Showing papers on "15-Crown-5 published in 2012"
TL;DR: Thermochemistry data calculated on the basis of the stable conformers of the complexes suggest that the ion selectivity of crown ethers is controlled primarily by the enthalpy change for the complex formation in solution, which depends strongly on the complex structure.
Abstract: Electronic and vibrational spectra of benzo-15-crown-5 (B15C5) and benzo-18-crown-6 (B18C6) complexes with alkali metal ions, M+•B15C5 and M+•B18C6 (M = Li, Na, K, Rb, and Cs), are measured using UV photodissociation (UVPD) and IR–UV double resonance spectroscopy in a cold, 22-pole ion trap. We determine the structure of conformers with the aid of density functional theory calculations. In the Na+•B15C5 and K+•B18C6 complexes, the crown ethers open the most and hold the metal ions at the center of the ether ring, demonstrating an optimum matching in size between the cavity of the crown ethers and the metal ions. For smaller ions, the crown ethers deform the ether ring to decrease the distance and increase the interaction between the metal ions and oxygen atoms; the metal ions are completely surrounded by the ether ring. In the case of larger ions, the metal ions are too large to enter the crown cavity and are positioned on it, leaving one of its sides open for further solvation. Thermochemistry data calcu...
62 citations
TL;DR: The behavior of magnesium octa(benzo-15crown-5)phthalocyaninate in water medium in the presence of sodium dodecyl sulfate was studied using both electronic and 1H NMR spectroscopy, including the method of two-dimensional 1H-1H correlation NOESY as discussed by the authors.
Abstract: The behavior of magnesium octa(benzo-15-crown-5)phthalocyaninate in water medium in the presence of sodium dodecyl sulfate was studied using both electronic and 1H NMR spectroscopy, including the method of two-dimensional 1H-1H correlation NOESY. In the microheterogeneous environment of the CH3(CH2)11OSO3Na solutions at the concentrations of the latter close to the CMC the phthalocyanine is in monomeric form, while at the concentration less than the critical micelle-formation concentration it becomes a dimer or even more aggregated. The results of the NMR spectroscopic investigation indicate that magnesium octa(benzo-15-crown-5)phthalocyaninate preferrably binds to the CH3(CH2)11OSO3Na micelle in the hydrophobic region of the latter.
25 citations
TL;DR: This work presents a systematic investigation of the low energy conformational landscape of the benchmark macrocycle 15-crown-5 ether (15c5) under isolated conditions and illustrates well the variety of conformers of prolate and oblate character that the 15c5 molecule displays within a narrow range of energies.
Abstract: Crown ether macrocyles constitute a central class of selective substrates in Supramolecular Chemistry. The backbone of crown ethers is particularly flexible which makes the spectroscopic and computational investigations challenging. In this work, we present a systematic investigation of the low energy conformational landscape of the benchmark macrocycle 15-crown-5 ether (15c5) under isolated conditions. Molecular beam Fourier transform microwave spectroscopy is employed to measure a broad ensemble of rotational transitions within the range of 4–11 GHz. The recorded spectra allow us to determine the rotational constants of eight individual 15c5 rotamers which are identified among the nine lowest energy conformers predicted by ab initio MP2 computations. The study illustrates well the variety of conformers of prolate and oblate character that the 15c5 molecule displays within a narrow range of energies. Implications for the supramolecular behavior of 15c5 are discussed.
13 citations
TL;DR: In this article, the stability constants for complexation reactions of Cr3+, Mn2+ and Zn2+ metal cations with macrocyclic ligand, 15-crown-5 (15C5), in acetonitrile (AN), ethanol (EtOH) and also in their binary solutions (AN-Etoh) were determined at different temperatures, using conductometric method.
