The reactivity of the triplet excited state of 1,4-diaza-9-fluorenones towards hydrogen and electron donors

Química Nova

Santos, Frances R. dos¹  Universidade Federal Rural do Rio de Janeiro, Seropédica, Brasil¹  Takaizumi, Andreza A. C.¹  Netto-Ferreira, José Carlos¹  Silva, Mônica T. da¹ 

关键词: fluorenones;    laser flash photolysis;    triplet excited state.;   

DOI  :  10.1590/S0100-40422009000700022

学科分类：化学（综合）

来源: Sociedade Brasileira de Quimica

【 摘 要 】

The effect of the introduction of nitrogen atoms upon the triplet excited state reactivity of 1,4-diaza-9-fluorenone (1) and 1,4-diaza-9-benz[b]fluorenone (2), in acetonitrile, was investigated employing the nanosecond laser flash photolysis technique. The intersystem crossing quantum yield (Φces) for 1 and 2 was determined using 9-fluorenone as a secondary standard (Φces= 0.48, in acetonitrile) and for both diazafluorenones a value of Φces= 0.28 was found. Quenching rate constants ranged from 8.17x104 L mol-1 s-1 (2-propanol) to 1.02x1010 L mol-1 s-1 (DABCO) for 1,4-diaza-9-fluorenone and from 6.95x105 L mol-1 s-1 (2-propanol) to 5.94x109 L mol-1 s-1 (DABCO) for 1,4-diaza-9-benz[b]fluorenone, depending if the quenching process involves energy, hydrogen or electron transfer. A comparison between quenching rate constants for both diazaflurenones and the parent compound, i.e. 9-fluorenone, a ketone with lowest triple state of ππ* configuration, lead to the conclusion that the reactive triplet excited state for 1,4-diaza-9-fluorenone and 1,4-diaza-9-benz[b]fluorenone has ππ* configuration.

【 授权许可】

Unknown