Through-Bond Energy Transfer Cassettes with Minimal Spectral Overlap between the Donor Emission and Acceptor Absorption: Coumarin-Rhodamine Dyads with Large Pseudo-Stokes Shifts and Emission Shifts
Through-Bond Energy Transfer Cassettes with Minimal Spectral Overlap between the Donor Emission and Acceptor Absorption: Coumarin-Rhodamine Dyads with Large Pseudo-Stokes Shifts and Emission Shifts
复制标题
供体发射和受体吸收之间具有最小光谱重叠的键通能量转移盒：具有大伪斯托克斯位移和发射位移的香豆素-罗丹明二元组
DOI：
10.1002/anie.200904515
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Song, Jizeng
中科院分区：
文献类型：
--
作者：
Lin, Weiying;Yuan, Lin;Song, Jizeng
Small-molecule organic dyes have been widely used in fluorescent probes,[1] labels,[2] logic gates,[3] light-emitting materials,[4] and light-harvesting systems.[5] However, the undesirable photophysical properties of various fluorophores still constrain the full potential of their applications. For instance, many bright organic dyes including rhodamine, fluorescein, boron dipyrromethane (BODIPY), and cyanine derivatives have the serious disadvantage of very small Stokes shifts (typically less than 25 nm), which can lead to serious self-quenching and fluorescence detection errors because of excitation backscattering effects.[6] Therefore, there is a need to develop dyes with improved properties. Since it is still difficult to judiciously design single organic dyes with desirable photophysical properties, considerable attention has recently been paid to the exploration of multifluorophores with energy-donor–acceptor architectures.[1m, 6b, 7–9] In this regard, some energy-donor–acceptor systems based on fluorescence resonance energy transfer (FRET) have been constructed.[6b, 8] FRET dyads are usually linked by a nonconjugated spacer, and the energy transfer occurs through space. Although the pseudo-Stokes shifts (the wavelength discrepancy between the donor absorption and the acceptor emission in an energy transfer system with almost 100% energy transfer efficiency [7]) of FRET-based energy cassettes are larger than the Stokes shifts of either the donor or acceptor dyes, FRET-based cassettes are still limited by the requirement that the donor emission must have strong overlap with the acceptor absorption.[10] This requirement essentially restricts the pseudo-Stokes shifts as well as the emission shifts (the emission wavelength shift between the donor and acceptor) of FRET-based systems. Like the pseudo-Stokes shift, the emission shift is also an important parameter in energy-transfer dyads. A large emission shift in energy transfer systems should result in two well-separated emission peaks, which is favorable for the precise measurement of the peak intensities and ratios.[6b, 11] Thus, energytransfer dyads with large pseudo-Stokes shifts and emission shifts are desirable.By contrast, through-bond energy transfer (TBET) is theoretically not subjected to the constraint of intense spectral overlap between the donor emission and the acceptor absorption.[9] Thus, TBET cassettes may have large pseudo-Stokes shifts and emission shifts. Unlike through-space energy-transfer cassettes, in TBET cassettes, the donor and the acceptor units are joined by a conjugated spacer. Burgess and co-workers have developed elegant TBET systems based on the conjugated fluorescein–rhodamine system.[9a, b] However, the fluorescein (donor) emission overlaps significantly with the rhodamine (acceptor) absorption and the advantage of TBET, that is, no requirement of strong spectral overlap between the donor emission and the acceptor absorption, was not really capitalized upon in these conjugated fluorescein–rhodamine energy transfer cassettes. Not surprisingly, the pseudo-Stokes shifts (< 120nm) and emission shifts (20–90 nm) in these fluorescein–rhodamine TBET systems are rather restricted.[9a, b]
