Ghosh Soumen, Bishop Michael M, Roscioli Jerome D, LaFountain Amy M, Frank Harry A, Beck Warren F
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824-1322, United States.
Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3036, United States.
J Phys Chem Lett. 2017 Jan 19;8(2):463-469. doi: 10.1021/acs.jpclett.6b02881. Epub 2017 Jan 9.
Excitation energy transfer from peridinin to chlorophyll (Chl) a is unusually efficient in the peridinin-chlorophyll a protein (PCP) from dinoflagellates. This enhanced performance is derived from the long intrinsic lifetime of 4.4 ps for the S (1B) state of peridinin in PCP, which arises from the electron-withdrawing properties of its carbonyl substituent. Results from heterodyne transient grating spectroscopy indicate that S serves as the donor for two channels of energy transfer: a 30 fs process involving quantum coherence and delocalized peridinin-Chl states and an incoherent, 2.5 ps process initiated by dynamic exciton localization, which accompanies the formation of a conformationally distorted intermediate in 45 fs. The lifetime of the S state is lengthened in PCP by its intramolecular charge-transfer character, which increases the system-bath coupling and slows the torsional motions that promote nonradiative decay to the S (2A) state.
在来自甲藻的多甲藻素 - 叶绿素a蛋白（PCP）中，从多甲藻素到叶绿素a的激发能量转移异常高效。这种增强的性能源于PCP中多甲藻素S(1B)态4.4皮秒的长本征寿命，这是由其羰基取代基的吸电子特性引起的。外差瞬态光栅光谱的结果表明，S作为两个能量转移通道的供体：一个30飞秒的过程涉及量子相干和离域的多甲藻素 - 叶绿素态，以及一个由动态激子局域化引发的2.5皮秒的非相干过程，该过程伴随着在45飞秒内形成构象扭曲的中间体。PCP中S态的寿命因其分子内电荷转移特性而延长，这增加了体系 - 浴耦合，并减缓了促进向S(2A)态非辐射衰变的扭转运动。
