Grema A. Mala, Abubakar A. Mindia, Hussaini Garba, Salihu A. Musa, and Ibrahim Waziri*
Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B. 1069,
Maiduguri, Borno State, Nigeria
*Corresponding author’s Email: triumph2236@gmail.com, doi.org/10.55639/607.020100137
ABSTRACT
A chlorinated tripodal Schiff base ligand (H₃L) was synthesized by the condensation of tris(2-aminoethyl)amine (tren) with 3,5 dichlorosalicylaldehyde and subsequently employed in the preparation of its Eu(III) complex. The ligand and complex were comprehensively characterized by elemental analysis, FTIR, UV–Visible spectroscopy, high-resolution mass spectrometry (HRMS), and single-crystal X-ray diffraction (SCXRD). Coordination of Eu(III) was confirmed by the shift of the azomethine stretching vibration from 1635 cm⁻¹ in the free ligand to 1604 cm⁻¹ in the complex, accompanied by changes in the phenolic C–O stretching frequency. Electronic absorption spectroscopy revealed two characteristic bands for H₃L at 263 and 335 nm, assigned to π→π* and n→π* transitions, respectively, whereas the Eu(III) complex exhibited absorption bands at 259, 321, and 412 nm, the latter indicating ligand-to-metal charge transfer following coordination. High resolution mass spectrometry further confirmed the proposed compositions, with the ligand displaying a sodium adduct peak at m/z 684.9870 ([M + Na]⁺; calculated. 684.9877) and the Eu(III) complex exhibiting a molecular ion peak at m/z 812.2216 ([M+H]⁺); calculated 812.9035. Single-crystal X-ray diffraction analysis of H₃L established the molecular structure and confirmed the formation of the anticipated chlorinated tripodal Schiff base ligand. The ligand crystallized in the trigonal R3 space group and adopted a rigid tripodal conformation stabilized by intramolecular O–H···N hydrogen bonding. The crystallographic analysis revealed a preorganized N4O₃ donor environment and an ordered three dimensional packing arrangement, providing structural evidence for its suitability as a heptadentate ligand. Collectively, the spectroscopic and crystallographic findings demonstrate that H₃L serves as an effective coordination platform for Eu(III), providing a structurally robust framework for the development of functional lanthanide complexes and future investigations of their photophysical, catalytic, and sensing properties.
KEYWORDS
Tripodal Schiff
base,
Europium(III)
complex,
Single-crystal
X-ray
diffraction,
Crystal
packing.