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Directed synthesis of noncentrosymmetric molybdates using composition space analysis
Thomas R Veltman1, Adam K Stover, Amy Narducci Sarjeant
1Department of Chemistry, Haverford College, Haverford, Pennsylvania 19041, USA.
Inorganic Chemistry
|July 4, 2006
Summary
This study explored molybdenum oxide (MoO3) reactions with 3-aminoquinuclidine, yielding new compounds with varying symmetries. Controlling reactant ratios enabled the synthesis of noncentrosymmetric materials with potential for second-harmonic generation.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Crystallography
Background:
- Investigated the MoO3/3-aminoquinuclidine/H2O system to understand factors influencing reaction product composition, hydrogen bonding, and symmetry.
- Explored composition space through 36 reactions under mild hydrothermal conditions using racemic 3-aminoquinuclidine.
Purpose of the Study:
- To systematically investigate the MoO3/3-aminoquinuclidine/H2O system.
- To synthesize new compounds and explore their structural and symmetry properties.
- To direct the synthesis of noncentrosymmetric compounds for potential nonlinear optical applications.
Main Methods:
- Composition space analysis of 36 hydrothermal reactions.
- Single-crystal X-ray diffraction for structure determination of five compounds.
- Measurement of second-harmonic generation (SHG) activities.
- Bond valence sum calculations to determine structure-directing properties.
Main Results:
- Synthesized and characterized three new compounds: [C7H16N2][Mo3O10] x H2O, [C7H16N2]2[Mo8O26] x H2O, and [C7H16N2]2[Mo8O26] x 4 H2O.
- Phase stabilities were found to depend on reactant mole fractions, guiding the synthesis of new noncentrosymmetric compounds.
- Two new noncentrosymmetric compounds, [(R)-C7H16N2]2[Mo8O26] and [(S)-C7H16N2]2[Mo8O26], were synthesized using chiral 3-aminoquinuclidine dihydrochlorides.
- These noncentrosymmetric compounds crystallize in the polar space group P2(1) (No. 4).
Conclusions:
- Reactant mole fractions are critical for controlling phase stability and product composition in the MoO3/3-aminoquinuclidine/H2O system.
- The synthesis of noncentrosymmetric molybdate compounds was achieved by utilizing chiral organic amines.
- The identified noncentrosymmetric compounds exhibit potential for second-harmonic generation applications.
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