Azacrown Ether Derivatives Research Articles

Preparation of Fluorous Aza-crown Ether with Two Bisfluorous Chain Type Propionyl Groups: An Investigation of its Partition Ratios in Fluorous Biphasic Systems and Recyclability During SN2-type Acetoxylation Reactions

Abstract: In this study, a new fluorous aza-crown ether derivative (1) conjugated with two Bfp (bisfluorous chain type propionyl) groups was prepared; then, the partition ratios of 1 in biphasic systems using FC 72 and several organic solvents were investigated. Next, the activities of 1 in an FC 72/acetonitrile biphasic system were assessed via the SN2-type acetoxylation reaction using 2- (bromomethyl)naphthalene and potassium acetate. Finally, the recyclability of 1 in a two-layer system based on its immobilization in an FC 72 solvent was examined during acetoxylation reactions.

A basket-type fluorescent sensor based calix[4]azacrown ether for multi-analytes: Practicability in living cells and real sample

A basket-type fluorescent calix[4]azacrown ether derivative (C[4]azacrown) was conceived and prepared to starting from NBD-chloride (4-chloro-7-nitro-benzofurazan), as a selective turn-off sensor of multi-analytes. The sensor designed as both an useful basket macrocycle and a fluorescent material was characterized by several techniques such as fluorescence spectroscopy, elemental analysis, NMR, FT-IR, and. The optical properties of sensor C[4]azacrown developed for multi-analytes were examined in the presence of anions and cations such as Na+, Ca2+, Mg2+, Fe3+, Fe2+, Ni2+, Co2+, Zn2+, Cu2+, Hg2+, Cr3+, Ag+, Al3+, and F−, Br−, Cl−, H2PO4−, I−, PO43−, SO42−, HSO4−, CH3COO−, NO3− and several ion/sensor ratios. Nano-basket fluorescent molecule, C[4]azacrown, has a fluorescence response with “on–off” mechanism towards CH3COO−, F− anions and Cu2+ cation with clear selectivity in aqueous medium (H2O/CH3CN 1/4, v/v). The fluorescence properties of C[4]azacrown was also demonstrated by using a confocal microscope in the human lung cancer cell line (A549). It was observed that the fluorescence intensity of the basket sensor quenched clearly in cells performed with Cu2+ ion, CH3COO−, and F− ions, respectively. Moreover, the detection of CH3COO−, F− and Cu2+ ions were performed in grape juice as a food sample. As a result, the basket-type macrocycle, C[4]azacrown, may be performed to recognize Cu2+, CH3COO− and F− ions in living cells and real samples.

Aza-crown ether locked on polyethyleneimine: solving the contradiction between transfection efficiency and safety during in vivo gene delivery.

We proposed a method using an aza-crown ether derivative to lock a hyperbranched polyethyleneimine, which endows the PEI25k with tumor targeting ability, anti-serum ability and extended circulation in the blood meanwhile retaining the high gene complexation and high transfection efficiency. The method we proposed here simultaneously endows cationic materials with high transfection efficiency and high safety, which greatly pushed the cationic materials to be applied in in vivo gene delivery.

МОНОСЛОИ ЛЕНГМЮРА АЗАКРАУН-ЭФИРНЫХ ПРОИЗВОДНЫХ КАЛИКС[4]АРЕНА

In this work, aggregation behavior of azacrown-ether derivatives on a macrocyclic calix[4]arene scaffold within ultrathin Langmuir films on water subphase is considered.

Aza-crown ether derivatives based on stilbene: Two-photon absorption and bioimaging

Two novel aza-crown ether derivatives based on stilbene were synthesized and characterized. Their linear photophysical properties were systematically investigated in various solvents. The nonlinear photophysical properties were investigated by two-photon induced fluorescence method. The two-photon absorption cross sections values measured by two-photon excited fluorescence were determined to be 328.2 GM and 246.55 GM for the dyes derived from monoaza 15-crown-5 and 18-crown-6, respectively, which accorded with dipole moment changes under photoexcitation. In addition, a single-photon fluorescence cell imaging experiment proved that dye derived from monoaza 15-crown-5 was suitable for biomedical imaging.

