On the formation of “symmetrical” phenoxazinone derivative related to the actinomycin D chromophore

In studies related to the synthesis of 2-deamino chromophores of actinomycin by reaction of nitrous acid in fluoroboric acid via diazotization of the 2-amino group in the chromophore, the unknown fluorescent product is identified as the symmetrical phenoxazinone by cmr and pmr.     

An observation on the Hulbert-Hirschfelder potential function

The Hulburt-Hirschfelder potential function is capable of reproducing a potential hump in the excited ¹Σ_u⁺ state of the argon dimer, as expected from experimental findings of Tanaka and Yoshino.     

Electric quadrupole transitions in LiI,BeII, BIII

Theoretical values of the weighted oscillator strengths for different electric quadrupole transitions of LiI, BeII and BIII have been calculated using analytic Hartree-Fock wave functions. An appropriate hypervirial check has been made to assess the accuracy of the values. Some interesting features of the hypervirial operator are discussed.     

Inverted porphyrins and expanded porphyrins: An overview

Porphyrins and metallopophyrins have attracted the attention of chemists for the past 100 years or more owing to their widespread involvement in biology. More recently, synthetic porphyrins and porphyrin-like macrocycles have attracted the attention of researchers due to their diverse applications as sensitizers for photodynamic therapy, MRI contrasting agents, and complexing agents for larger metal ions and also for their anion binding abilities. The number of π-electrons in the porphyrin ring can be increased either by increasing the numberof conjugated double bonds between the pyrrole rings or by increasing the number of heterocyclic rings. Thus, 22π sapphyrins, 26π rubyrins, 30π heptaphyrins, 34π octaphyrins and higher cyclic polypyrrole analogues containing 40π, 48π, 64π, 80π and 96π systems have recently been reported in the literature. These macrocycles show rich structural diversity where normal and different kinds of inverted structures have been identified. In this review, an attempt has been made to collect the literature of the inverted porphyrins and expanded porphyrins reported until December 2001. Since themeso aryl expanded porphyrins have tendency to form both inverted and non-inverted structures more emphasis has been given tomeso aryl expanded porphyrins.     

Kinetics and mechanism of sulphurous acid oxidation by hexachloroiridate(IV) in hydrochloric acid

Summary The reaction between sulphurous acid and hexachloroiridate(IV) appears to take place through the formation of an intermediate complex followed by decomposition to give oxidation products. The rate is retarded as the hydrogen ion concentration increases. Thermodynamic parameters associated with the equilibrium step as well as with the slowest step have been calculated. The probable mechanism of the reaction is discussed.     

The method of successive updated iterated defect correction and its application to second kind volterra integral equations

We present a new method for the numerical solution of Volterra integral equations of the second kind. This method is based on the technique of Iterated Defect Correction. Numerical examples are given to demonstrate the power of our method.Based on his research at Indian Institute of Technology, Kanpur, India.