A comparative study of the thermodynamic properties at the air–water interface and in the bulk of structurally related phenothiazine drugs aqueous solutions

Cheema, Mohammad Arif; Taboada, Pablo; Barbosa, Sílvia; Castro, Emilio; Siddiq, Muhammad; Mosquera, Vı́ctor

doi:10.1016/j.jct.2007.06.008

Cited by 24 publications

(7 citation statements)

References 62 publications

(129 reference statements)

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“…These differences arise from the sensitivity of methods. ,, The surface tension method measures just the micelle formation in the solution; however, the conductivity method measures the conductivity of all the ionic species including micelles present in the solution. Furthermore, surface tension results show, in general, no second critical micelle concentration (cmc*) as found from conductivity measurements …”

Section: Resultsmentioning

confidence: 83%

“…This is attributed to the NaCl promoting structural rearrangement of the micelles. Unfortunately, there are a limited number of reports on systems containing two cmc’s which assumed to result from two states of aggregation or a structural rearrangement of the previously formed aggregates. − The pure and mixed surfactant systems including more than one cmc have not been fully understood yet …”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, surface tension results show, in general, no second critical micelle concentration (cmc*) as found from conductivity measurements. 22 The other adsorption quantities Γ max , A min , and ΔG ads°, were also derived from the surface tension measurements. The maximum surface excess concentration (Γ max ) at the air/ solution interface was obtained from the slope below the cmc using the Gibbs adsorption isotherm: 11,16,17,27 …”

Section: ■ Materials and Methodsmentioning

confidence: 99%

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Effect of Salt on the Micellization of Partially Fluorinated Octylesters and Hydrogenated Dodecylesters in Water

Olutaş

Acımış

2014

J. Chem. Eng. Data

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The effect of added salt, NaCl, on micellization and structural properties of four enantiomeric/racemic surfactant pairs obtained from partially fluorinated octylesters (PFOEs) and hydrogenated dodecylesters (DDEs) of alanine and serine were investigated by electrical conductivity, surface tension, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The Krafft temperatures, the critical micelle concentrations, the degree of counter−ion ionization, and the Gibbs free energy of micellization were determined. The Gibbs free energy of adsorption of the esters at the air/solution interface was greater than that of micellization. The hydrodynamic radius (R H ) increased with salt concentration, and the polydispersity index exhibited a shift from monodisperse to polydisperse aggregates. The PFOEs of serine could incorporate only a minimum amount of salt, but it exhibited the largest R H (37.9 nm). DLS and TEM results indicated that the esters formed micelles of spherical shapes. Neither of the methods could detect an appreciable difference in the micelle sizes of the L-and DL-amphiphiles. The DDEs exhibited greater antibacterial activity against some gram−positive bacteria than the reference antibiotic, tetracycline, but the PFOEs did not show any activity. ■ INTRODUCTIONSurfactants, (amphiphilic molecules) owing to the delicate balance of their hydrophilic and hydrophobic moieties, selfassociate in water to form aggregates called micelles. The micelle formation first occurs at a certain minimum concentration called critical micelle concentration (cmc). This is of paramount importance because the application of surfactants in technology and science is based on the formation of a micelle structure that is able to solubilize a large number of ionic, polar, or neutral materials.The structure of micelles of chiral amphiphilic molecules, because their properties related to chiral recognition may be of importance, then the most biologically active compounds vital to life are chiral. Therefore, in the foregoing paper we studied the micellization process in aqueous solution of a new class of enantiomeric and racemic amphiphilic esters (surfactants) obtained from esterification of the amino acids, alanine (A), and serine (S) with partially fluorinated n-octyl alcohol and hydrogenated dodecyl alcohol, respectively. 1 As a result, we found that the cmc values, the thermodynamic functions (ΔG mic°, ΔH mic°, ΔS mic°) , the adsorption parameters at the air/ water interface (the surface excess concentration, Γ max , the minimum area per headgroup of the molecule, A min , and the surface tension at the cmc, γ cmc ) and the volumetric parameters (the changes in the molal volumes, ΔV φ mic ) of the partially fluorinated esters were strikingly different from those of the hydrogenated ones.Among the adsorption parameters, the quantities, Γ max and A min , for the partially fluorinated octylesters PFOEs of serine were particularly different from all of the studied systems. For comparison and space saving purposes onl...

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Salt on the Micellization of Partially Fluorinated Octylesters and Hydrogenated Dodecylesters in Water

Olutaş

Acımış

2014

J. Chem. Eng. Data

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“…Published data for a number of amphiphiles makes it clear that process of micellization may be more spontaneous even if cmc is increasing. The increase in cmc means delay in micellization process and increase in negative value of ∆G is indicative of spontaneity of process 6 .…”

Section: Resultsmentioning

confidence: 99%

“…The rigidity and planarity of aromatic groups, although an important requirement for latter is not the only structural feature influencing the mode of association, playing also alkyl side chain attached to it, a key role. We have already examined thermodynamic properties of Phenothiazine drug thioridazine hydrochloride 3 butriptyline and doxepine hydrochloride 4 , warfarine sodium salt 5 , promazine and triflupromazine hydrochlorides 6 , certizine hydrochloridel 7 , Dexamethasone Sodium Phosphate 8 and Citalopram Hydrobromide 9 in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Thermodynamic Properties of Structurally Related Phenothiazine Drugs in Aqueous Solution

Usman

Cheema

Khan

et al. 2013

J. Chil. Chem. Soc.

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Association characteristics of amphiphilic phenothiazine drugs Fluphenazine and Trifluperazine dihydrochloride in water have been examined and their thermodynamic parameters have been calculated using conductometry. The electrical conductivity was measured as a function of concentration at various temperatures and cmc was calculated in the temperature range of 20-50°C. Thermodynamic parameters i.e. standard free energy of micellization,

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Solubilization and Release of a Model Drug Nimesulide from PEO–PPO–PEO Block Copolymer Core–Shell Micelles: Effect of Size of PEO Blocks

2013

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A comparative study of the thermodynamic properties at the air–water interface and in the bulk of structurally related phenothiazine drugs aqueous solutions

Cited by 24 publications

References 62 publications

Effect of Salt on the Micellization of Partially Fluorinated Octylesters and Hydrogenated Dodecylesters in Water

Effect of Salt on the Micellization of Partially Fluorinated Octylesters and Hydrogenated Dodecylesters in Water

A Comparative Study of Thermodynamic Properties of Structurally Related Phenothiazine Drugs in Aqueous Solution

Solubilization and Release of a Model Drug Nimesulide from PEO–PPO–PEO Block Copolymer Core–Shell Micelles: Effect of Size of PEO Blocks

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