A solid state e.s.r. study of manganese(II) halide-triphenylphosphine oxide complexes

Summary Ph₃PO adducts with manganese(II) halides, viz. MnX₂-(OPPh₃) ₂ (X = Cl or Br) were heated for 1 h and their X-band e.s.r. spectra recorded at room temperature. The chloride adduct, MnCl₂(OPPh₃)₂ completely transformed into the symmetrised product, [Mn(OPPh₃)₄] [MnCl₄] at 175 and 225° C. The bromide adduct, MnBr₂-(OPPh₃)₂, which is probably a mixture of its nonionic and ionic forms at room temperature, showed hyperfine coupling in the g = 2.029 region.     

On probabilistic elimination of generalized quantifiers

Let ?? be a collection of generalized quantifiers. We give a convenient characterization for the cases where the logic ??(??) has quantifier elimination for an arbitrary class of structures. The results provide a method to prove zero‐one and convergence laws for such logics with arbitrary sequences of probability measures of finite structures. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 19, 1–36, 2001     

N-Arylation of a hindered indoline as a route to 2-(2-methyl-1-(4-oxo-3,4-dihydrophthalazin-1-yl)-1H-indol-3-yl)acetic acid derivatives

A convenient synthesis of 2-(2-methyl-1-(4-oxo-3,4-dihydrophthalazin-1-yl)-1H-indol-3-yl)acetic acid derivatives is described using a microwave-promoted multi-step S_NAr reaction. The desired products were found to exhibit atropisomerism.     

Nonionic Micellar Catalyzed Oxidation of Vitamins by Chloramine-T in HClO4 Medium: A Kinetic Study

The kinetics of oxidation of vitamin B₁ (thiamine hydrochloride) and vitamin B₆ (pyridoxine hydrochloride) by chloramine-T (CAT) in perchloric acid medium and in presence of a non ionic surfactant (Triton x-100) have been investigated. A catalytic effect of the nonionic micelle on the rate of oxidation has been observed and rate is found to be proportional to 7lcub;k′ + k″ [Triton x-100]}, where k′ and k″ are the rate constants in absence and presence of surfactant, respectively. The rate shows a first-order, a fractional order and a zero order dependence on [Chloramine-T]_o, [Vitamin]_o and [H⁺]₀, respectively in absence as well as in presence of surfactant. A mechanism involving association/binding between the oxidant and the surfactant micelle, which is supported by spectrophotometric evidence has been proposed. The binding parameters have also been evaluated using a pseudo-phase kinetic model.     

Novel Copolymers of Styrene. 4. Halogen Ring-Substituted Butyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylenes, halogen ring-substituted butyl 2-cyano-3-phenyl-2-propenoates, RPhCH ? C(CN)CO₂C₄H₉ (where R 2-Br, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 2-F, 3-F, 4-F) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and butyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C?NMR. The order of relative reactivity (1/r₁) for the monomers is 3-F (22.97) > 3-Br (6.05) > 2-Cl (4.32) > 4-F (3.19) > 4-Br (2.47) > 4-Cl (1.92) > 2-F (1.74) > 3-Cl (1.10) > 2-Br (1.07). Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (2.3–5.9% wt.), which then decomposed in the 500–800°C range.     

Photophysics of aminoxanthone derivatives and their application as binding probes for DNA

Xanthones with amino substituents were synthesized to diminish the photoreactivity of the xanthone chromophore with DNA, with the objective of using these molecules to study their binding dynamics with DNA. The aminoxanthones showed a strong solvatochromic effect on their singlet and triplet excited-state photophysics, where polar solvents led to a decrease of the energies for the excited states. Quenching of the triplet excited states by nitrite anions was used to determine the binding dynamics, and a residence time in the microsecond time domain was estimated for the bound 2-aminoxanthone with DNA. The quenching experiments performed showed that this methodology will not be applicable to study the binding dynamics of a wide variety of guests with DNA.