Copolymers containing second-order nonlinear optical (NLO) active transition metal complexes into the main chain were synthesized and characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), TG, and DSC analyses for the first time. The Cu(II) complex Ia of the N,N’-bis(2,4-dihydroxybenzylidene)-1,2-phenylenediamine ligand was synthesized and used as the NLO unit. The polycondensation between the copper(II) complex Ia (NLO unit) and butanediol bischloroformate was performed to obtain the exactly alternating copolycarbonate II. Two copolyethers, III ana IV, containing different amounts of NLO units in the main chain (10% and 47%, respectively), were obtained by reaction of dibromomethane and suitable mixtures of the Cu(II) diimine complex Ia and bisphenol A in different molar ratios. The resulting copolymers II-IV were characterized by MALDI-TOF MS. The structure of low molecular weight oligomers contained in each polymeric sample inferred by MALDI spectra was found diagnostic of their composition and microstructure. Copolymers II-TV exhibit very good thermal stability and are promising candidates for second-order NLO materials.