RESUMO
Results of our study on ultrafast electron transfer (eT) dynamics from coumarins (coumarin-1, coumarin-480, and coumarin-153) incarcerated within octa acid (OA) capsules as electron donors to methyl viologen dissolved in water as acceptor are presented. Upon photoexcitation, coumarin inside the OA capsule transfers an electron to the acceptor electrostatically attached to the capsule leading to a long-lived radical-ion pair separated by the OA capsular wall. This charge-separated state returns to the neutral ground state via back electron transfer on the nanosecond time scale. This system allows for ultrafast electron transfer processes through a molecular wall from the apolar capsular interior to the highly polar (aqueous) environment on the femtosecond time scale. Employing femtosecond transient absorption spectroscopy, distinct rates of both forward (1-25 ps) and backward eT (700-1200 ps) processes were measured. Further understanding of the energetics is provided using Rehm-Weller analysis for the investigated photoinduced eT reactions. The results provide the rates of the eT across a molecular wall, akin to an isotropic solution, depending on the standard free energy of the reaction. The insights from this work could be utilized in the future design of efficient electron transfer processes across interfaces separating apolar and polar environments.
Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Cumarínicos/química , Substâncias Macromoleculares/química , Viologênios/química , Hidrocarbonetos Aromáticos com Pontes/efeitos da radiação , Cumarínicos/efeitos da radiação , Elétrons , Imidazóis/química , Imidazóis/efeitos da radiação , Luz , Substâncias Macromoleculares/efeitos da radiação , Modelos Químicos , Simulação de Dinâmica Molecular , Oxirredução , Quinolizinas/química , Quinolizinas/efeitos da radiaçãoRESUMO
A 810 nm STED nanoscopy setup and an appropriate combination of two fluorescent dyes (Si-rhodamine 680SiR and carbopyronine 610CP) have been developed for near-IR live-cell super-resolution imaging. Vimentin endogenously tagged using the CRISPR/Cas9 approach with the SNAP tag, together with a noncovalent tubulin label, provided reliable and cell-to-cell reproducible dual-color confocal and STED imaging of the cytoskeleton in living cells.