冠醚菁染料的研究 Ⅵ.含苯并咪唑环的冠醚菁染料的合成

关于冠醚硫碳菁染料的合成及其光谱增感作用的研究已有报道.这类含冠醚结构因子的新型菁染料被证明具有良好的增感性能和稳定性. 为了进一步研究冠醚结构对菁染料感光性能和理化性能的影响,合成了含苯并咪唑环的冠醚咪碳菁染料以及与菁有关的冠醚苯乙烯型染料. 新染料1—7的结构得到质谱、核磁共振谱、红外和紫外光谱的证实.染料中间体季铵盐8的合成已在前文报道.     

冠醚菁染料的研究——Ⅰ.冠醚菁染料的合成

Dix等^[1]曾讨论冠醚偶氮染料、冠醚二苯甲烷染料和冠醚三苯甲烷染料的研究结果,关于冠醚菁染料迄今还未见报道.鉴于菁染料发色团之甲川链的可调性[2a]和冠醚空腔大小的可调性^[3],作者设想将菁染料结构因子和冠醚结构因子结合于同一分子之中,可望延伸出一系列富于颜色变化的离子选择性络合的冠醚菁染料;也可能用于分析化学和生物膜的研究等.     

冠醚方酸碲碳菁染料的合成研究

合成了不对称冠醚方酸碲碳菁染料和对称冠醚方酸碲碳菁染料，并探讨了对称冠醚方酸碲碳菁的合成方法及反应条件，提出了其可能的反应机理。     

冠醚菁染料的研究 Ⅳ.一些新冠醚菁染料的合成

冠醚菁染料的合成及其光谱增感作用已有报道.带有冠醚结构因子的新型菁染料具有良好的增感效应和稳定性. 为进一步研究冠醚菁某些基本结构因素对感光和理化性能的影响,根据冠醚空腔和菁甲川链的可调性,参照前文合成路线,研究了单苯并-18-冠-6的溴化、硝化、二硫化及还原缩合反应,制得了关键中间体2-甲基-5,6-并-18-冠-6-苯并噻唑(3),经两种季铵化反应后合成各种菁染料. 本工作合成的中间体(1～7)以及不同盐基的,对称和不对称及中位取代的苯并-18-冠-6型的冠醚菁(9～12,15)和苯并-15-冠-5型的冠醚菁(13,14)均未见文献报道.这些新化合物均经元素分析、红外光谱和紫外光谱鉴识.     

不对称冠醚碲碳菁染料的合成

合成了５种不对称冠醚碲碳菁染料．对合成关键中间体冠醚苯并碲唑所用的４－硝基苯并１５－冠－５的还原酰化方法进行了改进，比较和研究了杂原子在同一主族的４个菁染料的可见吸收光谱，计算了它们的“Ｂｒｏｏｋｅｒ偏差”     

冠醚苯并恶唑菁染料的合成

本文报道含冠迷苯并恶唑菁染料及半菁染料的合成,采用一种简便方法合成了关健中间体2-甲基6,7-二羟基苯并恶唑:从2,3,4-三羟基苯乙酮肟经beckmann重排而得到,将它再与三甘醇或四甘醇二氯化物反应 ,分别得到相应的冠醚化合物:2-甲基-6,7-并(12-冠-4)苯并恶唑和2-甲基-6,7-并(15-冠-5)苯并恶唑,将它们制成相应的季铵盐 ,然后分别与原甲酸乙酯或对二甲胺基甲醛作用,得到相应的冠醚恶唑菁染料,或半菁染料.     

感绿增感染料电子能级和增感性能的研究

本文应用Hückel分子轨道理论,对一系列对称和不对称的噁碳菁、咪噁碳菁以及喹啉噻菁染料的电子能级进行了计算,测定了这些染料的激发能,极谱半波还原电位和在溴氯化银乳剂中的光谱增感性能,计算值与观测值取得了很好的一致性。     

近红外吸收菁染料分子链结构对其光氧化稳定性能的影响

本文对具有不同分子链结构及不同链长,而母核结构分别为吲哚类及喹啉类的六种菁染料在溶液中的光氧化稳定性能进行了研究。结果表明菁染料的光褪色主要是由光氧化反应所致,当在分子链上引入不饱和环体结构时,可以使菁染料分子的光稳定性能增加;而随着分子链长的增加菁染料的光氧化稳定性能则明显下降。通过顺磁共振谱测定结果表明,在菁染料的自敏光氧化反应原初过程中,既存在单重态氧过程又存在超氧负离子过程。     

方酸菁染料在有机太阳能电池中的研究进展

方酸菁作为一种重要的菁类染料,由于它在可见-近红外区有强烈的吸收和发射性质,以及良好的光热稳定性,使它在太阳能电池的研究中越来越受到重视.随着理论的不断完善,以及太阳能电池制作技术的成熟,方酸菁将在这一领域继续得到快速发展.综述了近年来方酸菁染料在染料敏化太阳能电池和本体异质结太阳能电池中的应用,从机理角度着重讨论了染料分子结构等因素对电池性能的影响,并提出了未来的研究方向.     

