Structural and multi-functional properties of novel thorium complex bearing higher analogue of guanidine base

Abstract

New-fangled water mediated and air stable thorium complex of molecular formula (AgunH)2[Th(dip)3].H2O have been prepared by reacting thorium(IV) nitrate, dipicolinic acid (H2dip) and aminoguanidine bicarbonate (AgunH.HCO3) at appropriate molar ratio via., template method. The complex has been systematically characterized by chemical analysis, elemental, spectral, thermal and single crystal studies including luminescence and antioxidant properties. The IR spectrum of the resulting complex infers that the carboxylate anion behaves as a monodentate and facilitates to form a monomeric rather than polymeric environment. This is further confirmed by single crystal X-ray diffraction studies. Thermal stability of the title compound undergoes step-wise decomposition to endure ThO(CO3) as the end residue. The single crystal X-ray study reveals that the thorium complex crystallizes in the triclinic crystal system with centric space group (P-1) of Z = 2. Each dipicolinate anion (dip2−) exhibits tridentate coordination modes through a nitrogen atom of pyridine ring and oxygen atoms of the carboxylate groups to form nine coordination with tri-capped trigonal prismatic geometry. Further, the anionic complex is neutralized by two aminoguanidinium (AgunH+) cations and stabilized along with a lattice water molecule. This material shows enhanced luminescent properties, this is due to the crucial role of dipicolinate anion not for aminoguanidinium moiety. Whereas, the aminoguanidinium species is promote to act as a secondary antioxidant.