Complexation and transport of amino acid esters and their salts with synthesised chiral novel aza crown ether derivatives

The syntheses of four aza-15-crown-5 ethers bearing phenyl and phenoxymethyl moieties attached to a stereogenic centre on the crown ring were achieved. Macrocycles have exhibited strong binding ability (Ka = 5364–12,969 M− 1) and modest enantiomeric discrimination towards the enantiomers of amino acid methyl ester salts by UV titration method in CHCl3 at 25°C. Computer modelling results supported experimental data providing a detailed understanding of the molecular recognition mode between hosts and guests and the likely binding sites involved. Macrocycles were used for chiral discrimination of amino acids in their zwitterionic forms or as potassium and sodium salts in transport experiments across a bulk chloroform membrane with satisfactory selectivity.

Synthesis and application of novel magnetite nanoparticle based azacrown ether for protein recognition

This article is the first report showing the human serum albumin (HSA) binding studies by using a new magnetite nanoparticle containing azacrown ether moieties via solid-liquid extraction process. The structure of the newly prepared magnetite nanoparticle was clarified by using attenuated total reflectance (ATR) infrared spectro- scopy, scanning electron microscopy (SEM), UV-vis and elemental analysis. Analytic results indicated that modifi- cation of the surface of the magnetite nanoparticles with azacrown ether derivative was successfully carried out. The protein binding studies exhibited that the modified magnetite nanoparticles could be efficiently used for the binding of the human serum albumin (HSA) in aqueous solutions via non-covalent interaction between crown ether cavity and amino group of the protein.

Mannich reaction of secondary amines, aldehydes and alkynes in water using Cu/C nanoparticles as a heterogeneous catalyst

The use of 2 mol% of Cu/C nanoparticles, as an easily accessible and inexpensive heterogeneous catalyst, promoted a one-pot three-component condensation of an amine, aldehyde, and an alkyne in water to produce the corresponding propargylamine in good to high yields. This method was proved to be applicable to a wide range of substrates and is especially practical for the synthesis of new azacrown ether derivatives. The catalyst was quantitatively recovered from the reaction by a simple filtration and reused for at least ten times with almost consistent activity.

N-(4-amino-7-nitrobenzaoxa-1,3-diazole)-substituted aza crown ethers: complexation with alkali, alkaline earth metal ions and ammonium

Three novel aza-crown ether derivatives incorporating 4-amino-7-nitrobenzaoxa-1,3-diazole (NBD) chromophore were synthesized and their structure confirmed by (1)H-NMR, IR and elemental analysis. The influence of the solvent polarity and protonation on the photophysical properties of NBD-15-crown-5 was studied by UV/Vis and fluorescence methods. The influence of the investigated cations on the absorption spectra of the ligands was negligible, however emission was strongly affected. Complexation and binding stability of NBD-aza-15-crown-5 and NBD-aza-18-crown-6 were studied using fluorescence spectroscopy. NBD-aza-18-crown-6 exhibits strong selectivity toward Ca(2+) and Sr(2+) ions with formation constants about 10(3) times higher than the formation constants with the other ions included in the study.

Intercalation of Macrocyclic Crown Ether into Well-Crystallized LDH: Formation of Staging Structure and Secondary Host−Guest Reaction

A carboxyethyl substituted azacrown ether derivative (CSAE) was intercalated as a second host into a parent host of well-crystallized crystal of Mg−Al layered double hydroxide (MgAl-LDH) by a CSAE/NO3− ion-exchange reaction. The influence of intercalation temperature on the structures and compositions of CSAE−LDH nanocomposites was investigated. The composites obtained at the temperatures below 70 °C had almost the same CASE contents and layered structures with a basal spacing of about 1.6 nm, corresponding to the vertical orientation of CSAE plane to the LDH layer. The chemical analysis showed that a considerable amount of CO32− (with CO32−/CSAE molar ratio of 1.4) was incorporated in the interlayer of LDH. The CSAE content decreased while CO32− content increased with an increase of the intercalation temperature in the region above 70 °C. At 100 °C, a second staging phase of 2.33 nm appeared, attributed to the ordered stacking of the 1.6 nm phase and a 0.77 nm phase produced by the CO32−/CSAE exchange. At higher temperatures, a new phase with a basal spacing of 1.18 nm appeared, which corresponds to the tilt/twisted orientation of CSAE anions in the interlayer. The other second staging phase of 2.08 nm appeared obviously at 150 °C, due to the regular stacking of the 1.18 and 0.77 nm phases. The adsorptive properties for transition metal ions were studied using the 70 and 150 °C reacted composites. The 70 °C reacted one showed higher adsorptivity toward transition metal ions; the adsorptive capacity increased in the sequence of Cu2+ > Ni2+ > Co2+ > Zn2+, and distribution coefficient for Cu2+ was markedly higher than those for the other ions. However, the 150 °C reacted one showed little adsorptivity toward these ions. The adsorption for transition metal ions was accompanied by the intercalation of nearly equivalent amount of nitrate ions. This shows that the interlayer CSAE ions in the 1.6 nm phase act as a second host, but those in the 1.18 nm phase do not.

