芳香胺双席夫碱的合成及谱学性质

采用冰浴合成法合成了一系列席夫碱, 其中4种化合物为首次报道, 研究了其IR, 1H NMR波谱性质, 测定了它们在溶液中以及固态时的紫外吸收光谱和荧光光谱, 探讨了席夫碱类化合物分子结构与光谱之间的关系. 实验结果表明, 水杨醛上的邻羟基是席夫碱类化合物具有荧光性质必要条件; 极性溶剂中, 苯甲醛邻位和对位上OH的存在均可引起双席夫碱结构的变化.     

三种水杨醛类席夫碱的合成与性质研究

以取代水杨醛和3-氨基噻吩为原料合成了三种水杨醛类席夫碱,探讨了水杨醛结构中酚羟基对位取代基结构变化对于该席夫碱探针的激发态内质子转移过程、pH响应和金属离子响应的影响。研究结果表明,改变取代基团的推、吸电子能力,可调节酚氧负离子对活泼氢的束缚能力,进而影响这些席夫碱分子的激发态内质子转移性能。同时,酚氧负离子的电荷密度也决定了其与阳离子的配位能力,从而表现出不同结构的席夫碱对金属离子的选择性和灵敏性差异。     

新型席夫碱锌配合物的合成及其在染料敏化太阳能电池中的应用

摘要合成了新型席夫碱配体及其锌配合物, 并利用核磁共振氢谱、 紫外 可见吸收光谱和荧光光谱等方法对配体及其配合物进行了表征. 将席夫碱及其锌的配合物作为光敏剂应用在染料敏化纳米薄膜太阳能电池中, 配合物染料比席夫碱配体的光电转化效果更好, 能量转化效率为1.45%(AM 1.5, 100 mW·cm^-2).     

一种识别苯及Cu2+的多功能荧光探针的合成与性能研究

以三苯胺为电子给体,苯为共轭桥,二氨基马来腈为电子受体和识别基团,合成了一种席夫碱型多功能荧光探针TB-DAT。通过质谱、元素分析、¹H NMR、¹³C NMR等表征了其结构,利用紫外吸收光谱和荧光光谱对其光物理性能及对检测目标的特异性识别。结果显示,所合成的荧光探针该在苯溶剂中发出最大发射峰为530 nm的黄绿色荧光,从而在一系列苯系物中识别出有毒的苯。另外,该荧光探针还能够在乙腈溶液中通过明显的荧光增强行为实现铜离子的特异性识别,检测限低至0.73μM,且对其他金属离子有很好的抗干扰能力。     

含羧基双氮席夫碱配体对甲基三氧化铼催化烯烃环氧化反应的影响

摘要: 以2-吡啶甲醛与氨基苯衍生物缩合制备了3个双氮席夫碱配体,对其结构进行了表征。将这些席夫碱配体用作甲基三氧化铼(MTO)催化30% H2O2环氧化烯烃反应的添加物,研究了席夫碱结构对MTO催化性能的影响。结果表明,含有吸电子的羧基的双氮席夫碱配体由于具有适宜的配位能力和酸性,可显著提高MTO催化烯烃环氧化反应选择性,而反应速率没有明显降低,并且在低温下对MTO催化性能的改进更好;不具吸电子基羧基的双氮席夫碱配体尽管可以提高环氧化物的选择性,但同时却降低了MTO的催化活性。     

水溶性金属席夫碱与DNA相互作用的荧光光谱

研究了几种水溶性的金属席夫碱与 DNA相互作用的光谱性质。在所研究的金属中 Mn的络合物与 DNA的相互作用最强,荧光强度改变最大且其激发和发射峰均有微小紫移。其紫外可见光谱亦有明显的减色效应和微紫移。 KI猝灭和 Mn席夫碱与溴化 3, 8 _ 二氨基 _ 5 _ 乙基 _ 6 _ 苯基菲啶的竞争实验证实了 Mn席夫碱与 DNA之间的作用方式是嵌入方式。同时也考察了 pH值、温度对 Mn席夫碱及 Mn席夫碱－ DNA体系荧光强度影响。 Mn席夫碱仅与 DNA的一部分键位发生作用, Mn席夫碱相对荧光强度与加入的小牛胸腺 DNA的浓度,在 3× 10－ 6～ 2× 10－ 4 mol/L范围内呈线性关系。水溶性 Mn席夫碱可以作为一种新型荧光探针用于微量 DNA的检测。     

