Extending the short and long wavelength limits of bacteriochlorin near-infrared absorption via dioxo- and bisimide-functionalization.
Extending the short and long wavelength limits of bacteriochlorin near-infrared absorption via dioxo- and bisimide-functionalization.
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DOI：
10.1021/jp512818g
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
Pothiappan Vairaprakash;Eunkyung Yang;Tuba Sahin;M. Taniguchi;M. Krayer;J. Diers;Alfred Wang;
中科院分区：
文献类型：
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作者：
Pothiappan Vairaprakash;Eunkyung Yang;Tuba Sahin;M. Taniguchi;M. Krayer;J. Diers;Alfred Wang;
合成并表征了六种新的菌绿素，将强近红外 (NIR) 吸收（Qy 波段）的范围扩大到较短和较长的波长（~690 至~900 nm）。该结构包括菌绿素-双酰亚胺，其具有跨越3,5-和13,15-大环位置的六元酰亚胺环或跨越β-吡咯2,3-和12,13-位置的五元酰亚胺环。两种双酰亚胺类型的吸收波长明显长于菌绿素前体（无稠合环），而 7- 或 7,17- 位的氧代基团将 Qy 带移动到新的短波长极限。令人惊讶的是，具有五元β-吡咯中心酰亚胺环的菌绿素双酰亚胺的Qy带更接近于六元菌绿素单酰亚胺的Qy带。然而，五元双酰亚胺（相对于六元菌绿素-单酰亚胺）具有显着增强的吸收强度，同时荧光产率高出约2倍（约0.16对约0.07）和更长的单线态激发态寿命（约4纳秒对约2纳秒）。光物理增强部分源自五元酰亚胺环的最低未占据前沿分子轨道与菌绿素骨架的混合。一般来说，所有新型菌绿素都具有足够长的激发态寿命（1-4 ns），足以用于光化学应用的分子系统。
Six new bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin-bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin-bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin-monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin-monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer singlet excited-state lifetime (∼4 ns vs ∼2 ns). The photophysical enhancements derive in part from mixing of the lowest unoccupied frontier molecular orbitals of the five-membered imide ring with those of the bacteriochlorin framework. In general, all of the new bacteriochlorins have excited-state lifetimes (1-4 ns) that are sufficiently long for use in molecular-based systems for photochemical applications.