Diazacrown Ethers Research Articles

The formation of complexes between aza derivatives of crown ethers and primary alkylammonium salts. Part 9. Bicyclic derivatives of diaza crown ethers

The bridged diaza-15-crown-5 derivatives (12a–c) and (16) form complexes with alkylammonium cations RNH3 in organic solvents. The 1H n.m.r. spectra of the complexes (12). RNH3 show that they are mostly of the inclusion type (3) but in a few cases a second diastereoisomeric complex, possibly (4), is also formed. These bicyclic hosts do not show particularly high selectivity in complexation on the basis of competition between pairs of guest cations.

Metal complexes of 1,4,10-trioxa-7,13 -diazacyclopentadecane- N,N'-diacetic acid

The cyclic diaza-crown ether complexone cTOPDA (1,4,10-trioxa-7,13-diaza- cyclopentadecane- N,N'-diacetic acid) has been synthesized and characterized by elemental analysis, titration and NMR spectroscopy. Its ionization constants and the stability constants of its ML and M 2L complexes formed with alkali, alkaline-earth and some transition and representative metals were determined at 25.0±0.1°C and ionic strength 0.10 M (Me 4NNO 3). This ligand forms considerably more stable complexes with the transition metals than the analogous tetraoxa-diaza crown ether complexone cTOODA (1,4,10,13- tetraoxa-7,16-diazacyclooctadecane- N,N'-diacetic acid), but this last ligand favours ions with larger size, particularly K +. The cobalt(II) complex of cTOPDA is more stable than the nickel(II) complex, hence the Irving-Williams' order of stability is not obeyed for its transition-metal complexes. These effects are discussed in terms of the size of the cavity of the ligand and of the stereochemical constraints that it may impose.

Extraction and photometric determination of lead with diazacrown ether dye

N,N'-Bis(2-hydroxy-5-nitrobenzyl)cryptand-22 (22-Koshland) forms yellow complexes with bivalent metal ions, and these are extractable into 1,2-dichloroethane. The overall extraction constants have been estimated for lead (10 −5.4), copper (10 −5.6), mercury (10 −5.8) and cadmium (10 −8.4). The result obtained has been applied to extraction and photometric determination of lead. The molar absorptivity at the absorption maximum (406 nm) is 4.47 × 10 4 l·mole −1·cm −1. The interferences from copper and mercury can be eliminated by the addition of sodium thiosulphate and the interference from cadmium can be eliminated by calculation from the absorbances at 406 and 391 nm (the cadmium complex with 22-Koshland has its absorption maximum at 391 nm). The method has been successfully applied to the determination of lead in zinc powder.

Macroheterocycles; XXX. Synthesis of Chiral Cryptands and Polynuclear Crown Ethers

Syntheses of novel chiral bi- and trinuclear crown ethers and cryptands by alkylation of mono- and diazacrown ethers with L-1,2:3,4-diepoxybutane are described.

ChemInform Abstract: DIAZA CROWN ETHERS BASED ON SYM‐TRIAZINE DERIVATIVES

AbstractDie Umsetzung der Dichlortriazine (1) mit den Dinatriumderivaten von Diethylen‐ und Triethylenglykol (II) liefert in wasserfreiem Dioxan bei hoher Verdünnung die Verbindungen Bis‐(Z‐ dialkylamino‐1,3,5‐triazino)‐l,l l‐diaza[20]krone‐8 bzw. ‐1,14‐diaza[26]krone‐l0 (III).

Formation of complexes between aza derivatives of crown ethers and primary alkylammonium salts. Part 8. 12-Crown-4, 15-crown-5, 21-crown-7, and 24-crown-8 derivatives

The monoaza-crown ethers (3), (4), and (5) and the diaza-crown ethers (6), (7), (10). and (11) form complexes with primary alkylammonium thiocyanates in organic solvents. The diaza-15-crown-5 system (11) forms well defined 1:1 complexes with the cis-,cis-stereochemistry shown in (16) but the diaza-24-crown-8 derivative (7) forms a 2:1 complex (G:H ratio) with benzylammonium thiocyanate having the cis,cis,trans,trans-stereochemistry (17a). The diaza-24-crown-6 derivative (10) forms weak 1:1 complexes which apparently adopt the double nesting conformation (18).

Dynamic 1H nuclear magnetic resonance spectroscopic studies of complexes formed between substituted ammonium cations and two chiral diaza-crown ethers incorporating asymmetric carbohydrate units

Two diaza-18-crown-6 derivatives (1) and (2), incorporating methyl 4,6-O-benzylidene- and methyl 4,6-O-[(S)-phenylethylidene]-α-D-mannopyranosidic residues, have been shown, by variable-temperature high-field 1H n.m.r. spectroscopy, to form strong anisometric 1 : 1 complexes with substituted ammonium cations in CD2Cl2 solutions. Although there are a few examples of almost equally populated anisometric complexes, in most cases the major complex is associated with the β-face of the macrocyclic ring. Relevant thermodynamic data have been obtained from integration of appropriate signals in the low-temperature spectra. Approximate kinetic data have been evaluated using appropriate equations for site exchange between unequally populated sites.

Syntheses of calcium-selective, substituted diaza-crown ethers: a novel, one-step formation of bibracchial lariat ethers (BiBLES)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSyntheses of calcium-selective, substituted diaza-crown ethers: a novel, one-step formation of bibracchial lariat ethers (BiBLES)Vincent J. Gatto and George W. GokelCite this: J. Am. Chem. Soc. 1984, 106, 26, 8240–8244Publication Date (Print):December 1, 1984Publication History Published online1 May 2002Published inissue 1 December 1984https://doi.org/10.1021/ja00338a038RIGHTS & PERMISSIONSArticle Views1280Altmetric-Citations133LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (705 KB) Get e-Alerts Get e-Alerts

Diaza crown ethers based on sym-triazine derivatives

The reaction of 2-dialkylamino-4,6-dichloro-1,3,5-triazines with the disodium derivatives of di- and triethyleneglycols, has given four new diaza crown ethers. The structures of the compounds synthesized have been established by IR and PMR spectroscopy and elementary analysis.