取代席夫碱铜金属卟啉的微波辅助合成

微波辅助合成了取代席夫碱铜金属卟啉。 实验结果表明,取代苯甲醛与四(对氨基苯基)铜金属卟啉的缩合反应速率和产率与芳香醛取代基的种类有关,含吸电子基团的芳香醛大于含给电子基团的芳香醛,且随吸电子性的增强而增加,随给电子性的增强而减少。 水杨醛席夫碱铜金属卟啉侧链可与铜离子在碱性条件下形成铜配合物,其催化氧化环己烷的转化率达到了7.68%,环己酮的选择性达到了60.87%。     

水杨醛乙酰腙席夫碱作为Al3+荧光探针分子的理论研究

用密度泛函理论和含时密度泛函理论研究了实验上合成的一种基于水杨醛席夫碱的Al~(3+)荧光探针的性质.通过优化探针分子及其与Al~(3+)形成的配合物可能存在的异构体的几何结构,并模拟各异构体的电子吸收光谱,找到了最可能存在的异构体.最后模拟了它们的荧光光谱,进一步验证了前面推测的异构体的正确性,加深了人们对这一探测过程的认识.     

Ionic polymers VI. Chemical stability of strong base anion exchangers in aggressive media

The chemical stability in aggressive media of two types of strong base anion exchangers was studied. The anion exchangers were a commercial Amberlite IRA-400 with a styrene structure and an unconventional resin obtained by the quaternization of a 4-vinylpyridine: 8% divinylbenzene copolymer with methylchloride. The presence of the quaternary nitrogen atoms in or out of the aromatic ring had a great influence on the chemical stability of the ion exchangers.     

The Mechanism of Schiff Base Formation of Some Arylidenes-p-Aminosalicylic Acid

Formation of a series of Schiff bases derived from p-aminosalicylic acid I and various aromatic aldehydes has been studied kinetically in ethanol medium in presence of piperidine as a basic catalyst. The order of the reaction is determined to each reactant by following the concentration of the Schiff base formed during the reaction. The reaction is Kinetically third-order in the presence of low concentration of piperidine, first-order to each of I , aldehyde and piperidine. On the other hand, in presence of ≥5×10^?4 M of piperidine the order of the reaction changed to second-order, thus much the reaction is independent of piperidine concentration. The rate determining step is suggested to be the dehydration of the carbinolamine intermediate step 4. Variation in reaction rate constants with the different substituent of the aromatic aldehyde, with substituents of aromatic amine and with the nature of the hydroxylic organic solvents as reaction medium are studied and discussed.     

Montmorillonite as a Heterogeneous Catalyst in the Efficient,Mild and One Pot Synthesis of Schiff Bases under Solvent‐Free Conditions

A mild and efficient method has been reported for preparation of Schiff base ligands through condensation reaction of various aromatic aldehydes and ketones with different aromatic amines in the presence of montmorillonite as a heterogeneous catalyst under solvent free conditions. The advantages of this friendly, economically, environmentally and mild method are such as; simplicity of the reaction procedure, reusability of catalyst, simple work‐up, high product yields and very short reaction times.     

