|
|
Sensitizers, Acceptors and Secondary Sources of Singlet Oxygen and Their Supramolecular Complexes with Cyclodextrins
Slavětínská, Lenka ; Mosinger, Jiří (advisor) ; Němcová, Irena (referee) ; Sýkora, Jan (referee)
l. Introduction 1.1. Singlet oxygen Singlet molecular oxygen 'o, 1'Á,) has been intensively investigated by the chemists and biologists over the few decades, primarily due to its high reactivity and cytotoxity. singlet oxygen is common term for oxygen molecules in two lowest-lying excited energy states lo2 1'Á.1 and 'oz('E.) differing in occupation of HoMo orbitals, energy and lifetime. First singlet excited state 'o, (t^r) is generated, if two electrons with antiparallel spin occupy one antibonding n* orbital. The configuration of the molecular orbitals ofthe singlet excited state r02(rts) is identical to that ofthe ground state' except that the last two electrons have antiparallel spinsr'2. Singlet oxygen is short-lived' highly oxidative cýotoxic species. Its |ifetime significantly depends on type of solvent2'r. Singlet oxygen can be generated vla photosensitized reaction. The mechanism includes the formation of the sensitizer triplet state and transfer of energy to triplet oxygen leading to lo,1'Á,) formation o.''u 1see Fig. l). Singlet ox;-'een can be a|so produced by the number of chemical reactions. e.g. using H2O2/CIO' ,.r, Hrorl MoOq2- e'r. and H2o2/cao2rr systems based on disproporcionation of H2o2that leads to H2o andrO2.
|
guest ::
RSS feed.