Synthesis and ESI‐MS Study of New N‐Functionalized Macrocyclic Polyamine and Azacrown Ether Derivatives.

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Synthesis and Fluorescence Behavior of Cation Chemosensor Based on Azacrown Ether Fluoroionophore Carrying Styrylanthracene

Recently, the development of chemosensor associated with fluoroionophore has attracted great attention. Fluoroionophore is a compound combining the ionophore and fluorophore, where ionophore binds selectively with a specific ion and fluorophore generates a fluorescence signal upon ion binding. Depending on the nature of fluorophore-ionophore interaction in fluoroionophore, fluorescence properties of fluorophore such as fluorescence intensity or fluorescence wavelength maximum may be influenced by ion capture of ionophore. Sensitivity of fluorophore may be associated with the ionic recognition ability of the ionophore, if the fluorophore may be perturbed by the coordination of cation. The recent increase of interest in the synthesis of crown ether derivatives incorporating different fluoroionophores is recently due to their application as alkali metal ion sensors in biochemical analysis and medical diagnostics. In particular, azacrown ether, a typical ionophore, acts as an electron-rich donor as well as a ligand of the cation. The electron pair on the nitrogen heteroatom in electron-rich azacrown ether could be transferred towards electron deficient fluorophore in a π-conjugated D-A arrangement, through the charge transfer interaction between ionophore, an electron donor, and fluorophore, an electron acceptor. The efficient intramolecular charge transfer takes part in the modification of the first electronic transition state of the fluorophore and may lead to weaken the fluorescence from fluorophore. Upon binding of a cation into ionophore cavity, the electron pair on nitrogen heteroatom of ionophore is stabilized and the intramolecular charge transfer is inhibited. Therefore, the original electronic configuration of the unsubstituted fluorophore is recovered, so that fluorescence may be strengthened. Many fluoroionophores including stilbenyl-, aryl-, or styryl-crown ether derivatives containing a stilbene, styrene or aryl moiety as a fluorophore and a crown ether/azacrown ether moiety as an ionophore have been investigated. However, the main disadvantage of these fluoroionophore is the relatively small changes in fluorescence intensity upon cation binding. Incorporation of more efficient fluorophore such as anthracene into fluoroionophore may lead to more remarkable change of fluorescence signal depending on the cation binding. Recent work has concerned the binding of various fluorophores to the N-phenylaza-15-crown-5 and their spectroscopic and complexation properties. This paper concerns the synthesis of N-phenylaza-15-crown-5 derivative containing anthrylethene chromophore and the effect of the complexation with various alkali metal cations on the absorption and fluorescence behavior. We prepared N-[4-(2-anthracen-9-yl-vinyl)-phenyl]-aza15-crown-5 (1), a azacrown ether derivative containing 1-(9anthryl)-2-phenylethene (9-APE) moiety, by Wittig coupling between N-[4-formyl-phenyl]-aza-15-crown-5 and 9bromomethylanthracene. It is known that t-9-APE, a styrene derivative containing highly fluorescent anthracene, shows fairly strong fluorescence (Φf = 0.45, λf = 476 nm in acetonitrile), coming from the locally excited state which the excitation energy is localized on anthracene ring. For 1-(9-anthryl)-2-(4-methoxyphenyl)ethene (MeO-APE) containing an electron donating substituent methoxy group, fluorescence becomes weak and is red-shifted (Φf = 0.028, λf = 494 nm in acetonitrile) due to the contribution of the intramolecular

Application of ring closing metathesis in efficient synthesis of macrocyclic crown compounds

RCM of suitable α,ω-dienes led to efficient atom economic synthetic approaches towards azacrown ether derivatives with 8–40 membered ring sizes.

