A rare trimetallic Cu^II complex, [Cu₃(L)₂(NO₃)₂] (1) has been afforded incorporating a [CuL] metalloligand, [where H₂L = N,N′-bis(salicylidene)-1,3-propanediamine]. In 1, in addition to the double phenoxido bridge, the two terminal Cu^II atoms are linked to the central Cu^II by means of syn–anti bridging nitrate anions giving rise to a linear arrangement. Complex 1 exhibits strong antiferromagnetic coupling and shows an χ_MT value of 0.703 cm³ mol⁻¹ K at 300 K. DFT computational studies reveal that there is a clear magneto-structural correlation between the Cu–O–Cu angle and the J_Cu–Cu values, which is in accordance with the experimental evidence. The biological effect of 1 on the viability of different human carcinoma cells was evaluated using MTT assay and the results indicate that this complex induces a decrease in cell-population growth of human colorectal carcinoma cells (COLO 205) with apoptosis.