Quenching of triplet states of organic compounds by tris([beta]-dionato)iron(III) chelates

The rate constants of quenching of triplet states of 14 organic compounds by 3 tris([beta]-dionato)iron(III) coordination compounds were measured in benzene using the technique of laser flash photolysis. The coordination compounds tris(4,4-dimethyl-1,3-propanedionato)iron(III), Fe(bpdo)3, tris(1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionato)iron(III), Fe(tert-Bu-tfa) 3, and tris(3-cyano-2,4-pentanedionato)iron(III), Fe(acac-CN)3 are shown to be very efficient quenchers and triplets with energies much lower than the lowest excited states of the quenchers, give relatively high quenching constants, i.e. -3x108dm3mol-1s-1. [Continues.]