Abstract: The stability constants (Kf) for the complexation reactions of Cr3+, Mn2+ and Zn2+ metal cations with macrocyclic ligand, 15-crown-5 (15C5), in acetonitrile (AN), ethanol (EtOH) and also in their binary solutions (AN–EtOH) were determined at different temperatures, using conductometric method. 15C5 forms 1:1 complexes with Cr3+, Mn2+ and Zn2+ cations in solutions. A non-linear behaviour was observed for changes of logKf of the metal ion complexes versus the composition of the mixed solvent. The order of stability of the metal–ion complexes in pure AN and in a binary solution of AN–EtOH (mol% AN = 52) at 25 °C was found to be: (15C5Zn)2+ > (15C5·Mn)2+ > (15C5·Cr)3+, but in the case of pure EtOH at the same temperature, it changes to: (15C5·Zn)2+ > (15C5·Cr)3+ > (15C5·Mn)2+. The results also show that the stability sequence of the complexes in the other binary solutions of AN–EtOH (mol% AN = 26 and mol% AN = 76) varies in order: (15C5·Cr)3+ ~ (15C5·Zn)2+ > (15C5·Mn)2+. The values of the standard thermodynamic quantities (ΔHC°, ΔSC°) for formation of (15C15-Cr3+), (15C5-Mn2+) and (15C5-Zn2+) complexes were obtained from the temperature dependence of the stability constants and the results show that the thermodynamics of complexation reactions is affected by nature and composition of the solvent systems and in most solution systems, the complexes are enthalpy stabilized but entropy destabilized.
13 citations
TL;DR: In this paper, Li-NMR spectroscopy was used to study the complexation of Li + ion with 12C4, 15C5, C222, C221, C211 in acetonitrile (AN) and its 50% (wt/wt) mixtures with two new room temperature ionic liquids, 1-ethyl-3-methylimidazolium hexafluorophosphate (EMim PF 6 ) and 1-methyl-3methyloride tetrafluoroborate(EMim BF 4 ) at
9 citations
TL;DR: In this article, the enthalp size of 15-crown-5 (15C5) ether in methanol-water mixtures has been measured at 293.15-308.15 K. The relative importance of the solvation mechanism depended on co-solvent properties.
8 citations
01 Jan 2012
8 citations
TL;DR: In this paper, a new benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared by condensation of corresponding crown ether diamine with salicylaldehyde derivatives.
Abstract: New benzo-15-crown-5 derivatives containing nitro, amine and imine groups were prepared. Nitro compound (1) was prepared after the reaction 4′,5′-bis(bromethyl)benzo-15-crown-5 and o-nitrophenol in the presence of NaOH. After reduction process by using hydrazine hydrate and Pd/C amine compound (2) was formed. New crown ether imine compounds (3–5) were synthesized by the condensation of corresponding crown ether diamine (2) with salicylaldehyde derivatives. Sodium complexes of the crown compounds (1a–5a) form crystalline 1:1 (Na+: ligand) complexes with sodium perchlorate. Nickel(II) complexes (3b–5b) with 1:1 (Ni2+:ligand) stoichiometries were also been synthesized from the Schiff bases (3–5). The results indicated that the Schiff base ligands coordinated through the azomethine nitrogen and phenolic oxygen. The extraction ability of compounds (1, 3, 4 and 5) were also evaluated in chloroform by using several alkali and transition metal picrates such as Li+, Na+, K+, Cr3+, Mn2+, Ni2+, Cu2+, Zn2+ and Pb2+.
8 citations
TL;DR: In this paper, the stochastic stability of N-phenylaza-15-crown-5 (PhA15C5) with UO2 2 + cation was studied in acetonitrile-methanol (AN-MeOH), AN-BuOH, AN-DMF and methanol-propylencarbonate (MeOH-PC) binary solutions, at different temperatures by conductometry method.
Abstract: The complexation reaction of N-phenylaza-15-crown-5 (PhA15C5) with UO2
2+ cation was studied in acetonitrile–methanol (AN–MeOH), acetonitrile–butanol (AN–BuOH), acetonitrile–dimethylformamide (AN–DMF) and methanol–propylencarbonate (MeOH–PC) binary solutions, at different temperatures by conductometry method. The conductance data show that the stoichiometry of the complex formed between PhA15C5 with UO2
2+ cation in most cases is 1:1 [M:L], but in some solvent systems a 1:2 [M:L2] complex is formed in solutions. The results revealed that, the stability constant of (PhA15C5·UO2)2+ complex in the binary mixed solvents varies in the order: AN–BuOH>AN–MeOH>AN–DMF. In the case of the pure organic solvents, the sequence of the stability of the complex changes as: AN>PC>BuOH>DMF. A non-linear relationship was observed for changes of logKf of (PhA15C5·UO2)2+ complex versus the composition of the binary mixed solvents. The corresponding standard thermodynamic parameters (ΔHc°, ΔSc°) were obtained from temperature dependence of the stability constant. The results show that the values and also the sign of these parameters are influenced by the nature and composition of the mixed solvents.
