Diazacrown Ethers Research Articles

The syntheses of phenol-containing diazamacrocycles and liquid membrane transports of alkali cations

Two new bisphenol-containing diazacrown ether derivatives, 7,16-bis(2-hydroxy-5-ethylbenzoatebenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane ( 1) and 7,16-bis(2-hydroxy-3,4-dimethylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane ( 2), have been synthesized via one-pot Mannich reaction. The compound 1 is structurally characterized. The liquid membrane transports of alkali metal cations using these two new diazamacrocycles and the other previously prepared diazamacrocyclic derivative 7,16-bis(3-hydroxy-6-methyl-2-pyridylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane ( 3) as ion-carriers are also studied. The results show that the rates of cation transports are closely related to the number of nitrogen donors and the steric effect of the substituted groups. Compared with other macrocyclic compounds, compound 1 shows a good selectivity for Li +, therefore providing a new efficient carrier for Li + extraction.

Synthesis and inclusion ability of a bis-β-cyclodextrin pseudo-cryptand towards Busulfan anticancer agent

The synthesis of a C 2-symmetric receptor including two β-cyclodextrins connected by urea linkers to a chiral diaza-crown ether organising platform is reported. This molecular system, long thought to be a potent selective carrier for chiral/achiral organic/inorganic guests at the supramolecular level, was found to be an efficient complexing tool towards the Busulfan anticancer agent.

Novel phosphazene derivatives: Synthesis, anisochronism and structural investigations of mono- and ditopic spiro-crypta phosphazenes

The reactions of hexachlorocyclotriphosphazatriene, N 3P 3Cl 6, with N 2O 2-donor type coronands (diaza-crown ethers) 1– 3 afford novel monotopic 4– 7 and ditopic 8– 10 spiro-crypta phosphazenes, respectively. It has been observed that the reactions of N 3P 3Cl 6 with 1 equivalent amount of coronands 1– 3 yield only monotopic spiro-derivatives, while three equivalent amount of coronands 2 and 3 give dominantly ditopic dispiro-crypta-phosphazene skeletons. On the other hand, the 31P NMR spectrum of 8 indicates that the ditopic spiro-ansa phosphazene 10 is present besides the ditopic dispiro derivative 8. Unexpectedly, the reaction of 6 with excess amount of pyrrolidine leads to the formation of geminal product 7. The 31P NMR spectra of 4, 5, 6 and 10 indicate that all of these compounds have anisochronism. The structures of 5, 8 and 9 have been determined by X-ray crystallography. The relative radii of macrocyclic hole sizes of 5, 8 and 9 are calculated from the crystallographic results. The relationships between the exocyclic NPN and endocyclic NPN bond angles of the analogous compounds with δP-shifts of NPN phosphorus atoms have been discussed. Thus, sums of the bond angles around the nitrogen atoms are in the range of [342.7(2)°–354.4(2)°], showing that the nitrogen atoms have pyramidal configurations. The pyramidal configuration gives rise to stereogenic properties. The salient spectroscopic features [FTIR, 1H, 13C, 31P NMR, HETCOR (for 5 and 7) and MS] of all the compounds are presented.

Synthesis, Characterization and Complexation Behavior Investigations of Novel Bis- and Tris-crown Ethers

Novel bis- and tris-crown ethers were synthesized from 1-aza and diaza-crown ethers with 2-acryloyloxy-methyl crown ethers through Michael addition. The synthesized bis- and tris-crown ethers were characterized by their elemental analyses, -NMR, -NMR, mass spectra, IR spectra, respectively. The complexation behavior of the bis- and tris-crown ethers with , , , , was examined by -NMR, FAB mass, and UV spectrometry.

Synthesis, characterization and extraction studies of a new vic-dioxime and its complexes containing bis(diazacrown ether) moieties

