María José Tapia

Universidad de Burgos | UBU · Department of Chemistry

The interaction between polyelectrolytes and metal ions is governed by different types of interactions, leading to the formation of different phases, from liquid state to weak gels, through an appropriate choice of metal ion/polyelectrolyte molar ratio. We have found that lanthanide ions, europium(III) and terbium(III), are able to form polymer com...

The modulation of conjugated polyelectrolyte fluorescence response by nonionic surfactants is dependent on the structures of the surfactant and polymer, polymer average molecular weight, and polyelectrolyte–surfactant interactions. In this paper, we study the effect of nonionic n-alkyl polyoxyethylene surfactants (CiEj) with different alkyl chain l...

The interaction between conjugated polyelectrolytes (CPEs) and surfactants in aqueous solutions is reviewed, based on results from absorption and fluorescence spectroscopy, NMR, dynamic light scattering (DLS), small angle X-ray (SAXS) and neutron (SANS) scattering, electrical conductivity and molecular dynamics simulations. It is shown that the con...

The combination of various experimental techniques with theoretical simulations has allowed elucidation of the mode of incorporation of fluorene based derivatives into phospholipid bilayers. Molecular dynamics (MD) simulations on a fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) bilayer, with benzene (B), biphenyl (BP), fluor...

We have studied the effect of head group and alkyl chain length on β-phase formation in poly(9,9-dioctylfluorene) (PFO) solubilized in phospholilpid liposomes. Systems studied have three different alkyl chain lengths (1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC), 1,2-didodecanoyl-sn-glycero-3-phosphatidylcholine (DLPC), 1,2-dipalmitoyl-s...

The interaction between sodium octanoate, decanoate, and dodecanoate and aluminum(III) and chromium(III) has been studied in water at natural pH values, starting well below the surfactant critical micelle concentration, using electrical conductivity, turbidity, and potentiometric measurements. With decanoate or dodecanoate, maximum interaction occu...

The well-structured β-phase emission of the neutral poly(9,9-dioctylfluorene) (PFO) is observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers, either as polydisperse aqueous liposomes or as the lamellar phase in thin films, and has been characterized by absorption, fluorescence (steady-state and time-resolved), and fluorescence ani...

The interaction between aqueous solutions of trivalent lanthanide ions (M(3+): La(III) and Gd(III) and Tb (III)) at fixed (1mM) concentrations and various concentrations of sodium dodecyl sulfate (SDS), ranging from pre- to post-micellar, has been investigated by ICP-AES (La(III) and Gd(III)), luminescence spectra (Gd(III)) and lifetimes (Tb(III))...

In this paper, the interaction between three water soluble conjugated polymers: sodium poly{9,9-bis[(4-butylsulfonate)phenoxy]-2,7-fluorene-alt-1,4-phenylene} (PBS-PFP), poly{9,9-bis[(6'-N,N,N-trimethylammonium) hexyl]-2,7-fluorene-alt-1,4-phenylene) dibromide (HTMA-PFP) and poly(9,9'-bisl(6 ''-N-acetyltyrosine)hexyl]-2,7-fluorene-alt-1,4-phenylene...

The competitive interaction has been studied between double-stranded DNA (dsDNA), the cationic conjugated polyelectrolyte (CPE) poly[9,9-bis(6-N,N,N-trimethylamonium)hexyl)-fluorene-phenylene)] bromide (HTMA-PFP) and anionic or neutral surfactants (sodium dodecyl sulfonate, SDSu, and n-dodecyl pentaoxyethylene glycol ether, C(12)E(5)) in 4% (v/v) d...

We provide a brief overview of the structural characteristics of the main groups of conjugated polyelectrolytes (CPEs) as well as the methods of synthesis and their behaviour in solution. Their tendency to form aggregates in solution, which is one of the key points to be taken into account for them to be used in polynucleotide sensing, is also cons...

The diffusion behavior of the conjugated polyelectrolyte poly{[9,9-bis(6'-N,N,N-trimethylammonium)hexyl]fluorene-phenylene) bromide (HTMA-PFP) with different molecular weights has been studied in dimethyl sulfoxide (DMSO) + water solutions. Samples of HTMA-PFP with various molecular weights were obtained by synthesis of poly[9,9-bis(6'-bromohexyl)f...

