Benzocrown Ethers Research Articles

Cucurbit[7]uril Complexes of Crown-Ether Derived Styryl and (Bis)styryl Dyes

In this paper, we report the interaction of the CB[7] molecular container with crown ether styryl and (bis)styryl dyes 1-6. The interaction of monostyryl dyes (1 and 2) with CB[7] results in the formation of 1:1 complexes where the CB[7] molecule is located on the region of the guest encompassing the pyridinium ring, C=C double bond, and a portion of the aryl ring of benzocrown ethers 1 and 2. For (bis)styryl dyes (3-5), the formation of two types of complexes with composition dye.CB[7].dye and CB[7].dye.CB[7] was confirmed by a combination of optical and electrospray ionization mass spectroscopy (ESI-MS) methods. In the case of (bis)styryl dye (6), both 2:1 and 1:1 compositions 6.CB[7].6 and CB[7].6 were formed. Complex formation is accompanied by substantial changes in the optical characteristics of the dyes and formation of long-lived excimer species. We tested the stimuli responsiveness of this system in response to metal ions. We find that the metal ions prefer to bind to the electrostatically negative ureidyl C=O portals of the CB[7] rather than with the crown ether moiety of the styryl dyes.

Photochemical transformations of chalcone-podands into cyclobutane-containing benzocrown ethers

A method for the synthesis of cyclobutane-containing benzocrown ethers by the template photocycloaddition of the corresponding chalcone-podands in solutions was developed. It was shown by X-ray diffraction analysis, 1H and 13C NMR, and UV spectroscopy that the intramolecular [2π+2π] photocycloaddition (PCA) is stereoselective with the predominant formation of structures of the β- and γ-truxinic type. The PCA rate was shown to depend on the size of the oxyethylene spacer and stereoorientation of the chalcone fragments in the podands. The selectivity of the PCA process can be controlled by a change in the concentration of the template (alkaline metal ions) and variation of the wavelength range of irradiation.

Viscoelastic characterization of benzo-crown ether functionalized electroactive films

Electrochemical, acoustic wave and imaging (AFM) methods were used to characterize electroactive poly[Ni(3-Mesalophen-b15-c5)] films. The distinct physical principles of these techniques generate different responses to film characteristics, such that their simplistic correlation in the context of a single uniform film model does not adequately describe the data. Film behaviour can only be rationalised using a two layer model comprising a dense (poorly solvated) inner layer and an outer layer comprising islands of diffuse (highly solvated) polymer. The two layers can be observed directly by AFM imaging. The balance of their contributions shifts with polymer coverage: the inner layer dominates thin films and the outer layer dominates thick films. The inner layer is acoustically more rigid and, even if ion transport is slow, is sufficiently thin as to pose no major barrier to electrochemical communication with the underlying electrode. For very thin films, gravimetric interpretation of the acoustic wave response correlates simply with coulometric data; thicker films require viscoelastic phenomena to be considered. The low polymer segment density of the outer layer facilitates ion transport but results in weak acoustic coupling, such that the acoustic and coulometric assays differ. By combining the AFM, acoustic wave and electrochemical responses one can establish a quantitative picture of component layer populations and characteristics.

A Simple Method for Iodination of Benzo- and Dibenzocrown Ethers

Iodination of benzo-12-crown-4, benzo-15-crown-5 and benzo-18-crown-6 by equimolar amounts of N-iodosuccinimide in ethanol in the presence of sulfuric acid additions proceeds quickly and selectively and results in corresponding 4I-iododerivatives with 78-86% yields. Reactivity of [3.3]dibenzo-18-crown-6 slightly differs from that of benzocrown ethers and diiodide (mixture of cisand trans-isomers) is obtained with 76% yield.

