engleski

Photothermal Reactions Derivatives Nitrosobenzene In Solid State

It is well known that nitrosobenzenes can exist in three distinct molecular forms: monomers which are blue or green, and (Z) or (E)-dimers which are yellow or colorless. [1] At ambient temperature in solid state most of the organic nitroso compounds exist as dimers, while in solution monomer-dimer equilibrium is established. [2] It known that at low temperature nitroso dimers can be converted to nitroso monomers photolytically and reverted back to dimers by a simple thermal process. [3] Such a photothermal systems in which we are able break the chemical bond between two nitrogen atoms and bind them together again can be used as a chemical “ off-on” switch in the possible development of intelligent materials. In this work we were investigated monomer-dimer equilibrium of the nitrosobenzene (1), m-chloronitrosobenzene (2) and p-chloronitrosobenzene (3) in the solid state under cryogenic photochemical conditions. It was found that compound 1 and 3 can be converted to monomers after irradiation with UV light at 12 K, while compound 2 cannot be converted to monomers. Temperature conversion monomers to dimers was also determined and it is amount to 270 K for compound 1 while for compound 3 it is 295 K. Monomer-dimer equilibriums were monitored by FTIR spectroscopy. Kinetic of dimerisations for compound 3 was determined by measuring the IR spectral changes at different temperatures and the typical sigmoid kinetic curve was obtained. We have shown that a photothermal process on compound 3 could be repeated several times without destroying state of systems. Above mentioned compound at ambient temperature cannot be photolytically converted to monomers.

solid state; monomer-dimer equilibrium; photothermal reactions

nije evidentirano