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Dyes That Bear Thiazolylazo Groups as Chromogenic Chemosensors for Metal Cations
Author(s) -
Ábalos Tatiana,
Moragues María,
Royo Santiago,
Jiménez Diego,
MartínezMáñez Ramón,
Soto Juan,
Sancenón Félix,
Gil Salvador,
Cano Joan
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201100834
Subject(s) - chemistry , protonation , acetonitrile , bathochromic shift , aniline , moiety , absorption (acoustics) , heteroatom , deprotonation , metal , ligand (biochemistry) , photochemistry , crystallography , inorganic chemistry , stereochemistry , ring (chemistry) , fluorescence , organic chemistry , biochemistry , receptor , ion , physics , quantum mechanics , acoustics
Abstract A family of dyes ( L 1 – L 6 ) that contain a thiazolylazo group as signalling subunit and several macrocyclic cavities with different ring sizes and type and number of heteroatoms as binding sites has been synthesized and characterized. Solutions of L 1 – L 6 in acetonitrile show broad and structureless absorption bands in the 554–577 nm range with typicalmolar absorption coefficients that range from 20000 to 32000 M –1 cm –1 . A detailed protonation study was carried out with solutions of L 1 , L 2 and L 5 in acetonitrile. Addition of one equivalent of protons to L 1 and L 2 resulted in the development of a new band at 425 and 370 nm, respectively, which was ascribed to protonation in the aniline nitrogen. In contrast, protonation of L 5 resulted in a bathochromic shift of 25 nm of the absorption band that was conceivable with protonation of one of the nitrogen atoms of the azo moiety. These results were in agreement with 1 H NMR spectroscopic data. Theoretical studies on the model ligand L 1 and on different possible protonation species were also performed by using density functional theory (DFT) quantum mechanical calculations. Colour modulations in solutions of L 1 – L 6 in acetonitrile in the presence of the metal cations Fe 3+ , Ni 2+ , Zn 2+ , Cd 2+ , Pb 2+ and Hg 2+ have been studied. A selective chromogenic response of L 4 in the presence of Pb 2+ and L 5 in the presence of Hg 2+ was observed. To get a better insight into the chromophoric nature in the presence of metal cations, the interaction of Hg 2+ with the model compound L 1 in two different coordination modes was studied theoretically by using density functional theory (DFT) quantum mechanical calculations.