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Polynuclear manganese amino acid complexes
Chrysa Kozoni1, Efi Manolopoulou, Milosz Siczek
1Department of Chemistry, University of Crete, 71003, Herakleion, Greece.
Dalton Transactions (Cambridge, England : 2003)
|August 4, 2010
Summary
This study reports the synthesis of novel polynuclear manganese complexes using DL-valine and glycine, which are the first of their kind with natural alpha-amino acids. Magnetic studies reveal complex interactions and ground states for these new manganese compounds.
Area of Science:
- Inorganic Chemistry
- Coordination Chemistry
- Materials Science
Background:
- Polynuclear manganese complexes are of interest due to their diverse magnetic properties and potential applications.
- The incorporation of biologically relevant ligands like amino acids can lead to novel complex structures and functionalities.
Purpose of the Study:
- To synthesize and characterize new polynuclear manganese complexes.
- To investigate the structural and magnetic properties of these complexes, particularly those involving alpha-amino acids and para-aminobenzoic acid.
- To explore the formation of manganese complexes with oxime ligands and amino acids.
Main Methods:
- Reaction of manganese chloride tetrahydrate with various oximes (Et-saoH(2), saoH(2), Me-saoH(2)) and amino acids (DL-valine, Glycine, para-aminobenzoic acid) in methanol.
- Use of bases like NEt(4)OH, Ca(OH)(2), and CH(3)ONa to facilitate complex formation.
- Structural characterization of the resulting manganese complexes.
- Magnetic susceptibility studies to determine magnetic interactions and ground states.
Main Results:
- Three novel polynuclear manganese complexes were synthesized: [Mn(III)(3)Mn(IV)(2)O(2)(CH(3)O)(Et-sao)(6)(Val)].Val.1.5H(2)O, [Mn(III)(3)O(sao)(3)(Gly)Cl(MeOH)(3)].1.87 MeOH.0.13H(2)O, and [Mn(6)O(2)(PABA)(2)(Me-sao)(6)(MeOH)(4)(H(2)O)(2)].2[Mn(6)O(2)(PABA)(2)(Me-sao)(6)(MeOH)(2)].11 MeOH.
- Complexes 1 and 2 are the first polynuclear manganese complexes reported with any naturally occurring alpha-amino acid.
- Complex 3 is the first structurally characterized manganese para-aminobenzoate complex.
- Magnetic studies on complexes 1 and 2 indicated both ferromagnetic and antiferromagnetic interactions, resulting in S = 2 ground states.
Conclusions:
- The study successfully synthesized novel polynuclear manganese complexes incorporating alpha-amino acids and para-aminobenzoic acid.
- The synthesized complexes exhibit interesting magnetic properties arising from competing magnetic interactions.
- This work expands the library of manganese complexes with biologically relevant ligands and provides insights into their structural and magnetic behavior.
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