Arnbjerg Jacob, Paterson Martin J, Nielsen Christian B, Jørgensen Mikkel, Christiansen Ove, Ogilby Peter R
Department of Chemistry, University of Aarhus, DK-8000 Arhus, Denmark.
J Phys Chem A. 2007 Jul 5;111(26):5756-67. doi: 10.1021/jp071197l. Epub 2007 Jun 12.
Singlet molecular oxygen, O2(a1Deltag), can be efficiently produced in a photosensitized process using either one- or two-photon irradiation. The aromatic ketone 1-phenalenone (PN) is an established one-photon singlet oxygen sensitizer with many desirable attributes for use as a standard. In the present work, photophysical properties of two other aromatic ketones, pyrene-1,6-dione (PD) and benzo[cd]pyren-5-one (BP), are reported and compared to those of PN. Both PD and BP sensitize the production of singlet oxygen with near unit quantum efficiency in a nonpolar (toluene) and a polar (acetonitrile) solvent. With their more extensive pi networks, the one-photon absorption spectra for PD and BP extend out to longer wavelengths than that for PN, thus providing increased flexibility for sensitizer excitation over the range approximately 300-520 nm. Moreover, PD and BP have much larger two-photon absorption cross sections than PN over the range 655-840 nm which, in turn, results in amounts of singlet oxygen that are readily detected in optical experiments. One- and two-photon absorption spectra of PD and BP obtained using high-level calculations model the salient features of the experimental data well. In particular, the ramifications of molecular symmetry are clearly reflected in both the experimental and calculated spectra. The use of PD and BP as standards for both the one- and two-photon photosensitized production of singlet oxygen is expected to facilitate the development of new sensitizers for application in singlet-oxygen-based imaging experiments.
单线态分子氧O₂(a¹Δg)可通过单光子或双光子照射的光敏化过程高效产生。芳香酮1-菲醌(PN)是一种成熟的单光子单线态氧敏化剂，具有许多用作标准物质的理想特性。在本工作中，报道了另外两种芳香酮芘-1,6-二酮(PD)和苯并[cd]芘-5-酮(BP)的光物理性质，并与PN的光物理性质进行了比较。在非极性（甲苯）和极性（乙腈）溶剂中，PD和BP均以接近单位量子效率敏化单线态氧的产生。由于其更广泛的π网络，PD和BP的单光子吸收光谱比PN的延伸到更长波长，从而在约300 - 520 nm范围内为敏化剂激发提供了更大的灵活性。此外，在655 - 840 nm范围内，PD和BP的双光子吸收截面比PN大得多，这反过来导致在光学实验中很容易检测到单线态氧的量。使用高水平计算获得的PD和BP的单光子和双光子吸收光谱很好地模拟了实验数据的主要特征。特别是，分子对称性的影响在实验光谱和计算光谱中都得到了清晰的体现。预计将PD和BP用作单线态氧单光子和双光子光敏化产生的标准物质，将有助于开发用于基于单线态氧的成像实验的新型敏化剂。
