醚链桥接芳香二醛及其缩氨硫脲的合成

一些缩氨硫脲及其衍生物对结核、麻风、风湿、疟疾、天花、真菌和某些肿瘤有一定的药理活性。缩氨硫脲的真菌活性是由于它的配位原子在生物体的新陈代谢中和真菌所需的金属离子螯合。缩氨硫脲具有与氨基酸、肽、蛋白质、酶、核糖核酸等生物配体相同的配位原子、被看作研究生物配体和痕量金属离子配位的优良模型。因为聚乙二醇醚链上的氧原子能与金属离子配位,所以在缩氨硫脲分子中连接上聚乙二醇醚链,增加缩氨硫脲分子中的配位原子种类和数目,也许能够增强螯合剂的配位能力,扩展其与金属离子的螯合围范。为此,我们将缩乙二醇二氯化物和苯环上带酰基的苯酚反应,制成化合物1_(a-h),然后再与硫代氨基脲缩合,得到醚链桥接的芳香醛缩氨硫脲2_(a-g)。它们的合成路线和主要结构如下:     

Molecular orbitals studies on two limiting structures of conjugated vinyl cation,C4H4F+

Nonempirical LCAO-MO-SCF calculations employing STO-3G minimal basis set have been carried out to examine the two limiting, open and bridged, structures of a conjugative fluorovinyl cation system and the interconversion of these two structures. The bridged ion is found to be 37.6 kcal/mole higher in energy than the open ion. Three pathways of converting the open ion to bridged ion were investigated. The pathway in which conjugation is preserved along the reaction profile gives the lowest energy barrier and depicts the bridged ion as a transition state.     

Construction of Bridged Benzazepines via Photo-Induced Dearomatization

Bridged benzazepine scaffolds, possessing unique structural and physicochemical activities, are widespread in various natural products and drugs. The construction of these skeletons often requires elaborate synthetic effort with low efficiency. Herein, we develop a simple and divergent approach for constructing various bridged benzazepines by a photocatalytic intermolecular dearomatization of naphthalene derivatives with readily available α-amino acids. The bridged motif is created via a cascade sequence involving photocatalytic 1,4-hydroaminoalkylation, alkene isomerization and cyclization. Interestingly, the diastereoselectivity can be regulated through different reaction modes in the cyclization step. Moreover, aminohydroxylation and its further bromination have also been demonstrated to access highly functionalized bridged benzazepines. Preliminary mechanistic studies have been performed to get insights into the mechanism. This method provides a divergent synthetic approach for construction of highly functionalized bridged benzazepines, which have been otherwise difficult to access.     

Conformational effects of bay substituents on optical, electrochemical and dynamic properties of perylene bisimides: macrocyclic derivatives as effective probes

A series of diagonally and laterally bridged regioisomeric macrocycles based on 1,6,7,12-tetraaryloxy-substituted perylene bisimides (APBIs) have been synthesized and characterized. The different orientations of the aryloxy residues, that is, horizontal or perpendicular to the perylene core, in the regioisomeric macrocycles have been elucidated by NMR spectroscopy, and the dynamic properties of the laterally bridged regioisomers have been investigated by temperature-dependent NMR measurements. The influence of the different orientations of the aryloxy substituents on the electrochemical properties of APBIs is demonstrated by cyclic voltammetry, which reveals that a perpendicular orientation of the aryloxy residues relative to the perylene core leads to a substantial decrease of the LUMO energy level of the perylene bisimide electrophore. The optical properties of the regioisomeric macrocycles have been determined by UV/Vis and fluorescence spectroscopy. It has been shown that the diagonally bridged macrocycles exhibit optical properties that differ significantly from those of an open-chain reference compound, whereas the optical properties of the laterally bridged isomers resemble those of the reference system. This demonstrates that unrestricted aryloxy substituents prefer the lateral conformation in solution. Solvent-dependent fluorescent properties have been exemplified for one diagonally bridged derivative, suggesting a photoinduced electron transfer process as fluorescence quenching mechanism for APBIs. From these investigations, guidelines toward highly fluorescent APBI dyes in polar media could be derived.     

