A Co( ii ) complex of a vitamer of vitamin B 6 acts as a sensor for Hg 2+ and pH in aqueous media

• Published in: New journal of chemistry 2016, Vol.40 (7), p.6396-6404
• Main Authors: Sing, Nilam, Roy, Sanjay, Guin, Partha Sarathi, Mahali, Kalachand, Majee, Prakash, Mondal, Sudip Kumar, Mahata, Partha, Sengupta, Partha Sarathi, Mondal, Palash
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C6NJ00410E

A Co( ii ) complex of molecular formula C 48 H 96.8 N 12 O 22.4 Co 2 Cl 2 , 1, was synthesized from the Schiff base [H 2 pydmdp]Cl by a template reaction of pyridoxal (pyd), a vitamer of vitamin B 6 , N -methyl-1,3-diaminopropane (mdp) and cobalt( ii ) acetate. It was characterized by elemental analysis, 1 H NMR, IR and UV-Vis spectroscopy, thermal analysis, electrochemistry and single crystal X-ray diffraction. The experimental results suggested that in complex 1, the central Co( ii ) is bonded to two phenolato-oxygens, two imine nitrogens and two amine nitrogens in an octahedral geometry. In aqueous media complex 1 exhibits an intense fluorescence emission peak at 506 nm when it was excited at 425 nm. The fluorescence behavior of complex 1 in aqueous media was employed to determine whether it acts as a chemosensor for some selective toxic metal ions. The studies showed that the present complex behaves as a promising sensor for Hg 2+ even at the sub-micromolar level. In addition in aqueous solution, complex 1 acts as a sensor for the pH of the medium. A detailed study on the mechanism of sensing behavior established that Hg 2+ interacts with complex 1 via weak non-covalent interaction with the N-atom of the pyridine moiety of the molecule. The pyridine nitrogen also plays a vital role in sensing the pH of the medium.