Absorption spectrometric and thermodynamic study of charge transfer complexes of menadione (Vitamin K3) with a series of phenols.

The electron donor-acceptor (EDA) interactions between menadione (i.e., 2-methyl-1,4-naphthoquinone, which is also called 'Vitamin K3') and a series of phenols (viz., phenol, resorcinol and p-quinol) have been studied in CCl4 medium. In all the cases, charge transfer (CT) bands have been located. The CT transition energies (h nu(CT)) of the complexes are found to change systematically with change in the number and position of the -OH groups in the aromatic ring of the phenol moiety. From the trends in the h nu(CT) values, the Hückel parameters (h(O) and k(C-O)) for the -OH group have been obtained. The CT transition energies are well correlated with the ionisation potentials of the phenols. From an analysis of this variation the electron affinity of Vitamin K3 has been found to be 2.28 eV. The stoichiometry of the complexes in each case has been found to be 1(menadione):2 (phenol). Formation constants of the complexes have been determined at four different temperatures from which the enthalpies and entropies of formation of the complexes have been estimated.

Study of charge transfer complexes of menadione (vitamin K3) with a series of anilines.

Menadione (vitamin K(3)) has been shown to form charge transfer complexes with N,N-dimethyl aniline, N,N-dimethyl p-toluidine and N,N-dimethyl m-toluidine in CCl(4) medium. The CT transition energies are well correlated with the ionisation potentials of the anilines. The formation constants of the complexes have been determined at a number of temperatures from which the enthalpies and entropies of formation have been obtained. The formation constants exhibit a very good linear free energy relationship (Hammett) at all the temperatures studied.

A tribute to Sir Jagadish Chandra Bose (1858-1937).

First, we provide a brief description of the life of Sir Jagadish Chandra Bose (1858-1937), his contemporaries, and some of his achievements. He is known for demonstrating the World's first wireless communication link at a wavelength of 5 mm. Then, we describe his contribution to photosynthesis research, as published in one of the earliest books on photosynthesis-a 1924 book entitled "Physiology of Photosynthesis." His pioneering work on photosynthesis preceded much of the future work in this area. In particular, we emphasize his work on Hydrilla that was a precursor to C-4 photosynthesis.