Functionalization of polymethylhydrosiloxane gels with an allyl ureido benzocrown ether derivative: Complexation properties

AbstractCrosslinked polymethylhydrosiloxane (PMHS) thin films prepared by sol–gel polycondensation have been functionalized by Pt‐catalyzed hydrosilylation of SiH groups with an allyl ureido crown ether precursor. To this purpose, both 4′‐allylurea‐benzo‐15‐crown‐5 (1) and 1‐allyl‐3‐propyl‐urea (2) were synthesized and characterized. We have shown that competitive side‐reactions occurred following hydrosilylation due to the hydrolysis of part of the SiH groups resulting in the formation of new crosslinks Si(CH3)O3/2 as shown by solid‐state 29Si‐NMR. This is explained by the deactivation of the Pt catalyst toward hydrosilylation by amide groups. For thin films (∼ 1 μm) prepared on silicon wafers, a quantitative method based on FT‐IR transmission spectroscopy was used to measure the crosslinking density of the network, and the percentage of functionalization (SiC %) following hydrosilylation. The results are discussed in relation to the mesh size of the network, and the diffusion of alkenes and water molecules within lightly crosslinked PMHS gels obtained by varying the amount of triethoxysilane crosslinker (mol %) from 15 to 1%. The self‐organization properties of ureido groups by H‐bonding were studied by FT‐IR for the functionalized thin films. The complexation properties of the crown ether 1‐functionalized thin films were evidenced by using FT‐IR following diffusion‐reactions of NaSCN and KSCN salts in CHCl3 : MeOH solvent mixtures within thin films. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Modular synthesis of di- and tripeptides of luminescent crown ether aminocarboxylic acids

Luminescent benzo crown ether aminocarboxylic acids with ammonium ion affinity were prepared and converted into linear bis- and tris benzo crown ether amides using standard peptide coupling protocols. The affinities of the new crown ethers to ammonium ions and di- and tetrapeptides bearing ammonium ion moieties were determined by emission titration in methanol and buffered water.

Anion–π Interactions—Interactions Between Benzo-Crown Ether Metal Cation Complexes and Counter Ions

The loss of X(.) radical from [M + Cu + X](+) ions (copper reduction) has been studied by the so called in-source fragmentation at higher cone voltage (M = crown ether molecule, X(-) = counter ion, ClO(4)(-), NO(3)(-), Cl(-)). The loss of X(.) has been found to be affected by the presence/lack of aromatic ring poor/rich in electrons. Namely, the loss of X(.) occurs with lower efficiency for the [NO(2)-B15C5 + Cu + X](+) ions than for the [B15C5 + Cu + X](+) ions, where NO(2)-B15C5 = 3-nitro-benzo-15-crown-5, B15C5 = benzo-15-crown-5. A reasonable explanation is that Anion-pi interactions prevent the loss of X(.) from the [NO(2)-B15C5 + Cu + X](+) ions. The presence of the electron-withdrawing NO(2) group causes the aromatic ring to be poor in electrons and thus its enhances its interactions with anions. For the ion containing the aromatic ring enriched in electrons, namely [NH(2)-B15C5 + Cu + ClO(4)](+) where NH(2)-B15C5 = 3-amino-benzo-15-crown-5, the opposite situation has been observed. Because of Anion-pi repulsion the loss of X(.) radical proceeds more readily for [NH(2)-B15C5 + Cu + X](+) than for [B15C5 + Cu + X](+). Iron reduction has also been found to be affected by Anion-pi interactions. Namely, the loss of CH(3)O(.) radical from the ion [B15C5 + Fe + NO(3) + CH(3)O](+) proceeds more readily than from [NO(2)(-)B15C5 + Fe + NO(3) + CH(3)O](+).

Synthesis and fluorescence of crown ethers containing coumarin

The syntheses and fluorescence properties of a series of novel crown ethers containing coumarin group are presented. 2-(Benzocourmarin-3-acyloxymethyl) crown ethers were synthesized by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 2-hydroxymethyl crown ethers, while 4′-(benzocourmarin-3-carboxamido) benzo crown ethers were secured by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 4′-aminobenzo crown ethers. Only the ester-type crown ethers were fluorescent. As the polarity of the solvent increased, the emission maximum λ em showed a slight red shift. DMSO was used as the fluorescence quenching solvent. Increased fluorescence was observed upon the addition of alkali and alkaline earth metal ions.

