title: Fluorescence and chemiluminescence properties of indolylmaleimides: experimental and theoretical studies.
abstract: Various indolylmaleimides (IMs) were synthesized, and their fluorescence (FL) and chemiluminescence (CL) were measured. The substitution at the 2-position of the indole ring and the 3- or 4-position of the maleimide moiety caused an obvious change in the FL and CL of the IMs. An almost on-off switching of the FL of the IMs was observed. The intramolecular charge transfer from the indole moiety to the maleimide moiety occurred in 3-(1H-3-indolyl)-2,5-dihydro-1H-2,5-pyrroledione. In the FL of the IMs, CASPT2 calculations showed deprotonation of the NH group of the indole ring and the maleimide moiety at the excited state. The C[double bond, length as m-dash]C bond in the maleimide moiety was needed for strong CL in the IMs without substitution at the 2-position of the indole ring. The relationships between the FL or CL properties and the structures of the IMs were clarified. These results provide significant information on the rational design of IMs as FL and CL probes.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. nakazono@phar.kyushu-u.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakazono
authors.forename: Ai
authors.initials: A
authors.lastname: Jinguji
authors.forename: Shinkoh
authors.initials: S
authors.lastname: Nanbu
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Kuwano
authors.forename: Zilong
authors.initials: Z
authors.lastname: Zheng
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Saita
authors.forename: Yuji
authors.initials: Y
authors.lastname: Oshikawa
authors.forename: Yuta
authors.initials: Y
authors.lastname: Mikuni
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Murakami
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sasaki
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Zaitsu
mesh_terms: D007211:Indoles / Q000737:chemistry*; D008163:Luminescent Measurements; D008301:Maleimides / Q000138:chemical synthesis / Q000737:chemistry*; D008962:Models, Theoretical; D008968:Molecular Conformation; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D007211:Indoles; D008301:Maleimides; C043592:maleimide; C030374:indole