Synthesis And Sensing Property Investigation Of Novel Cationic Ir(?) And Ru(?) Complexes

As a result of intersystem crossing from the singlet to the triplet excited state facilitated by strong spin - orbit coupling of the iridium or ruthenium heavy atom, Ir (III) and Ru(II)complexes own the properties of the room temperature phosphorescence. Luminescent cyclometalated Ir(III) and Ru(?) complexes have attracted grate attention, due to their high quantum yields, relatively long lifetimes, large Stokes shift and facile tuning of emission wavelength. These complexes have extensive applications in organic light emitting diodes(OLEDs), light-emitting electrochemical cells (LECs), photodynamic therapy (PDT),biological labeling and imaging. In this dissertation, novel iridium(III) and ruthenium (II)complexes containing special functional groups were designed and prepared for the detection of Cu2+, ClO- and cysteine.This dissertation contains three parts. The first part concerns the study of the novel iridium(III) or ruthenium(II) complexes containing DPA (N,N-Bis(2-pyridylmethyl)amine)group as "Turn-Off" phosphorescent probes for the detection of Cu2+ ion (Chapter 2-3). The second part concerns the study of the novel iridium(III) complexes containing schiff base structure as "Turn-On" phosphorescent probes for the detection of ClO- (Chapter 4). The last part concerns the study of the novel iridium(III) complexes as phosphorescent probes for the detection of cysteine by the use of Michael reaction between ethylenic bond and sulfydryl(Chapter 5). The major work is briefly described as follows:1. In Chapter 2, we reported the synthesis and characterization of a novel aggregation induced emission (AIE) active cyclometalated Ir(III) complex [Ir(dfppy)2(phen-DPA)]PF6, and an orange phosphorescent Ru(II) was also prepared for comparison. They both showed remarkable selectivity for Cu2+ in aqueous solution containing 2% acetonitrile over other competitive ions with the detection limit of 65 nM and 150 nM. By means of a series of experimental studies, the results indicated that the two complexes both exhibited 1:1 coordinates with Cu2+, and the relative association constants were 2.96×104M-1 and 7.64×104 M-1 . Furthermore, the interactions between Cu2+ and novel complexes were chemically reversible.2. In order to further investigate the effect of the receptor unit (DPA) on the Cu2+ sensing properties of the complexes, we presented the synthesis and characterization of two luminescent cyclometalated Ir(III) complexes [Ir(dfppy)2(bpy-DPA)]PF6 and [Ir(dfppy)2(bpy-BiDPA)]PF6 containing one or two DPA groups in Chapter 3. Of them, [Ir(dfppy)2(bpy-BiDPA)]PF6 with two DPA groups owned a quite high quantum yield (93.83%) and a long lifetime (101.17 ?s),which was wonderful among the Ir(III) complexes. And [Ir(dfppy)2(bpy-BiDPA)]PF6 exhibited both high selectivity and sensitivity towards Cu2+ over other metal ions. The job curve and the mass spectra suggested the formation of a 1:2 bonding mode between [Ir(dfppy)2(bpy-BiDPA)]PF6 and Cu2+ in aqueous solution with a relative association constant of 1.68× 1011 M-2.The photoluminescence (PL) intensity quenching curve indicates that [Ir(dfppy)2(bpy-BiDPA)]PF6 could enable rapid and reversible detection of Cu2+ with a low detection limit of 13 nM. Furthermore, a linear relationship could be observed between the PL lifetime value of[Ir(dfppy)2(bpy-BiDPA)]PF6 and the concentration of Cu2+ ions in the range of 0-8 ?M. These results suggested that [Ir(dfppy)2(bpy-BiDPA)]PF6 might be used as not only a promising photoluminescence intensity sensor, but also a promising lifetime sensor for Cu2+ in aqueous solution.3. Besides metal ions, Ir(III) complexes could also be used as anion probes. In Chapter 4,two weak phosphorescent Ir(III) complexes [Ir(ppy)2(m-ipbo)]PF6 and [Ir(ppydmn)2phen]PF6 were designed and prepared by the insertion of schiff base groups into the ligands. The novel complexes both showed a dramatic increase in phosphorescent intensity after interaction with ClO- under neutral or alkaline medium, and the phosphorescence of [Ir(ppy)2(m-ipbo)]PF6 with ClO- was 12 times as intense as before while [Ir(ppydmn)2phen]PF6 was 86 times. The results of mass spectrum analysis of the sample with and without ClO- was in line with expectations.4. As one of the most important amino acids in biological body, cysteine plays a crucial role in many biological activities, and the cysteine imbalance may lead to many diseases.Therefore, the design and preparation of novel probes for the efficient detection of cysteine is imperative. In Chapter 5, in consideration of the Michael reaction between ethylenic bond and sulfydryl, four novel complexes Ir(dfppy)2(o-ippa)]PF6, [Ir(dfppy)2(p-ippa)]PF6,[Ir(dfppy)2(phen-bia)]PF6 and [Ir(ppyppeo)2phen]PF6 were prepared by the insertion of acrylate and 1-Phenyl-2-propen-l-one group into the ligands. Of them, [Ir(dfppy)2(phen-bia)]PF6 might be used as a "Turn-Off" probe for the detection of cysteine with a detection limit of 1.17 ?M,while [Ir(ppyppeo)2phen]PF6 could be used as a ”Turn-On" probe with a detection limit of 2.08?M. The .relative linear detection ranges were 0?140 ?M and 20?250 ?M,respectively.