菁染料和份菁染料的合成及其溶液的光稳定性研究

利用UV-Vis吸收光谱仪和光化学反应器,研究了菁染料和份菁染料的光降解动力学.研究结果表明,染料在乙腈溶液中的光褪色反应遵循假一级或零级动力学衰减.与相应的份菁染料相比,携带正电荷的菁染料具有相对较好的光稳定性.     

Electrochemical properties of 3,5-diphenylaniline units encapsulated within a crown ether. Effects of the macrocycle’s aromatic functionality and ring size

This Letter describes a series of [2]rotaxanes featuring a 3,5-diphenylaniline terminus in their dumbbell-shaped component and crown ethers as the macrocyclic component, prepared through imine formation and hydrogen bond—guided self-assembly. Electrochemical studies of these [2]rotaxanes revealed that the oxidation potential of the aniline moiety when positioned within the cavity of a crown ether was shifted negatively relative to that of the corresponding dumbbell-shaped compound, and that a crown ether possessing a small cavity and a large number of aromatic rings had a more negative effect on the oxidation potential of the aniline moiety than did a large-cavity crown ether featuring no aromatic rings. UV experiments showed that absorption band of the rotaxanes bearing small crowns shifted to longer wavelengths as compared to those of the rotaxanes having large crowns.     

Cyclitol based metal complexing agents. Preference for the extraction of lithium by myo-inositol based crown-4-ethers depends on the relative orientation of crown ether oxygen atoms

myo-Inositol derived crown-4-ethers in which two of the oxygen atoms in the crown ether moiety have different relative orientations were prepared. Metal picrate binding studies revealed that the crown ether having 1,3-diaxial orientation shows the highest selectivity for binding to lithium although the crown ether having 1,2-diequatorial orientation exhibited the highest binding constant for lithium picrate. These results suggest that relative binding affinity of metal ions to crown ethers can be tuned by varying the relative orientation of crown ether oxygen atoms. The relevance of these results to the previously observed regioselectivity during the O-substitution of myo-inositol orthoesters is discussed.     

Properties of cis- and trans-bis(crown ether)s for complexation and extraction of alkali metal picrates

The properties of cis- and trans-bis(crown ether)s containing benzo-15-crown-5 or benzo-18-crown-6 units as complexants and extractants for alkali metal picrates have been studied. The optical spectra suggest that the cis-bis(crown ether)s can form intramolecular 2:1 crown ether unit/cation complexes with particular metal cations easily, while the trans-bis(crown ether)s can form only 1:1 crown ether unit/cation complexes because of the unfavourable trans configuration for the formation of the 2:1 complexes. It was found that the cis isomer possesses much higher extractive power than the trans isomer for the metal cations, which also reflects their complexing properties. The extraction equilibrium constants and thermodynamic quantities have been also evaluated, and the effect of the stereochemical structure of the bis(crown ether) on the complexing and extractive properties is discussed.     

Chiral NMR discrimination of piperidines and piperazines using (18-crown-6)-2,3,11,12-tetracarboxylic acid

Enantiomeric discrimination is observed in the (1)H and (13)C NMR spectra of piperidines and piperazines in the presence of (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid. The amines are protonated by the carboxylic acid groups of the crown ether to produce the corresponding ammonium and carboxylate ions. Association of the ammonium ion with the crown ether likely involves two hydrogen bonds with the crown ether oxygen atoms and an ion pair with the carboxylate anion. Methyl, hydroxymethyl, phenyl, carboxyl, pyridyl, and cyclohexyl substituent groups alpha to the nitrogen atom do not inhibit binding of the ammonium ion to the crown ether. The NMR spectra of piperidines with the stereogenic center alpha or beta to the nitrogen atom exhibit substantial enantiomeric discrimination. Dibasic substrates such as the piperizines are likely converted to their diprotonated form in the presence of the crown ether, and both nitrogen atoms appear to associate with the crown ether moiety.     

Synthesis and photochromism of spirobenzopyran derivatives bearing an oxymethylcrown ether moiety: metal ion-induced switching between positive and negative photochromisms

Spirobenzopyran derivatives carrying an oxymethylcrown ether moiety were synthesized, and their photochromism was studied in the presence of various metal ions in acetonitrile. The metal ion complexing ability of the crown ether moiety in crowned spirobenzopyrans affects both thermal isomerization and photoisomerization of their spirobenzopyran moiety to a great extent. When the interaction of the crown ether moiety with a metal ion was strong enough to cause thermal isomerization of the spirobenzopyran moiety to its corresponding merocyanine form and to suppress UV-induced isomerization to the merocyanine form, a negative photochromism appears. On the other hand, a relatively weak interaction of the crown ether moiety with a metal ion affords a positive photochromism. This phenomenon enables us to switch the photochromic behavior between positive and negative photochromisms.     

