The photodecomposition mechanism of tert-butyl-9-methylfluorene-9-percarboxylate: new insight from femtosecond IR spectroscopy
作者:Christian Reichardt、Jörg Schroeder、Dirk Schwarzer
DOI:10.1039/b806359a
日期:——
The ultrafast photodissociation of tert-butyl-9-methylfluorene-9-percarboxylate (TBFC) is studied by mid-infrared transient absorption spectroscopy after UV excitation at 266 nm. By means of 13C-labeled TBFC and additional DFT calculations transient IR bands in the fingerprint region were unambiguously assigned to the methylfluorenyl radical. The experiments show that the fragmentation is controlled by the S1-lifetime of TBFC and, dependent on the solvent, within 0.8–2.1 ps leads to tert-butyloxy and methylfluorenyl radicals plus CO2via concerted bond breakage of the O–O and the fluorenyl–C(carbonyl) bond. In accordance, the CO2 quantum yield is determined to be unity.
利用中红外瞬态吸收光谱法研究了在266 nm紫外激发后,叔丁基-9-甲基芴-9-过羧酸盐(TBFC)的超快光解离反应。通过13C标记的TBFC和额外的DFT计算,明确地将指纹区的瞬态红外谱带归属于甲基芴基自由基。实验表明,碎裂反应受TBFC的S1寿命控制,且依赖于溶剂,在0.8-2.1 ps内通过O-O键和芴基-C(羰基)键的协同断裂,生成叔丁氧自由基、甲基芴基自由基和二氧化碳。因此,测得的二氧化碳量子产率为1。