An artificial aspartic proteinase system

A series of aza crown ether derivatives with or without carboxyl groups in their side arms were synthesized and the former showed deacylation activities toward amino acid p-nitrophenyl ester hydrohalides. Substrate-selective phenomena were also observed. The relationship between the structures and deacylation activities of corresponding compounds suggested a nucleophilic catalytic mechanism. The results partially simulate some aspartic proteinases in the case of catalytic mechanism and are also useful for us to understand the detailed catalytic process of aspartic proteinases.

Photoresponsive Liquid Membrane Transport of Alkali Metal Ions Using Crowned Spirobenzopyrans

Several azacrown ether derivatives, which are monoaza-12-crown-4, -15-crown-5, and -18-crown-6 and diaza-12-crown-4 and -18-crown-6, bearing one or two spirobenzopyran(s), which we call crowned spirobenzopyran or crowned bis(spirobenzopyran), were synthesized and were used as carriers for liquid membrane transport of alkali metal ions. The passive alkali metal transports through liquid membranes containing crowned spirobenzopyrans were carried out under dark, and UV- and visible-light irradiation conditions. The metal ion transport was accelerated and retarded by UV- and visible-light irradiation, respectively. On the other hand, the photoresponse of the metal ion selectivity in membrane transport by crowned spirobenzopyrans was different, depending on the kind of crown ether units. Especially, diaza-12-crown-4-bis(spirobenzopyran) exhibited an excellently selective and effective transporting ability for Li(+). The uphill transports of Li(+) through a liquid membrane containing monoaza-12-crown-4-spirobenzopyran or diaza-12-crown-4-bis(spirobenzopyran) were realized under the conditions where the same aqueous solution was used as the source and receiving phases with UV and visible lights being irradiated onto the boundary phases between the source and membrane phases and between the receiving and membrane phases, respectively. The uphill transport of Li(+) from the source to receiving phases through a liquid membrane containing a crowned spirobenzopyran was also attained by the proton-concentration gradient between the source and receiving phases under dark conditions, and the transporting ability was remarkably increased by photoirradiation.

Preparation of N‐Aryl Azacrown Ether Derivatives, Using Arene—Iron Chemistry.

m- or p-phenylenediamine and m- or p-chlorophenyl-substituted azacrown ether derivatives were synthesized through sequential nucleophilic substitution of [(η5-cyclopentadienyl)(η6-(m- or p-dichlorobenzene))]iron hexafluorophosphate by azacrown ethers and cyclohexaamines. Monoarylation is the main reaction for diazacrown ethers. The overall yield from the starting complex is 50−96% for multiple steps.

A Novel One-Dimensional Copper(II) Complex of a Carboxymethylated Tricyclic Azacrown Ether Derivative Linked by Hydrogen Bonding

The complex [CuL]·H2O(H2L=4,13-dioxa-1,7,10,16-tetraaza-1,16:7,10-bis(ethylene)-9,18-diacetic acid cyclooctadecane-8,17-dione) has been synthesized and structurally characterized. It crystallizes in the triclinic system, space group P1 with a=9.0111(7), b=9.4371(7), c=14.3092(11)Å, a=89.846(2), β=81.871(2), γ=65.616(2)°, V=1095.05(14)Åsup3;, and Z=1. The structure of the complex consists of two different CuL coordination moieties in which six-coordinated copper ions each have different coordination environments. In both CuL moieties, copper ions are coordinated to two tertiary nitrogen and four oxygen atoms, two from the crown ether ring and two from the pendant carboxylate groups. These two different CuL moieties are linked alternately by water molecules to form an infinite one-dimensional chain structure through hydrogen bonding between the water molecule and the uncoordinated oxygen atom of the carboxyl group.

Preparation of N-aryl azacrown ether derivatives, using arene-iron chemistry.

m- or p-phenylenediamine and m- or p-chlorophenyl-substituted azacrown ether derivatives were synthesized through sequential nucleophilic substitution of [(eta(5)-cyclopentadienyl)(eta(6)-(m- or p-dichlorobenzene))]iron hexafluorophosphate by azacrown ethers and cyclohexaamines. Monoarylation is the main reaction for diazacrown ethers. The overall yield from the starting complex is 50-96% for multiple steps.

Efficient Atom Economic Approaches Towards Macrocyclic Crownamides via Ring Closure Metathesis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Efficient atom economic approaches towards macrocyclic crownamides via ring closure metathesis

RCM of suitable 1,ω-dienes led to efficient atom economic synthetic approaches towards azacrown ether derivatives with eight- to twenty four-membered ring sizes.