A new vicinal dioxime ligand containing bis(diazadioxa-12-crown-4 ethoxy) units ( H 2 L) has been synthesized by the reaction of cyanogendi- N-oxide with 3,4-bis(2-{10-[(4-methylphenyl)sulfonyl]-1,7-dioxa-4,10-diazacyclododecan-4-yl}ethoxy)aniline, which was prepared by the reduction of 4-[(4-methlyphenyl)sulfonyl]-10-[2-((4-nitro-2-{2-[10-phenylsulfonyl)-1,7-dioxa-4,10-diazacyclododecan-4-yl]ethoxy}phenoxy)ethyl]-1,7dioxa-4,10-diazacyclododecan. A mononuclear nickel(II) and copper(II) complexes with a metal:ligand ratio of 1:2 for H 2 L were also synthesized. The mononuclear cobalt(III) complex of H 2 L has been isolated with L′ = pyridine, together with chlorine as an axial ligand. In addition, a cobalt(III) complex containing the BF 2 + bridge macrocycle was synthesized using a precursor hydrogen-bridged cobalt(III) complex via the template effect. The extraction abilities of 1, 3, 6 and 10 were also evaluated in 1,2-dichloroethane by using several alkali (Li +, Na +, K +, Cs +) and transition metal picrates such as Ag +, Pb 2+, Cd 2+, Cu 2+, Zn 2+. The structure of the dioximes and their complexes are proposed according to elemental analyses, 1H and 13C NMR, FT-IR UV–Vis and mass spectra.

The 1:2 and 1:1 molecular complexes of N, N′-dibenzyl-4,13-diaza-18-crown-6 with 4-nitrobenzenesulfonamide and dithiooxamide

The reaction of diazacrown ether, N, N′-dibenzyl-1,7,10,16-tetraoxo-4,13-diazacyclooctadecane (DD18C6) with 4-nitrobenzenesulfonamide, 4-O 2NPhSO 2NH 2 and dithiooxamide, (H 2NCS) 2 results in the molecular complexes of 1:2 (complex 1) and 1:1 (complex 2) ratios, correspondingly. The crystals of 1 are monoclinic, space group P2 1/ c, a=9.256(2), b=9.214(2), c=24.379(5) Å, β=100.87(3)°, V=2041.9(7) Å 3, Z=2. The crystals of 2 are triclinic, space group P-1 , a=8.458(2), b=9.314(1), c=20.098(5) Å, α=87.51(1), β=85.46(1), γ=67.52(1)°, V=1458.2(5) Å 3, Z=2. The complexes are sustained by N–H⋯O and N–H⋯N hydrogen bonds and exhibit zero-dimensional molecular complex and one-dimensional chain structures, correspondingly.

Novel crowned-porphyrin ligands. Synthesis and conformational studies

Three new macromolecules—a cryptand, a bis-macrocycle, and a tris-macrocycle—have been synthesized as chelating ligands for cation binding. They result from the surprisingly simple reaction of various bis-functionalized meso-aryl porphyrins with a diaza-crown ether coupled one to each other through either one or several urea linkage(s). Indeed, the latter induces some additional rigidity in comparison with the usual amide linkage found in such macromolecules. Various strategies are reported to optimize the yield of the reaction towards the formation of a cofacial singly-linked crown-porphyrin, which is the most promising ligand to stabilize large cations such as bismuth(III) as the angle between the two macrocycles can vary.

Host−Guest Complexes with p-Sulfonatocalix[4,5]arenes Charged Crown Ethers and Lanthanides: Factors Affecting Molecular Capsule Formation

Incorporation of the smallest diprotonated diaza-functionalized crown ethers into host−guest assemblies with p-sulfonatocalix[4 or 5]arenes gives insight into the dominant factors in the formation of “molecular capsule” or “alternative host−guest bilayer” structures in the solid state, in the presence of aquated lanthanide(III) cations. For p-sulfonatocalix[4]arene, molecular capsule formation is dependent on guest size, protonation of the diaza-crown ether, and the pH of the reaction medium. In contrast, formation of (di)aza-crown ether-based molecular capsules with p-sulfonatocalix[5]arene was elusive under the conditions studied. Rather, an “alternative host−guest bilayer” structure formed in the presence of europium(III) ions.

Cucurbit[6]uril as Ligand for the Complexation of Diamines, Diazacrown Ethers and Cryptands in Aqueous Formic Acid

The complex formation between cucurbit[6]uril and different diamines, diazacrown ethers, and cryptands has been studied in aqueous formic acid solution. The complex stabilities and the thermodynamic values for the complex formation of diamines are reduced if any further donor atom (e.g., sulfur, oxygen, or nitrogen) is present in the molecules. The inclusion of this polar group inside the cavity of cucurbit[6]uril has a negative effect upon the complex formation. Diazacrown ethers and cryptands do not form inclusive complexes. One nitrogen donor atom interacts with the carbonyl groups at one of the portals.

