Detection of NaCN in aqueous media using a calixarene-based fluoroionophore containing ruthenium(ii)-bipyridine as the fluorogenic unit

Abstract

A new molecular sensor containing calixarene and ruthenium(II)-bipyridine as fluorophore bridged by amide moiety has been synthesised, characterized and its anion binding property has been investigated. It selectively detects cyanide in 95:5 water-acetonitrile when sodium salts of various anions such as F -, Cl -, Br -, I -, PO 4 2-, IO 4 -, BO 3 -, CH 3 COO -, CN -and SO 4 2-were used for investigation. The recognition event was monitored by fluorescence spectroscopy and the lower detection limit found is 70 ppb. However, when tetrabutylammonium salts of the same anions were used, then in addition to CN -, CH 3 COO -was also detected under similar experimental conditions. Interestingly, CN -exhibited substantial quenching, whereas CH 3 COOshowed enhancement in emission intensity. The interaction of anions with the fluoroionophore was also monitored by electrochemical technique and the result obtained is consistent to that found by fluorogenic method. Binding constants were determined from emission titration, composition of the anion-complexes formed were determined from mass and emission titration data, mechanistic aspects of the interaction has been discussed with the aid of NMR data and the role of cations in the contrast fluorescent off and on behaviour has also been discussed. This sensor has also been used to estimate cyanide in real samples and the result obtained is satisfactory.

Recent Advances in Macrocyclic Fluorescent Probes for Ion Sensing

“…More recently, Maity et al reported a ruthenium(II)-bipyridine-substituted calix[4]arene sensor 20 for the detection of CN − ( Figure 10 ) [ 93 ]. Of a range of sodium salts tested, NaCN alone led to fluorescence quenching and a blue-shift of the emission band at 624 nm (in 95:5 H 2 O:MeCN).…”

“… Ruthenium(II)-bipyridine-substituted calix[4]arene sensor 20 is a turn-off probe for CN − , which causes fluorescence quenching and a blue-shift of the emission band at 624 nm [ 93 ]. The simple, polyanionic calix[4]arene-based sensor 21 is an ‘on-off’ probe for spermine 22 [ 94 ], while a QD-appended calix[8]arene receptor forms the complex 23 with C 60 fullerene, which quenches the QD fluorescence output [ 95 ].…”

Pyrene and imidazole functionalized luminescent bimetallic Ru(ii) terpyridine complexes as efficient optical chemosensors for cyanide in aqueous, organic and solid media

“…2,5 Among the most classical luminescent metal complexes for the recognition of anions, Ru(II) complexes derived from bidentate bpy and/or phen-type ligands are particularly attractive because of their desirable photophysical, photochemical and electrochemical properties associated with the metal-to-ligand charge-transfer (MLCT) excited states. [35][36][37][38][39][40][41][42][43][44][45][46][47][48] However, chirality inherently introduced in the [Ru(bpy/phen) 3 ] 2+ type complexes leads to isomeric mixtures whose separation in most cases is very difficult. 49 On the other hand, the structurally more appealing [Ru(tpy) 2 ] 2+ type complexes derived from tridentate terpyridine-type ligands are achiral and are most suitable for the construction of linear rod-like systems by functionalization of the 4′-position of the tpy ligands.…”

Investigation of the formation of the [2(iohexol) + Mg]2+ complex and its fragmentation in electrospray ionization tandem mass spectrometry

“…[4][5][6] The chemotoxicity of the contrast medium frequently comes from the stability of the organic iodine. [7][8][9] This type of organic iodine is likely transformed to the ionic type by a redox reaction which may be catalyzed by metal ions in vivo. Primary research illustrating this reactivity can be easily realized through the study of organometallic reaction in vitro.…”

“…However, several adverse effects caused by these contrast agents still happen sometimes in clinical application, including allergic‐type reactions, extravasations and renal toxicity . The chemotoxicity of the contrast medium frequently comes from the stability of the organic iodine . This type of organic iodine is likely transformed to the ionic type by a redox reaction which may be catalyzed by metal ions in vivo .…”