Bimetallic cyano-bridged complexes as a bi-functional molecular device for simultaneously detection and degradation of aqueous environmental pollutants and photophysical properties of isocyano complexes

The aim of this research was to investigate the potential multi-functionality of bimetallic complexes through synthesis, characterization, and catalytic studies. Herein we proposed a molecule design strategy called indicator/catalyst displacement assay (ICDA), which are composed of an indicator and receptor for molecular sensing, meanwhile the indicator/receptor serve as catalyst to amplify the sensor signal and degrade the molecules into smaller substances.
In chapter 2, a bimetallic complex {[Ru(ᵗBubpy)(CN)₄]₂–[Fe(H₂O)₃Cl]₂}•2H₂O (RuFe 1) (ᵗBubpy = 4,4’-di-tert-butyl-2,2’-dipyridyl) was synthesized and characterized, and proved is capable of functioning as a chemodosimeter for oxalic acid with restoration of [Ruᴵᴵ(ᵗBubpy)(CN)₄]²⁺ characteristic emissive properties. Meanwhile, the Feᴵᴵᴵ form adduct with oxalic acid which catalyze the photooxidation of oxalic acid into carbon dioxide and also catalyze the decolorization of organic dye methyl orange, the sensing properties of this complex can be amplified up to 50 times.
Another example of ICDA, a bimetallic complex {[Fe(ᵗBubpy)(CN)₄]– [Cu(dien)(ClO₄)]₂}·CH₃C(O)CH₃ (FeCu 1) (dien = diethylenetriamine) was reported in chapter 3. This complex was synthesized and characterized, the presence of cyanide induce colorimetric change. The Cuᴵᴵ-cyanide adducts can be oxidized to cyanate with hydrogen peroxide. The addition of coloring agent phenolphthalin can also amplify the signal with detection limit from 500 ppb to 9.5 ppb. A series of Fe(II)-Cu(II) complexes with different number cyanide subunits were synthesized. The complexes [Feᴵᴵ(CN)₆]– [Cuᴵᴵ(dien)(H₂O)]₂ (FeCu 2), [Feᴵᴵ(ᵗBubpy)(CN)₄]– [Cuᴵᴵ(dien)Cl]₂ (FeCu 3) and {[Feᴵᴵ(ᵗBubpy)₂(CN)₂]₂–[Cuᴵᴵ(dien)]}Cl₂ (FeCu 4) were also found capable of oxidizing cyanide, but only when the cyanide concentration reach threshold. Further kinetic and thermodynamic measurements were conducted and suggested that the differences in threshold were controlled by both thermodynamic and kinetic properties of the complex.
In chapter 4, a series of ruthenium (II) 2-(2-hydroxyphenyl)benzoxazole (HPBO) complexes 1-3 containing different isocyanide ligands have been synthesized and characterized. The structures of complexes trans,trans,trans-[Ru(PBO)₂(PhNC)₂] (1b), trans,trans,trans-[Ru(PBO)₂(Br₃PhCN)₂] (1e), cis,trans-[Ru(PBO)₂(PPh₃)(ClPhNC)] (2c) and cis,trans,cis-[Ru(PBO)₂(PhNC)₂] (3b) have been determined by X-ray crystallography. The photophysical properties so as the electrochemical properties of the complexes were also studied. All rights reserved.