Rapid development of industry and technological processes associated with the use of heavy metals makes it important to control their content in different environments. The Cd2+ cations have a pronounced toxic effect. Therefore an important task is to improve the methods for their detection and develop new materials for appropriate sensors. In this regard, in this paper, the possibility of binding lupinine-1,2,3-triazole derivatives to the Cd2+ ion was theoretically investigated using several recently synthesized lupininyl derivatives with 1,2,3-triazole ring as an example. Using the Density Functional Theory (DFT) method, the geometries of molecules in their most stable states were studied and the electron absorption spectra were modeled in the practically important range of 200–500 nm. The paper discusses the geometries of the resulting complexes and the energies of electron transitions in optical absorption. Moreover, a conclusion is made about the sensor molecular structure which may be more promising in practice.