A series of new core–shell structure materials based on lanthanide complexes [H₂NMe₂]₃[Ln(dpa)₃] (Ln = Eu, Tb, Sm, Dy, Nd, and Yb; [H₂NMe₂]⁺ = dimethylamino cation; dpa = 2-dipicolinate) and silica microspheres has been prepared under solvothermal conditions. Electron microscopy reveals that the nanosized materials SiO₂@Ln-dpa are spherical with a narrow size distribution and a [H₂NMe₂]₃[Ln(L)₃] coating was generated on the surface of silica microspheres successfully. The core–shell structure materials exhibit excellent optical performance. The white-light-emitting material SiO₂@(Dy:Eu)-dpa has a potential application in the development of a white-light device, as a result of the fact that its CIE chromaticity coordinate is very close to that of pure white. Then, we selected SiO₂@Eu-dpa as a representative sample for sensing experiments. Eventually, we found that the core–shell structure sensors are highly selective and sensitive for acetone and Cu²⁺ cations. The detection of Cu²⁺ in the human body is an important issue. Interestingly, the core–shell structure materials display better selectivity and higher sensitivity than the pure lanthanide complexes in sensing Cu²⁺ and the value of the quenching effect coefficient has increased by more than 20%.