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Sanchez F, Barrios A, Lopez-Lopez M, Lopez-Cornejo P, Bernal E, Sarrion B, Lebron J, Marchena M. A New Formulation for Quenching Processes under Restricted Geometry Conditions in the Slow Exchange Limit. Progress in Reaction Kinetics and Mechanism 2014. [DOI: 10.3184/146867814x13981545065017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A quantitative treatment of quenching processes under restricted geometry conditions in the Slow Exchange Limit is presented. The expressions for KSV have been obtained for this limit in some common situations that can arise in studies under restricted geometry conditions, such as an inhomogeneous quencher distribution in the solution, the presence of oxygen in solution, or the case of solutions containing a mixture of receptors. These situations have been considered and incorporated into the treatment.
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Affiliation(s)
- F. Sanchez
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - A. Barrios
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - M. Lopez-Lopez
- Department of Chemical Engineering, Physical Chemistry and Organic Chemistry, University of Huelva, Avenida de las Fuerzas Armadas s/n, Huelva, 21071, Spain
| | - P. Lopez-Cornejo
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - E. Bernal
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - B. Sarrion
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - J.A. Lebron
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
| | - M. Marchena
- The Department of Physical Chemistry, University of Sevilla, C/Profesor Garcia Gonzalez s/n, 41012 Sevilla, Spain
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García JP, Marrón E, Martín VI, Moyá ML, Lopez-Cornejo P. Conformational changes of DNA in the presence of 12-s-12 gemini surfactants (s=2 and 10). Role of the spacer's length in the interaction surfactant-polynucleotide. Colloids Surf B Biointerfaces 2014; 118:90-100. [PMID: 24736044 DOI: 10.1016/j.colsurfb.2014.03.040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/22/2014] [Accepted: 03/16/2014] [Indexed: 12/27/2022]
Abstract
A multifaceted study on the interaction of calf-thymus DNA with two different cationic gemini surfactants alkanediyl-α-ω-bis(dodecyldimethyl-amonium)bromide, 12-s-12,2Br(-) (with s=2, G2, and 10, G10) was carried out. The measurements were done at different molar ratios X=[surfactant]/[DNA]. Results show two different conformational changes in DNA: a first compaction of the polynucleotide corresponding to a partial conformational (not total) change of DNA from an extended coil state to a globular state that happens at the lower molar ratio X. A second change corresponds to a breaking of the partial condensation, that is, the transition from the compacted state to a new more extended conformation (for the higher X values) different to the initial extension. According to circular dichroism spectra and dynamic light scattering measurements, this new state of DNA seems to be similar to a ψ-phase. Measurements confirm that interactions involved in the compaction are different to those previously obtained for the analog surfactant CTAB. X values at which the conformational changes happen depend on the length of the spacer in the surfactant along with the charge of the polar heads.
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Affiliation(s)
- J P García
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain
| | - E Marrón
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain
| | - V I Martín
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain
| | - M L Moyá
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain
| | - P Lopez-Cornejo
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/Prof. García González n° 1, Sevilla 41012, Spain.
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Lopez-Lopez M, Montilla F, Olivares M, Lebron JA, Moya ML, Lopez-Cornejo P. Interaction between monomers of two surfactants derived from the [Ru(2,2'-bpy)(3)](2+) complex and α, β and γ-cyclodextrins: formation of [2]- and [3]-pseudorotaxanes. Dalton Trans 2013; 42:6171-81. [PMID: 23525374 DOI: 10.1039/c3dt32197e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two new surfactants derived from the tris(2,2'-bipyridine) ruthenium(II) complex, [Ru(2,2'-bpy)(3)](2+), were synthesized and characterized: the double-tailed [Ru(2,2'-bipy)2(4,4'-(C(11)H(23))(2)-2,2'-bipy)](2+) surfactant (RuC11) and the mono-tailed [Ru(2,2'-bipy)(2)(4-(CH(3))-4'-(C(13)H(27))-2,2'-bipy)](2+) surfactant (RuC13). The main characteristic of these species is the presence of an inorganic complex as the polar head of the surfactant with interesting luminescence properties, which were used to study the interaction of these cationic surfactants with α-, β- and γ-cyclodextrins (CD). The results showed the formation of [2]- and [3]-pseudorotaxanes. The binding constant values as well as the stoichiometry of the complexes formed were obtained; the results were confirmed, from a qualitative point of view, with NMR spectra.
