A sensitive phosphorescent thiol chemosensor based on an iridium(III) complex with alpha,beta-unsaturated ketone functionalized 2,2'-bipyridyl ligand.
An iridium(III)-containing phosphorescent chemosensor Ir(ppy)(2)(L)(PF(6)) (1, ppy = 2-phenylpyridine) containing a 2,2'-bipyridyl ligand (L) functionalized with an alpha,beta-unsaturated ketone for selective detection of thiol was synthesized and characterized by spectroscopic and photophysical measurements. The structure of complex 1 was determined by X-ray crystallography. In order to get an insight into 1,4-addition reactions of thiol to complex 1, the adduct 2 from reaction of 1 with benzenethiol was successfully prepared and characterized. Complex 1 shows a lowest energy absorption at ca. 450 nm, primarily ascribable to an intraligand charge transfer (ILCT) transition from the HOMO (pi) resident on the fragment -C(O)C(6)H(4)N(C(2)H(5))(2) to the LUMO (pi*) localized on the 2,2'-bipyridyl moiety in the functionalized 2,2'-bipyridyl ligand as suggested from DFT computational studies. Complex 1 is weakly emissive at ca. 587 nm at ambient temperature, arising likely from the (3)ILCT excited state. Upon addition of thiol to a semi-aqueous solution of complex 1, the lowest energy absorption is obviously blue-shifted and the emission is remarkably enhanced due probably to a conversion from the primary ILCT state to the predominant [pi(ppy)-->pi*(L)] LLCT and the [5d(Ir)-->pi*(L)] MLCT state caused by the formation of the 1-thiol adduct. The sensing properties of 1 to thiol were also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.
Zhao
Na
N
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
Wu
Yu-Hui
YH
Shi
Lin-Xi
LX
Lin
Qi-Pu
QP
Chen
Zhong-Ning
ZN
D015082:2,2'-Dipyridyl / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005456:Fluorescent Dyes / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011789:Quantum Theory; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds / Q000737:chemistry*
D056831:Coordination Complexes; D005456:Fluorescent Dyes; D008024:Ligands; D013438:Sulfhydryl Compounds; D007495:Iridium; D015082:2,2'-Dipyridyl