Synthesis and physico-analytical studies of some novel ferrocenyl Schiff base derivatives

A series of ferrocenyl Schiff base derivatives was synthesized by condensation reactions of 1,1′-ferrocenedicarboxaldehyde and aromatic amines containing long chain alkyl groups as free ends which were characterized by their physical properties, elemental, FTIR, ¹H NMR, ¹³C NMR spectral and thermal analysis. The thermal behaviour of the synthesized compounds was studied by differential scanning calorimetry (DSC) which revealed that these compounds may exhibit mesomorphic properties. The DSC results of aromatic amines and ferrocenyl Schiff bases were compared to study the effects of structure, i.e. rigid core and terminal chain length, on the phase transition behaviour.     

Synthesis and Antimicrobial Activity of Substituted Phenophosphazines

Several Schiff base derivatives of phenophosphazines were synthesized by the reaction of amino phenophosphazines and aromatic aldehydes in equimolar ratio, using methanol as solvent. Possible structures have been proposed on the basis of elemental analysis, IR, and ¹H NMR spectral studies. The antibacterial and antifungal activities of the above mentioned Schiff base derivatives have been evaluated against pathogens E. coli, S. typhi, S. aureus, B. subtilis, A. niger, and C. Albicans.     

An Efficient and Environment Friendly Procedure for the Synthesis of Arylmethylenemalononitrile Catalyzed by Strong Base Anion‐Exchange Resin in Water

Abstract

Knoevenagel condensation of malononitrile with aromatic aldehydes catalyzed by strong base anion‐exchange resin in water results arylmethylenemalononitrile in 74–98% yield at room temperature.     

SiO2 负载壳聚糖席夫碱钯催化剂催化芳香醛酮还原为芳香烃

 制备了 SiO2 负载的壳聚糖席夫碱钯催化剂, 利用 X 射线衍射、红外光谱和热重等方法对催化剂进行了表征, 并考察了该催化剂催化羰基加氢为亚甲基的反应性能, 以二苯甲酮为底物, 系统地研究了反应时间、反应温度和催化剂用量等因素对反应性能的影响. 结果表明, 该催化剂具有较高的催化芳香羰基加氢为亚甲基的活性和选择性, 且反应可在较低的温度和常压的温和条件下进行. 关键词：壳聚糖; 席夫碱;     

碱催化醛、丙二腈和邻苯二甲酰肼的、三组分反应合成酞嗪衍生物

经过实验验证引入水有利于芳香醛、丙二腈和邻苯二甲酰肼三组分的反应进行,催化量的有机碱三乙胺(Et 3 N)或无机碱磷酸氢二钾(K 2 HPO 4[DK1]·3H 2 O)可以在常规条件下促进该反应。本文以39%~97%的产率合成一系列1 H-吡唑[1,2-b]酞嗪-5,10-二酮衍生物。两种催化剂均溶于水,因此,反应结束后催化剂的分离与产物提纯简便易行。此方法具有反应条件温和、绿色环保、操作简单、后处理方便等特点。     

一种制备Schiff碱的新型方法

介绍了一种制备Schiff碱的新型方法——超音速气流固相法,其原理是在超音速气流下使芳醛和芳胺在反应器中摩擦活化,再通过撞击固定靶产生迅速的能量交换而发生化学反应.利用该方法成功制备了两种对氨基苯甲酸类Schiff碱,采用DTA对其反应进行了定性分析,并用IR、MS、1HNMR表征产物的结构,实验结果显示该方法制备Schiff碱无需溶剂,操作简单,反应时间短,转化率高.     

Electrogenerated acetonitrile anions/tetrabutylammonium cations: an effective catalytic system for the synthesis of novel chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines

An efficient and convenient synthesis of novel chromeno[3′,4′:5,6]pyrano[2,3-d]pyrimidines is described, using the electrogenerated anion of acetonitrile as the base in the presence of tetrabutylammonium fluoride as an effective supporting electrolyte in a one-pot, three-component condensation of barbituric acid, an aromatic aldehyde or isatin, and 4-hydroxycoumarin. The reaction is carried out in an undivided cell containing an iron electrode as the cathode and a Pt electrode as the anode, at a constant current at room temperature.