Development of FET-type albumin sensor for diagnosing nephritis

An albumin biosensor based on a potentiometric measurement using Biofield-effect-transistor (BioFET) has been designed and fabricated, and its characteristics were investigated. The BioFET was fabricated using semiconductor integrated circuit (IC) technology. The gate surface of the BioFET was chemically modified by newly developed self-assembled monolayer (SAM) synthesized by a thiazole benzo crown ether ethylamine (TBCEA)–thioctic acid to immobilize anti-albumin. SAM formation, antibody immobilization, and antigen–antibody interaction were verified using surface plasmon resonance (SPR). The output voltage changes of the BioFET with respect to various albumin concentrations were obtained. Quasi-reference electrode (QRE) and reference FET (ReFET) has been integrated with the BioFET, and its output characteristic was investigated. The results demonstrate the feasibility of the BioFET as the albumin sensor for diagnosing nephritis.

Utilizing Reversible Copper(II) Peptide Coordination in a Sequence‐Selective Luminescent Receptor

Although vast information about the coordination ability of amino acids and peptides to metal ions is available, little use of this has been made in the rational design of selective peptide receptors. We have combined a copper(II) nitrilotriacetato (NTA) complex with an ammonium-ion-sensitive and luminescent benzocrown ether. This compound revealed micromolar affinities and selectivities for glycine- and histidine-containing sequences, which closely resembles those of copper(II) ion peptide binding: the two free coordination sites of the copper(II) NTA complex bind to imidazole and amido nitrogen atoms, replicating the initial coordination steps of non-complexed copper(II) ions. The benzocrown ether recognizes the N-terminal amino moiety intramolecularly, and the significantly increased emission intensity signals the binding event, because only if prior coordination of the peptide has taken place is the intramolecular ammonium ion-benzocrown ether interaction of sufficient strength in water to trigger an emission signal. Intermolecular ammonium ion-benzocrown ether binding is not observed. Isothermal titration calorimetry confirmed the binding constants derived from emission titrations. Thus, as deduced from peptide coordination studies, the combination of a truncated copper(II) coordination sphere and a luminescent benzocrown ether allows for the more rational design of sequence-selective peptide receptors.

Solvent Extraction of Divalent Metal Ions with Azacrown Ether Substituted Acylpyrazolones

Novel 4-acyl-5-pyrazolones having aza-15-crown-5 (HPMP-A15C5) and aza-18-crown-6 (HPMP-A18C6) moieties as an intramolecular synergist have been synthesized by simple coupling reactions between 1-phenyl-3-methyl-4-chloroacetyl-5-pyrazolone and the corresponding azacrown ethers. The solvent extraction of the divalent metal ions (Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+)) were examined. Synergistic extractions with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and benzocrown ethers were also examined for a comparison. Extractions with the novel acylpyrazolones were unique and quite different from those with HPMBP and benzocrown ethers. The synergistic effect with benzocrown ethers was low, and an obvious difference brought by the ring size was not observed. The extractions of the divalent metal ions with HPMP-A18C6 were generally enhanced, as compared to those alone with HPMBP; on the contrary, the extractions with HPMP-A15C5 were relatively poor.

New fluorescent benzocrown ether derivatives of tetrathiafulvalene: facile synthesis and recognition properties

Two new fluorescent crown ether derivatives of tetrathiafulvalene (TTF) (2a and 2b) were synthesized and characterized; their electrochemical response to Na+ ions and fluorescence properties were investigated. The mechanism of the strong fluorescence has also been explored.

A novel family of Ru(II) polypyridyl complexes containing benzocrown ether for Na+ and Li+ probing

Two polypyridyl ligands 4′-(imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzo-12-crown-4 (L1), 4′-(imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzo-15-crown-5 (L2) and corresponding complexes [(bpy)2RuL1–2](PF6)2 (1, and 2) and [Ru(L1–2)3](PF6)2 (3, and 4) have been synthesized. These complexes show metal-to-ligand charge transfer absorption at 458–468nm and emission at 585–592nm. Binding ability of the complexes with Li+ and Na+ were investigated by fluorescence and UV–vis titration.

