Selective fluorescence sensing of Ni2+ by tetradentate ligands: Synthesis of nickel complexes and crystal structures

•The ligands Gimpy and Timpy exhibited fluorescence properties.•Enhancement in emission intensities was observed in presence of Ni(II) ions.•Nickel complexes of the ligands were synthesized and characterized by spectroscopic techniques.•Molecular structures of Gimpy and nickel complex of Timpy were authenticated by X-ray crystallographic studies also.•Magnetic properties of the nickel complexes of Gimpy and Timpy were also investigated.

Nickel complexes [(Ni(Gimpy)(μ–Cl))2](ClO4)2 (Gimpy, ((1Z,2Z)-1,2-bis(2-phenyl-2-(pyridine-2-yl)hydrazono)ethane)) (1) and [(Ni(Timpy)(μ–Cl))2](ClO4)2·2(CH3)2CO (Timpy, (1,2-bis((E)-(2-phenyl-2-(pyridine-2-yl)hydrazono)methyl)benzene)) (2·2(CH3)2CO) were synthesized and characterized by spectroscopic studies. The molecular structures of ligand Gimpy and [(Ni(Timpy)(μ–Cl))2](ClO4)2·2(CH3)2CO were established by X-ray crystallography. Redox and magnetic properties are also described. Both Gimpy and Timpy exhibited fluorescence characteristics which were significantly enhanced in the presence of Ni2+ in methanol indicating that these molecules may be exploited as molecular sensors for Ni2+ ion.

Graphical abstractThe emission spectral properties of two Schiff’s bases namely Gimpy and Timpy were examined with various divalent metal ions. In presence of Ni(II) ions, enhancement in emission intensities of these ligands was observed. Nickel complexes of Gimpy and Timpy were synthesized and characterized by various spectroscopic techniques. Molecular structures of Gimpy and nickel complex of Timpy were authenticated by X-ray crystallography. Magnetic and redox properties of the nickel complexes were also examined.Figure optionsDownload full-size imageDownload as PowerPoint slide