对叔丁基杯[6]-1,4-2,5-双冠醚的合成、构象及其对阳离子的识别性能研究

采用分步法高产率地合成了系列新型对叔丁基杯[6]双冠醚，并得到了除杯式与1，2，3－交替式构象之外的第3种稳定构象的杯[6]衍生物：1，4－交替式杯[6]-1,4-2,5-双冠醚。研究了它们对碱金属及脂肪胺离子的两相萃取性能，发现杯[6]双冠醚具有与杯[6]单冠醚不同的识别能力。     

The Different Fluorescent Response of Quin 2 to the Binding of Ca^2＋ and La^3＋ and its Application

The fluorescence spectra of Quin 2, (2-[(2-bis-[carboxymethyl] amino-5-methylphenoxy)methyl]-6-methoxy-8-bis [carboxymethyl] aminoquiniline), a Ca^2 probe, were investigated upon incubation with Ca^2 or La^3 . The results showed that binding of La^3 to Quin 2 resulted in different fluorescent spectrum from that of Ca^2 . Based on this observation, a fluorescent method was developed for simultaneously determination of the dissociation rates of Ca^2 and La^3 from a Ca-La- calmodulin complex (Ca2La2CaM).     

Transport of Ca^2＋ Ion through a Bubbling Pseudo—emulsion Liquid Membrane with Calixarenes and Calixcrowns as Carriers

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用C60键合硅胶固定相液相色谱分离杯芳烃及杯芳冠醚类化合物

以自合成的C60 键合硅胶液相色谱固定相 ,分别选用3种不同选择性的流动相体系 :异丙醇 -环己烷 ,氯仿 -环己烷和二氯甲烷 -环己烷 ,考察了流动相组成对杯芳烃及杯芳冠醚化合物保留行为和分离选择性的影响。在一定的流动相条件下溶质能得到较好分离。     

新型香豆素类荧光探针的合成及其对Cu~(2+)的识别性能

以2-羟基-4-甲氧基苯甲醛和丙二酸二乙酯为起始原料,设计并合成了一种新型的Cu~(2+)荧光探针7-甲氧基-2-氧代-N-[2-(苯基氨基)乙基]-2H-色烯-3-甲酰胺(NPC),其结构经~1H NMR,~(13)C NMR,MS(EI)和元素分析表征。并研究了室温下,NPC在乙醇和水的混合溶液中对Cu~(2+)的识别性能。结果表明:NPC对Cu~(2+)表现出荧光猝灭效应,具有对Cu~(2+)的选择性识别性能。     

A density functional theory study on the mechanism of the permanganate oxidation of substituted alkenes.

Oxidation of substituted alkenes by permanganate follows a (3 + 2) cycloaddition mechanism. DFT calculations (Becke3LYP/6-31G(d)) strongly favor the (3 + 2) pathway against a (2 + 2) pathway that proceeds through a metallaoxetane. The difference in free activation energy between the two pathways is around 40 to 45 kcal/mol for the nine compounds covered. The results for the (3 + 2) cycloaddition mechanism are in agreement with experimentally observed kinetic data reported earlier. Symmetric transition states are calculated for alkenes with at least one CH2 group between the double bond and the acid group, while all others are unsymmetrical due to the repulsion between the permanganate oxygens and the carboxylic oxygens. Steric bulk, introduced by the number and position of substituents at the double bond, has no significant effect on the activation energies. A higher level of theory (Becke3LYP/6-311G(d,p)) leads to a reduction of the rmsd between experimental and calculated values, but has little influence on the calculated geometries.     

杯芳冠醚对铯离子的配位用及其在处理含铯废水中的应用

简单介绍了杯芳冠醚在处理含铯废水中的应用，对目前已有的杯芳冠醚与铯离 子配位作用进行了初步的探讨，并从晶体结构出发，利用电子云理论，作了一些简 单的预测。     

Synthesis of a tetrahomodioxacalix[4]arene tetraamide and the crystal structure of its lead ion complex

The 1,4-alternate tetrahomodioxacalix[4]arene tetraamide 4 with four p-phenyl groups on its upper rim was synthesized. In two-phase metal picrate extraction, 4 exhibited Pb2+ selectivity with formation of a 1:1 complex in chloroform. In the solid-state structure of the 4*Pb(Pic)2 complex, Pb2+ is bound by the carbonyl oxygens of two adjacent amide groups and an aryl-alkyl ether oxygen atom of one of these amide-containing substituents. The crystal structure and 1H NMR spectrum of the 4*Pb2+ complex reveals pi-metal ion complexation of one aromatic ring in the ligand with Pb2+.     

