A highly fluorescent anthracene-containing hybrid material exhibiting tunable blue-green emission based on the formation of an unusual "T-shaped" excimer.
A series of flexible bis(9-anthryldiamine) ligands (L1-L3) linked with alkyl spacers of different chain length was synthesized and characterized, in order to investigate the coordination behavior of these diamine ligands with metal ions (Zn2+, etc.) based on fluorescence measurements. The results showed that, in the case of anthryldiamine ligands bearing two- or four-carbon links, the zinc ion induced a chelation-enhanced fluorescence (CHEF) effect in aqueous media, while a trace amount of water could selectively quench the blue emission of the Zn(II) complex with a three-carbon-linked ligand (1). Meanwhile, the introduction of more water (concentration >11 %) resulted in the formation of a new green luminescent species; the luminescence intensity was enhanced stepwise to a maximum with addition of approximately 30 % water in THF solution. The peak position (centered at approximately 500 nm) and the lifetime measurement (tau=19.59 ns) indicated that the green luminescence was attributable to a novel edge-to-face dimeric conformation ("T-shaped" conformation) of anthracene, and not to the more common face-to-face dimeric conformation. Accordingly, 1H NMR spectroscopic studies in nonaqueous or aqueous solution confirmed this T-shaped conformation, which is consistent with the results of single-crystal X-ray structure analysis and solid-state photoluminescence studies.
Zhang
Guoqi
G
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
Yang
Guoqiang
G
Wang
Shuangqing
S
Chen
Qingqi
Q
Ma
Jin Shi
JS
D000873:Anthracenes / Q000737:chemistry* / Q000528:radiation effects; D018360:Crystallography, X-Ray; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000528:radiation effects; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry* / Q000528:radiation effects
D000873:Anthracenes; D005456:Fluorescent Dyes; D008024:Ligands; D014867:Water; C034020:anthracene; D015032:Zinc