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Affiliation(s)
- M Lopez-Lopez
- Departamento de Ingeniería Química, Química Física y Química, Orgánica, Universidad de Huelva, Campus El Carmen, Facultad de Ciencias Experimentales, E-21071, Spain
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Sanchez F, Lopes-Costa T, Montilla F, Roldan E, Lopez-Cornejo P. On the applicability of the two state (pseudophase) model to photochemical reactions under restricted geometry conditions. J Photochem Photobiol A Chem 2012. [DOI: 10.1016/j.jphotochem.2012.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Grueso E, Cerrillos C, Hidalgo J, Lopez-Cornejo P. Compaction and decompaction of DNA induced by the cationic surfactant CTAB. Langmuir 2012; 28:10968-10979. [PMID: 22755509 DOI: 10.1021/la302373m] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A multifaceted study on the interaction of the cationic surfactant CTAB with calf thymus DNA was carried out by using different techniques. The measurements were done at different molar ratios X = [CTAB]/[DNA]. Results show the conformational change that DNA suffers due to the interaction with surfactant molecules at low molar ratios: the condensation of the polynucleotide, from an extended coil state to a globular state. The effect observed at the higher molar ratios is worth noting: the decondensation of DNA, that is, the transition from a compact state to a more extended conformation. Experimental data obtained confirm that this latter state is not exactly the same as that found in the absence of the surfactant. Attractive interactions between different parts of the molecule by ion correlation effects are the driving force to produce both the compaction and decompaction events. Results also show the importance of choosing both a proper system for the study and the most seeming measuring technique to use. The study demonstrates that, in some cases, the use of several techniques is desirable in obtaining reliable and accurate results.
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Affiliation(s)
- E Grueso
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, Sevilla, Spain
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Lopez-Lopez M, Lopez-Cornejo P. Salt Effects on the Formation of the Rotaxane [Ru(NH3)5(4,4′-bpy)/β-CD/Fe(CN)5]−. J SOLUTION CHEM 2011. [DOI: 10.1007/s10953-011-9746-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Villa I, Sanchez F, Lopes T, Lopez-Cornejo P, Perez-Tejeda P. Photoinduced Electron-Transfer Reactions: A Study of the Diffusion-Controlled and Activation-Diffusion-Controlled Processes. J Phys Chem A 2010; 114:7912-7. [DOI: 10.1021/jp104681n] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- I. Villa
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville. c/Profesor García González, s/n, 41012. Seville, Spain
| | - F. Sanchez
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville. c/Profesor García González, s/n, 41012. Seville, Spain
| | - T. Lopes
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville. c/Profesor García González, s/n, 41012. Seville, Spain
| | - P. Lopez-Cornejo
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville. c/Profesor García González, s/n, 41012. Seville, Spain
| | - P. Perez-Tejeda
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville. c/Profesor García González, s/n, 41012. Seville, Spain
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Lopez-Cornejo P, Bote B, Felix R, Infantes I, Lopez P, Martin A, Mateos E, Perez M, Rojas A, Suarez R. Binding of Ru(NH3)5pz2+ to 4-sulfocalix[4]arene sodium salt. Effects of the host-guest interaction on electron transfer processes. J Phys Chem B 2009; 113:12721-6. [PMID: 19722494 DOI: 10.1021/jp903715t] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactions [Ru(NH3)5pz]2++S2O8(2-) and [Ru(NH3)5pz]2++[Co(C2O4)3]3- have been studied in solutions of 4-sulfocalix[4]arene sodium salt. Results show a binding of the ruthenium complex to the calixarene with a 2:1 stoichiometry; that is, a ruthenium molecule binds to two calixarene molecules. This stoichiometry changes when NaCl is added to the medium. Thus, a mixture of 1:1 and 2:1 adducts is found in the presence of 0.1 mol dm(-3) NaCl and only 1:1 adducts when the salt concentration is increased up to 0.3 mol dm(-3). Results show that the binding of the ruthenium complex to the calixarene is due to electrostatic and nonelectrostatic interactions. Kinetic data are interpreted by using the pseudophase model and taking into account the stoichiometry of the ruthenium binding to calixarene. The presence of a supporting electrolyte in the medium produces ion pair formation which exerts an influence on the kinetic rate constants.
