title: Synthesis and coordination properties of quinoline pendant arm derivatives of [9]aneN(3) and [9]aneN(2)S as fluorescent zinc sensors.
abstract: The coordination chemistry of three new quinoline pendant arm derivatives of [9]aneN(3) (L(1), L(2)) and [9]aneN(2)S (L(3)) toward Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) has been investigated both in solution and in the solid state. The protonation constants for L(1)-L(3) and stability constants with the aforementioned metal ions have been determined potentiometrically in 0.10 M NMe(4)Cl MeCN/H(2)O (1:1 v/v) solution at 298.1 +/- 0.1 K; the measured values show that Cu(II) has the highest affinity for all three ligands, followed by Zn(II), Hg(II), Pb(II), and Cd(II). For each metal ion considered, 1:1 complexes with L(1)-L(3) have also been isolated in the solid state and [Cu(L(1))](BF(4))(2) (1), [Zn(L(1))](BF(4))(2) (2), [Cd(L(1))](ClO(4))(2) (3), [Hg(L(1))](NO(3))(2) (4), [Pb(L(1))](ClO(4))(2) x MeCN (5), [Zn(2)Cl(2)(L(2))(2)](BF(4))(2) x 1/2 MeNO(2) x H(2)O (6), [Cu(L(3))](ClO(4))(2) (7), [Zn(L(3))(NO(3))]NO(3) (8), [Cd(L(3))(NO(3))(0.82)Cl(0.18)]NO(3) (9), and [Hg(L(3))](ClO(4))(2) x MeCN (10) have also been characterized by X-ray crystallography. The optical response of L(1)-L(3) to the presence of the above-mentioned metal ions has been investigated in MeCN/H(2)O (1:1 v/v) and H(2)O solutions. All three ligands show a stronger "OFF-ON" CHEF (chelation enhancement of fluorescence) effect in the Zn(II) complexes than in the Cd(II) complexes in both media. The results have been examined by considering the ratio I(rel)(Zn(II))/I(rel)(Cd(II)), within the emerging idea that the relative strength of the CHEF effect for the small Zn(II) ion as compared to larger Cd(II) ion might be determined by steric crowding in the corresponding complexes with quinoline-based fluorescent chemosensors.
authors.affiliation: Dipartimento di Chimica Inorganica ed Analitica, S.S. 554 Bivio per Sestu, Università degli Studi di Cagliari, 09042 Monserrato (CA), Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Mameli
authors.forename: M Carla
authors.initials: MC
authors.lastname: Aragoni
authors.forename: Massimiliano
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authors.lastname: Arca
authors.forename: Marta
authors.initials: M
authors.lastname: Atzori
authors.forename: Andrea
authors.initials: A
authors.lastname: Bencini
authors.forename: Carla
authors.initials: C
authors.lastname: Bazzicalupi
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: Claudia
authors.initials: C
authors.lastname: Caltagirone
authors.forename: Francesco A
authors.initials: FA
authors.lastname: Devillanova
authors.forename: Alessandra
authors.initials: A
authors.lastname: Garau
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hursthouse
authors.forename: Francesco
authors.initials: F
authors.lastname: Isaia
authors.forename: Vito
authors.initials: V
authors.lastname: Lippolis
authors.forename: Barbara
authors.initials: B
authors.lastname: Valtancoli