Synthesis of N, N′-diallyl dibenzo 18-crown-6 crown ether crosslinked chitosan and their adsorption properties for metal ions

The preparation of two novel diaza-crown ether crosslinked chitosan was described. Diazacrown ether chitosan (CTSDC) was synthesized by the reaction of chitosan (CTS) with N, N′-diallyl dibenzo 18-crown-6 crown ether. Diazacrown ether crosslinked chitosan (CCTSDC) was prepared by the crosslinked reaction of CTSDC and epichlorohydrin. Their structures were confirmed with infrared spectra analysis and X-ray diffraction analysis. The adsorption properties of CTSDC and CCTSDC for metal ions were also investigated. The adsorption capacities for metal ions were measured and the selectivity was determined in mixture of several metal ions. At 20 ± 1 °C and pH = 4, the adsorption capacities of CTSDC and CCTSDC for Pd 2+ is 248.1 mg g −1, 215.4 mg g −1, for Ag + is 157.8 mg g −1, 85.1 mg g −1, respectively. CTSDC and CCTSDC also showed high uptake rates for Pd 2+ and Ag +.

Selective anion recognition: Charged diaza crown ethers based electrochemical sensors for chromate ions

Attempts have been made to develop a poly(vinyl chloride) (PVC) based sensor for CrO 4 2− ions using positively charged diaza crown ethers (12-crown-4 and 18-crown-6) with dibutylphthalate (DBP), dioctylphthalate (DOP) and chloro naphthalene (CN) and dioctylsebacate (DOS) as plasticizing solvent mediators. These sensors work well over a wide concentration range 5.0 × 10 −6 to 1.0 × 10 −1 M (detection limit up to 0.3 ppm) with Nernstian slope (29.6 mV/decade) between pH 6.5 to 10.0 with a fast response time of <10 s. The selectivity coefficient values as determined by Match Potential Method (MPM) indicate excellent selectivity for Cr(VI) ions over a large number of ions. Interference caused by common anions, viz. Cl − and SO 4 2− has been investigated in simulated mixtures containing high concentration level of interfering ions and the sensor was found to be tolerant against these anions. These sensors exhibit adequate shelf-life (>3 months) with good reproducibility (S.D. ±0.2 mV). Quantification of Cr(VI) in electroplating waste was successfully achieved using the proposed sensor.

Synthesis and Complexing Properties of N,N′-Bis(2-hydroxyethyl) Diaza Crown Ethers

The stability constants of complexes of 12-, 15-, and 18-membered diaza crown ethers, N,N′-dimethyl diaza crown ethers, and N,N′-bis(2-hydroxyethyl) diaza crown ethers with alkali and alkaline-earth metal ions in 95% aqueous methanol at 25°C were determined. The stability of the complexes of unsubstituted diaza crown ethers with alkali metal cations is low, probably because of stabilization of the exo,exo conformation of the ligands due to interaction of the nitrogen lone electron pairs with the solvent. The complexes with the double-charged cations are appreciably more stable. N,N′-Dimethyl diaza crown ethers form stable complexes with all the ions studied. As compared to the dimethyl derivatives, N,N′-bis(2-hydroxyethyl) diaza crown ethers form more stable complexes with the Na+, K+, Ca2+, Sr2+, and Ba2+ ions, which is due to participation of the side hydroxyethyl groups in the coordination.

Conductometric Determination of the Stability Constants of the Inclusion Complexes of Alkali Cations with [22-DD] Diaza Crown Ether, [211] and [221] Cryptands in Acetonitrile

An equilibrium study concerning the association of Na+, K+, Rb+ and Cs+ with 4, 7, 13, 18-tetraoxa-1,10-diazabicyclo [8, 5, 5]-eicosane [211], 4, 7, 13, 16, 21-pentaoxa-1, 10-diazabicyclo [8, 8, 5]-tricosane [221] and 4, 13-didecyl-1, 7, 10, 16-tetraoxa-4, 13-diazacyclooctadecane [22-DD] in acetonitrile has been carried out at 25 °C by using a conductometric technique. The observed molar conductivity, Λ, of a test solution was found to decrease significantly for mole ratios less than 1:1 upon the addition of the complexing ligand. A model based on 1:1 stoichiometry has been used to analyze the conductivity data. The data have been fitted according to a non-linear least-squares analysis that provides the stability constant, K, and the molar conductivity, Λc, for each cation – ligand inclusion complex. The binding sequences were found to follow the order: Na+ > K+ > Rb+ ≫ Cs+ (K ≈ 0) for [211], Na+ > K+ > Rb+ > Cs+ for [221] and K+ > Na+ > Rb+ > Cs+ for [22-DD] complexes. Trends in ionic conductivities of complexed ions are also discussed.

