Pt(dithiolene)-Based Colorimetric Chemosensors for Multiple Metal-Ion Sensing

Abstract

Colorimetric chemosensors are widely employed for in-field analysis to detect transition metal ions in real-time with the naked eye. Colorimetric chemosensors have attracted considerable attention because they can conveniently provide quantitative and qualitative information at a low cost. However, the development of colorimetric chemosensors for multiple-ion sensing where metal cations coexist has been limited. For this reason, we developed a new type of transition metal ion sensing material by selectively replacing functional groups on (diphosphine)Pt(dmit) molecules. The terminal groups of the diphosphine ligand were successfully substituted by the cyclohexyl groups, increasing the electron density of the thione moiety. Due to the electron donation ability of the cyclohexyl terminal groups, the proposed chemosensing material was able to selectively detect the mixture of Hg2+, Cu2+, and Ag+ in the presence of many types of interfering cations. To gain insight into the binding mechanisms between the metal ions and the developed (dchpe)Pt(dmit) molecule, density functional theory calculations were also performed.

Rational Design of Fluorescent/Colorimetric Chemosensors for Detecting Transition Metal Ions by Varying Functional Groups

“…The stoichiometric binding ratio between 4 and Hg 2+ is 1:1 according to the Job's plot analysis. DFT calculation data support strong binding affinity to Hg 2+ , Cu 2+ , and Ag + ; thereby, 4 showed high selectivity without interference of other metal ions [34]. Scheme 4.…”

“…In design of a chemosensor, a promising strategy for controlling the electron transfer mechanism is in coordination of the functional groups, which can modify the electron distributions and spectroscopic properties [16,[29][30][31]; furthermore, functional groups can enhance the receptor affinity to the metal ions by varying its electron density for stronger interact with those sensing target. Depending on the functional groups, the target metal ions can also be selectively detected in solutions even with interfering ions [32][33][34].…”

cis/trans-[Pt(C∧N)(C≡CR)(CNBut)] Isomers: Synthesis, Photophysical, DFT Studies, and Chemosensory Behavior

“…Another strategy is to introduce nitrogen or sulfur atoms into the ligands to favor the interaction. It is the case of two half-lantern platinum complexes with selective turn-off phosphorescent detection of Hg 2+ in water described by Sicilia and co-workers or recent selective colorimetric chemosensors based on diphosphine platinum complexes bearing a dithiolate ligand responsible for Hg 2+ binding …”