Triethylenetetramine complexes of cobalt(III) having anion binding sites: synthesis, characterisation, crystal structure, anti-bacterial and anti-cancer properties of [Co(trien)(NO2)2]2Cr2O7 and [Co(trien)(NO2)2]SCN

Crystals of cobalt(III) salts dinitro(triethylenetetramine)cobalt(III) dichromate [Co(trien)(NO 2 ) 2 ] 2 Cr 2 O 7 ( 1 ) and dinitro(triethylenetetramine)cobalt(III) thiocyanate [Co(trien)(NO 2 ) 2 ]SCN ( 2 ) have been synthesized to investigate [Co(trien)(NO 2 ) 2 ] + cation as a promising host to capture dichromate and thiocyanate anions. The characterization of the newly synthesized compounds was accomplished by elemental analysis and spectroscopic techniques (IR, UV/visible and 1 H-NMR) and solubility product measurement. The asymmetric unit of complex 1 has a half dichromate anion and one [Co(trien)(NO 2 ) 2 ] + cation while that of complex 2 has one thiocyanate anion and one [Co(trien)(NO 2 ) 2 ] + cation as divulged by X-ray structure determination. The structural investigation exhibited that the crystal lattice was stabilized by second sphere hydrogen bonding interactions such as N–H trien ···O (dichromate), C–H trien ···O (dichromate), N–H trien ···N (thiocyanate) and C–H trien ···N (thiocyanate) interactions resulting in the formation of supramolecular assemblies. The complexes 1 and 2 were further examined for antibacterial activity and the findings unveiled moderate activity against gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa species. These complexes were also scrutinized for anti-proliferative activity against malignant PANC-1 cells using MTT cell survival analysis. Complex 1 exhibited remarkable anticancer activity whereas complex 2 has comparatively lesser anticancer potential. Graphic abstract Crystals of cobalt(III) ion [Co(trien)(NO 2 ) 2 ].X (X= ½.Cr 2 O 7 (1)/ SCN (2)) have been synthesized and characterized by various spectroscopic and analytical techniques. Structural study of 1 and 2 were established and divulge formation of supramolecular assemblies through H-bonding. Complex 1 and 2 were further examined for antibacterial and antiproliferative activity. Complex 1 exhibited remarkable anticancer activity whereas complex 2 has comparatively lesser anticancer potential