Articles written in Journal of Chemical Sciences
Volume 93 Issue 6 August 1984 pp 1003-1014 Inorganic Chemistry
Transition metal complexes display a number of charge-transfer bands in the absorption spectra. Optical excitation of the metal complexes produces a variety of products depending upon the nature of the excited state. Cobalt (III) ammine complexes on excitation in the CTTM bands produce cobalt(II) and oxidised ligand. Ruthenium(II) complexes on excitation in the cm. band leads to the oxidation of the metal centre. In certain reactions participation of the solvent in the primary photoredox reactions has also been reported. In recent years extensive investigations have been undertaken to utilize the photoredox systems of coordination compounds to convert solar energy to electricity or hydrogen.
Volume 97 Issue 3-4 October 1986 pp 417-448
Cyclic voltammetric studies were carried out for dioxygen-bridged dinuclear cobalt(III) complexes using platinum electrodes at different values of pH and ionic strength. Reversible electrode reactions occur particularly for the dioxygen complexes [(phen)2Co(μ-O2,NH2)Co(phen)2] (ClO4)42H2O and [(bpy)2Co(μ-u-O2, NH2)Co(bpy)2] (ClO4)4H2O with 1,10-phenanthroline (phen) and 2,2-bipyridine (bpy) as the non-bridging ligands. For complexes with ammonia (NH3) ethylenediamine (en) as the terminal ligands, there is quasi-reversible electrode behaviour at pH < 3 due to protonation of the peroxo complexes which subsequently undergo equilibration with isomeric forms. Such behaviour is well-marked for the peroxo complex [(en)2Co(μ-O2 NH2)Co(en)2](NO3)3. The decaammine complex [(NH35Co(μ-O2Co(NH3)5](NO3)5 shows only a cathodic peak due to intramolecular charge transfer decomposition in solution after reduction at the electrode. Diffusion coefficients for all the dioxygen complexes were determined from the plots of
Volume 102 Issue 3 June 1990 pp 319-328
In cobalt(III) amine complexes containing amino acids, photolysis in the chargetransfer bands leads to the formation of alkyl cobalt(III) complexes. Steady and flash photolysis of complexes [Co(LL)2X]2+ and [Co(LL)2Y2]+ (LL = ethylene diamine, polypyridyl or propylenediamine, X = amino acid and Y = nitro ligand) were carried out. Steady irradiation of [Co(bpy)2(gly)]2+ ion (bpy = bipyridine, gly = glycine) in aqueous medium (pH 1–7) produces the six-coordinated complex [Co(bpy)2(CH2NH2)]2+. Flash photolysis of the complex under identical conditions gives an alkyl complex. The alkyl complex formed in the case of [Co(bpy)2(gly)]2+ ion is stable and could be isolated; the corresponding alkyl complex formed from [Co(bpy)(en)(gly)]2+ ion leads to the labilisation of the ethylenediamine ligand in acidic solutions. Photolysis of the nitro complexes of the type [Co(en)2(NO2)2]+ ion in acetonitrile, methanol and ethanol produces a
Volume 104 Issue 6 December 1992 pp 627-627
Volume 104 Issue 6 December 1992 pp 762-790
J Basu K K Rohatgi-Mukherjee S Chatterjee S Sarkar S N Bhattacharyya G K Dasmahapatra Thomas Wolff Gunther Von Bunau S N Dhawan Dipankar Sen Subhash Ch Bera S C Gupta N S Yadav Manabendra Sahu Manjubikash Saha V Masilamani D Sastikumar Pradipta Kumar Behera Ashok Kumar Mishra S Muthusamy V T Ramakrishnan P Ramamurthy S Sampath R Narayan M C Durai Manickam C Srinivasan K Pitchumani M Roja S Rajagopal Reba Ray Samaresh Mukherjee A Samanta E Natarajan S Selvaraj P Natarajan S S Talwar K Viswanathan P Natarajan Aruna Dhathathreyan K S Dhathathreyan Basanti Biswal Pill-Soon Song S Das M Muneer A Haridas V B Manilal R Jayakumar T Ramasami M Julliard M Chanon P N Joshi U C Biswal C L Joshy E Purushothaman Bhaskar G Maiya S Ganesan B Nagarajan V Narayanan Prasanna Mohanty V Shubin S D S Murthy N V Karapetyan R Ramaraj K V Gobi V Gomathi Sankareswari S Ranganayaki K Bahadur Sajal Kumar H R Sonawane D G Kulkarni N R Ayyangar N Sukumar T V Venkitachalam A S Rao S I Ali Harpal Kaur V Anbalagan T S Srivastava Awadhesh Kumar P K Chowdhury K V S Rama Rao J P Mittal N Balasubramanian S Balasubramanian G B Dutt S Doraiswamy Bidyut Kumar Manna K K Rohatgi-Mukherjee A Chandra B Bagchi S Arunachalam J R Devadason T Dhanasekaran K Joseph Prabahar Lizamma Mathew V Ramakrishnan J Rajaram V R S Rao P Narayanan V N Sivasankara Pillai K I Priyadarsini T Rajendran M Palaniandavar M Kaneko A Kira M S Sidhu Arti Chopra Barinder Gill Thomas Baby V P N Nampoori
Volume 112 Issue 3 June 2000 pp 382-382
Volume 121 Issue 5 September 2009 pp 711-718
The phenosafranine adsorbed onto the micro and mesoporous materials prepared by ion exchange method and interaction of the dye with host materials were studied by X-ray photoelectron spectroscopy to elucidate the influence of the host matrix on the binding energy of N 1s orbital. Core level N 1s X-ray photoelectron spectroscopy reveals the interaction between the dye and the solid surface through the hydrogen bonding between the hydrogen atoms of primary amino groups in dye molecule and the oxygen atom of surface hydroxyl groups. The strength of the hydrogen bonding depends on the nature of the solid surface. In the dye adsorbed onto the micro and mesoporous materials the interaction between adsorbed phenosafranine and the surfaces of the porous materials are found to modify the optical spectra and the excited state dynamics of the confined phenosafranine molecules. The change in photophysical properties of phenosafranine adsorbed on to the host materials on dehydration at elevated temperatures is attributed to the modification of host surface during dehydration process.
Volume 123 Issue 5 September 2011 pp 531-553
The photoredox reactions of cobalt(III), nickel(II) complexes and organic dyes are reviewed with particular emphasis on using flash photolysis methods to identify the transients in the time scale from milliseconds to subpicoseconds. The excitation flash radiation initially was limited to flash lamps with a time resolution to study the decay of the excited states and the fast reactions of photo produced transients in milliseconds and microseconds. Some of the photolysis reactions investigated provide details in real time including the thermal reactions of molecular oxygen with cobalt(II) amine systems and the cobalt (III) alkyl complex formation on photolysis of cobalt(III) aminoacid complexes. Photoredox reactions of thiazine and safranine dyes are investigated using time resolved absorption and emission techniques in solution and on encapsulation in micro and mesoporous host materials. Picosecond and femtosecond diffuse reflectance fluorescence investigations in the porous solid host materials show intramolecular proton transfer reactions of the dyes and deprotonation of the dyes in the excited states. Photosensitization of nanoparticles of semiconductors, anatase TiO2 and ZnO by the excited states of dyes in meso and microporous silicate hosts is investigated using pico and femtosecond fluorescence and transient absorptions techniques and the results are reviewed.
Volume 132, 2019
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