2024/01/01 by Giovanni Parolin, Bidhan Chandra Garain, Saikat Mukherjee +3 · 1 voice · 9 citations
Chemistry · Materials Science · #Analytical Chemistry and Chromatography #Atomic physics #Chemical physics #Chemistry #Computational chemistry #Dynamics (music) #Excimer #Excited state #Fluorescence #Maxima and minima #Molecular dynamics #Optics #Organic chemistry #Photochemistry #Photochemistry and Electron Transfer Studies #Physics #Porphyrin and Phthalocyanine Chemistry #Pyrene
paper · open access · doi:10.1039/d4cp03947e
published in Physical Chemistry Chemical Physics 26(47), 29351-29363 (Royal Society of Chemistry)
openalex publication_date 2024/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/02
The conformational dynamics of the pyrene excimer play a critical role in its unique fluorescence properties. Yet, the influence of multiple local minima on its excited-state behavior remains underexplored. Using a combination of time-dependent density functional theory (TD-DFT) and unsupervised machine learning analysis, we have identified and characterized a diverse set of stable excimer geometries in the first excited state. Our analysis reveals that rapid structural reorganization towards the most stable stacked-twisted conformer dominates the excimer's photophysics, outcompeting radiative relaxation. This conformer, which is primarily responsible for the characteristic red-shifted, structureless fluorescence emission, reconciles experimental observations of long fluorescence lifetimes and emission profiles. These findings provide new insights into the excited-state dynamics of excimers. They may inform the design of excimer-based materials in fields ranging from organic electronics to molecular sensing.