Laboratory of Photochemistry

Head of Laboratory: Professor, Dr. Sci. V.F. Plyusnin
Researchers:
Professor, Dr. Sci. N.M. Bazhin, Dr. Sci. N.L. Lavrik, Cand. Sci. V.V. Korolev, Cand. Sci. E.M. Glebov, Cand. Sci. I.P. Pozdnyakov
Staff:
L.A. Zernova
Research area.
Investigation of primary mechanisms of photochemical reactions and the reactivity of active intermediate particles.
Research Activities
During the recent years, basic attention has been aimed at the development of pulse methods in photochemical processes and their applications to the problems of photochemistry.
Studies of geminate pairs by luminescence quenching. A geminate pair is formed in the condensed phase under the action of light from either pulse or continuous source. One of the particles in the pair serves as a donor of electron excitation energy and another as an acceptor. After the pair is formed, at a definite moment the donor is excited by the light in order to observe the luminescence, its intensity and kinetic parameters being dependent on the distance between the particles in the pair. Recording the kinetics of luminescence changes allows to obtain information concerning the distribution of distances in pairs and its temporal dependence. The method has been tested with systems containing anthracene endoperoxide as the initial compound. The photolysis of this molecule leads to the formation of geminate pair anthracene-oxygen in which anthracene is the donor and oxygen is the acceptor of the energy of electron excitation. Oxygen mobility measured in different matrices at low temperatures was found to be as low as 10-23 cm2/s which gives a 1 A/year change of relative positions.
The studies of the mechanisms of photochromic and photochemical processes by means of spectroscopic pulse and low-temperature methods involving modern methods of quantum chemistry. A triplet adiabatic mechanism has been stated for 1-methyl- and 1-acyl-oxy derivatives of anthraquinone and the connection between the reactivity of the studied anthraquinones and their chemical structure has been explained. Rate constants of elementary stages of photochromic transformations have been determined and the connection has been established between the reactivity of active intermediates and their chemical structure. Most recent investigations deal with the spectroscopy and reactivity of singlet aromatic nitrenes which are key intermediates in the photolysis of aromatic azides.
Studies of the mechanism of primary photochemical processes for a wide class of halide complexes of the ions of transition metals and heavy precious metals. It has been shown that the primary process is electron transfer from the molecules of the medium (solvent) to the excited complex. The solvent radical forms primary radical complex with the photoreduced ion. This complex decomposes within several tens nanoseconds in liquid solution at room temperature. At low temperatures in the presence of oxygen the primary radical complex is transformed into secondary complexes containing peroxy radical in its coordination sphere. Optical and ESR spectra of these intermediate particles have been recorded and kinetic parameters have been determined. The studies are carried out of the photochemistry of unusual coordination compounds in which central ion exhibits superhigh oxidation degree or ligand is free radical. It has been shown that photochemical sensitivity of such particles (for example, for Ni(IV) dithiocarbamate complexes) is shifted to red spectral region and they can possess unique photochromic properties.
Investigations of magnetic field effect on luminescence and photochemical reactions of gas phase molecules. It is shown that, depending on the structure of molecules, magnetic field induces the interaction between the levels leading to the acceleration of the relaxation of electron excitation energy. This leads to the acceleration of photochemical reactions or to their deceleration, depending on what level does photodissociation occur from.
International cooperation
1. Energetic Center of The Netherlands
2. Chemistry Department, The Ohio State University, USA
3. Technological University of Tampere, Finland
Selected publications
1. N.M. Bazhin. Sources and sinks of atmospheric methane. Chemistry for Sustainable Development, v.1, N 3, p.381-396, 1994.
2. Plyusnin V.F., Grivin V.P., Larionov S.V. Photochemistry of Fe(III), Fe(IV), Ru(III), Mo(VI), and Ni(IV) dithiocarbamate complexes. Coord. Chem. Rev., 1997, V.159. P.121-133.
Address:
Plyusnin V.F.
Institutskaya 3, Novosibirsk, 630090, Russia
Phone: +7(383) 333-23-85
E-mail