title: Rationally designed fluorescence turn-on sensors: a new design strategy based on orbital control.
abstract: Herein, we explore a new strategy in the chemo-sensor field for fluorescence amplification upon binding with metal ions based on controlled participation of the nitrogen lone pair orbital. The basic architecture of the sensor entails a fluorophore, the sp(2) hybridized nitrogen lone pair (-C═N-), and a chelator site referred to as the control part. Though nonplanar and nonfluorescent, compound IC1 achieved pseudo planarity from binding with Zn(2+) as indicated by the increased fluorescence signal. Its other analogue (IC2) is also planar, and unlike IC1-Zn(2+) was fluorescent with a lack of binding affinity to metal ions. The time-dependent density functional theory (TDDFT) calculations revealed that the fluorescence amplification was due to the blocking of the nitrogen lone pair orbital; unlikely geometrical rearrangements were insignificant. This could indicate a breakthrough concept in the future design of fluorescent turn-on sensors.
authors.affiliation: Department of Chemistry, Korea University, Seoul, 136-704, Korea.
authors.forename: Hyo Sung
authors.initials: HS
authors.lastname: Jung
authors.forename: Kyoung Chul
authors.initials: KC
authors.lastname: Ko
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Lee
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Kim
authors.forename: Sankarprasad
authors.initials: S
authors.lastname: Bhuniya
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Youngmee
authors.initials: Y
authors.lastname: Kim
authors.forename: Sung Jin
authors.initials: SJ
authors.lastname: Kim
authors.forename: Jong Seung
authors.initials: JS
authors.lastname: Kim
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D015195:Drug Design; D004583:Electrons; D005456:Fluorescent Dyes / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D015032:Zinc; D009584:Nitrogen