Length dependence for intramolecular energy transfer in three- and four-color donor-spacer-acceptor arrays.

A series of donor-spacer-acceptor triads has been synthesized and fully characterized. Both donor and acceptor units are built from boron dipyrromethene (BODIPY) dyes but they differ in their respective conjugation lengths, and thereby offer quite disparate optical properties. The spacer units comprise an oligomer of 1,4-phenylene-diethynylene repeat units and allow the boron-boron separation distance to be varied progressively from 18 to 38 A.

Electronic energy transfer to the S2 level of the acceptor in functionalised boron dipyrromethene dyes.

Taking the high road: Highly efficient electronic energy transfer takes place from a set of appended aryl polycyclic hydrocarbons to an expanded boron dipyrromethene (Bodipy)-based dye (see figure) despite negligible spectral overlap with the lowest-energy excited state localised on the acceptor.A multi-component array has been constructed around an expanded boron dipyrromethene (Bodipy) dye that absorbs and emits in the far-red region. One of the appendages is a perylene-based moiety that is connected to the boron atom of the terminal Bodipy by a 1,4-diethynylphenylene connector.

A near-IR emitting bodipy-based dye fitted with ancillary light harvesting units.

Despite limited spectral overlap and quite wide spatial separation, essentially quantitative electronic energy transfer occurs from peripheral Bodipy units to an expanded Bodipy core, the latter being attached via its B centre, so as to generate near-IR fluorescence.

Rapid intersystem crossing in closely-spaced but orthogonal molecular dyads.

A borondipyrromethene (bodipy) dye is equipped with a 4-pyridine residue attached via the meso position. The strong fluorescence inherent to this class of dye is extinguished on protonation of the pyridine N atom. For the corresponding N-methylpyridinium derivative, fluorescence from the dye fragment is also extensively quenched due to the onset of a light-induced charge-shift reaction.

Competing through-space and through-bond, intramolecular triplet-energy transfer in a supposedly rigid ruthenium(II) tris(2,2'-bipyridine)--fullerene molecular dyad.

A ditopic ruthenium(II) tris(2,2'-bipyridyl)-based fullerene conjugate has been synthesized so as to separate the photoactive terminals by way of a short ethynylene spacer group that is expected to act as a rigid rod. Intramolecular triplet-energy transfer from the metal complex to the fullerene is quantitative at all temperatures and there is no indication for competing electron transfer. Temperature dependence studies indicate two pathways for triplet-energy transfer.

Synthesis and photophysical properties of borondipyrromethene dyes bearing aryl substituents at the boron center.

Several borondipyrromethene (Bodipy) dyes bearing an aryl nucleus linked directly to the boron center have been prepared under mild conditions. The choice of Grignard or lithio organo-metallic reagents allows the isolation of B(F)(aryl) or B(aryl)2 derivatives; where aryl refers to phenyl, anisyl, naphthyl, or pyrenyl fragments. A single crystal, X-ray structure determination for the bis-anisyl compound shows that the sp3 hybridized boron center remains pseudo-tetrahedral and that the B-C bond distances are 1.