Maciej SpiegelHow does a tiny natural molecule like hypericin become a powerful dye against cancer without using heavy metals? đ§Źâ¨
My new paper reveals that aggregation is the key! By stacking together, these dyes suppress energy loss and enhance triplet yields through "vibronic coupling control".
This "strength in numbers" mechanism explains why hypericin is so effective in PDT.
Read more: https://doi.org/10.1021/acs.jnatprod.5c01289
#ScienceTwitter #CancerResearch #Chemistry #BioTech #NaturalProducts
Aggregation Suppresses Internal Conversion and Enhances Triplet Yield in Ď-Rich Natural Dyes by Vibronic Coupling Control: A Case Study of Hypericin Supramolecular Assembly
Hypericin, a Ď-rich anthraquinone natural product, exhibits anomalously high triplet yields despite inherently weak spinâorbit coupling. Using long-time-scale molecular dynamics integrated with time-dependent density functional theory calculations, it is demonstrated that early stage supramolecular aggregation modulates hypericinâs excited-state dynamics through vibronic control. Dimerization constrains low-frequency nuclear motions, reducing nonadiabatic couplings and thereby suppressing internal conversion. Concurrently, excitonic redistribution compresses singletâtriplet energy gaps, enabling efficient intersystem crossing in the absence of heavy atoms. Quantitative coupling analysis reveals mixed vibronicâexcitonic regimes that account for the experimentally observed enhancement of triplet formation under self-assembly conditions. These findings establish a mechanistic basis for hypericinâs photodynamic activity.
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