Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, Kerela, India.
J Comput Chem. 2020 Apr 30;41(11):1068-1080. doi: 10.1002/jcc.26152. Epub 2020 Jan 22.
Nonradiative decay pathways associated with vibronically coupled S (ππ*)-S (nπ*) potential energy surfaces of 3- and 5-hydroxychromones are investigated by employing the linear vibronic coupling approach. The presence of a conical intersection close to the Franck-Condon point is identified based on the critical examination of computed energetics and structural parameters of stationary points. We show that very minimal displacements of relevant atoms of intramolecular proton transfer geometry are adequate to drive the molecule toward the conical intersection nuclear configuration. The evolving wavepacket on S (ππ*) bifurcates at the conical intersection: a part of the wavepacket moves to S (nπ*) within a few femtoseconds while the other decays to S minimum. Our findings indicate the possibility of forming the proton transfer tautomer product via S (nπ*), competing with the traditional pathway occurring on S (ππ*).
通过采用线性振子耦合方法研究了 3-和 5-羟基色原酮的 S(ππ*) - S(nπ*)势能表面上与振动耦合相关的非辐射衰减途径。根据对计算得到的势能面关键点的能量和结构参数的仔细检查，确定了在 Franck-Condon 点附近存在一个锥形交叉点。我们表明，只需对分子内质子转移几何结构中相关原子进行非常小的位移，就足以将分子推向锥形交叉核构型。S(ππ*)上的演化波包在锥形交叉处分叉：一部分波包在几飞秒内转移到 S(nπ*)，而另一部分则衰减到 S 最低能态。我们的研究结果表明，通过 S(nπ*)形成质子转移互变异构体产物是可能的，这与在 S(ππ*)上发生的传统途径相竞争。
