【摘要】 以二种高量子产率的异三核PtM2(M=Ag,Au)铂-炔-膦配合物为前驱体分别与Ln(hfac)3(H2O)2(Ln=Nd,Er,Yb;hfac=六氟乙酰丙酮)反应得到六种PtM2Ln2异五核稀土加合物,研究了它们在二氯甲烷溶液和固态的发光性能.通过激发PtM2发色团在可见光区的吸收,PtM2Ln2稀土加合物都发射出相应稀土离子的特征近红外发光.更多还原

【Abstract】 With two highly phosphorescent heterotrinuclear complexes [PtM2(dpmp)2(C≡CC6H4tpy)2][(ClO4)2](1, M=Ag; 2, M = Au; dpmp = PPh2PPhPPh2) as precursors, six PtM2Ln2 heteropentanuclear adducts {[PtM2(dpmp)2-(C≡CC6H4tpy)2][Ln(hfac)3]2}[(ClO4)2](Ln=Nd, Er, Yb) were synthesized by the reactions of PtM2 complexes with two equiv. Ln(hfac)3(H2O)2. The crystal structures of PtAg2Nd2(1Nd) and PtAu2Nd2(2Nd) complexes were characterized by X-ray crystallography. PtM2 complexes 1 and 2 exhibit intense low-energy absorption and strong room-temperature phosphorescence, which qualifies them as favorable energy donors to facilitate PtM2→Ln energy transfer in corresponding PtM2Ln2 heteropentanuclear adducts. The addition of Ln(hfac)3(H2O)2 to dichloromethane solution of PtM2 complexes results in a gradually deepening of the color from yellow-green to yellow, which is associated with the enhanced and red-shifted LLCT(ligand-to-ligand charge transfer) absorption bands upon formation of the PtM2Ln2 arrays, as indicated by the change of the UV-vis absorption spectra of 2 upon titration with Yb(hfac)3(H2O)2. Upon visible light excitation at 390 nm≤λex≤450 nm which is the absorption region of PtM2 chromophores, while the phosphorescence of PtM2 chromophores vanishes mostly, near-infrared(NIR) luminescence from NdIII, ErIII, or YbIII centers is successfully achieved through effective sensitization from PtM2 chromophores following PtM2→Ln energy transfer. Titration of 2 with Yb(hfac)3(H2O)2 in dichloromethane induces rapid attenuation of the emission of PtM2 chromophore so that the phosphorescence in visible region is mostly quenched whereas the NIR emission from YbIII is remarkably enhanced upon the addition of 2 equiv. Yb(hfac)3(H2O)2, further demonstrating that energy transfer from PtM2 sensitizers to LnIII centers indeed occurs. The rates(kET) of energy transfer were estimated as 6.5×108 s-1 for 1Nd, 4.42×108 s-1 for 1Er, 2.83×108 s-1 for 1Yb, 4.04×108 s-1 for 2Nd, 1.36×108 s-1 for 2Er and 5.44×107 s-1 for 2Yb species. The rates of PtM2→Ln energy transfer following PtM2Nd2>PtM2Er2>PtM2Yb2 can be rationally elucidated by spectroscopic overlapping degree between the emission spectra of PtM2 complexes and the f-f absorption bands of LnIII ions.更多还原