3285-98-1Relevant academic research and scientific papers
Rational design of fluorescein-based fluorescence probes. Mechanism-based design of a maximum fluorescence probe for singlet oxygen
Tanaka,Miura,Umezawa,Urano,Kikuchi,Higuchi,Nagano
, p. 2530 - 2536 (2007/10/03)
Fluorescein is one of the best available fluorophores for biological applications, but the factors that control its fluorescence properties are not fully established. Thus, we initiated a study aimed at providing a strategy for rational design of functional fluorescence probes bearing fluorescein structure. We have synthesized various kinds of fluorescein derivatives and examined the relationship between their fluorescence properties and the highest occupied molecular orbital (HOMO) levels of their benzoic acid moieties obtained by semiempirical PM3 calculations. It was concluded that the fluorescence properties of fluorescein derivatives are controlled by a photoinduced electron transfer (PET) process from the benzoic acid moiety to the xanthene ring and that the threshold of fluorescence OFF/ON switching lies around -8.9 eV for the HOMO level of the benzoic acid moiety. This information provides the basis for a practical strategy for rational design of functional fluorescence probes to detect certain biomolecules. We used this approach to design and synthesize 9-[2-(3carboxy-9,10-dimethyl)anthryl]-6-hydroxy-3H-xanthen-3-one (DMAX) as a singlet oxygen probe and confirmed that it is the most sensitive probe currently known for 1O2. This novel fluorescence probe has a 9,10-dimethylanthracene moiety as an extremely fast chemical trap of 1O2. As was expected from PM3 calculations, DMAX scarcely fluoresces, while DMAX endoperoxide (DMAX-EP) is strongly fluorescent. Further, DMAX reacts with 1O2 more rapidly, and its sensitivity is 53-fold higher than that of 9-[2-(3-carboxy-9,10-diphenyl)anthryl]-6-hydroxy-3H-xanthen-3-ones (DPAXs), which are a series of fluorescence probes for singlet oxygen that we recently developed. DMAX should be useful as a fluorescence probe for detecting 1O2 in a variety of biological systems.
Rotational isomerization of (E)-(2-anthryl)ethenes. A consideration: Why are the s-cis rotamers more stable than the s-trans rotamers in the excited state and less stable in the ground state?
Karatsu, Takashi,Itoh, Hajime,Yoshikawa, Nobuko,Kitamura, Akihide,Tokumaru, Katsumi
, p. 1837 - 1849 (2007/10/03)
Rotational isomerism between s-cis and s-trans rotamers of (E)-1-(2- anthryl)-2-phenylethene (E-2APE) and (E)1-(2-anthryl)-3(3-dimethyl-1-butene (E-2ADB) were investigated by comparing the absorption, emission and transient absorption spectra with those of the model compounds. The s-trans isomer is more stable than the s-cis rotamer in the ground state; however, the s-cis isomer is more stable than the s-trans rotamer in the excited state (the lowest singlet and triplet excited state). In the triplet excited state, s-trans→s-cis one-way rotational isomerization is observed with activation energies of 30 and 18 kJ mol-1 for E-2APE and E-2ADB, respectively. Explanations of why the s-cis rotamer is more stable than the s-trans rotamer in the excited state and less stable in the ground state are proposed using the HOMO and LUMO coefficients estimated by a MOPAC93 (PM3) calculation.
