Protocol matters! This work shows how different ion exchange protocols impact SCR activity of Cu-SSZ-13, even when they lead to the same metal content. This work suggests an underappreciated approach to influencing catalytic activity....
Ultrafast Photophysics of Regioisomeric Triphenylamine Dyes Having Dipolar D‐π‐A‐A and Octupolar D‐(π‐A‐A)3 Character with a Benzothiazole Unit in Matched or Mismatched Orientation
Von Wiley-VCH zur Verfügung gestellt
Match or mismatch? Steady state and ultrafast spectroscopy reveal the decisive role of the benzothiazole orientation in the Intramolecular Charge Transfer and excited state dynamics of octupolar molecules of the D-(π-Α)3 type.
Benzothiazole is among prominent electron-withdrawing heteroarene moieties used in a variety of π-conjugated molecules. Its relative orientation with respect to the principal dipole vector(s) of chromophores derived thereof is crucial, affecting photophysical and nonlinear optical properties. Here we compare the photophysics and ultrafast dynamics of dipolar and octupolar molecules comprising a triphenylamine electron-donating core, ethynylene π-conjugated linker(s) and benzothiazole acceptor(s) having the matched or mismatched orientation (with respect to the direction of intramolecular charge transfer), while a carbaldehyde group is attached as an auxiliary acceptor. Among chromophores without the auxiliary acceptor, stronger fluorescence solvatochromism and faster excited state dynamics are exhibited for the derivatives with the mismatched geometry. On the contrary, introduction of the auxiliary acceptor to the benzothiazole unit enhances the intramolecular charge transfer ICT (featuring ultrafast dynamics of the excited state) for the matched geometry. The data confirm the crucial role of the relative orientation of asymmetric heteroaromatic unit (regioisomeric effect) in dipolar as well as in multipolar molecules in tuning linear and nonlinear optical properties as well as excited state dynamics.Zum Volltext
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