Synthesis and linear and nonlinear absorption properties of dendronised ruthenium(II) phthalocyanine and naphthalocyanine

Ruthenium phthalocyanines and naphthalocyanines with axial dendronised pyridine ligands show high solubility in a variety of solvents, and exhibit solid-state absorption spectra that are comparable to those obtained in dilute solution, making them interesting candidates for optical limiting in the visible.     

Computational investigation of O2 reduction and diffusion on 25% Sr-doped LaMnO3 cathodes in solid oxide fuel cells

The oxygen reduction reaction (ORR) and diffusion mechanisms on 25% Sr-doped LaMnO(3) (LSM) cathode materials as well as their kinetic behavior have been studied by using spin-polarized density functional theory (DFT) calculations. Bader charge and frequency analyses were carried out to identify the oxidation state of adsorbed oxygen species. DFT and molecular dynamics (MD) results show that the fast O(2) adsorption/reduction process via superoxide and peroxide intermediates is energetically favorable on the Mn site rather than on the Sr site. Furthermore, the higher adsorption energies on the Mn site of the (110) surface compared to those on the (100) surface imply that the former is more efficient for O(2) reduction. Significantly, we predict that oxygen vacancies enhance O(2) reduction kinetics and that the O-ion migration through the bulk is dominant over that on the surface of the LSM cathode.     

Synthesis of new thieno[2,3‐d]pyrimidines,thieno[3,2‐e]pyridines,and thieno[2,3‐d][1,3]oxazines

o‐Aminothiophene dicarbonitrile 1 on neat reaction with cyclic ketones in anhydrous ZnCl₂ yielded mixture of fused aminopyridine 3 and iminospirooxazine 4 derivatives. Similarly, pyrimidine derivatives 5 and 8 were obtained by the reaction of this intermediate 1 with formic acid and DMF‐DMA followed by hydrazine hydrate, respectively. The reaction of o‐amino‐thiophene dicarboxamide 2 at ambient temperature with cyclic ketones yielded spiropyrimidine 10 as a sole product in quantitative yield. The regioselective anellated pyrimidine 9 , 11 , and dihydropyrimidine 12 derivatives were also obtained by the reaction with aromatic aldehydes in presence of piperidine and iodine respectively. J. Heterocyclic Chem., (2012).     

Synthesis of benzohetero[3, 2-a]pyrimidines using cyclic β-keto lactone as a building block

Abstract  

A novel method for the synthesis of 3-(2-substituted ethyl)-2-methylbenzohetero[3,2-a]pyrimidines in high yield (80–85%) was achieved, which involves a dihydrofuranone intermediate, readily obtained from β-ketolactone to 2-aminobenzoheterocycles. The major advantage of the methodology is the high yield and product purity.     

Synthesis and Fluorescence Properties of Donor-Acceptor-Substituted Novel Dipyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>:3′,4′-<Emphasis Type="Italic">d</Emphasis>]Pyridines (DPP)

A rapid and efficient method for the synthesis of novel dipyrazolo[3,4-b:3′,4′-d]pyridines (DPP) from pyrazolo[3,4-b]pyridine was successfully developed. The DPP derivative was further N-alkylated (6, 8) as well as N-linked with amino acids (13) and their photophysical properties were studied along with N-aryl DPP 4 and observed that the chromophores at C₄ position in the aryl ring changed the absorption and emission λ_max.     

A note on spatially weighted subarray covariance averaging schemes

In spatial smoothing, the effective correlation among the impinging sources goes to zero only asymptotically with the number of subarrays. K. Takao and N. Kimura (ibid., vol.AP-35, p.1389-96, Dec. 1987) and A. Paulraj et al. (IEEE J. Ocean Eng., vol.OE-12, p.163-72, Jan. 1987) proposed Toeplitzization and adaptively weighted subarray covariance averaging methods, respectively, wherein the impinging sources are perfectly decorrelated whenever the number of subarrays exceeds a minimum value. While both methods achieve the same result, the formulations of the two methods are different. The present work first suggests an alternate formulation of the same problem and then compares the three methods showing that the solutions obtained by them are equivalent     

Ion-solvent interactions of silver(I)-18-crown-6 perchlorate complex in methanol-acetonitrile mixtures

The standard Gibbs transfer energies of the silver(I)-18-crown-6 perchlorate complex salt from methanol to various compositions of methanol-acetonitrile mixtures were determined from solubility measurements at 30°C and these data were separated into the corresponding ionic contributions by employing the negligible liquid junction potential method of Parkeret al. The solvent transport numbers _AN, for the salt were also determined at various solvent compositions using a concentration cell with transference.The Gibbs transfer energy of the silver(I)-18-crown-6 complex cation is negative and decreases with the addition of acetonitrile but the transfer energy of the anion is positive and increases under the same conditions. The solvent transport number, _AN, increases and passes through a maximum value of 5.48 at _AN=0.55. These results indicate that the complex salt is heteroselectively solvated in these mixtures with the cation being preferentially solvated by acetonitrile and the anion by methanol molecules.     

Friedländer condensation of 5‐aminopyrazole‐4‐carbaldehydes with reactive α‐methylene ketones: Synthesis of pyrazolo[3,4‐b]pyridines

A series of 1,3,6‐trisubstituted and 1,3,5,6‐tetrasubstituted pyrazolo[3,4‐b]pyridines 5 has been synthesized by Friedlander condensation of 5‐arninopyrazole‐4‐carbaldehydes 3 with α‐methylene ketones such as acetone (4a) or acetophenones 4b‐f with potassium hydroxide as basic catalyst. Condensation of 5‐aminopyrazole‐4‐carbaldehydes 3 and unsymmetric dialkylketones 6 yielded mixtures of isomeric pyra‐zolo[3,4‐b]pyridine derivatives 7 and 8 . Condensation of 5‐aminopyrazole‐4‐carbaldehydes 3 with CH‐acidic acylacetonitriles 9 and acylacetates 11 with piperidine as basic catalyst yielded pyrazolo[3,4‐b]pyri‐dine‐5‐carbonitriles 10 and pyrazolo[3,4‐b]pyridine‐5‐carboxylates 12 ; with diethyl malonate 13 as CH‐acidic component, pyrazolo[3,4‐b]pyridin‐6‐ones 14 were obtained.     

Conductance of iron(III) laurate solutions in binary liquid mixtures

Summary The specific conductivity of iron(III) laurate solutions in binary liquid mixtures shows that the soap aggregates into micelles and CMC is found to be independent of temperature and concentration of benzene, acetone and tetrachloromethane in 1-butanol. The variation of molecular conductance,, with soap concentration, C, is expressed by the equation: = 10^AC^B. Both constants A and B vary with solvent composition but B remains constant with increase in temperature. Several parameters such as molecular conductance at infinite dilution, , dissociation constant, K, heat of dissociation, H, entropy, S and free energy, G of dissociation of soap have been evaluated and the effect of the nature of solvents has been discussed.