Methoxy-substituted TQEN family of fluorescent zinc sensors

Two methoxy-substituted TQEN (N,N,N',N'-tetrakis(2-quinolylmethyl)ethylenediamine) derivatives, T(MQ)EN (N,N,N',N'-tetrakis(6-methoxy-2-quinolylmethyl)ethylenediamine) and T(TMQ)EN (N,N,N',N'-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)ethylenediamine), have been prepared, and their fluorescence properties with respect to Zn2+ coordination were investigated. Introduction of a methoxy substituent at 6-position of the quinoline ring enhances the fluorescence intensity by 10-fold, and the three methoxy substituents in the 5,6,7-positions afford significant enhancement of the long-wavelength component of the fluorescence of zinc complex. The substituents did not alter the binding affinity of these compounds toward zinc ion significantly. T(MQ)EN was proved to be effective in detection of zinc ion in cells by fluorescent microscopy.     

A Naphthalimide‐Based Cd2+ Fluorescent Probe with Carbamoylmethyl Groups Working as Chelators and PET‐Promoters under Neutral Conditions

We have developed a novel naphthalimide‐based Cd²⁺ fluorescent probe ( 1 ), featuring almost no background response, high sensitivity and selectivity toward Cd²⁺ through its high association constant [K=(2.10±0.423)×10⁶], and a practical working pH range. Membrane‐permeability was conferred on 1 by replacing the imide and amide substituents with n‐butyl groups, and hence the derivative ( 4 ) has found practical utility on fluorescent imaging of Cd²⁺ in HeLa cells. Comparison of fluorescent properties between various compounds derived from 1 has demonstrated that the carbamoylmethyl groups in 1 function not only as Cd²⁺ chelators but also as promoters for photoinduced electron transfer (PET) by lowering the basicity of the two tertiary amino groups. As a result, 1 and 4 exhibited highly practical performance as Cd²⁺ probes under neutral conditions.     

Synthesis of AX7593, a quinazoline-derived photoaffinity probe for EGFR

[structure: see text] The synthesis of a photoaffinity probe for EGFR is described. O-Alkylation of 4-(meta-azidoanilino)-6-methoxy-7-hydroxy-quinazoline with a protected tetraethyleneglycol linker followed by the attachment of tetramethylrhodamine yielded the fluorescent probe AX7593. Photoaffinity labeling of EGFR by AX7593 (K(b) = 280 nM) was shown to have an efficiency of 34% and to be competitive with the EGFR inhibitors PP2 and AG1478.     

Steered molecular dynamics studies of the potential of mean force of a Na+ or K+ ion in a cyclic peptide nanotube

Potential of mean force (PMF) profiles of a single Na+ or K+ ion passing through a cyclic peptide nanotube, cyclo[-(D-Ala-Glu-D-Ala-Gln)2-], in water are calculated to provide insight into ion transport and to understand the conductance difference between these two ions. The PMF profiles are obtained by performing steered molecular dynamics (SMD) simulations that are based on the Jarzynski equality. The computed PMF profiles for both ions show barriers of around 2.4 kcal/mol at the channel entrances and exits and energy wells in the middle of the tube. The energy barriers, so-called dielectric energy barriers, arise due to the desolvation of water molecules when ions move across the nanotube, and the energy wells appear as a result of attractive interactions between the cations and negatively charged carbonyl oxygens on the backbone of the tube. We find more and deeper energy wells in the PMF profile for Na+ than for K+, which suggests that Na+ ions have a longer residence time inside the nanotube and that permeation of Na+ ions is reduced compared to K+ ions. Calculations of the radial distribution functions (RDF) between the ions and oxygens in the water molecules and in carbonyl groups on the tube and an investigation of the orientations of the carbonyl groups show that, in contrast with the dynamic carbonyl groups observed in the selectivity filter of the KcsA ion channel, the carbonyl groups in the cyclic peptide nanotube are relatively rigid, with only slight reorientation of the carbonyl groups as the cations pass through. The rigidity of the carbonyl groups in the cyclic peptide nanotube can be attributed to their role in hydrogen bonding, which is responsible for the tube structure. Comparison of the PMF profiles with the electrostatic energy profiles calculated from the Poisson-Boltzmann (PB) equation, a dielectric continuum model, reveals that the dielectric continuum model breaks down in the confined region within the tube that governs ion transport.     

