title: Photophysical study of a polyoxo ethylene linked naphthalene-based fluorescent chemosensor for Mg2+ and Ca2+ detection.
abstract: A naphthalene-based bichromophoric fluorescent sensor 2,2'-[oxy-bis(2-oxatetramethyleneoxy)]-bis[N-(2-naphthyl)-benzamide)] (1) was synthesized and characterized. Fluorescence decay for 1 in alcoholic solvents in the region of 415-460 nm revealed bi-exponential behavior. The faster component of the decay can be attributed to the formation of dimers. Above 480 nm, besides the dimer, there is also a little excimer formation and this excimer emits at longer wavelengths than the dimer. The observation of the change of the fluorescence emission spectra upon addition of water in EtOH-water mixtures is in line with the formation of water-bridged complexes preventing excimer formation. The sensor shows an increase in fluorescence intensity upon increasing Mg(2+) or Ca(2+) concentration in EtOH because the formation of the excimer can be hindered upon complexation with Mg(2+) or Ca(2+) ions. Because of the competition between hydrated metal ions and the water-bridged complex, spectral changes by complexation with Mg(2+) or Ca(2+) in EtOH-H2O (9 : 1 v/v) are quite different from those in neat ethanol. The ground-state dissociation constant K(d) estimated for the complex with Mg(2+) or Ca(2+) was found to be around 2.0 mM in EtOH-H2O (9 : 1 v/v), which makes it suitable for the measurement of the concentrations of these ions in physiologically relevant concentration ranges.
authors.affiliation: Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xiang
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Yali
authors.initials: Y
authors.lastname: Guo
authors.forename: Weisheng
authors.initials: W
authors.lastname: Liu
authors.forename: Wenwu
authors.initials: W
authors.lastname: Qin
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives* / Q000737:chemistry; D001549:Benzamides / Q000737:chemistry*; D002118:Calcium / Q000032:analysis*; D000431:Ethanol / Q000737:chemistry; D005030:Ethylenes / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008274:Magnesium / Q000032:analysis*; D009281:Naphthalenes / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: C585642:2,2'-(oxybis(2-oxatetramethyleneoxy))-bis(N-(2-naphthyl)benzamide); D001549:Benzamides; D005030:Ethylenes; D005456:Fluorescent Dyes; D007477:Ions; D009281:Naphthalenes; D014867:Water; C031721:naphthalene; D000431:Ethanol; C036216:ethylene; D015057:1-Naphthylamine; D008274:Magnesium; D002118:Calcium