title: Salicylyl Fluorene Derivatives as Fluorescent Sensors for Cu(II) Ions.
abstract: Two derivatives of fluorene containing salicylic acid groups are successfully synthesized by palladium-catalyzed coupling reactions and subsequent hydrolysis of salicylate esters. The compounds are characterized by various spectroscopic methods. In phosphate buffer (pH 8.0) solutions, these compounds are well soluble. They show maximum absorption wavelengths in the range of 304-330 nm and exhibit maximum emission wavelength around 420 and 430 nm with the quantum yields of 2.7 and 4.4 %, respectively. The compound with alkynyl salicylate groups (2) exhibits a selective fluorescence quenching towards Cu(II) and Fe(II) with a relatively similar sensitivity. The selectivity favoring Cu(II) over Fe(II) and other metal ions can be achieved upon the addition of 30 μM Triton X-100. The Cu(II) detection limit in solution phase is 1.47 ppb. The fluorescence signal recovery upon the addition of EDTA indicate a reversible complexation between 2 and Cu(II) ion. Fabrication of 2 on filter paper using a 50 μM solution in THF affords a naked-eye detection for Cu(II) and Fe(II) in aqueous media at picomole level.
authors.affiliation: Program of Petrochemistry and Polymer Science, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.
authors.forename: Chenwit
authors.initials: C
authors.lastname: Khaokeaw
authors.affiliation: Organic Synthesis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand.|Nanotec-CU Center of Excellence on Food and Agriculture, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
authors.forename: Mongkol
authors.initials: M
authors.lastname: Sukwattanasinitt
authors.affiliation: Organic Synthesis Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Pathumwan, Bangkok, 10330, Thailand. paitoon.r@chula.ac.th.|Nanotec-CU Center of Excellence on Food and Agriculture, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand. paitoon.r@chula.ac.th.
authors.forename: Paitoon
authors.initials: P
authors.lastname: Rashatasakhon
mesh_terms: D003300:Copper / Q000032:analysis*; D005449:Fluorenes / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D007501:Iron / Q000032:analysis; D057230:Limit of Detection; D012459:Salicylates / Q000737:chemistry*; D014867:Water / Q000032:analysis*
chemical_list: D005449:Fluorenes; D005456:Fluorescent Dyes; D012459:Salicylates; D014867:Water; D003300:Copper; D007501:Iron
keywords: Copper ion; Fluorene; Fluorescent sensor; Paper-based sensor; Salicylic acid; Triton X-100