NMR paramagnetic probing of polymer solutions using manganese(II) ions

© 2017, Pleiades Publishing, Ltd. Nuclear magnetic relaxation studies show that manganese(II) ions can serve as paramagnetic probes for investigation of aqueous solutions of polyelectrolytes (polystyrene sulfonate and polyethylenimine) and their mixtures. The analysis of the measured rates of spin–lattice (R 1 ) and spin–spin (R 2 ) relaxations reveals the differences in the binding character of manganese(II) ions with polystyrene sulfonate and polyethylenimine. In a mixture of the polymers in acidic and neutral media, manganese(II) forms two types of ternary complexes. Using the suggested method for definition of the hydration degree of a coordination sphere of the bound probe ions, the number of water molecules in the first sphere of the polymer-bound manganese(II) ions is found on the basis of the value of the R 2 /R 1 ratio

The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions

The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V

NMR paramagnetic probing of polymer solutions using manganese(II) ions

© 2017, Pleiades Publishing, Ltd. Nuclear magnetic relaxation studies show that manganese(II) ions can serve as paramagnetic probes for investigation of aqueous solutions of polyelectrolytes (polystyrene sulfonate and polyethylenimine) and their mixtures. The analysis of the measured rates of spin–lattice (R 1 ) and spin–spin (R 2 ) relaxations reveals the differences in the binding character of manganese(II) ions with polystyrene sulfonate and polyethylenimine. In a mixture of the polymers in acidic and neutral media, manganese(II) forms two types of ternary complexes. Using the suggested method for definition of the hydration degree of a coordination sphere of the bound probe ions, the number of water molecules in the first sphere of the polymer-bound manganese(II) ions is found on the basis of the value of the R 2 /R 1 ratio

Complex formation of MnII with tetra(p-tert-butyl)thiacalix[4] arene acid in aqueous solutions of surfactants and polymers

The formation of manganese(II) complexes with different stereoisomers of tetraacid based on p-tert-butylthiacalix[4]arene in water, in micellar solutions of nonionogenic surfactants, and in polymer solutions was studied. The formation of complexes with different degrees of ligand protonation was revealed by pH-metric titration and nuclear magnetic relaxation. On the basis of experimental data, the composition and stability constants of the solubilized complexes of stereoisomers of thiacalixarene acid with manganese(II) ions were determined using mathematical simulation methods. The manganese thiacalixarene complexes are unstable in solutions, especially upon the addition of calcium cations and in the presence of nitrilotriacetic acid. © 2014 Springer Science+Business Media, Inc

Complex formation of MnII with tetra(p-tert-butyl)thiacalix[4] arene acid in aqueous solutions of surfactants and polymers

The formation of manganese(II) complexes with different stereoisomers of tetraacid based on p-tert-butylthiacalix[4]arene in water, in micellar solutions of nonionogenic surfactants, and in polymer solutions was studied. The formation of complexes with different degrees of ligand protonation was revealed by pH-metric titration and nuclear magnetic relaxation. On the basis of experimental data, the composition and stability constants of the solubilized complexes of stereoisomers of thiacalixarene acid with manganese(II) ions were determined using mathematical simulation methods. The manganese thiacalixarene complexes are unstable in solutions, especially upon the addition of calcium cations and in the presence of nitrilotriacetic acid. © 2014 Springer Science+Business Media, Inc

Complex formation of MnII with tetra(p-tert-butyl)thiacalix[4] arene acid in aqueous solutions of surfactants and polymers

The formation of manganese(II) complexes with different stereoisomers of tetraacid based on p-tert-butylthiacalix[4]arene in water, in micellar solutions of nonionogenic surfactants, and in polymer solutions was studied. The formation of complexes with different degrees of ligand protonation was revealed by pH-metric titration and nuclear magnetic relaxation. On the basis of experimental data, the composition and stability constants of the solubilized complexes of stereoisomers of thiacalixarene acid with manganese(II) ions were determined using mathematical simulation methods. The manganese thiacalixarene complexes are unstable in solutions, especially upon the addition of calcium cations and in the presence of nitrilotriacetic acid. © 2014 Springer Science+Business Media, Inc

Understanding the Nucleation and Growth of Iron Oxide Nanoparticle Formation by a “Heating-Up” Process: An NMR Relaxation Study

The formation of iron oxide nanoparticles obtained by the thermal decomposition of iron-oleate complexesviaa “heating-up” process was monitored by the NMR relaxation method, which allows us to track the average diameter of iron oxide nanoparticles. The analysis of dependencies of theT1/T2ratio and 1/T2values on time at the heating of the reaction mixture demonstrated that the nucleation and nanoparticle growth processes could proceed in two ways depending on the presence of oleic acid in the solution: continuously without separation of the nucleation stage or discretely with the separation of the nucleation and growth of nanoparticles. In the case of excess of oleic acid, the nucleation process follows the well-known LaMer model, characterized by a burst of nucleation and separation of nucleation and growth under continuous monomer supply. In the absence of oleic acid in the system, the nucleation and growth of nanoparticles are not separated and proceed continuously. The presence of a sufficient amount of oleic acid is the reason why the process of nucleation and growth of nanoparticles by heating up follows the path of “burst nucleation,” which is similar to the “hot injection” method. That is, oleic acid acts as a “fuse” for the explosive “burst nucleation.” This new approach shows that the “hot injection” method can be carried out not only mechanically (by introducing a precursor into the reaction system) but also chemically, with the help of a reagent that has been in the system from the very beginning

The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions

The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V

The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions

The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V

The effect of temperature induced phase transitions in aqueous solutions of triblock copolymers and Triton X-100 on the EPR, magnetic relaxation and luminescent characteristics of Gd(III) and Eu(III) ions

The present report is inspired by the idea to develop novel spectroscopy based techniques to detect the phase transitions in solutions of triblock copolymers with the use of Gd(III) and Eu(III) ions as probes. The choice of (PEO)13(PPO)30(PEO)13 (L64), (PPO)14(PEO)24(PPO)14 (17R4), (PPO)8(PEO)22(PPO)8 (10R5) and Triton X-100 is conditioned by their phase transitions occurring in mild conditions. The cloud point extraction (CPE) data reveal the conditions (pH and chelating agent) where the binding of lanthanides with surfactant rich phase of triblock copolymers and Triton X-100 occurs. The effect of phase transitions in solutions of triblock copolymers on the temperature resolved line widths in EPR spectra of Gd(III) aqua ions and transverse relaxation rates of Gd(III) inner-sphere water protons depends on the architecture of triblock copolymers and pH conditions. The steady state luminescence of Eu(III) complexes with phosphine oxide in aqueous solutions of triblock copolymers and TX-100 is influenced by the temperature induced aggregation and phase separation in solutions of reverse triblock copolymers 17R4 and 10R5, while the effect of the aggregation is insignificant for L64. © 2012 Elsevier B.V