Selective turn-off phosphorescent and colorimetric detection of mercury(II) in water by half-lantern platinum(II) complexes

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 44; no. 15; pp. 6936 - 6943
• Main Authors: Sicilia, Violeta, Borja, Pilar, Baya, Miguel, Casas, José M
• Format: Journal Article
• Language: English
• Published: England 21.04.2015
• Subjects: Binding; Cations; Colorimetry; Complexation; Constants; Coordination Complexes - chemistry; Detectors; Dimethyl Sulfoxide - chemistry; Luminescence; Mercury (metal); Mercury - analysis; Mercury - chemistry; Metal ions; Phosphorescence; Platinum - chemistry; Spectrophotometry, Ultraviolet; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry
• DOI: 10.1039/c5dt00087d
• ISSN: 1477-9226

The platinum(ii) half-lantern dinuclear complexes [{Pt(bzq)(μ-C7H4NS2-κN,S)}2] () and [{Pt(bzq)(μ-C7H4NOS-κN,S)}2] () [bzq = benzo[h]quinolinate, C7H4NS2 = 2-mercaptobenzothiazolate, C7H4NOS = 2-mercaptobenzoxazolate] in solution of DMSO-H2O undergo a dramatic color change from yellowish-orange to purple and turn-off phosphorescence in the presence of a small amount of Hg(2+), being discernible by the naked-eye and by spectroscopic methods. Other metal ions as Ag(+), Li(+), Na(+), K(+), Ca(2+), Mg(2+), Ba(2+), Pb(2+), Cd(2+), Zn(2+) and Tl(+) were tested and, even in a big excess, showed no interference in the selective detection of Hg(2+) in water. Job's plot analysis indicated a 1 : 1 stoichiometry in the complexation mode of Hg(2+) by /. The phosphorescence quenching attributed to the formation of [/ : Hg(2+)] complexes showed binding constants of K = 1.13 × 10(5) M(-1) () and K = 1.99 × 10(4) M(-1) (). The limit of detection has been also evaluated. In addition, dried paper test strips impregnated in DMSO solutions of and can detect concentration of Hg(2+) in water as low as 1 × 10(-5) M for and 5 × 10(-5) M for , making these complexes good candidates to be used as real-time Hg(2+) detectors. The nature of the interaction of the Pt2 half-lantern complex with the Hg(2+) cation, has been investigated by theoretical calculations.