Ultrafast transient lens spectroscopy of various C40 carotenoids:: lycopene, β-carotene, (3R,3′R)- zeaxanthin, (3R,3′R,6′R)-lutein, echinenone, canthaxanthin, and astaxanthin
Ultrafast transient lens spectroscopy of various C40 carotenoids:: lycopene, β-carotene, (3R,3′R)- zeaxanthin, (3R,3′R,6′R)-lutein, echinenone, canthaxanthin, and astaxanthin
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DOI：
10.1039/b506574g
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发表时间：
2005-01-01
影响因子：
3.3
通讯作者：
Ushakov, VG
中科院分区：
文献类型：
--
作者：
Kopczynski, M;Lenzer, T;Ushakov, VG
利用双色瞬态透镜（TL）泵浦-探测光谱技术，研究了7种C-40类胡萝卜素在室温、不同溶剂中的超快内转换动力学。我们提供了全面的数据集羰基类胡萝卜素黄质，虾青素，和-为。第一次-海胆烯酮，以及番茄红素，β-胡萝卜素，（3R，3 'R）-玉米黄质和（3R，3' R，6 'R）-叶黄素在溶剂中的新数据，尚未在文献中研究。进行测量以确定IC过程如何受到类胡萝卜素的共轭长度、额外的取代基和溶剂的极性的影响。在400 nm处激发到类胡萝卜素S-2带的高能边缘后，在800 nm处记录TL信号。对于S-2寿命，估计所有研究的类胡萝卜素的溶剂独立上限为100 - 200 fs量级。S-1寿命在皮秒范围内，并随着共轭长度的减小而系统地增加。例如，在序列黄质/海胆酮/ B-胡萝卜素（13/ 12/ 11双键）中为1。发现对于S-1 -> S-0 IC过程，τ（1）分别近似为5、7.7和9 ps。未连接到缀合系统的羟基对tau（1）没有明显的影响，如对于黄质/虾青素所观察到的（tau（1）在两种情况下都接近5 ps）。对于所研究的所有类胡萝卜素，发现tau（1）对溶剂极性不敏感。这在海胆酮、黄质和虾青素的情况下特别有趣，因为早期对其他羰基类胡萝卜素的测量，如E。例如，在一个实施例中，多甲素部分表现出显着差异。在极性溶剂中稳定的C-40羰基类胡萝卜素的激发态歧管中可能存在分子内电荷转移态，这显然对测量的tau（1）没有影响。
The ultrafast internal conversion ( IC) dynamics of seven C-40 carotenoids have been investigated at room temperature in a variety of solvents using two- color transient lens ( TL) pump - probe spectroscopy. We provide comprehensive data sets for the carbonyl carotenoids canthaxanthin, astaxanthin, and - for the. first time - echinenone, as well as new data for lycopene, beta- carotene, ( 3R, 3'R)- zeaxanthin and ( 3R, 3'R, 6'R)- lutein in solvents which have not yet been investigated in the literature. Measurements were carried out to determine, how the IC processes are influenced by the conjugation length of the carotenoids, additional substituents and the polarity of the solvent. TL signals were recorded at 800 nm following excitation into the high energy edge of the carotenoid S-2 band at 400 nm. For the S-2 lifetime solvent- independent upper limits on the order of 100 - 200 fs are estimated for all carotenoids studied. The S-1 lifetimes are in the picosecond range and increase systematically with decreasing conjugation length. For instance, in the sequence canthaxanthin/ echinenone/ b- carotene ( 13/ 12/ 11 double bonds) one. finds tau(1) approximate to 5, 7.7 and 9 ps for the S-1 -> S-0 IC process, respectively. Hydroxyl groups not attached to the conjugated system have no apparent influence on tau(1), as observed for canthaxanthin/ astaxanthin ( tau(1) approximate to 5 ps in both cases). For all carotenoids studied, tau(1) is found to be insensitive to the solvent polarity. This is particularly interesting in the case of echinenone, canthaxanthin and astaxanthin, because earlier measurements for other carbonyl carotenoids like, e. g., peridinin partly showed dramatic differences. The likely presence of an intramolecular charge transfer state in the excited state manifold of C-40 carbonyl carotenoids, which is stabilized in polar solvents, has obviously no influence on the measured tau(1).