Fluorometric Chemosensors. Interaction of Toxic Heavy Metal Ions Pb^II, Cd^II, and Hg^II with Novel Mixed-Donor Phenanthroline-Containing Macrocycles:  Spectrofluorometric, Conductometric, and Crystallographic Studies

Abstract

The macrocycles L(1)-L(3) incorporating N(2)S(3)-, N(2)S(2)O-, and N(2)S(2)-donor sets, respectively, and containing the 1,10-phenanthroline unit interact in acetonitrile solution with heavy metal ions such as Pb(II), Cd(II), and Hg(II) to give 1:1 ML, 1:2 ML(2), and 2:1 M(2)L complex species, which specifically modulate the photochemical properties of the ligands. The stoichiometry of the complex species formed during spectrofluorometric titrations and their formation constants in MeCN at 25 degrees C were determined from fluorescence vs M(II)/L molar ratio data. The complexes [Pb(L(1))][ClO(4)](2).(1)/(2)H(2)O (1), [Pb(L(2))][ClO(4)](2).MeNO(2) (1a), [Pb(L(3))(2)][ClO(4)](2).2MeCN (1b), and [Cd(L(3))][NO(3)](2) (2b) were also characterized by X-ray diffraction studies. The conformation adopted by L(1)-L(3) in these species reveals the aliphatic portion of the rings folded over the plane containing the heteroaromatic moiety with the ligands trying to encapsulate the metal center within their cavity. In 1, 1a, and 2b the metal ion completes the coordination sphere by interacting with counteranion units and solvent molecules. On the contrary, the 1:2 complex 1b shows Pb(II) sandwiched between two symmetry-related molecules of L(3) reaching an overall [4N + 4S] eight-coordination.

Highly Selective and Reversible Optical, Colorimetric, and Electrochemical Detection of Mercury(II) by Amphiphilic Ruthenium Complexes Anchored onto Mesoporous Oxide Films

“…[3,4] Therefore, the extensive use of mercury compounds in industry is of major concern: they are environmental pollutants, and a simple, sensitive method for detecting them is required. [5] There are several, luminescent, [6][7][8][9][10][11][12][13][14][15] chemical, [16][17][18][19] electrochemical, [20][21][22] and biosensor-based [23] analytical methods for detecting mercury that have been reported in the past few years. Most of these systems have limitations, which include interference from other metal ions, and the need to use organic or aqueous organic solvents.…”

Coupling of Cyclic Voltammetry and Electrochemical Impedance Spectroscopy for Probing the Thermodynamics of Facilitated Ion Transfer Reactions Exhibiting Chemical Kinetic Hindrances

“…The compounds 2,8-dithia [9],(2,9)-1,10-phenanthrolinophane (PhenS 2 ) and 5-oxo-2,8-dithia [9],-(2,9)-1,10-phenanthrolinophane (PhenOS 2 ) were synthesized according to the procedure described in the literature. 43,44 Their structures are shown in Scheme 1. Mili Q-plus water (18 MΩ cm) was used for the preparation of all aqueous solutions, as well as for rinsing.…”

Synthesis, coordination properties, and analytical applications of mixed donor macrocycles containing the 1,10-phenanthroline sub-unit

“…A cyclisation reaction performed under high dilution conditions between the dichloro derivative of 1,10-phennathroline and the appropriate dithiol in DMF in the presence of Cs 2 CO 3 affords the required macrocylic ligand with yields ranging from 20% (L 4 ) to 69% (L 1 ) [35][36][37][38][39]. Crystals of L 2 ·½H 2 O and L 3 ·H 2 O were grown from a MeCN/Et 2 O solution [36,47].…”

“…The presence of soft S-donors in the macrocyclic ligands L 1 -L 7 and the well known photophysics properties of the phen sub-unit prompted us to study their coordination properties also towards toxic d 10 soft metal ions such as Pb 2+ , Cd 2+ , and Hg 2+ in order to test the potentiality of these cyclic phenanthroline derivatives, L 1 -L 3 in particular, as efficient complexing agents and selective extractants of these environmental important metal ions, and as fluorescent sensors for their detection in solution [38]. In fact, L 1 -L 3 as well as all the other ligands in Fig.…”