Intramolecular substitution of unactivated aryl groups by thioamide anion

The general reaction of intramolecular nucleophilic substitution of unactivated aryl groups by thioamide anion in dipolar aprotic amide solvent is extended by the syntheses of 6-chloro-5-methoxy-2-methylbenzothiazole from 2′,4′-dichloro-5′-methoxythioacetanilide and 6-methoxy-2-methylbenzothiazole from 4′-methoxy-2′-nitrothioacetanilide. The six-membered fused ring heterocycles, 2-methyl-4H,3-benzothiazine and 6,8-dichloro-3-rnethyl-1H-4,1,2-benzothiadi-azine are also prepared.     

Interaction of actinide ions with [NaP5W30O110]14- and [P2W18O62]6-

Stability constants (log b₁₀₁) of Th⁴⁺, UO₂ ²⁺, NpO₂ ⁺ and Am³⁺ with [NaP₅W₃₀O₁₁₀]^14- were determined by solvent extraction (m = 0.1M NaCl) and found to be 6.18±0.07, 3.80±0.06, 2.98±0.04, and 5.85±0.05, respectively. The order of stability constants: Th⁴⁺>Am³⁺>UO₂ ²⁺>NpO₂ ⁺ is due to electrostatic repulsion between the actinyl oxygens and oxygens on the polyoxometalate surface. The order of stability constants for metal complexes with [P₂W₁₈O₆₂]^6- is Th⁴⁺>UO₂ ²⁺>Eu³⁺>NpO₂ ⁺ because the steric repulsion between actinyl oxygens and oxygens on polyoxometalate are less important. Enthalpies of complexation were measured by calorimetric titration of Th⁴⁺, UO₂ ²⁺, Nd³⁺ with [NaP₅W₃₀O₁₁₀]^14- and [P₂W₁₈O₆₂]^6-. The results indicate that the conformation and charge distribution of the microscopic surface structures are important factors in the formation of pseudocolloids.     

Design and Syntheses of Novel Calix[4]crown: Calix[4]‐Dixanthates‐Crowns

Abstract

A series of novel calix[4]‐dixanthates‐crowns were designed and synthesized by the “1 + 1 condensation” of reacting calix[4]‐1,3‐dixanthate salts derivative (4) with polyethylene glycol ditosylates in 40–60% yields. It was found that the new calixcrowns showed outstanding complexation abilities towards soft cations. Calix[4]‐dixanthate‐crown‐4 (5b) exhibited high complexation selectivity towards Ni²⁺.     

Synthesis of aromatic phosphates via cycloaddition of phosphate dienes

Cycloadditions of phosphate dienes and quinones can be used to generate aromatic phosphates. Diethyl 3-methoxy-1-methylene-2-propenyl phosphate shows reactivity, stability, and regioselectivity comparable to the corresponding silyloxy diene. Because the phosphate ester in the product originates in the diene, cycloadditions with quinones will place this ester regiospecifically in the B-ring and allow facile distinction between the B- and A-ring oxygens of the cycloadduct.     

Molecular Topology in Crystals of a Potassium(I) Complex with [Z-5-(2-Chlorobenzylidene)-4-Oxoimidazolin-2-YL]-3-Amino-Propanoate

In a complex with [ Z -5-(2-chlorobenzylidene)-4-oxoimidazolin-2-yl]-3-amino-propanoate acid (APAC), potassium ion adopts distorted square-bipyramidal (4 + 2) coordination. All donor atoms are oxygens; four of them originate from carboxylate groups of APAC, while the remaining ones are water oxygens. The equatorial plane of coordination polyhedron is composed of two carboxylate oxygens (with K-O distances of 2.769 and 2.806 Å) and two water oxygens (with K-O distances of 2.722 and 2.749 Å). Two axial K-O bonds (2.663 and 2.664 Å), involving the remaining carboxylate O atoms, complete the sixfold coordination of the K atom. Coordination polyhedra are condensed in two ways. The distance between two potassium pairs are significantly different, 4.224 and 3.801 Å. APAC molecules are held together by a network of hydrogen bonds and create a gap along the [ab] plane with molecular ribbons of potassium ions and water molecules inside. Due to the potassium alignment of aliphatic chains in two neighbouring, crystalgraphically independent APAC molecules, small cavities are created, which form small channels along the b axis with the remaining water molecule.     