Proton-assisted interaction between luminescent species containing diazacrown ethers and anthryl chromophores

The multicomponent species 1 and 2 (structural formulas shown in Fig. 1), made of diazacrown receptors and anthracene-based chromophores, have been synthesized, together with 3, an already-known species containing the anthracene chromophore and an appended amino group. The absorption spectra and luminescence properties of 1–3 have been studied in acetonitrile solution, both in the absence and presence of protons. All of the compounds exhibit luminescence, the intensity of which is enhanced in the presence of protons, and have the role of inhibiting the reductive electron transfer emission quenching processes operating in non-protonated 1–3. The emission intensity of an equimolar solution of 1 and 3 is increased by proton addition, as expected, however the maximum of the intensity is reached when acid concentration is about 1.5 times higher than those of 1 or 3. This suggests that proton-assisted interaction between 1 and 3 takes place. The equimolar solution of 2 and 3 exhibits two emission features, each one assigned to a component chromophore. Low acid concentration leads to enhancement of the 400 nm emission, related to the species 3, and higher acid concentration allows for enhancement of the 520 nm emission, related to the species 2. A closer observation of the luminescence titration curve, as well as NMR data, indicates that a 2·3 adduct is present even before proton addition, and the adduct is further stabilized by protonation to form 2·H·3.

Synthesis of Lariat Diazacrown Ethers with Terminal Amino Groups in the Side Chains.

Treatment of diazacrown ethers with N-(haloalkyl)- and N-(haloethoxy)phthalimides gives the corresponding N,N'- substituted diazacrown ether. Hydrazinolysis of the latter then gives diazacrown ethers with terminal primary amino groups in the side chain. Their reductive methylation using formaldehyde in formic acid gives the dimethylamino derivatives. The presence of a lariat effect was demonstrated by treating the compounds obtained with picrates of alkali and alkaline-earth metals.

Synthesis of Formyl Derivatives of Benzodiazacrown Ethers and Benzocryptands.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis and crystal structure of copper complex of bis( p-chlorophenol)-containing diaza-18-crown-6 ligand

A lariat crown ether ligand 7,16-bis (5-chloro-2-hydroxybenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclo octadecane (H 2L 3) has been prepared via one-pot Mannich reaction. Reaction of H 2L 3 with Cu(NO 3) 2 affords complex Cu–L 3. The complex was characterized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been determined by X-ray diffraction study. The complexation results of Cu(NO 3) 2 with diazacrown ethers containing different phenolic side arms are summarized and analyzed.

Spectroscopic and structural investigations on [(DD18C6)H 2]I 8 formed in the reaction of N, N′-dibenzylated diazacrown ether (DD18C6) with iodine

Photometric titration measurements indicated in the reaction of diazacrown ether N, N ′-dibenzyl-1,4,10,13-tetraoxo-7,16-diazacyclooctadecane (DD18C6, 2) with iodine in chloroform that a complex was formed in the molar ratio DD18C6:I 2=1:4. This complex was also prepared on a preparative scale as dark brown compound and characterized by microanalysis, UV–Vis, IR, and Raman spectroscopy. By X-ray diffraction analysis the solid-state structure of the complex was shown to be [(DD18C6)H 2]I 8 ([ 3]I 8) consisting of a doubly protonated macrocycle and an octaiodide dianion (I 8 2− ) in the typical (nearly planar) Z-shaped geometry. The macrocycle is C i symmetric and the protonated nitrogen atoms adopt an endo– endo orientation that is stabilized by the three-center hydrogen bonds N–H(⋯O) 2, where the oxygen atoms of the macrocycle act as hydrogen acceptors. The orientation of the phenyl groups of the benzyl sidearms are turned above and below the macrocycle. Quantum chemical calculations on the DFT level of theory of the non-protonated and the doubly protonated macrocycle (DD18C6, 2c) and [(DD18C6)H 2] 2+ ( 3c), respectively, were performed and discussed for 3c in terms of conformational strain of the macrocycle, the strength of the intramolecular N–H⋯O hydrogen bonds and cation–π interactions.

Enantioselective transport of amino acids as their potassium and sodium salts by optically active diaza-18-crown-6 ethers having arene sidearms

The enantioselective transport of amino acids as their sodium and potassium salts has been investigated by optically active diaza crown ethers. The reversed enantioselectivity of chiral crown ether 1 was observed.

Synthesis and Enantiodifferentiating Properties of Chiral Aza Crown Ethers.

AbstractFor Abstract see ChemInform Abstract in Full Text.