The Peculiarities of the Reaction of Benzo- and Dibenzocrown Ethers with N-Halogenosuccinimides

Corresponding author E-mail: kotlyar_sk@mail.ru The aromatic halogenation of benzo- and dibenzocrown ethers by N-halogenosuccinimides in solid phase, water or organic medium was researched for the first time. Under mechanochemical activation depending on stoichiometry of the process, benzocrown ethers smoothly and selectively transform into corresponding mono or dihalogeno derivatives. Addition of solid N-halogenosuccinimides to benzocrown ethers’ water solutions with high yields leads to mono halogenation products. At that, the process proceeds under the action of hypohalogenous acids, i.e. imide hydrolysis products. However, only 4

ChemInform Abstract: A Biaryl Cross‐Coupling Strategy for Functionalization of Benzocrown Ethers.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Ammonium Ion Optical Sensor Formation and Characterization of a Self‐Assembled Thiazole Containing Dibenzo‐18‐Crown‐6 Monolayer toward Developing Ammonium Ion‐Sensing Interface

This letter demonstrates a selective NH4 + detection using a synthesized thiazole benzo crownether ethylamine‐lipoic acid conjugate (1) monolayer. A self‐assembled monolayer (SAM) of 1 was formed on Au surface and well characterized by atomic‐force microscopy, Fourier transform infrared reflection absorption spectroscopy and cyclic voltammetry (CV). A good selectivity for NH4 + sensing was observed in a range of 1.0×10−1 to 1.0×10−6 M by surface plasmon resonance.

Synthesis of Crown-Based Sulfones via Rongalite: Diversity-Oriented Approach to Annulated Benzocrowns by Diels-Alder Reactions

Benzocrown ether compounds containing a sulfone moiety have been prepared using Rongalite. The resulting sulfones were employed as diene equivalents (o-quinodimethane) for the synthesis of various annulated benzocrown ethers using the Diels-Alder strategy.

Strong Molecular Aggregation of Neutral Carriers Bearing Perfluoroalkyl Chains in Liquid-Crystalline Ion-Sensor Membranes

A liquid-crystalline benzocrown ether, 4'-[(4''-1,1,2,2-tetrahydroperfluorooctyloxy)biphenyloxycarbonyl]benzo-15-crown-5, was used as a neutral carrier of ion-selective electrodes (ISEs) to elucidate the effect of highly ordered assembling of the neutral carrier on the sensor properties through fluorophilic interactions. The properties for the membrane and the resulting ISEs based on a benzocrown ether bearing a perfluoroalkyl chain were compared with those based on the corresponding crown ether bearing an alkyl chain. Atomic force microscopy and fluorescence measurements suggested that the neutral carrier bearing a perfluoroalkyl chain formed highly aggregational states in the membranes of ISEs.

Synthesis and fluorescent properties of new derivatives of 4-amino-7-nitrobenzofurazan

The following new compounds were obtained by reacting 4-chloro-7-nitrobenzofurazan (NBD- Cl, 1) with five primary amines: 3b with a benzo-crown ether 18C6; 3c with an N-(α-naphthyl)- ethylenediamine group; 3d, with a 2,2,6,6-tetramethylpiperidin-N-oxyl group; 3e, with an α- picolyl group; and 3f, derived from tris(hydroxymethyl)aminomethanol. Also, from the reaction of 1 with N-methylhydroxylamine an N-hydroxy-N-methyl-NBD derivative (3g) was prepared. All these six new NBD derivatives 3b-g were studied (in comparison with the known compound 3a prepared from 1 and aniline) for their physical and chemical properties, with special emphasis on hydrophobicity, UV-Vis, fluorescence, using also structural studies trough QSPR.

A biaryl cross-coupling strategy for functionalisation of benzocrown ethers

Preparation of (di)benzocrown-substituted aryl-zinc or -boron reagents and their palladium-catalysed cross-coupling with functionalised aryl halides is described for convenient synthesis of novel crown ether systems.