Chemistry, Physics and Technology of Surface

ISSN 2518-1238 (Online), ISSN 2079-1704 (Print)

During last decades сoordination compounds of lanthanides with polychelating β-diketones and their derivatives have attracted increasing interest due to the possibility of using such compounds in biomedical research, as contrast reagents for NMR tomography studies and MOLED technology. That is why the selection of appropriate ligands, which are effective sensitizers of lanthanide luminescence and can form thermodynamically stable complexes, is especially important.

Carbacylamidophosphates (CAPh ligands) of general formula (R¹)C(O)NHP(O)(R²)₂ are structural analogues of β-diketones, which can serve as an antenna providing more efficient energy transfer to the lanthanide ion followed by Ln(III) luminescence.

The present work is devoted to the mass-spectrometric studies of the stability of coordination compound of terbium(III) with new CAPh ligand using methods of soft ionization such as matrix activated laser desorption / ionization (MALDI), its modification – LDI (laser desorption ionization). The main preference of the «soft ionization» methods is the possibility of unfragmented ions registration.

Terbium coordination compound with new bis-chelating carbacylamidophosphate ligand (Tb(HL)₂(NO₃)) (where HL^– = tetramethyl[pyridine-2,6-diyldi(iminocarbonyl)]diamidophosphate anion) has been synthesized and studied by IR spectroscopy and X-ray diffraction. It was shown that the deprotonated arm of each ligand is coordinated to the terbiumion in the bidentate manner and the protonated arm in monodentate manner via the oxygen atom of phosphoryl group. The nitrate ion is bidentate coordinated, completing coordination number of terbium to eight.

The components of the LDI mass spectrum of the synthesized coordination compound have been identified. The positive region of the mass spectrum of the complex Tb(HL)₂(NO₃) is characterized by the presence of smaller fragments due to the effect of the metal ion on the fragmentation of the ligand molecules and the molecular ion is not observed due to formation of more complex and stable structures based on Tb(III) ions.

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