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Affiliation(s)
- P Lopez-Cornejo
- Department of Physical Chemistry, Faculty of Chemistry, University of Seville, c/ Prof. Garcia Gonzalez s/n, 41012 Seville, Spain.
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Abstract
The process *Ru(bpy)(3)(2+) + S(2)O(8)(2-) in two different reaction media, the SB4.5G dendrimer and DNA solutions, was studied. In both media, the receptors have anionic characteristics. This fact will produce a binding of the ruthenium complex to the two receptors by attractive electrostatic interactions. On the contrary, the peroxodisulfate ions will be preferentially located in the aqueous solution due to electrostatic repulsions with the receptors. Despite the similarities of the receptors, some differences are observed in these two reaction media. These differences arise from the fact that the binding of the *Ru(bpy)(3)(2+) complex to DNA shows a negative cooperativity, whereas the binding to the dendrimer is noncooperative in character. The anticooperative character of the binding that happens in DNA solutions becomes noncooperative when an electrolyte, NaNO(3), is added to the medium. This is related to a condensation of the salt's counterions on the surface of the DNA which produces a decrease of the equilibrium constant corresponding to the binding of the complex to the receptor. Therefore, it is shown that the ionic strength of the reaction medium exerts a great influence on the cooperative nature of the ligand/receptor binding. This also explains the different behavior observed in DNA and dendrimer solutions.
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Affiliation(s)
- T Lopes-Costa
- Departamento de Quimica Fisica, Universidad de Sevilla, Sevilla, Spain
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Martin VI, Lopez-Cornejo P, Sanchez F. Abnormal salt effects on reactions between ions: The coupling of salt and solvent effects. INT J CHEM KINET 2009. [DOI: 10.1002/kin.20434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jimenez R, Martin C, Lopez-Cornejo P. Formation of a Rotaxane from the End-Capping Process of a Pseudorotaxane. Effects of the Solvent. J Phys Chem B 2008; 112:11610-5. [DOI: 10.1021/jp804918t] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. Jimenez
- Departamento de Química Física. Universidad de Sevilla, c/ Prof. García González s/n, 41012 Sevilla, SPAIN
| | - C. Martin
- Departamento de Química Física. Universidad de Sevilla, c/ Prof. García González s/n, 41012 Sevilla, SPAIN
| | - P. Lopez-Cornejo
- Departamento de Química Física. Universidad de Sevilla, c/ Prof. García González s/n, 41012 Sevilla, SPAIN
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Jimenez R, Diaz J, Mariscal J, Mendez A, Piñero C, Lopez-Lopez M, Mozo J, Lopez-Cornejo P. Micellar effects upon the forward and reverse processes corresponding to the reaction between acetonitrile pentacyanoferrate(II) and pentaamminepyrazineruthenium(II). Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2007.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Sanchez A, Jiménez R, Ternero F, Mesa R, Piñero CA, Muriel F, Lopez-Cornejo P. Rigidity and/or Flexibility of Calixarenes. Effect of the p-Sulfonatocalix[n]arenes (n = 4, 6, and 8) on the Electron Transfer Process [Ru(NH3)5pz]2+ + Co(C2O4)33-. J Phys Chem B 2007; 111:10697-702. [PMID: 17713942 DOI: 10.1021/jp072827m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction [Ru(NH3)5pz]2+ + Co(C2O4)33- has been studied in aqueous solutions of p-sulfonatocalix[n]arene (n = 4, 6, and 8). The results are interpreted by using the pseudophase model. Results show that the rigidity and/or flexibility of the assembled rings have a great effect on the thermodynamics of inclusion of the guest into the host and, therefore, on the kinetics of the electron transfer processes that take place in these media. The obtained results are discussed from the viewpoint of two types of interactions: electrostatic and nonelectrostatic. From surface potential measurements, the guest-host interactions have been demonstrated to be mainly due to nonelectrostatic interactions, although the species are charged. So, the nonelectrostatic contribution to the equilibrium constant in all the calixarenes studied is 1 order of magnitude higher than the electrostatic one (Knel = 144 and 884 mol-1 dm3 for p-sulfonatocalix[n]arene (n = 4 and 6, respectively) and Kel approximately 10 mol-1 dm3). Electrostatic interactions also affect the kinetic results.
