Design nano azo chelates containing barbituric acid and o-amino benzoic acid spectral, thermal investigation, modelling and biological activity

•The azodye ligand 2-((2,4,6-trioxohexahydropyrimidin-5-yl)diazenyl) was derived from diazotization coupling reaction between o-aminobenzoic acid and barbituric acid and utilized for metallization with different valent metal ions Ti(IV), VO(II), Mn(II), Fe(III), Cu(II) Zr(IV), Ru(III), Ag(I) and Hf(IV).•All chelates were non-electrolytes except Fe(III), Zr(IV), Ru(III), Ag(I) and Hf(IV) that had electrolytic nature.•XRD and TEM studies revealed that all compounds were formed in nano particle size.•The azo ligand and some of its chelates were evaluated against antimicrobial and human hepatocellular carcinoma (Hep-G2).•Fe(III) complex has a higher cytotoxicity in comparison to the free ligand and other metal complexes, with IC50 values of 8.10 μg ml−1.•Cu(II) complex showed high activity against aspergillus brasiliensis fungi, Bacillus cereus Gram-positive bacteria and Proteus vulgaris Gram-negative bacteria comparable to that of control drugs.