Articles written in Journal of Chemical Sciences
Volume 120 Issue 5 September 2008 pp 485-491
Preparation and characterization of absolutely pure and stable nanoparticles of 5,10,15,20-meso-tetrakis phenyl porphyrin (TPP) and catalytically repute 5,10,15,20-meso-tetrakis pentaflurophenyl porphyrin (H2F20TPP) by improved ‘reprecipitation method’ is described. The innovation of this modified `reprecipitation method’ lies on the judicial selection of organic solvent and amount of porphyrin solution to be injected in the aqueous media. Exactly similar process produces relatively small nanoparticles for TPP than that of H2F20TPP while the stability of the H2F20TPP nanoparticles is bit higher than nanoparticles of TPP. Absorption and emission spectra reveal that the formation of nanoparticles for both the cases is induced by J- and H-type aggregation. DFT calculations predict the optimized geometries and frontier molecular orbital, which favours the strength of face-to-face interaction with neighbour molecules to be more facile for TPP than that of H2F20TPP helping the latter to form bigger and relatively more stable and free-standing nanoparticles. The use of no other compounds except dichloromethane, a highly volatile organic solvent and respective porphyrins give absolutely pure nanoparticles. This improved method will lead to produce organic nanoparticles of 𝜋-conjugated systems easily and efficiently.
Volume 127 Issue 8 August 2015 pp 1329-1338 Regular Articles
The reaction of [Ru(𝜂6-cymene)Cl2]2 and PPh2Cl in the ratio 1:2 gives a stable [Ru(𝜂6-cymene) Cl2(PPh2Cl)] complex. Attempts to make the cationic [Ru(𝜂6-cymene)Cl(PPh2Cl)2]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of [Ru(𝜂6-cymene)Cl2 (PPh2OH)]. Attempts to make a phosphinite complex by reacting [Ru(𝜂6-cymene)Cl2]2 with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give [Ru(𝜂6-cymene)Cl2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor.
Volume 128 Issue 2 February 2016 pp 165-175 Regular Articles
Ternary copper(II) complexes of salicylaldehyde-histamine Schiff base (HL) and pyridyl ligands, viz. [Cu(bpy)(L)](ClO4) (
Volume 128 Issue 9 September 2016 pp 1405-1415 Regular Article
Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols in water. A ruthenium hydride species is identified as the active species by NMR spectroscopy and isotopic labelling experiments.Maximum enantio-selectivity was attained when a phenyl group was directly attached to the primary amine on the diamine ligand derived from proline.