The influence of water–ethanol mixture on the thermodynamics of complex formation between 18-crown-6 ether and l-phenylalanine

Усачева, Т. Р.; Шарнин, В. А.; Chernov, I. V.; Matteoli, Enrico; Терехова, И. В.; Kumeev, R. S.

doi:10.1016/j.cplett.2012.06.054

Cited by 15 publications

(14 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The influence of a solvent on solvation and complex formation equilibria of stable metal ions and ligands is a known phenomenon (Helm and Merbach 2005 ). For example, preferential solvation may occur when the solution is a mixture of two or more solvents, and effects the reactivity of all participants specifically (Helm and Merbach 2005 ; Rode et al 2005 ; Usacheva et al 2012 ). This phenomenon, however, was never applied in radiopharmaceutical synthesis to economize effectively metal-based radiolabeling.…”

Section: Discussionmentioning

confidence: 99%

“…It was shown previously, that this effect may in particular lead to an increased efficiency of radiometal-ligand complex formation (Usacheva et al 2012 ). Accordingly, a well-designed addition of a certain non-aqueous solvent to a typical aqueous solution might interestingly be used to reduce (a) reaction time, (b) temperature or (c) amount of required precursor of M 3+ -L type radiolabeling reactions.…”

Section: Introductionmentioning

confidence: 90%

See 1 more Smart Citation

Improved radiolabeling of DOTATOC with trivalent radiometals for clinical application by addition of ethanol

Eppard

Pérez-Malo

Rösch

2016

EJNMMI radiopharm. chem.

View full text Add to dashboard Cite

BackgroundTypically, metal-based radiopharmaceuticals are synthesized in aqueous solutions with no or low ethanol content. Labeling yields are defined by temperature, period of labeling, amount of precursor, pH etc. As recently observed, radiolabeling yields (RCY) seem to increase in the presence of non-aqueous solvents. Consequently, this effect was investigated systematically using ethanol as non-aqueous solvent (n-as), which is widely utilized in medicine, and DOTATOC as model compound.MethodsTo determine the impact of ethanol on the radiolabeling efficacy, “standard” labeling conditions of 68Ga-DOTATOC (95–100 °C, 10–15 min, 20–50 μg DOTATOC, aqueous solution), i.e. 10 nmol (2.9 μM, 14.2 μg), were modified in terms of lower temperature (70 °C) to achieve lower RCY (<75 %). From those lower RCY, positive effects of increasing amounts of ethanol (0–40 vol%) could directly be observed. Labeling parameters were finally evaluated in terms of shorter reaction time and lower amount of precursor. To investigate whether the effects observed are also true for other trivalent radiometals, labeling was also performed with 44Sc.ResultsFor increasing amounts of ethanol, 68Ga-DOTATOC RCY at 70 °C improved significantly. RCY of ~95 % can be achieved within 10 min using 30 vol% ethanol compared to 46 % in the pure aqueous system. If “standard” temperatures of 95 °C are applied, high RCY of 89 % can be achieved within 5 min with much lower amounts of precursor, i.e. even at 0.93 nmol (0.3 μM, 1.3 μg). This also represents significantly increased specific activities. Similar behavior was observed for 44Sc where RCY increase successively with increasing amounts of ethanol.ConclusionThere is clear experimental evidence, that adding more than 20 vol% ethanol to the reaction mixtures significantly improve labeling efficacies. This could be demonstrated for 68Ga-DOTATOC and 44Sc-DOTATOC in terms of temperature, time and concentration of required precursor. Whether this is a principal phenomenon with practical impact on the radiopharmaceutical chemistry of trivalent metals and whether this applies to other non-aqueous solvents as well - and what the physico-chemical reasons are, remains to be studied in more detail. Nevertheless, the effect observed here will improve 68Ga-DOTATOC labeling and may save at least half of the usually applied amount of precursor.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Improved radiolabeling of DOTATOC with trivalent radiometals for clinical application by addition of ethanol

Eppard

Pérez-Malo

Rösch

2016

EJNMMI radiopharm. chem.

View full text Add to dashboard Cite

show abstract

“…The changes in the stability of the molecular complexes [BA⊂β-CD] were compared with those of the molecular complexes of 18-crown-6 ether (18C6) with glycyl–glycyl–glycine (3Gly), [3Gly18C6] [ 51 , 52 ], glycine (Gly), [Gly18C6] [ 53 , 54 ] and phenylalanine (Phe) [Phe18C6] [ 55 , 56 ] during the transfer from water to water–organic solvents ( Figure 10 and Figure 11 ). These objects were selected for comparison of the “guest–host” molecular complexes formation in aqueous-organic solvents.…”

