Deciphering the complexation processes of creatinine-cobalt and creatinine-cobalt-2-nitrobenzaldehyde: Morphological, spectroscopic and electrochemical analysis.

• Preparation of two new complexes, [Co(CR) 3 (H 2 O)]Cl 2 and [Co(CR) 3 (H 2 O) 2 (2-NBA)]Cl 3. • The complexes have rod-shaped and nano-fibrous morphology respectively. • The oxidation states of cobalt ions in the complexes are +2 and +3 respectively. • The coordination process described here promises creatinine sensor development. Owing to creatinine's coordinating property with transition metal ions, its oxidation by 2-nitrobenzaldehyde, and the ability of the nitrite group to form chelate and bridging compounds with cobalt ions, different conditions-dependent pathways of reactions can be undertaken when any two of the three components (cobalt ion, creatinine, and 2-nitrobenzaldehyde) react. Bringing these three components together opens up multiple reaction possibilities. In this work, the effect of 2-nitrobenzaldehyde on a new complexation pathway of creatinine-cobalt has been explored, under some controlled conditions. As a result, a 4-coordinated complex, [Co(CR) 3 (H 2 O)]Cl 2, and a 7-coordinated complex, [Co(CR) 3 (H 2 O) 2 (2-NBA)]Cl 3 , were obtained, where CR= creatinine and 2-NBA= 2-nitrobenzaldehyde. P-XRD analysis confirmed the formation of new amorphous complexes and SEM analysis revealed their rod-shaped and nano-fibrous morphologies respectively. FTIR and Raman analysis established the coordination of cobalt ions with endocyclic nitrogen of creatinine and chelation with the nitro group of 2-NBA. From EDX analysis, close similarities between the experimental and theoretical elemental compositions of the complexes were determined. EPR analysis established the paramagnetic nature of the complexes. While DRS studies indicated different d -configurations of the cobalt ions in the complexes, CV and DPV confirmed their respective oxidation states to be +2 and +3. The coordination pathways described here can be put into a creatinine sensor development application. [Display omitted] [ABSTRACT FROM AUTHOR]