Algebraic characterization of bridged polycyclic compounds

An approach based on the topological distance matrix is used for algebraic characterization of bridged polycyclic compounds. The classical bridged structures which have external bridges between cycles were examined together with the more complicated three-dimensional polycyclic systems regarded as containing internal bridges. Thirteen rules are given for characterizing the main types of structural rearrangements in these compounds. The important topological characteristic of (poly)cyclic systems, the molecular cyclicity, is examined in the polycyclic condensed, spiro- and bridged structures, respectively.     

桥联异多核配合物稳定性的ESR研究

用电子自旋共振方法研究了咪唑和T,T~1-联吡啶桥联配合物的稳定性。结果表明,咪唑桥联异双核和异三核配合物中的咪唑桥均在pH=7.8～8.5范围内断裂,形成单核配合物[(NH_3)_5CoIm]~(2+)和[(dien)CuH_2O]~(2+),而T,T~1-联吡啶桥联的异双核配合物的联吡啶桥则在pH<6.0时才开始断裂,形成单核配合物。当pH=3.7～2.5时,[(dien)CuH_2O]~(2+)经水合反应,形成[Cu(H_2O)_6]~(2+)。     

Aromaticity in bridged heteroannulenes

The aromatic stabilities of bridged hetero[n]annulenes (n = even, odd) and the parent structures of hetero-[n]annulenes and hetero[n]polycycles have been predicted by the topological resonance energy, TRE, approach. The TRE criterion places bridged structures in all cases studied between the hetero[n]annulenes and hetero[n]polycyclic systems. The extra aromatic stability of the bridged heteroannulenes compared to heteroannulenes is attributed to homoaromatic interaction across the ring at the bridge sites. Available experimental evidence supports the theoretical results.     

线型共轭Cx桥联双金属有机化合物

分子电子器件是近年来的一个热门课题。线型共轭Cx桥联双金属有机化合物是分子导线、分子开关等分子电子器件的模型化合物之一。本文介绍了线型共轭Cx桥联双金属有机化合物的结构、合成及光电性质。     

X射线单晶衍射研究系列功能七元杂环桥联联苯构象

含有七元杂环桥联联苯的π-共轭聚合物是重要的宽禁带光电材料, 其发光性质决定于两苯环间扭曲角. 利用X射线单晶衍射仪确定了系列功能的七元杂环桥联联苯化合物的晶体结构, 比较了桥联原子, 6,6位取代基及分子间弱氢键对这类桥联联苯扭曲构象的影响. 桥联键是—CH2—O—CH2—和—CH2—S—CH2—的七元杂环桥联联苯两苯环间的扭曲角分别为39°和51°, 在6,6位上含有不同取代基的双氧桥联七元杂环桥联联苯的扭曲角存在5°的差异. 在双氧桥联的七元杂环桥联联苯的二聚物中, 桥联的氧原子与非桥联的苯亚基-苯亚基2,2’位置上的两个氢原子之间形成的氢键网络结构导致中心联苯呈现平面构象, 但氢键并没有改变桥联联苯的构象. 七元杂环桥联联苯的构象主要由桥联原子决定, 同时分子间相互作用亦能轻微调控这类桥联联苯的扭曲角.     

Spectral and electrochemical investigations on some condensation products of copper(II)-amino acid complexes

Summary Condensation products of several copper(II) amino acid complexes with formaldehyde or acetaldehyde have been prepared together with ethene-bridged copper(II) amino acid complexes. Structures were deduced from analytical and spectral data. Electronic spectral, e.s.r. and electrochemical behaviour at neutral and various low pH conditions were examined. Spectra of the unbridged complexes indicate the formation of [CuL]⁺ type species at pHca. 5, whereas the bridged complexes are stable at pH 3. The electrochemical behaviour of each complex is identical except for the doubly bridged complex. These results are explained in terms of a three-step electrode mechanism. The data show that the planarity of the complexes increases from unbridged, to bridged, to doubly bridged structures.     

