Department of Chemistry, University of Florida, Gainesville, FL 32611, USA.
Talanta. 1986 Jan;33(1):17-25. doi: 10.1016/0039-9140(86)80008-x.
The phosphorescence characteristics (excitation and emission spectra and lifetimes) of acetophenone (AP), benzophenone (BP), p-aminobenzophenone (PABP) and Michler's ketone (MK) adsorbed on Whatman No. 1 filter paper were measured at various temperatures, and compared with the phosphorescence characteristics in different solvent glasses at 77 K. Both AP and BP phosphoresce on filter paper only at low temperature (208 K). The phosphorescence lifetimes of AP and BP are < 1 msec, indicating a (3)(n,pi()) lower triplet level for paper substrates. With PABP, the low lying triplet state in polar solvents is (3)(CT) and in non-polar solvents is (3)(n, pi()); PABP on filter paper results in spectral characteristics similar to those of PABP in polar solvents at 77 K. The lifetime of PABP is longer than that of BP, indicating a (3)(CT) low-lying triplet state. MK, like PABP, has strongly environment-dependent photophysical properties. MK, when adsorbed on filter paper, has an intense long-lived luminescence at room temperature, resulting in a limit of detection of 3 ng ml or 3 pg, and a linear dynamic range of over 3 orders of magnitude. MK appears to be strongly hydrogen-bonded to the filter paper. In studies in ethanol and other solvents, MK adsorbed on filter paper shows a dramatic change in its phosphorescence spectrum when the temperature is lowered from 298 K to 208 K; the phosphorescence peak moves to longer wavelengths and the intensity decreases. The temperature effect could arise from the presence of several conformers of MK or be due to different environmental sites or E-type delayed fluorescence. The low-lying triplet state of MK on filter paper is most likely a (3)(CT) state. Lowering the temperature appears to increase the phosphorescence intensity for ketones which phosphoresce in the (3)(n,pi()) triplet state, but affects it only slightly for analytes which phosphoresce in the (3)(pi,pi()) triplet state. Room-temperature phosphorescence seems to arise for aromatic ketones and aldehydes with low-lying (3)(pi, pi(*)) or (3)(CT) triplet states.
在不同温度下测量了吸附在 Whatman No.1 滤纸上的苯乙酮 (AP)、二苯甲酮 (BP)、对氨基二苯甲酮 (PABP) 和米克耳酮 (MK) 的磷光特性（激发和发射光谱以及寿命），并与 77 K 下不同溶剂玻璃中的磷光特性进行了比较。AP 和 BP 仅在低温（208 K）下在滤纸上发磷光。AP 和 BP 的磷光寿命<1 毫秒，表明纸基质的三重态能级较低（3）（n，pi())。对于 PABP，在极性溶剂中低能三重态为（3）（CT），在非极性溶剂中为（3）（n，pi())；PABP 在滤纸上的结果与 77 K 下极性溶剂中 PABP 的光谱特征相似。PABP 的寿命长于 BP，表明其三重态能级较低（3）（CT）。MK 与 PABP 一样，具有强烈依赖于环境的光物理性质。MK 吸附在滤纸上时，在室温下会发出强烈的长寿命发光，检测限为 3 ng/ml 或 3 pg，线性动态范围超过 3 个数量级。MK 似乎与滤纸强烈氢键结合。在乙醇和其他溶剂中的研究中，当温度从 298 K 降至 208 K 时，吸附在滤纸上的 MK 的磷光光谱会发生剧烈变化；磷光峰移向较长波长，强度降低。温度效应可能源于 MK 的几种构象的存在，也可能是由于不同的环境位置或 E 型延迟荧光。MK 在滤纸上的低能三重态很可能是（3）（CT）态。降低温度似乎会增加在（3）（n，pi())三重态中发磷光的酮的磷光强度，但对在（3）（pi，pi())三重态中发磷光的分析物影响很小。室温磷光似乎是由具有低能（3）（pi，pi(*)) 或（3）（CT）三重态的芳香酮和醛产生的。