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Affiliation(s)
- A Sanchez
- Departamento de Química Física, Universidad de Sevilla, c/Prof. Gacía GonzAlez s/n, 41012 Sevilla, Spain
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Chavanieu A, Guichou JF, Prado-Gotor R, Perez-Tejeda P, Jimenez R, Lopez-Cornejo P, Sanchez F. Strength and character of peptide/anion interactions. J Phys Chem B 2007; 109:19676-80. [PMID: 16853544 DOI: 10.1021/jp051233l] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The binding free energy of complex [Co(C(2)O(4))(3)](3-) to three peptides H-Lys-Gly-Lys-Gly-Lys-Gly-Lys-NH(2) (P-1), H-(Lys-Gly-Lys-Gly-Lys-Gly-Lys)(2)-NH(2) (P-2), H-(Lys-Gly-Lys-Gly-Lys-Gly-Lys)(3)-NH(2) (P-3) and to the monomers (amino acids) forming the peptides has been obtained using the kinetics of the electron-transfer reaction between [Ru(NH(3))(5)py](2+) and [Co(C(2)O(4))(3)](3-) as the probe. The polymerization of the monomers increases the negative free energy of binding and changes its character, noncooperative for the monomers and anticooperative for the peptides. This increase in the negative free energy represents a driving force for the polymerization process. The magnitude of the gain in negative free energy, as a consequence of the anticooperative character of the binding of the cobalt complex to the peptide, depends on the ratio of [complex]/[monomers].
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Affiliation(s)
- A Chavanieu
- Centre de Biochemie Structurale CNRS UMR 5048 INSERM UMR 554, Université de Montpellier 1 29, route de Navacelles 34090 Montpellier Cedex, France
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Martin C, Sanchez F, Jimenez R, Prado R, Perez-Tejeda P, Lopez-Cornejo P. Salt and solvent effects on the kinetics and thermodynamics of the inclusion of the ruthenium complex [Ru(NH3)5(4,4'-bpy)]2+ in beta-cyclodextrin. J Phys Chem B 2007; 110:12959-63. [PMID: 16805599 DOI: 10.1021/jp060659c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influences of solvents (in water-cosolvent mixtures) and salts on the kinetics and thermodynamics of the inclusion of [Ru(NH3)5(4,4'-bpy)]2+ in beta-cyclodextrin (beta-CD) have been studied. Solvent effects on the kinetics can be described as a consequence of the competition of the cosolvent for the beta-CD cavity. The salt effects on the kinetics depend on the ion pairing of the anions with the [Ru(NH3)5(4,4'-bpy)]2+ complex. On the other hand, the solvent effects on the equilibrium constant depend on the stabilization of the 4,4'-bipyridine ligand in the water-cosolvent mixture relative to water. Finally, salt effects on the equilibrium constant are interpreted as a consequence of ion pairing between the anion of the salt and the inclusion complex.
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Affiliation(s)
- C Martin
- Department of Physical Chemistry, Faculty of Chemistry, University of Sevilla, c/Profesor García González s/n, 41012 Sevilla, Spain
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Lopes-Costa T, Lopez-Cornejo P, Villa I, Perez-Tejeda P, Prado-Gotor R, Sanchez F. Salt and Solvent Effects on the Kinetics of the Oxidation of the Excited State of the [Ru(bpy)3]2+ Complex by S2O82-. J Phys Chem A 2006; 110:4196-201. [PMID: 16553370 DOI: 10.1021/jp055189l] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The title reaction was studied in different reaction media: aqueous salt solutions (NaNO3) and water-cosolvent (methanol) mixtures. The observed rate constants, k(obs), show normal behavior in the solutions containing the electrolyte, that is, a negative salt effect. However, the solvent effect is abnormal, because a decrease of the rate constant is observed when the dielectric constant of the reaction medium decreases. These effects (the normal and the abnormal) can be explained using the Marcus-Hush treatment for electron transfer reactions. To apply this treatment, the true, unimolecular, electron-transfer rate constants, k(et), have been obtained from k(obs) after calculation of the rate constants corresponding to the formation of the encounter complex from the separate reactants, k(D), and the dissociation of this complex, k(-D). This calculation has been carried out using an exponential mean spherical approach (EMSA).
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Affiliation(s)
- T Lopes-Costa
- Departamento de Química Física, Facultad de Química, Universidad de Sevilla, c/ Profesor García Gonzalez s/n, 41012 Sevilla, Spain
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