7 citations
TL;DR: In this article, the complexation reaction between Y3+ cation with N-phenylaza-15-crown-5(Ph-N15C5.Y)3+ complex was studied at different temperatures in acetonitrile-methanol (AN/MeOH), acetitrilepropanol (AN)/PrOH, acetrile-1,2 dichloroethane (AN,DCE), and acetitile-water(AN/H2O) binary mixtures using the conductometric method.
Abstract: The complexation reaction between Y3+ cation with N-phenylaza-15-crown-5(Ph-N15C5) was studied at different temperatures in acetonitrile–methanol (AN/MeOH), acetonitrile–propanol (AN/PrOH), acetonitrile–1,2 dichloroethane (AN/DCE) and acetonitrile–water (AN/H2O) binary mixtures using the conductometric method. The results show that in all cases, the stoichiometry of the complex is 1:1 (ML). The values of formation constant of the complex which were determined using conductometric data, show that the stability of (Ph-N15C5.Y)3+ complex in pure solvents at 25 °C changes in the following order: PrOH > AN > MeOH and in the case of binary mixed solutions at 25 °C it follows the order: AN–DCE > AN–PrOH > AN–MeOH > AN–H2O. The values of standard thermodynamic quantities (∆Hc° and ∆Sc°) for formation of (Ph-N15C5.Y)3+ complex were obtained from temperature dependence of the formation constant using the van’t Hoff plots. The results show that in most cases, the complex is entropy and enthalpy stabilized and these parameters are influenced by the nature and composition of the mixed solvents. In most cases, a non-linear behavior was observed for variation of log Kf of the complex versus the composition of the binary mixed solvents. In all cases, an enthalpy–entropy compensation effect was observed for formation of (Ph-N15C5.Y)3+ complex in the binary mixed solvents.
6 citations
TL;DR: In this paper, the binding properties of benzodiaza-15-crown-5 ether derivatives towards different metal ions (Mg(II), Cd, Ni, Ni and Ag(I)) in acetonitrile and water by potentiometric and optical methods were analyzed.
TL;DR: In this article, the crystal and molecular structures of the resulting compounds were determined by X-ray diffractometry, showing sodium-sulfur and sodium-selenium interactions, respectively, forming discrete inorganic chelate rings.
TL;DR: Two kinds of novel styryl chemosensory 2FMNC and 3FMNC derivatives were designed and synthesized by an apporiate introduction of 9-benzylidene-9H-fluorene group as fluorophore with the aim at avoiding photoisomerization as discussed by the authors.
Abstract: Two kinds of novel styryl chemosensory 2-FMNC and 3-FMNC, were designed and synthesized by an apporiate introduction of 9-benzylidene-9H-fluorene group as fluorophore with the aim at avoiding photoisomerisation. These 9-benzylidene-9H-fluorene derivatives showed the similar selectivity and sensitivity upon addition of metal ions. The sensitivity of FMNC to alkaline earth metal ions was Ba2+>Sr2+>Ca2+≈Mg2+.
TL;DR: In this article, the capability of 15-crown-5 ethers to form complexes with some metal cations (Li +, Na +, K +, Zn 2+, Cd 2+ and Hg 2+ ) was investigated by an ab initio quantum mechanical method.
Abstract: The capability of 15-crown-5 ethers to form complexes with some metal cations (Li + , Na + , K + , Zn 2+ , Cd 2+ and Hg 2+ ) was investigated by an ab initio quantum mechanical method. The calculations were performed at the RHF/lanl2mb level of theory. The interaction energies were used to evaluate the metal binding capability of the crown ether. The effect of nature of the metal on the binding properties was also studied. The results of the calculations showed that the interaction energy of the complexes increased in proportion with the ratio of ion charge, electronegativity and ionization potential to the cation diameter. In addition, based on the extraction distribution coefficient in the gas phase, it is found that the 15-crown-5 could not extract metal cations investigated.
