Electrochemical reduction of monovalent cation complexes of macrocyclic ionosphores. I. crown polyether complexes

Hofmanová, A.; Koryta, J.; Březina, M.; Mittal, M. L.

doi:10.1016/s0020-1693(00)87416-2

Cited by 59 publications

(15 citation statements)

References 25 publications

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“…4Wo.anion in the formation of the 2:1 complex is of great importance. The crystallographic structure of the 2: 1 sodium o-nitrophenolate complex with DB24(X3' shows the partition of the ligand molecule in two distinct and symmetrical regionsDownloaded by [McMaster University] at 10:Li' Mu; 2, Na' Mu; 3, Na' DB24C8; 4, Li'DB24C8.Variation of stabilities of different murexide and DB24C8 complexes with X, each sodium ion is hexacoordinated to the bidentate anion and four ether oxygens of the ring.It is interesting to note that extrapolation of the linear plot of log K, vs X, , , (Figure 5) to a DMF mole fraction of zero results in log K, = 4.16 for Na+-DB24C8 in pure acetonitrile, a value which is in satisfactory agreement with the previously reported log K, = 4.00 in this solvent 38. Unfortunately, there is no reported formation constant for Li' -DB24C8 complex in the literature for comparison.…”

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confidence: 90%

Spectrophotometric Study of the Thermodynamics of Complexation of Lithium and Sodium Ions With Dibenzo-24-Crown-8 in Binary Dimethylformamide-Acetonitrile Mixtures Using Murexide as a Metallochromic Indicator

Khajesharifi

Shamsipur

1995

Journal of Coordination Chemistry

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Complexation of Li' and Na' with dibenzo-24-crown-8 has been studied in dimethylformamideacetonitrile mixtures by means of a competitive spectrophotometric technique using murexide as metal ion indicator. Stabilities of the resulting I:I complexes were investigated at various temperatures and enthalpies and entropies of complexation were determined from the temperature dependence of the formation constants. Sodium forms a more stable complex with the crown ether than lithium. There is an inverse linear relationship between log K, and the molc fraction of DMF in thc solvent mixturcs. Thc AH"-TAS" plot of all thcrmodynamic data. obtaincd for both crown complexes in different solvent mixtures, shows a fairly good linear correlation. indicating thc existence of an enthalpy-entropy compensation effect in complexation.

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confidence: 90%

Spectrophotometric Study of the Thermodynamics of Complexation of Lithium and Sodium Ions With Dibenzo-24-Crown-8 in Binary Dimethylformamide-Acetonitrile Mixtures Using Murexide as a Metallochromic Indicator

Khajesharifi

Shamsipur

1995

Journal of Coordination Chemistry

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“…The solvent effect is known to influence the complexation and extraction selectivities of the crown ethers, for instance, 18C6 prefer K 1 in polar protic solvents (water, methanol), 61,62 but Na 1 in acetonitrile. 63 15-crown-5 selectively complexes Na 1 in acetonitrile 64 and in pyridine, 65 4 L/Na 1, so the affinity of the crown ether part of L for Na 1 is reduced by coordinating with the W(CO) 4 fragment at the 2,2 0 -bipyridyl site of L, and this result is in a good agreement with the experiments. 13 The rigidity of the crown ether of L is increased because of the introduction of the W(CO) 4 fragment at bpy site of it.…”

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confidence: 79%

Density functional theory study of a molecular allosteric switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5

et al. 2010

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A classical model of "molecular machine," which acts as an ON-OFF switch for 2,2'-bipyridyl-3,3'-15-crown-5 (L), has been theoretically studied. It is highly important to understand the mechanism of this switch. The alkali-metal cations (Na(+) and K(+) ) and W(CO)(4) fragment are introduced to coordinate with the different active sites of L, respectively. The density functional theory (DFT) method is used for understanding the stereochemical structural natures and thermodynamic properties of all the target molecules at B3LYP/6-31G(d) and SDD (Stuttgart-Dresden) level, together with the corresponding effective core potential (ECP) for tungsten (W). The fully optimized geometries have been performed with real frequencies, which indicate the minima states. The nucleophilicity of L has been investigated by the Fukui functions. The natural bond orbital analysis is used to study the intermolecular charge-transfer interactions and explore the origin of the internal forces of the molecular switch. In addition, the binding energies, enthalpies, Gibbs free energies, and the cation exchange energies have been studied for L, W(CO)(4) L, and their corresponding complexes. The properties of the complexes displayed by in presence or absence of the W(CO)(4) fragment are also analyzed. The calculated results of allosterism displayed by L are in a good agreement with the experimental results.

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“…For instance, 18C6 prefers to K ＋ in polar protic solvents (water, methanol), 42,43 but Na ＋ in acetonitrile. 44 15-Crown-5 selectively complexes Na ＋ in acetonitrile 45 and in pyridine, 46 but K ＋ in methanol, 47 Cs ＋ in water 48 and Li ＋ in propylene carbonate. 49 The ring-contracted 14C5 has the lowest -∆E b in its series and indicates a mismatched situation when it coordinates with metal cations (Na ＋ and K ＋ ).…”

Section: Binding Energiesmentioning

confidence: 99%

DFT Study for a Series of Less‐Symmetrical Crown Ethers and Their Complexes with Alkali Metal Cations

et al. 2010

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A series of ring-contracted (14-crown-5, 17-crown-6) and ring-enlarged (16-crown-5, 17-crown-5, 19-crown-6, 20-crown-6) crown ethers and their complexes with alkali-metal cations Na ＋ and K ＋ had been explored using density functional theory (DFT) at B3LYP/6-31G* level in order to reveal the effects of the methylene-chain length in a crown ether. The nucleophilicity of all crown ethers had been investigated by the Fukui functions. The quantum chemistry parameters, such as the energy gap (∆E), the highest occupied molecular orbital energy (E HOMO ) and the lowest unoccupied molecular orbital energy (E LUMO ) for less-symmetrical crown ethers and symmetrical frameworks (15-crown-5, 18-crown-6) had been calculated. In addition, the thermodynamic energies of complexation reactions had also been studied. The results of the DFT calculations show that the methylene-chain length plays an important role in determining the structure characters of the crown ethers and also strongly influences the properties of the ethers. Some of the calculated results are in a good agreement with the experimental values.

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Electrochemical reduction of monovalent cation complexes of macrocyclic ionosphores. I. crown polyether complexes

Cited by 59 publications

References 25 publications

Spectrophotometric Study of the Thermodynamics of Complexation of Lithium and Sodium Ions With Dibenzo-24-Crown-8 in Binary Dimethylformamide-Acetonitrile Mixtures Using Murexide as a Metallochromic Indicator

Spectrophotometric Study of the Thermodynamics of Complexation of Lithium and Sodium Ions With Dibenzo-24-Crown-8 in Binary Dimethylformamide-Acetonitrile Mixtures Using Murexide as a Metallochromic Indicator

Density functional theory study of a molecular allosteric switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5

DFT Study for a Series of Less‐Symmetrical Crown Ethers and Their Complexes with Alkali Metal Cations

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