Effects of Axle‐Core,Macrocycle, and Side‐Station Structures on the Threading and Hydrolysis Processes of Imine‐Bridged Rotaxanes

Imine‐bridged rotaxanes are a new type of rotaxane in which the axle and macrocyclic ring are connected by imine bonds. We have previously reported that in imine‐bridged rotaxane 5 , the shuttling motion of the macrocycle could be controlled by changing the temperature. In this study, we investigated how the axle and macrocycle structures affect the construction of the imine‐bridged rotaxane as well as the dynamic equilibrium between imine‐bridged rotaxane 5 and [2]rotaxane 7 by using various combinations of axles ( 1 A , B ), macrocycles ( 2 a – e ), and side‐stations (XYL and TEG). In the threading process, the flexibility of the macrocycle and the substituent groups at the para position of the aniline moieties affect the preparation of the threaded imines. The size of the imine‐bridging station and the macrocyclic tether affects the hydrolysis of the imine bonds under acidic conditions.     

SYNTHESIS AND CHARACTERIZATION OF PALLADIUM COORDINATING IMINE SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANES

New thermotropic chloro-bridged dinuclear palladium coordinating imine side chain liquid crystalline polysiloxanes have been synthesized. Their mesomorphic properties have been investigated by DSC, X-ray diffraction and polarizing microscopy. The polymeric complexes show nematicdiscotic (Nd) mesophase. It is found that the temperature range of liquid crystalline state of chloro- bridged polymeric complexes is much wider than that of acetato- bridged ones and imine side chain polysiloxane. This indicates that the disc-like chloro-bridged palladium complexing units play a role as mesogen in mesophase.     

五甲川链上具有β,δ-次丙基桥链的二碳菁染料的合成及其在减色法彩色胶片感红层中的应用

合成了具有β,δ-次丙基桥链的八个二碳菁染料。照相性能试验表明,用β,δ-次丙基桥链五甲川染料,可以作为有效的感红增感剂。在青成色剂C-1存在下,用这些染料增感的乳剂与Rr1833比较,具有好的贮存稳定性。     

Conformational studies of monoterpenes. II–conformational studies of bicyclo[3.1.1]heptane derivatives by 13C NMR

The carbon-13 spectra of seventeen bicyclo[3.1.1]-heptane derivatives have been recorded and assigned. Study of the C-6 and C-7 chemical shifts permits the conformations to be assigned to the bridged chair, Y-shaped, or bridged boat conformations. The spectrum of verbenone is anomalous and is compared to that of umbellulone recorded earlier.     

A Metal‐Bridged Tricyclic Aromatic System: Synthesis of Osmium Polycyclic Aromatic Complexes

Aromaticity is one of the most important concepts in organic chemistry. A variety of metalla‐aromatic compounds have been recently prepared and in most of those examples, the metal participates only in a monocyclic ring. In contrast, metal‐bridged bicyclic aromatic molecules, in which a metal is shared between two aromatic rings, have been less developed. Herein, we report the first metal‐bridged tricyclic aromatic system, in which the metal center is shared by three aromatic five‐membered rings. These metalla‐aromatics are formed by reaction between osmapentalyne and arene nucleophiles. Experimental results and theoretical calculations reveal that the three five‐membered rings around the osmium center are aromatic. In addition, the broad absorption bands in the UV/Vis absorption spectra of these novel aromatic systems cover almost the entire visible region. This straightforward synthetic strategy may be extended to the synthesis of other metal‐bridged polycyclic aromatics.     