TL;DR: In this article, a crown-containing phthalocyanine with participation of water-soluble fullerene compounds was shown to dissolve in the presence of C60Cl(NHCH2CH2NH3 +)5(−OOCCF3)5.
Abstract: Octa[(4′-benzo-15-crown-5)oxy]phthalocyanine was shown to dissolve in the presence of water-soluble fullerene compounds C60Cl(NHCH2CH2NH3
+)5(−OOCCF3)5 or C60Cl(C6H4CH2CH2COONa)5. The solubilization of phthalocyanine was attributed to the possibility of formation of the hydrogen bonds N-H...O(CH2) and coordination of the sodium cations inside the cavities of the crown ether fragments for the cationic and anionic fullerene derivatives, respectively. Solubilization of the crown-containing phthalocyanine with participation of water-soluble fullerene compounds proceeded with the formation of aggregated forms. A monomeric form of nickel tetrasulfonated phthalocyaninate in the presence of an equimolar amount of C60Cl(NHCH2CH2NH3
+)5(−OOCCF3)5 in 50% ethanol is transformed into a dimeric form. The structures of the fullerene-containing compounds and their state in solution facilitate the stacking aggregation of phthalocyanines.
TL;DR: In this paper, two polypyridyl ligands, 5-(4′-ethynylbenzo-15-crown-5)-2,2′-bipyridine (L1), and their Ru(II) complexes [(bpy)2RuL](PF6)2 have been prepared and characterized.
Abstract: Two polypyridyl ligands, 5-(4′-ethynylbenzo-15-crown-5)-2,2′-bipyridine (L1) and 3-bromo-8-(4′-ethynylbenzo-15-crown-5)-1,10-phenanthroline (L2), and their Ru(II) complexes [(bpy)2RuL](PF6)2 have been prepared and characterized. Both complexes exhibit metal-to-ligand charge transfer absorption at around 452 nm and emission at around 640 nm in MeCN solution. Electrochemical studies of the complexes reveal a Ru(II)-centered oxidation at around 1.31 V and three ligand-centered reductions. The binding ability of the complexes with Na+ has been investigated by UV/Vis absorption, emission, and electrochemical titrations. Addition of Na+ to MeCN solutions of both complexes results in a progressive enhancement of the emission, a red-shift of the UV/Vis absorption, and a progressive cathodic shift of the Ru(II)-centered E1/2 couple. The stability constants for the 1:1 stoichiometry adducts of the complexes with Na+ have been obtained from the UV/Vis absorption titrations.
TL;DR: In this article, it was shown that syndiotactic polystyrene (sPS) forms crystalline complexes with 15-crown-5 (15C5) and 18-c Crown-6 (18C6).
Abstract: Neutron diffraction experiments were carried out in order to confirm that syndiotactic polystyrene (sPS) forms crystalline complexes with 15-crown-5 (15C5) and 18-crown-6 (18C6). A strong 010 refle...
Journal Article•
TL;DR: In this paper, the formation of charge transfer complexation between dibenzo-15crown-5 (DB15C5) and benzo-12crown 4 (B12C4) (Donor) and iodine is investigated spectrophotometrically in three chlorinated solvents, chloroform, dichloromethane (DCM) and 1,2-dichloroethane (DCE) solution at 25°C.
Abstract: The formation of charge-transfer complexation between dibenzo-15-crown-5 (DB15C5) and benzo-12crown-4 (B12C4) (Donor) and iodine is investigated spectrophotometrically in three chlorinated solvents, chloroform, dichloromethane (DCM) and 1,2-dichloroethane (DCE) solution at 25°C. The change in polarity of the solvent also doesn’t affect the stoichiometry of the complexes. Values of formation constants reflect the order of ionization potentials of the donors. The observed time dependence of the charge-transfer band and subsequent formation of I3ion are related to the slow formation of the initially formed 1:1 Donor.I2 outer complex to an inner electron donor-acceptor (EDAr) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion, as follows: Donor + I2 → Donor. I2 (outer complex), fast Donor.I2 (outer complex) → (Donor. I+)I(inner complex), slow (Donor . I+)I(inner complex) + I2 → (Donor .I+)I3-, fast The pseudo-first-order rate constants for the transformation process were evaluated in different solvent systems. The stability constants of the resulting EDAr complexes were also evaluated and the solvent effect on their stability are discussed. The resulting complexes were isolated and characterized by FTIR and 1HNMR spectroscopy.
