Spectrophotometric investigation of 5-nitroso-6-aminouracil and its methyl derivative in methanol by selective complexation with bivalent metal ions

Abstract

6-Amino-5-nitrosouracils are synthesized by the condensation reaction of urea or N,N′-dimethyl urea, cyanoacetic acid and acetic anhydride followed by nitrosation reaction with sodium nitrite. The synthesized compounds are characterized by various spectroscopic techniques like FTIR, NMR, single crystal XRD, and UV–vis absorption spectroscopy. From a single-crystal X-ray crystallography study of DANU, it is found that the compound is crystalline with one water molecule. The binding properties of both compounds with various metal ions are studied using UV–vis spectroscopy, where ANU shows a colour change from colourless to yellow colour-forming complex with cobalt metal ion. While DANU shows a colour change from colourless to dark yellow forming complex with copper and nickel cation, respectively. These compounds showed the job’s plots with Cu2+, Ni2+, and Co2+ in various stoichiometric ratios to form the respective metal complex. The association/binding constant (Ka) values are calculated by plotting Benesi–Hilderbrand plots of ANU with Co2+ ion and is found to be 9.524 × 102. Whereas, DANU with Cu2+, Ni2+ are found to be 3.956 × 103, 2.041 × 103, respectively. These cations may be used in metal ions complexation for the respective ligand. The LOD values for ANU-Co2+, DANU-Cu2+ & DANU-Ni2+ are obtained as 33.9428 μM, 93.8082 μM and 48.396 μM, respectively, whereas the LOQ values are found as 102.857 μM, 284.2675 μM and 146.653 μM, respectively.