In the current study, a novel heterocyclic azo ligand, 4-[6-(p-phenyl phenol)azo] cytosine(PAC), is synthesized through a general diazo coupling reaction with lanthanide ions [La(III), Nd(III), and Eu(III)]. The molecular formulae of the newly synthesized compounds were established using a variety of spectroscopic methods, including [FT-IR, UV-Vis, and HNMR], elemental analysis (C.H.N), thermal gravimetric analysis (TGA), magnetic measurement, molar conductivity measurement, stability constant, and Gibbs free energy. Using the mole ratio method, the complexes stoichiometry was determined using data from spectroscopic analyses of the complexes' solutions for the chosen ions. The metal to ligand mole ratio, however, was (1:2). When the biological effectiveness of each compound was tested against various bacteria and fungi strains, the results showed good activity when compared to the standard medication. additionally possess effective cancer prevention and dyeing performance