Structural and selectivity of 18-crown-6 ligand in lanthanide-picrate complexes

Muhammad I. Saleh, Eny Kusrini, Hoong K. Fun, Bohari Mohd. Yamin

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The selectivity factor in the separation of lanthanide could be associated with the coordination behaviour. Thus, we observed the study in the solid phase to understand the coordination pattern of Ln(III) with the 18-crown-6 (18C6) ligand. Good selectivity of the rigid 18C6 ligand toward Ln(III) depends on gradually smaller their ionic radii of Ln(III) in the complexes formation in the presence of picrate anion (Pic-), i.e. lanthanide contraction and steric effects as clearly shown in the series of [Ln(Pic)2(18C6)]+(Pic)- {Ln = La, Ce, Pr, Nd, Sm, Gd} and [Ln(Pic)3(OH2)3] · 2(18C6) · 4H2O {Ln = Tb, Ho} complexes. The La-Gd complexes crystallized in an orthorhombic with space group Pbca, while the Ho complex crystallized in triclinic with space group P over(1, ̄). The lighter lanthanides complexes [La-Sm] had a 10-coordination number from the 18C6 ligand and the two picrates, forming a bicapped square-antiprismatic geometry. Meanwhile, the middle lanthanide complex [Gd] had a nine-coordination number from the 18C6 ligand and the two picrates, forming a tricapped trigonal prismatic geometry. The heavier lanthanide [Ho] is rather unique, since Ho(III) coordinated with nine oxygen atoms from three picrates and three water molecules in the opposite direction whereas three 18C6 molecules surrounded in the inner coordination sphere, forming a trigonal tricapped prismatic geometry. The 18C6 ligand is effective in controlling the molecular geometry and coordination bonding of Ln-O and can use a crystal engineering approach. No dissociation of Ln-O bonds in solution was observed in NMR studies conducted at different temperatures. The photoluminescence spectrum of the Pr complex has typical 4f-4f emission transitions, i.e. 3P0 3F2 (650 nm), 1D2 3F2 (830 nm) and 1D2 3F4 (950 nm).

Original languageEnglish
Pages (from-to)2561-2571
Number of pages11
JournalJournal of Organometallic Chemistry
Volume693
Issue number15
DOIs
Publication statusPublished - 15 Jul 2008

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picrates
Lanthanoid Series Elements
Rare earth elements
selectivity
Ligands
Picrates
ligands
Geometry
geometry
coordination number
Crystal engineering
Molecules
contraction
solid phases
molecules
oxygen atoms
Photoluminescence
Negative ions
Nuclear magnetic resonance
18-crown-6

Keywords

  • 18-Crown-6
  • Lanthanide contraction
  • Picrate complexes
  • Selectivity

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Materials Science (miscellaneous)
  • Materials Chemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Biochemistry

Cite this

Structural and selectivity of 18-crown-6 ligand in lanthanide-picrate complexes. / Saleh, Muhammad I.; Kusrini, Eny; Fun, Hoong K.; Mohd. Yamin, Bohari.

In: Journal of Organometallic Chemistry, Vol. 693, No. 15, 15.07.2008, p. 2561-2571.

Research output: Contribution to journalArticle

Saleh, Muhammad I. ; Kusrini, Eny ; Fun, Hoong K. ; Mohd. Yamin, Bohari. / Structural and selectivity of 18-crown-6 ligand in lanthanide-picrate complexes. In: Journal of Organometallic Chemistry. 2008 ; Vol. 693, No. 15. pp. 2561-2571.
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N2 - The selectivity factor in the separation of lanthanide could be associated with the coordination behaviour. Thus, we observed the study in the solid phase to understand the coordination pattern of Ln(III) with the 18-crown-6 (18C6) ligand. Good selectivity of the rigid 18C6 ligand toward Ln(III) depends on gradually smaller their ionic radii of Ln(III) in the complexes formation in the presence of picrate anion (Pic-), i.e. lanthanide contraction and steric effects as clearly shown in the series of [Ln(Pic)2(18C6)]+(Pic)- {Ln = La, Ce, Pr, Nd, Sm, Gd} and [Ln(Pic)3(OH2)3] · 2(18C6) · 4H2O {Ln = Tb, Ho} complexes. The La-Gd complexes crystallized in an orthorhombic with space group Pbca, while the Ho complex crystallized in triclinic with space group P over(1, ̄). The lighter lanthanides complexes [La-Sm] had a 10-coordination number from the 18C6 ligand and the two picrates, forming a bicapped square-antiprismatic geometry. Meanwhile, the middle lanthanide complex [Gd] had a nine-coordination number from the 18C6 ligand and the two picrates, forming a tricapped trigonal prismatic geometry. The heavier lanthanide [Ho] is rather unique, since Ho(III) coordinated with nine oxygen atoms from three picrates and three water molecules in the opposite direction whereas three 18C6 molecules surrounded in the inner coordination sphere, forming a trigonal tricapped prismatic geometry. The 18C6 ligand is effective in controlling the molecular geometry and coordination bonding of Ln-O and can use a crystal engineering approach. No dissociation of Ln-O bonds in solution was observed in NMR studies conducted at different temperatures. The photoluminescence spectrum of the Pr complex has typical 4f-4f emission transitions, i.e. 3P0 → 3F2 (650 nm), 1D2 → 3F2 (830 nm) and 1D2 → 3F4 (950 nm).

AB - The selectivity factor in the separation of lanthanide could be associated with the coordination behaviour. Thus, we observed the study in the solid phase to understand the coordination pattern of Ln(III) with the 18-crown-6 (18C6) ligand. Good selectivity of the rigid 18C6 ligand toward Ln(III) depends on gradually smaller their ionic radii of Ln(III) in the complexes formation in the presence of picrate anion (Pic-), i.e. lanthanide contraction and steric effects as clearly shown in the series of [Ln(Pic)2(18C6)]+(Pic)- {Ln = La, Ce, Pr, Nd, Sm, Gd} and [Ln(Pic)3(OH2)3] · 2(18C6) · 4H2O {Ln = Tb, Ho} complexes. The La-Gd complexes crystallized in an orthorhombic with space group Pbca, while the Ho complex crystallized in triclinic with space group P over(1, ̄). The lighter lanthanides complexes [La-Sm] had a 10-coordination number from the 18C6 ligand and the two picrates, forming a bicapped square-antiprismatic geometry. Meanwhile, the middle lanthanide complex [Gd] had a nine-coordination number from the 18C6 ligand and the two picrates, forming a tricapped trigonal prismatic geometry. The heavier lanthanide [Ho] is rather unique, since Ho(III) coordinated with nine oxygen atoms from three picrates and three water molecules in the opposite direction whereas three 18C6 molecules surrounded in the inner coordination sphere, forming a trigonal tricapped prismatic geometry. The 18C6 ligand is effective in controlling the molecular geometry and coordination bonding of Ln-O and can use a crystal engineering approach. No dissociation of Ln-O bonds in solution was observed in NMR studies conducted at different temperatures. The photoluminescence spectrum of the Pr complex has typical 4f-4f emission transitions, i.e. 3P0 → 3F2 (650 nm), 1D2 → 3F2 (830 nm) and 1D2 → 3F4 (950 nm).

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