Electronic energy transfer has been studied between the cationic conjugated polyelectrolyte, poly{9,9-bis[6-N,N,N-trimethylammonium)hexyl]fluorene-co-1,4-phenylene} dibromide (HTMA-PFP), and three, oppositely charged meso-tetrakis-phenylporphyrinsulfonates in buffered (pH = 9.2), 4% (v/v) dimethyl sulfoxide-water (DMSO-water) solutions using steady...

Two anionic fluorene-thiophene alternating copolymers, poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-2,5-thienylene] (PBS-PFT) and poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-2,2'-bithiophene-5,5'-diyl] (PBS-PF2T), have been synthesized and their solution behaviors in water studied by UV-vis absorption spectroscopy, fluorescence,...

The interaction between three poly(9,9-bis(6-N,N,N-trimethylammonium)hexyl)fluorene phenylene) bromide (HTMA-PFP) samples of different molecular weights (Mn=14.5, 30.1 and 61.3 kg/mol) and both dsDNA and ssDNA secondary structures has been studied using UV-visible absorption and fluorescence spectroscopies (including steady-state, time-resolved, an...

The interaction of the trivalent lanthanide ions Ce(III) and Tb(III) with ribonucleic acid (RNA) and guanosine 5′-triphosphate (GTP) in aqueous solution has been studied using their luminescence spectra and decays. Complexation is indicated by changes in luminescence intensity. With the system terbium(III)–RNA and terbium(III)–GTP, changes in lumin...

Interaction between β-carboline-3-carboxylic acid N-methylamide, βCMAM, and nucleobases, nucleosides and nucleotides is studied in the ground state with UV-visible, 1H NMR and 31P NMR spectroscopies and in the first excited state, with steady-state and time-resolved fluorescence spectroscopy. Job plots show a predominant 1:1 interaction in both ele...

The aggregation of the fluorescent hairy rod, anionic conjugated polyelectrolyte poly{1,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) has been studied in aqueous solutions by molecular dynamics simulations, fluorescence and light scattering. Formation of clusters leads to considerable increases in light scattering, decr...

The interaction between the cationic HTMA-PFP (Poly-(9,9-bis(6'-N,N,N-trimethylammonium)hexyl-fluorene phenylene) bromide) and oppositely charged sodium n-alkyl sulfonate surfactants of different chain lengths has been studied in DMSO-water solutions (4% v/v) by UV-visible absorption, fluorescence spectroscopy, fluorescence lifetimes, electrical co...

The effect of three anionic, hairy-rod fluorene based conjugated polyelectrolytes on the cloud points of the alkyloxyethylene surfactants C10E3, C12E4, C12E5, and C12E6 has been studied in aqueous solution. Although the association behaviour of these rigid polymers with surfactants is different from that of more flexible polyelectrolytes, both type...

The complexation of beta-carboline-3-carboxylic acid N-methylamide (betaCMAM) with the sodium salts of the nucleotides polyadenylic (Poly A), polycytidylic (Poly C), polyguanylic (Poly G), polythymidylic (Poly T) and polyuridylic (Poly U) acids, and with double stranded (dsDNA) and single stranded deoxyribonucleic acids (ssDNA) was studied at pH 4,...

A new model polyamide compound that has a benzo-18-crown-6 moiety in the pendant structure is described. This model interacts with metal cations in the alkaline, earth alkaline, transition metal and heavy metal series. The interaction has been analyzed in terms of competitive cation extraction from aqueous solution by liquid model/dichloromethane p...

Understanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS-PFP) and cationic gemini surfactants a...

The interaction between trivalent lanthanide ions and poly(1,4,7,10,13-pentaoxacyclopentadecan-2-yl-methyl methacrylate), PCR5, in aqueous solution and in the solid state have been studied. In aqueous solution, evidence of a weak interaction between the lanthanides and PCR5 comes from the small red shift of the Ce(III) emission spectra and the slig...

Two cationic conjugated polyelectrolyte poly{9,9-bis[6-(N,N,N-trimethylammonium)alkyl] fluorene-co-1,4-phenylene} iodides in aqueous solution in the presence of the non-ionic surfactant pentaethyleneglycol monododecyl ether (C12E5) were studied using optical absorption and fluorescence, NMR, and small-angle neutron scattering (SANS) with a model of...