TL;DR: In this paper, a = 12.915(3) Å, b = 11.515(2)Å, c = 24.758(5)À, + = 92.12°, V = 3679.4 Å.
Abstract: C28H44AgNO10S4W, monoclinic, P21/n (no. 14), a = 12.915(3) Å, b = 11.515(2) Å, c = 24.758(5) Å, + = 92.12(3)°, V = 3679.4 Å, Z = 4, Rgt(F) = 0.059, wRref(F ) = 0.164, T = 291 K.
TL;DR: In this paper, the authors studied the complexation reaction of macrocyclic ligand (4′-nitrobenzo-15C5) with Y3+ cation with binary mixtures at different temperatures using conductivity data.
Abstract: The complexation reaction of macrocyclic ligand (4′-nitrobenzo-15C5) with Y3+ cation was studied in acetonitrile-methanol (AN-MeOH), acetonitrile-ethanol (AN-EtOH), acetonitrile-dimethylformamide (AN-DMF) and ethylacetate-methanol (EtOAc-MeOH) binary mixtures at different temperatures using conductometry method. The conductivity data show that in all solvent systems, the stoichiometry of the complex formed between 4′-nitrobenzo-15C5 and Y3+ cation is 1: 1 (ML). The stability order of (4′-nitrobenzo-15C5). Y3+ complex in pure non-aqueous solvents at 25°C was found to be: EtOAc > EtOH > AN ≈ DMF > MeOH, and in the case of most compositions of the binary mixed solvents at 25°C it was: AN≈MeOH ≈ AN-EtOH > AN-DMF > EtOAc-MeOH. But the results indicate that the sequence of the stability of the complex in the binary mixed solutions changes with temperature. A non-linear behavior was observed for changes of logKf of (4′-nitrobenzo-15C5 · Y3+) complex versus the composition of the binary mixed solvents, which was explained in terms of solvent-solvent interactions and also the hetero-selective solvation of the species involved in the complexation reaction. The values of thermodynamic parameters (ΔHcℴ and ΔScℴ) for formation of the complex were obtained from temperature dependent of the stability constant using the van′t Hoff plots. The results represent that in most cases, the complex is both enthalpy and entropy stabilized and the values and also the sign of thermodynamic parameters are influenced by the nature and composition of the mixed solvents.
Journal Article•
TL;DR: In this paper, the complexation reactions between aza-15-crown-5 (A15C5) ligand with Zn2+, Hg2+, Co2+, Ag+ and Cd2+ ions have been studied by conductometric and spectrophotometric methods in acetonitrile solution at various temperatures.
Abstract: In this paper, the complexation reactions between aza-15-crown-5 (A15C5) ligand with Zn2+, Hg2+, Co2+, Ag+ and Cd2+ ions has been studied by conductometric and spectrophotometric methods in acetonitrile solution at various temperatures. The formation constants of the resulting 1:1 complexes were calculated fromthe computer fitting of the molar conductancemole ratio data at different temperatures. At 25oC, the order of stability of the 1:1 complexes of theA15C5 ligand with different cations are as Hg2+> Co2+> Cd2+> Zn2+>Ag+.The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. In addition, 1HNMR study of complexes of nitrate salt of Cd+2 in acetonitrile withA15C5 ligand at 25i°C has been also undertaken to compare the results with those obtained by conductivity and UV measurements, which have been found to be in good agreement with each other. Finally, ab initio studies of the level of HF/lanl2dz have been done to investigate the binding energies of the ligand with Ag+ and Hg2+. All theoretical data are in line with the experimental ones.