Section: Discussionmentioning

confidence: 99%

Complexation of Cyclodextrins with Benzoic Acid in Water-Organic Solvents: A Solvation-Thermodynamic Approach

et al. 2021

View full text Add to dashboard Cite

The aim of this research is to obtain new data about the complexation between β-cyclodextrin (β-CD) and benzoic acid (BA) as a model reaction of the complex formation of hydrophobic molecules with cyclodextrins (CDs) in various media. This research may help developing cyclodextrin-based pharmaceutical formulations through the choice of the appropriate solvent mixture that may be employed in the industrial application aiming to control the reactions/processes in liquid phase. In this paper, NMR results for the molecular complex formation between BA and β-CD ([BA⊂β-CD]) in D2O-DMSO-d6 and in D2O-EtOH have shown that the stability of the complex in the H2O-DMSO-d6 varies within the experimental error, while decreases in H2O-EtOH. Changes in the Gibbs energy of BA resolvation in water and water–dimethylsulfoxide mixtures have been obtained and have been used in the analysis of the reagent solvation contributions into the Gibbs energy changes of the [BA⊂β-CD] molecular complex formation. Quantum chemical calculations of the interaction energy between β-CD and BA as well as the structure of the [BA⊂β-CD] complex and the energy of β-CD and BA interaction in vacuum and in the medium of water, methanol and dimethylsulfoxide solvents are carried out. The stability of [BA⊂β-CD] complex in H2O-EtOH and H2O-DMSO solvents, obtained by different methods, are compared. The thermodynamic parameters of the [BA⊂β-CD] molecular complexation as well as the reagent solvation contributions in H2O-EtOH and H2O-DMSO mixtures were analyzed by the solvation-thermodynamic approach.

show abstract

“…The equation (9) and the data of the 10is not possible now due to the absence of ΔtrG 0 values for succinic acid anion (trG 0 (L 2-)), and also those for Со 2+ (trG 0 (Со 2+ )). values are close each other form 0.0 up to 0.5 mole fractions of ethanol (Fig.…”

Section: H2l  H + + Hl -mentioning

confidence: 99%

“…The estimation of the influence of mixed solvent composition on the thermodynamic solvation parameters of reagents and products (G, H, S), and the derivation of proper relationships between their solvation parameters and those of reaction, allow to devise predictive models for complex formation reactions. Studies of the complex formation reaction of d-metal ions with amine, carboxylate and crown-ethers [1][2][3][4][5][6][7][8] as well as molecular complexes of crown-ether with amino acids and peptides [9,10] have revealed several general rules governing thermodynamics of reactions and solvation of the reagents in aqueous-organic solvents. These rules have shown the possibility of predicting the thermodynamic parameters of complex formations in different media according to a change in the solvation state of ligands.…”

Section: Introductionmentioning

confidence: 99%

STABILITY OF COORDINATION COMPOUNDS OF SOME d-METAL IONS WITH SUCCINIC ACID ANION IN AQUEOUS-ETHANOL SOLVENTS

Tukumova¹,

Усачева²,

Thuan³

et al. 2018

IVUZKKT

View full text Add to dashboard Cite

The paper provides an overview of own data on complexation of nickel (II), cobalt (II) and cooper (II) ions with succinic acid anion in water-organic mixed solvents. Proper data are compared with data reported in literature for d-metal complexes with anions of maleic and succinic acids. The effect of aqueous ethanol solvent compositions on the stability of coordination compounds of M2+ with succinic acid anion as well as on рК values of stepwise succinic acid dissociation was carried out by a potentiometric titration at ionic strength of 0.1 maintained with sodium perchlorate at 298.15 ± 0.10 K. Mono ligand complexes of Ni2+, Co2+ and Cu2+ ions with succinic acid anion become stronger when ethanol content rises. In aqueous solutions Cu2+ ion forms stronger complexes with succinic and maleic acid anions than Ni2+ and Co2+ ions. In the studied water - ethanol solution this ratio is maintained for complexes with succinic acid anion, but a water-isopropanol solvent exerts leveling effect on the stability of complexes of nickel (II) and cobalt (II). An increase in the stability of complexes of d-metal with anions of maleic and succinic acids is due to the destabilization of the ligand with increasing ethanol concentration. The principal contribution of the changes in the solvation state of ligand is a typical for the stability changes of d-metal complexes with amine, glycinate, and acetate type ligands in water-organic mixed solvents. For citation: Tukumova N.V., Usacheva T.R., Thuan Tran Thi Dieu, Sharnin V.A., Giancola C. Stability of coordination compounds of some d-metal ions with succinic acid anion in aqueous-ethanol solvents. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 15-22

show abstract

The influence of water–ethanol mixture on the thermodynamics of complex formation between 18-crown-6 ether and l-phenylalanine

Cited by 15 publications

References 26 publications

Improved radiolabeling of DOTATOC with trivalent radiometals for clinical application by addition of ethanol

Improved radiolabeling of DOTATOC with trivalent radiometals for clinical application by addition of ethanol

Complexation of Cyclodextrins with Benzoic Acid in Water-Organic Solvents: A Solvation-Thermodynamic Approach

STABILITY OF COORDINATION COMPOUNDS OF SOME d-METAL IONS WITH SUCCINIC ACID ANION IN AQUEOUS-ETHANOL SOLVENTS

Contact Info

Product

Resources

About