Do Thanh Nhut, Sim Jamie Hung Ni, Nguyen Hoang Long, Lu Yunpeng, Tan Howe-Siang
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.
J Phys Chem Lett. 2021 Jan 14;12(1):165-170. doi: 10.1021/acs.jpclett.0c03243. Epub 2020 Dec 15.
We perform two-dimensional electronic spectroscopy on chlorophyll (Chl) and molecules in aprotic solvents of different Lewis basicity. By analyzing the ultrafast spectral diffusion dynamics of the Q transition, we show that a certain timescale of the spectral diffusion dynamics is affected by the solvents' Lewis basicity. Control experiments with Chlorin-e6-a Chl molecule analog-and time-dependent density functional theory calculations confirm that we are directly probing the fluctuation dynamics of the dative bond between the solvent's lone pair and the Mg center in Chls that is responsible for the Lewis basicity. The observation is indicative of dative bond length and angular fluctuations with timescales ranging between ∼30 and 150 ps and the dative bond-strength-dependent perturbation on the Q transition frequency of Chls.
我们对叶绿素（Chl）以及处于不同路易斯碱度非质子溶剂中的分子进行了二维电子光谱分析。通过分析Q跃迁的超快光谱扩散动力学，我们发现光谱扩散动力学的特定时间尺度受溶剂路易斯碱度的影响。使用二氢卟酚e6（一种叶绿素分子类似物）进行的对照实验以及含时密度泛函理论计算证实，我们正在直接探测溶剂孤对电子与叶绿素中镁中心之间配位键的涨落动力学，而这种配位键是造成路易斯碱度的原因。该观察结果表明配位键长度和角度涨落的时间尺度在约30至150皮秒之间，并且配位键强度对叶绿素Q跃迁频率存在依赖性扰动。