In this paper, the interaction between the water-soluble conjugated polyelectrolyte poly{1,4-phenylene[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer and the amino acid glyceride conjugate 1-O-(L-arginyl)-2,3-O-dilauroyl-sn-glycerol dichlorohydrate (a mimic for the phospholipid lecithin) has been studied in aqueous solution by electr...

We report the synthesis and characterization of 10 novel polyamides containing the benzo-18-crown-6 subunit and its dipodal counterpart, along with their properties, and a comparison with homologous polyamides bearing benzo-12-crown-4, benzo-15-crown-5, and the corresponding dipodal systems. The anomalous polymerization of some of the diacid monome...

The interaction between the water-soluble anionic conjugated copolymer poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) and various surfactants has been studied in aqueous solution by UV–vis absorption spectra, fluorescence and electrical conductivity. It is suggested from the linear dependence of absorbance, fluor...

The interaction has been studied in aqueous solutions between a negatively charged conjugated polyelectrolyte poly{1,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer (PBS-PFP) and several cationic tetraalkylammonium surfactants with different structures (alkyl chain length, counterion, or double alkyl chain), with tetramet...

5,10,15,20-Tetrakis(2,6-dichloro-3-chlorosulfophenyl)porphyrin and its tin and zinc complexes were synthesized with high yields and fully characterized. The corresponding water-soluble 5,10,15,20-tetrakis(2,6-dichloro-3-sulfophenyl)porphyrins were obtained by hydrolysis with water. An extensive photophysical study of the new water soluble porphyrin...

The effect of the nonionic n-dodecylpentaoxyethylene glycol ether on the properties of the water-soluble poly {1,4-phenylene-[9,9-bis(4- phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer was discussed. It was observed that the aqueous solutions of PBS-PFP showed a broad absorption of around 381nm and a structured fluorescence. It was also found t...

The interaction between trivalent lanthanide ions and the polymer poly(1,4,7,10-tetraoxacyclododecan-2-ylmethyl methacrylate) (PCR4) containing pendant 1,4,7,10-tetraoxacyclododecane (12-crown-4) groups has been studied by various spectroscopic techniques, calorimetry and theoretical calculations. Evidence for the binding of Eu(III), Tb(III), and C...

The hydrogen bonding interactions of methyl β-carboline-3-carboxylate (BCCM) in both ground and first singlet excited electronic states have been studied in solvents with different properties in the presence of acetic acid, a hydrogen-bonding donor/acceptor. The methyl ester substituent reduces the pyridinic nitrogen basicity of this β-carboline de...

The photophysical properties and the acid–base equilibrium of β-carboline-3-carboxylic acid N-methylamide (βCMAM) in aqueous solution have been investigated. The pKa values in the ground and the first excited state have been spectrophotometrically determined using the Förster cycle for the excited state. This compound and methyl-β-carboline-3-carbo...

The photophysical properties and the acid–base equilibrium of methyl β-carboline-3-carboxylate in aqueous solution have been investigated. The pKa values in the ground and the first excited state have been spectrophotometrically determined using Förster cycle for the excited state and acidifying the solutions in the pH range with sulphuric acid and...

The interaction of trivalent lanthanide ions in sodium bis-2-ethylhexylsulfosuccinate/water/isooctane microelmuslions was studied. Luminescence and EPR spectroscopy were used to study the interactions of lanthanide cations with the negatively charged surfactant surface. It was observed that the trivalent lanthanide ions maintain a relatively high m...

Spectroscopic studies on the hydrogen-bonding interactions of norharmane with acetic acid (AcH), a proton acceptor/donor molecule, have been carried out in two non-polar solvents (benzene and p-dioxane) and in a polar solvent (acetonitrile). The steady and non-steady photophysical results show three different kinds of norharmane/AcH hydrogen-bonded...

The interaction of trivalent lanthanides with sodium dodecyl sulfate micelles (SDS) in aqueous solution has been studied by a variety of experimental techniques. Potentiometric measurements with a sodium selective electrode, steady-state fluorescence spectra of Ce(III), emission lifetime measurements of Ce(III), Tb(III), and Eu(III), and electronic...