Characteristic Transport Properties of Diaza-crown Ethers for Primary and Secondary Ammonium Cations

Abstract Simple lipophilic diaza-crown ethers show unique transport properties for primary and secondary ammonium salts, which are markedly different from those observed with common crown ether systems.

Diaza crown ether complexes of alkali metal and ammonium cations paired with organic anions

Formation of a series of diaza crown ether complexes of alkali metal and ammonium cations paired with organic anions is reported. Diaza 18-crown-6 (1) forms complexes with potassium, ammonium, and methylammonium 4-nitrophenolate to yield 1:1 colored crystalline compounds. The lowering of energy in the COC frequency absorption band and the solubility of all crown ether complexes in chloroform provided evidence of complex formation. The 1H nmr signal for −NH protons of crown ether is shifted the most in the [K-1] 4-nitrophenolate complex. The polyether (1) also yields a complex with potassium 2,4-dinotrophenolate but no complex with sodium could be isolated. However, diaza 15-crown-5 (2) yields 1:1 complexes with sodium as well as with potassium and ammonium 4-nitrophenolate salts.

Macrocyclic polyfunctional lewis bases-IX azacrown ethers

Several new diazacrown ethers and one tetraazacrown ether have been obtained.

Synthesis of chiral diaza-crown ethers incorporating carbohydrate units

A synthesis of a novel chiral diaza crown ethers derived from α-D-glucose, α-D-mannose, and α-D-galactose in two alternative pathways is described.

Synthesis of diaza-crown ethers on solid supports

Synthesis of diaza-crown ethers on solid supports

Synthesis of novel chiral [2.2.1]cryptands incorporating sugars

Chiral N, N'-dimethyl diaza-crown ethers bearing functionalized α-D-gluco-, α-D-galacto-, and α-D-mannopyranoside residues are transformed into the corresponding [2.2.1]cryptands with bis(2-iodoethyl) ether under high-pressure conditions and subsequent demethylation. Alternatively, α-D-manno-diaza-18-crown-6 reacts with diglycolic acid dichloride under high-dilution conditions to form bisamide which is reduced to the corresponding chiral [2.2.1]cryptand.

Photoresponsive Crown Ethers. 9. Cylindrical and Phane Crown Ethers with Azobenzene Segments as a Light-switch Functional Group

Abstract Cylindrical and phane crown ethers with azobenzene segments as a light-switch functional group were synthesized. Cylindrical ionophores in which two diazacrown ethers are linked by two photoresponsive azobenzene pillars change their binding ability for polymethylenediammonium salts in response to photoirradiation. Thus, the distance between the two crown rings can be photocontrolled. A phane-type ionophore in which 1,23-bis(p-aminophenoxy)-3,6,9,12,15,18,21-heptaoxatricosane is linked by a trans-4,4′-azobenzenedicarbonyl segment exhibits no affinity with all alkali metal cations but significantly binds Rb+ and Cs+ under UV-light irradiation. This is the example of the “all-or-nothing” control of the ion-binding ability and implies that a crown-like loop emerges only when the azobenzene segment is photoisomerized to the cis-configuration. These ionophores are categorized to novel photoresponsive crown ethers.

Thermodynamic and kinetic studies on complex formation of alkaline earth metal ions with diaza-crown ethers in methanol

Stability constants K s and rate constants of formation and dissociation of alkaline earth metal complexes with the diaza-crown ethers (2,2) and (2,2-Me 2) in methanol are reported, together with corresponding thermodynamic parameters. It od shown that it is possible to determine the dissociation rate constants k d of these crown ether complexes from stopped-flow experiments. The values of K s and k d for (2,2,) complexes are displaced parallel with respect to the corresponding values for (2,2-Me 2) complexes, and variations of K s with metal ion radius are reflected in similar (inverse) variations of k d. However, enthalpies and entropies of reaction and activation point to differences in the behaviour of the two ligands.

Synthesis of novel chiral macrocyclic ligands bearing methyl 4,6-O-benzylidene-α-D-mannopyranoside

O-Alkylation of methyl 4,6-O-benzylidene-α-D-mannopyranoside with t-butyl bromoacetate under phase-transfer conditions, followed by reduction and tosylation leads to an intermediate which was used in the formation of the two diaza-crown ethers (3a) and (3b)via condensation with 1,8-diamino-3,6-dioxaoctane in the presence of KF–Al2O3 and N,N-bisethoxycarbonyl-1,8-diamino-3,6-dioxaoctane in Me2SO–NaH–KBr, respectively.

High-pressure approach to the synthesis of novel chiral cryptands derived from methyl 4,6-O-benzylidene-α-D-manno-, -α-D-galacto-, and -α-D-gluco-pyranoside

Diaza crown ethers derived from sugars react under high pressure with bis-(2-iodoethyl) ether to give the quaternary salts in quantitative yield and their subsequent demethylation with triphenylphosphine affords chiral cryptands in high yield.

Diaza-crown ether capped cyclodextrin. A receptor with two recognition sites

The tetraoxadiazacyclo-octadecanyl-β-cyclodextrin (1) provides a molecular assembly with two recognition receptor sites, which co-operate in the association of alkali-metal p-nitrophenolates as substrates.