Extreme conformational constraints in pi-extended tetrathiafulvalenes: unusual topologies and redox behavior of doubly and triply bridged cyclophanes

Doubly and triply bridged 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (ex-TTF) derivatives have been synthesized. Key steps are the generation and macrocyclization reactions of ex-TTF-dithiolate reagents. The X-ray crystal structures of the doubly bridged cyclophanes 15 and 16 and the triply bridged system 23 show that the saddle-like conformation of the ex-TTF framework is enhanced by the short bridges between the dithiole rings. Unlike all previous ex-TTF derivatives (which display a single quasi-reversible two-electron oxidation wave, D0 --> D2+), cyclic voltammetry of the cyclophanes reveals two reversible, one-electron oxidation steps (D0 --> D*+ --> D2+), with differences between the half-wave potentials (E2(1/2) - E1(1/2)) of 0.22-0.26 V. The conformational changes and gain in aromaticity which drive the second oxidation process in unrestricted ex-TTF systems (including singly bridged cyclophanes) have been prevented by multiple bridging. The radical cation species gives rise to a very broad, low-energy band (lambdamax = 2175 and 2040 nm for 15 and 21, respectively), assigned to an intramolecular interaction. The steric constraints imposed by multiple bridging have become so extreme that the pi-framework of 15, 16, 21, and 23 exhibits remarkable optical and redox behavior which is not characteristic of ex-TTF systems.     

Mössbauer and Electrochemical Studies of Bridged Biferrocenes and Biferrocenylenes

A series of neutral and oxidized π-bridged biferrocenes (Fc—x—Fc) and biferrocenylenes (FC(—x—)₂Fc) (x= —CH=CH—, —CH₃,C=CCH₃—) were prepared and their physical properties have been studied by means of Mössbauuer and cyclic voltammetry. The electrode reaction of these bridged ferrocene derivatives appears to involve a consecutive two-step oxidation process. The results also show that the voltage difference between the first and second oxidaton potentials of the bridged biferrocenes was found to be largely exceeded that founded for the corresponding the bridged biferrocenylenes. The Mössbauer data show that the oxidation of doubly bridged Fc(—x—)₂Fc with iodine, DDQ, and TCNQ given the corresponding dioxidized salts only and no stable mixed-valence compounds were found.     

meso‐Pyrrole‐Substituted 22‐Oxacorroles: Building Blocks for the Synthesis of BODIPY‐Bridged 22‐Oxacorrole Dyads

Novel boron‐dipyrromethene (BODIPY)‐bridged 22‐oxacorrole dyads, using meso‐pyrrolyl 22‐oxacorrole as a key synthon, have been synthesized. The reactivity of the meso‐pyrrolyl group of 22‐oxacorrole was exploited to synthesize the first examples of BODIPY‐bridged 22‐oxacorrole dyads in ≈40 % yield. The dyads are stable and exhibited interesting spectral and electrochemical properties.     

Phenyl-bridging in the 2-phenylethyl radical. A molecular orbital study

Density functional theory at the UB3PW91/6-31G(d.p) level on the open and bridged forms of the 2-phenylethyl radical are reported here together with activation energies and calculated rate constants for rearrangement of the bridged to the open radical. In addition, the effect of substituents on the aryl ring upon the relative energies, activation energies, and rate constants for rearrangement from the bridged to open forms are presented. Para-substituents include CH3, CF3.CN, CHO.OH, SH, O-, S-, and NO. The parent bridged radical is found to be 10.1 kcal/mol higher in enthalpy than the open form. The activation energy for conversion of the bridged to open radical is 3.96 kcal/mol. Para-substitution by CN or CHO significantly lowers the difference in energy between the species, while substitution by NO renders the bridged form more stable. Para-substitution by CN or CHO coupled with substitution with CN in the ortho-positions makes the open and bridged radical approximately equivalent in energy.     

桥联环糊精仿酶研究进展

本文综述了具有两个疏水结合部位和多重识别功能的桥联环糊精仿酶研究进展.