Spectroscopic studies on the hydrogen-bonding interactions of norharmane with acetic acid (AcH), a proton acceptor/donor molecule, have been carried out in two non-polar solvents (benzene and p-dioxane) and in a polar solvent (acetonitrile). The steady and non-steady photophysical results show three different kinds of norharmane/AcH hydrogen-bonded...

Cadmium(II) and zinc(II) complexes with the chelating agents meso-2,3-dimercapto succinic acid, meso-monomethyl dimercapto succinate, meso-dimethyl dimercapto succinate and the related methylmercapto acetate and mercapto succinic acid were studied potentiometrically in 0.1 M KCl at 25°C. Models and hypotheses of coordination for the solution comple...

The interaction between trivalent lanthanide ions and the polyelectrolyte poly(vinyl sulfonate) (PVS) has been studied in aqueous solutions by monitoring lanthanide luminescence. The existence of specific binding of cations by PVS is indicated by blue-shifts in the maximum of the emission of cerium(III), effects on the decay of terbium(III) lumines...

The coordination of Pt(II) with different mercapto and dimercapto compounds has been studied using both potentiometric titration at 25°C in KCl 0.1 M and UV–Vis spectroscopy. The slow complex formation kinetics has been followed spectrophotometrically for several days on samples with different ligand molar fractions ranging from 0.1 to 1, keeping t...

The coordination of Pd(II) with a set of different mercapto and dimercapto compounds has been investigated by potentiometric titration at 25°C in KCl 0.1 M. The ligand concentration ranged from 10−4 M to 10−3 M, and for each ligand concentration the 0.25, 0.50, 0.75 and 1.00 Metal/Ligand ratios were examined in the 2.5–11 pH range. Using KCl 0.1 M...

Absorption and fluorescence spectroscopies are applied to study the adsorption of rhodamine 6G on saponite in aqueous suspensions. The interpretation of the experimental results suggests that the dye can be adsorbed as the monomeric and the dimeric forms on both the external and the interlamellar surfaces of the clay. A mechanism for the adsorption...

The photophysical properties of di-, mono- and non-ethyl 7-aminocoumarins have been investigated in different water/ethanol mixtures. The effect of the solvent composition on the spectral shifts and on the radiationless deactivation process depends on the molecular structure of the dye. The solvent effect is analyzed in terms of hydrogen bondings b...

The adsorption of rhodamine 6G on laponite B is investigated by electronic absorption and emission spectra for loadings higher than 15% of laponite cation exchange capacity (CEC). The experimental results suggest the formation of an externally adsorbed dimer. The spectroscopic and structural characteristics of this aggregate are compared to those o...

The adsorption of Rhodamine 6G (R6G) in aqueous suspensions of Wyoming montmorillonite (WyM) is investigated by electronic absorption and emission spectroscopies. The loading range studied is between 0.1% and 100% of the cation exchange capacity. The monomer of Rhodamine 6G can be adsorbed on the external and on the internal surfaces of the clay. E...

The formation of a twisted intramolecular charge transfer state (TICT model) and changing of the amino group from a planar to a pyramidal structure (ULM model) are applied to explain the radiationless deactivation of rhodamines with different molecular structures in water and in ethanol. Both theories offer valid interpretation for the photophysics...

The absorption and emission (fluorescence spectra and radiative decay curves) characteristics of rhodamine 3B and of the molecular forms of rhodamine B are determined in several water/ethanol mixtures. The results are compared to those previously obtained for the related monoethylamine-substituted rhodamines, i.e. rhodamine 6G and the molecular for...

The absorption and the emission (fluorescence spectra and radiative decay curves) characteristics of rhodamine R3B and R6G and of the molecular forms of RB and R19 are determined in different water/ethanol mixtures. The influences of molecular structure (alkylation of the amino groups and photonation or esterification of the carboxyphenyl group) an...

Realizado por los profesores del área de química física de la Facultad de Ciencias de Burgos. Objetivos: facilitar a los profesores y alumnos material sistematizado y de fácil acceso para la enseñanza y aprendizaje de la materia con el fin de optimizar los resultados del proceso de enseñanza-aprendizaje. Materiales elaborados: temario del área de q...