Synthesis,crystal structure and properties of three ternary dysprosium 2-halogenated benzoic acid complexes

Three ternary dysprosium complexes [Dy(2-ClBA)₃?·?phen]₂ (1), [Dy(2-ClBA)₃?·?2,2′-bipy]₂ (2), and [Dy(2-BrBA)₃?·?phen]₂ (3) (where 2-ClBAH?=?2-ClC₆H₄COOH, 2-BrBAH?= 2-BrC₆H₄COOH, phen?=?1,10-phenanthroline, and 2,2′-bipy?=?2,2′-bipyridine) have been synthesized and characterized by X-ray single crystal diffraction. Complex 1 consists of two independent binuclear molecules, [Dy(2-ClBA)₃?·?phen]₂ (a) and [Dy(2-ClBA)₃?·?phen]₂ (b), in which the coordination environment is similar. Each Dy³⁺ is nine coordinate with two nitrogens from phen and seven oxygens from five 2-ClBA groups. 2-ClBA groups coordinate to Dy³⁺ in three ways, bidentate chelating, bidentate-bridging and terdentate-bridging. Complexes 2 and 3 consist of one binuclear molecule. The crystal structure of 2 is similar to that of binuclear molecule (a) or (b) of complex 1. In 3, each Dy³⁺ ion is eight-coordinate by two nitrogens from phen and six oxygens from five 2-BrBA groups. 2-BrBA groups coordinate to the Dy³⁺ ion in two ways, bidentate chelating and bidentate-bridging. The complexes were studied by UV, DTA-TG, and fluorescence spectrometry.     

Sulfur Versus Oxygen in Interaction with the Double Bond: AB Initio Study of Electronic Structure and Prototropic Rearrangement of 1-Methoxy-2-propene and 1-Methylthio-2-propene

The ab initio calculations of 1-methoxy-2-propene ( 1 ), 1-methylthio-2-propene ( 2 ), and their anions are performed using the RHF/6-31+G* geometry optimization followed by MP2/6-31+G* energy calculations. Both 1 and 2 are found to rearrange toward 1-substituted 1-propenes with a comparable exothermic effect. However, the proton abstraction energies of 1 and 2 differ significantly. So, the acidity of propene is just slightly affected by the OCH 3 group while the SCH 3 group decreases its proton abstraction energy by 17.5 kcal/mol. Changes in charge distribution, bond lengths and bond orders suggest the negative hyperconjugation to stabilize anions of 2 but not that of 1 . This divergence is explained with a difference in sulfur and oxygen electronegativity. The d -functions of both sulfur and oxygen act in polarization. The Z -isomer of anion 1 is found to be by 2.9 kcal/mol more stable than its E -isomer, this could provide a predominant kinetic formation of the less stable Z -isomer of 1-methoxy-1-propene under base catalysis.     

Methoxyquinoline-diethylenetriamine conjugate as a fluorescent zinc sensor

A 6-methoxyquinoline conjugated diethylenetriamine derivative, N,N'-bis(6-methoxy-2-quinolylmethyl)diethylenetriamine (6-MeOBQDIEN) has been synthesized and its fluorescent response toward zinc ion was investigated. In the presence of zinc ion, 6-MeOBQDIEN exhibits fluorescence (λ(ex) = 329 nm, λ(em) = 418 nm, φ = 0.039). The fluorescent intensity of the zinc complex of the compound is two times higher than the parent BQDIEN (φ = 0.021) under the same conditions. The crystal structure of 6-MeOBQDIEN-Zn complex shows that all five nitrogen atoms participate to the metal coordination in a distorted square-pyramidal geometry (τ = 0.145) with the aliphatic nitrogen in an apical position. Fluorescent microscopic analysis using 6-MeOBQDIEN reveals the zinc ion concentration change in living cells.