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Title: Fluorescence of PRODAN in Water: a Computational QM/MM MD Study

Fluorescent properties of PRODAN (6-propionyl-2-dimethylaminonaphthalene) in water were studied by means of excited state molecular dynamics simulations employing a combined quantum mechanical and molecular mechanical approach with the time-dependent density functional theory (TD-DFT QM/MM MD). The state of the art coupled cluster method was used to benchmark density functional theory calculations. The influence of the water environment on PRODAN emission was investigated by employing several computational schemes with varying description of the solvent. The issue of the molecular geometry of the excited state PRODAN molecule in water was addressed. The experimental emission spectrum was reproduced for the planar excited state conformer of PRODAN in the extended environment of 300 explicit water molecules. The planar conformer was shown to be predominantly responsible for fluorescence. The twisted isomer is strongly stabilized in water, but rapidly evolve towards a conical intersection, and hence the twisted conformer is fluorescently inactive.
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Journal Article
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Journal Name: Chemical Physics Letters, 597:57-62
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
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Country of Publication:
United States
Time-dependent Density Functional Theory; fluorescent; PRODAN; QM/MM MD; molecular dynamics; calculations; Environmental Molecular Sciences Laboratory