Supramolecular diaryliodonium salt‐crown ether complexes as cationic photoinitiators

Diaryliodonium salts spontaneously form crystalline 1:1 supramolecular complexes at room temperature in good to excellent yields with 18‐crown‐6 ether and its cyclohexano‐ and benzo‐substituted analogs. The complexes were characterized using IR, UV, MS, ¹H, and ¹³C‐NMR spectroscopy and by single crystal X‐ray crystallography. The analytical data obtained were consistent with a structure in which the positively charged iodine atom of diaryliodonium cation is positioned above and over the center of the crown ether ring with the positively charged iodine atom coordinated to the crown ether oxygen atoms. The diaryliodonium salt‐crown ether complexes are photosensitive and were used to carry out the photoinitiated cationic polymerizations of a number of mono‐ and difunctional monomers. During irradiation with UV light, the supramolecular complexes undergo photolysis with the generation of a Brønsted acid and with the concomitant release of the crown ether. When used as photoinitiators, the crown ether that is released markedly influences the kinetics of the subsequent cationic polymerization of the monomer. Further studies demonstrated that the photolysis of diaryliodonium salt‐crown ether supramolecular complexes can be photosensitized using typical‐electron transfer photosensitizers. Free radical‐promoted photosensitization using typical unimolecular free radical photoinitiators such as 2,2‐dimethoxy‐2‐phenylacetophenone also takes place readily. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

New Potassium- and Cesium-selective Ionophoric Bis(crown ether)s Derived from Xanthene-4,5-dicarboxylic Acid

A series of bis(crown ether)sbased-upon a xanthene-4,5-dicarboxylic acid skeletonwas prepared and their ionophoric properties towardalkali metal cations were investigated. Bis(crownether)s bearing 15-crown-5 and 18-crown-6 moietiesexhibited pronounced extraction efficiencies towardK⁺ and Cs⁺ ions, respectively, and theextraction constant estimated by solvent extractionstudies was as high as 10⁹ for the 2-K⁺ and 3-Cs⁺ systems. Using UVtitration of potassium picrate with 2 in THF, thecomplex was found to have a structure of a completelyencapsulated guest in the host. In transportexperiments, the bis(crown ether)s showed nosignificant selectivity pattern compared withextraction results, again implying the strongcomplexation of bis(crown ether)s. Ion-selectiveelectrode studies also demonstrated that the selectiveionophoric properties of 2 toward K⁺ werereminiscent of the natural antibiotic valinomycinexcept for a somewhat slow response.     

Potassium-selective PVC membrane electrodes based on bis- and poly(crown ether)s

Potassium-selective PVC membrane electrodes based on bis- and poly (crown ether)s containing benzo-15-crown-5 moiety as neutral carrier were prepared and selectivity coefficients for various monovalent ions were measured in order to elucidate the effect of complexing property of these crown ether derivatives on the electrode response. In the preference for potassium over sodium of the electrodes, these bis- and poly (crown ether)s were found to exceed the corresponding monocyclic crown ether considerably, which reflects the easy complexation of stable 2:1 complexes of crown ether ring and ion, derived from the cooperative effect of two adjacent crown ether rings.     

Quantitative conformational study of redox-active [2]rotaxanes, part 2: Switching in flexible and rigid bistable [2]rotaxanes

Translational movement of the macrocycle in two structurally similar bistable [2]rotaxanes, which is induced by a four-step electrochemical process in solution, has been investigated by using a methodology developed in the preceding article (Chem. Eur. J. 2008, 14, 1107-1116). Both [2]rotaxanes contain a crown ether that can be accommodated by either of two interconnected viologen recognition sites. These sites are substantially different in terms of their affinity towards the crown ether and they possess considerably different electrochemical reduction potentials. The two [2]rotaxanes differ in the length and the rigidity of a bridge that links these sites. A combination of molecular mechanics modelling and NOE spectroscopy data provides information about the conformations of both [2]rotaxanes in the parent oxidation state when the crown ether exclusively populates the strong recognition site. To determine the population of the recognition sites at subsequent stages of reduction, a paramagnetic NMR technique and cyclic voltammetry were used. The key finding is that the flexibility of the connecting bridge element between the recognition sites interferes with shuttling of the crown ether in [2]rotaxanes. It can be demonstrated that the more flexible trimethylene bridge is folded, thus limiting the propensity of the crown ether to shuttle. Consequently, the crown ether populates the original site even in the second reduced state of the flexible [2]rotaxane. On the contrary, in the [2]rotaxane in which two viologen sites are connected by a larger and more rigid p-terphenylene bridge, the predominant location of the crown ether at the weak recognition site is achieved after just one single electron reduction.     

Synthesis of cyanine dyes derived from benzotellurazo‐15‐crown‐5

A series of crown ether cyanine dyes including crown ether styryl cyanine dyes, crown ether merocyanine dyes and crown ether squarylium cyanine dyes (unsymmetric and symmetric) derived from key intermediate 2‐methyl‐5,6(15‐crown‐5)benzotellurazole ( 1 ) were prepared.