Structural, Luminescent and Thermal Properties of Heteronuclear Pd
II⁻Ln
III⁻Pd
II Complexes of Hexadentate N₂O₄ Schiff Base Ligand.
Molecules 2018;
23:molecules23102423. [PMID:
30241422 PMCID:
PMC6222701 DOI:
10.3390/molecules23102423]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 11/27/2022] Open
Abstract
New PdII–LnIII–PdII complexes of hexadentate N2O4 Schiff base ligand (H4L: N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diamino-2,2-dimethylpropane) with Eu (1), Tb (2), Er (3) and Yb (4) ([Pd2Eu(H2L)2NO3](NO3)2∙2H2O∙2CH3OH 1, [Pd2Ln(H2L)2H2O](NO3)3∙3H2O, where Ln = Tb 2, Er 3, [Pd2Yb(H2L)2H2O](NO3)3∙5.5H2O 4) were synthesized and characterized structurally and physicochemically by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC) and luminescence measurements. The compounds 1–4 are built of cationic heterometallic PdII–LnIII–PdII trinuclear units. The palladium(II) centers adopt a planar square geometry occupying the smaller N2O2 cavity of the Schiff base ligand. The lanthanide(III) is surrounded by two Schiff base ligands (eight oxygen atoms) and its coordination sphere is supplemented by a chelating bidentate nitrate ion in 1 or by a water molecule in 2–4. The complexes have a bent conformation along the PdII–LnIII–PdII line with valence angles in the ranges of 162–171°. The decomposition process of the complexes results in mixtures of: PdO, Pd and respective lanthanide oxides Eu2O3, Tb2O3, Tb4O7, Er2O3, Yb2O3. The luminescent measurements show low efficiency intramolecular energy transfer only in the complex of terbium(III) (2).
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