Experimental evidence of the S state and fluorescence emission from the intramolecular charge transfer states in fucoxanthin.

Fucoxanthin is a typical carotenoid that absorbs light in the blue region of the visible spectrum, and its detailed electronic structures remain to be clarified. It is well known that carotenoids harvest energy from sunlight and transfer it to chlorophylls (Chls) and/or bacteriochlorophylls (BChls) through its excited states as the intermediate states; however, some excited states still need evidence to be definitely confirmed. Through steady-state fluorescence emission spectroscopy and femtosecond time-resolved fluorescence up-conversion technique, we provide new evidence for the identification of the excited S state in fucoxanthin, a representative of carotenoids.

Origin of Intersystem Crossing in Red-Light Absorbing Bodipy Derivatives: Time-Resolved Transient Optical and Electron Paramagnetic Resonance Spectral Studies with Twisted and Planar Compounds.

We studied the intersystem crossing (ISC) property of red-light absorbing heavy atom-free dihydronaphtho[]-fused Bodipy derivatives (with phenyl group attached at the lower rim via ethylene bridge, taking constrained geometry, i.e., and the half-oxidized product ) and dispiroflourene[]-fused Bodipy () that have a twisted π-conjugated framework.

Charge Transfer and Intersystem Crossing in Compact Naphthalenediimide-Phenothiazine Triads: Synthesis and Study of the Photophysical Property with Transient Optical and Electron Paramagnetic Resonance Spectroscopic Methods.

In order to obtain a long-lived charge separation (CS) state in compact electron donor-acceptor molecular systems, we prepared a series of naphthalenediimide (NDI)-phenothiazine (PTZ) triads, with phenylene as the linker between the donor and acceptor. Conformation restriction is imposed to control the mutual orientation of the NDI and PTZ units by attaching methyl groups on the phenylene linker to tune the electronic coupling between the donor and the acceptor. Moreover, the PTZ moiety was oxidized to sulfoxide to tune the ordering of the CS state and the LE state (LE: locally excited state).