title: Zn2+/Cd2+ optical discrimination by fluorescent chemosensors based on 8-hydroxyquinoline derivatives and sulfur-containing macrocyclic units.
abstract: Four new fluorescent chemosensors for metal ions based on 8-hydroxyquinoline (8-HDQ) derivatives and sulfur-containing macrocyclic units were synthesized and characterized, namely 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L1), 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L2), 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L3), and 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L4). Preliminary fluorimetric titrations indicated L1 as the only member of the family of ligands to give a selective CHEF-type response to the presence of Zn(2+) in MeCN-H2O (1:1, v/v) solutions, which allowed imaging of this metal ion in Cos-7 cells in vitro. The other ligands either did not show any fluorescence response (L3, L4) to any of the metal ions considered (Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+)) or gave (L2) a CHEF-type response also to the presence of Cd(2+). The coordination properties of L1 towards Zn(2+) were, therefore, fully investigated by potentiometric measurements and absorption and emission spectroscopy at different pH values, which indicated that the formation of 2:1 L1/Zn(2+) complexes is responsible for the CHEF-type effect observed. The complexes [Zn(L1)2H2O](BF4)2 and [Zn(L3)](ClO4)2 were characterized in the solid state by X-ray crystallography, and DFT calculations were performed to understand the origin of the Zn(2+)/Cd(2+) optical discrimination of the 8-HDQ-based "conjugate" fluorescent chemosensors reported.
authors: Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, S.S. 554 bivio per Sestu, 09042 Monserrato, CA, Italy. lippolis@unica.it.
authors: M Carla
authors: MC
authors: Aragoni
authors: Massimiliano
authors: M
authors: Arca
authors: Andrea
authors: A
authors: Bencini
authors: Claudia
authors: C
authors: Caltagirone
authors: Alessandra
authors: A
authors: Garau
authors: Francesco
authors: F
authors: Isaia
authors: Mark E
authors: ME
authors: Light
authors: Vito
authors: V
authors: Lippolis
authors: Carlos
authors: C
authors: Lodeiro
authors: Marta
authors: M
authors: Mameli
authors: Riccardo
authors: R
authors: Montis
authors: M Cristina
authors: MC
authors: Mostallino
authors: Anna
authors: A
authors: Pintus
authors: Stefano
authors: S
authors: Puccioni
mesh_terms: D000818:Animals; D019556:COS Cells; D002104:Cadmium / Q000737:chemistry*; D002522:Chlorocebus aethiops; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D047028:Macrocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D055620:Optical Phenomena; D015125:Oxyquinoline / Q000138:chemical synthesis / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013455:Sulfur / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D047028:Macrocyclic Compounds; D002104:Cadmium; D015125:Oxyquinoline; D013455:Sulfur; D015032:Zinc