Chowdhury Uttam, Mondal Shrabanti, Dey Subhajit, Habib Md, Sarkar Ritabrata, Gumber Shriya, Chattopadhyay Pabitra, Sarkar Pranab, Prezhdo Oleg, Pal Sougata
Department of Chemistry, University of Gour Banga, Malda 732103, India.
Department of Chemistry, Sripat Singh College, Jiaganj 742122, India.
J Am Chem Soc. 2025 Jun 18;147(24):20748-20758. doi: 10.1021/jacs.5c04270. Epub 2025 Jun 5.
We employ the fundamental chemical concepts of hard-soft acid-base to formulate general principles governing excited-state dynamics in zinc porphyrin (ZnP)/carbon nanotube (CNT) hybrids for energy photoconversion. Atomistic quantum dynamics simulations demonstrate that electron-withdrawing and donating substituents at the ZnP β-pyrrolic position strongly influence the dynamics. ZnP photoexcitation produces subpicosecond electron transfer (ET) from ZnP to CNT, in agreement with the experiment. Substitutions of CN by H and Bu accelerate the ET. The trend is directly related to the hard-soft acid-base concept because the soft-soft interaction between the Bu-ZnP acid and the mild CNT base enhances the donor-acceptor coupling. Longer coherence and more active vibrational modes facilitate the ET in Bu-ZnP/CNT. Electron-hole recombination in CN-ZnP/CNT occurs on a hundred picosecond time scale, nicely corroborated by the experiment. The exciton lifetime is extended beyond a nanosecond by the substitutions. The soft-soft interaction in Bu-ZnP/CNT increases the splitting between the highest occupied orbitals of the two subsystems, reduces their mixing, and decreases nonadiabatic coupling between the ground and excited states. Rapid decoherence and involvement of low-frequency vibrations favor longer lifetimes. Our investigation reveals that larger p of the β-pyrrolic acid gives rapid ET and slow recombination and provides detailed mechanistic information, essential for future optoelectronic applications.
我们运用硬软酸碱的基本化学概念，来制定关于锌卟啉（ZnP）/碳纳米管（CNT）杂化体系中能量光转换激发态动力学的一般原理。原子尺度的量子动力学模拟表明，ZnP β-吡咯位置上的吸电子和供电子取代基对动力学有强烈影响。ZnP光激发产生从ZnP到CNT的亚皮秒级电子转移（ET），这与实验结果一致。用H和Bu取代CN会加速ET。这种趋势与硬软酸碱概念直接相关，因为Bu-ZnP酸与温和的CNT碱之间的软-软相互作用增强了供体-受体耦合。更长的相干性和更活跃的振动模式促进了Bu-ZnP/CNT中的ET。CN-ZnP/CNT中的电子-空穴复合发生在百皮秒时间尺度上，这得到了实验的很好证实。通过取代，激子寿命延长到纳秒以上。Bu-ZnP/CNT中的软-软相互作用增加了两个子系统最高占据轨道之间的分裂，减少了它们的混合，并降低了基态和激发态之间的非绝热耦合。快速退相干和低频振动的参与有利于更长的寿命。我们的研究表明，β-吡咯酸较大的p值会导致快速ET和缓慢复合，并提供了详细的机理信息，这对未来的光电子应用至关重要。
