α′-三氟甲基-含氟β-二酮镧系螯合物的合成及其甩作位移试剂的研究

Study on the Synthesis of the Lanthanide Chelates of α'-Trifluoromethyl-polyfluoroalkyl β-diketones and Their Application as ~1H NMR Shift Reagents

本文合成了α′-三氟甲基-含氟β-二酮镧系螯合物Ln{CF_3CF_2[CF_2OCF(CF_3)]_nCOCHCOC·(CH_3)_3}_3[n=1;Ln=Eu(1a),Pr(1b),Nd(1c),Sm(1d),Gd(1e),Tb(1f),Dy(1g),Er(1h).n=2;Ln=Eu(2a),Pr(2b),Nd(2c),Sm(2d),Gd(2e),Tb(2f),Dy(2g),Er(2h)],并研究了它们的位移性能.1a、1b、2a和2b在用作位移试剂时,不仅具备Ln(fod)_3(Ln=Eu,Pr)的所有优点,而且还有另外两个优点:(1)在底物存在时,试剂自身的叔丁基峰明显向高场迁移,特别是在醇类化合物存在下,δ-Bu^t接近于0ppm,因此,1a和2a的t-Bu峰总是处于底物ω-甲基的高场,不干扰图谱的解析.(2)1b和2b虽为镨类螯合物,但与1a或2a一样,都能得到非常清晰的一级图谱.c、f和g均使谱峰向高场迁移,而h却使谱峰向低场迁移.c的位移能力略低于b.f、g和h的位移能力极强.

The synthesis of the lanthanide chelates of α'-trifluoromethyl-polyfluoroalkyl β-diketones Ln{CF_3CF_2[CF_2OCF(CF_3)]_nCOCHCOC(CH_3)_3}_3[n=1, Ln=Eu(1a), Pr (1b), Nd(1c), Sm(1d), Gd(1e), Tb(1f), Dy(1g), Er(1h); n=2; Ln=Eu(2a), Pr(2b), Nd(2c), Sm(2d), Gd(2e), Tb(2f), Dy(2g), Er(2h)] was reported and the ~1H NMR shift properties were studied using alcohol, ketone, ether and amine as substrates. Compounds 1a, 1b, 2a and 2b induce shifts similar to that induced by Ln(fod)_3(Ln=Eu, Pr). However, 1a and 2a are superior to Eu(fod)_3, because their ~1H. signal shifts to higher field in the presence of substrate than that of Eu(fod)_3 does. For example, δ_H for 1a and 2a is close to zero ppm in the presence of alcohol. Very satisfactory first order spectra can be obtained using 1a, 2a, 1b and 2b as ~H NMR shift reagents respectively, 1c, 1f, 1g, 2c, 2f and 2g produce upfield shifts, and 1h and 2h produce downfield shifts. 1c and 2c induce shifts smaller than that of 1b and 2b, whereas 1f, 1g, 1h, 2f, 2g and 2h induce very large shifts.