Noncentrosymmetry in New Templated Gallium Fluorophosphates

Abstract

Two new noncentrosymmetric polar gallium fluorophosphates have been synthesized under mild hydrothermal conditions through the use of enantiomorphically pure sources of either R-2-methylpiperazine or S-2-methylpiperazine. A centrosymmetric analogue was also prepared using a racemic source of the amine. Novel [Ga(3)F(PO(4))(4)](n)(4n-) layers, constructed from [Ga(3)O(3)F(PO(4))(4)] building units, are observed in all three compounds. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers, while using a single enantiomer destroys the inversion symmetry and orders the amines. Second harmonic generation measurements were performed on [(R)-C(5)H(14)N(2)](2)[Ga(3)F(PO(4))(4)] x 5.5 H(2)O and [(S)-C(5)H(14)N(2)](2)[Ga(3)F(PO(4))(4)] x 4.75 H(2)O, both of which display type 1 phase-matching capabilities and exhibit activities of approximately 50 x alpha-SiO(2). The structures of these compounds were determined using single crystal X-ray diffraction, infrared spectroscopy, and thermal analyses. [C(5)H(14)N(2)](2)[Ga(3)F(PO(4))(4)] x 5.25 H(2)O, a = 13.0863(5) A, c = 9.9023(4) A, trigonal, P-3 (No. 147), Z = 2; [(R)-C(5)H(14)N(2)](2)[Ga(3)F(PO(4))(4)] x 5.5 H(2)O, a = 13.0887(2) A, c = 29.9439(4) A, trigonal, P3(1) (No. 144), Z = 6; [(S)-C(5)H(14)N(2)](2)[Ga(3)F(PO(4))(4)] x 4.75 H(2)O, a = 13.0871(2) A, c = 29.8350(6) A, trigonal, P3(2) (No. 145), Z = 6.

Synthesis, crystal structures and thermal behaviour of organic–inorganic hybrids incorporating a chiral diamine

“…These MeO w distances are provided in Table 2 2.834(2) Å. These values agree with those currently observed in inorganic salts containing the organic groups used in this work [5,7,38]. One again, extended, supramolecular structures are constructed from these molecular units by hydrogen-bonding.…”

“…This technique has been used with success in a variety of systems [5,17,38]. The role of 2-methylpiperazinediium cations in these reactions is three-fold.…”

[R-C7H16N2][V2Te2O10] and [S-C7H16N2][V2Te2O10]; new polar templated vanadium tellurite enantiomers

“…Second, the formation of a distinct phase, in which the [R-aqnH 2 ] 2 þ and [S-aqnH 2 ] 2 þ cations are related to one another through inversion symmetry, could occur. This behavior has been observed in templated polyoxomolybdates [65] and gallium phosphates [64]. Third, the [R-aqnH 2 ] 2 þ and [S-aqnH 2 ] 2 þ cations could form domains within each crystal, resulting in an inversion twin, as observed in some templated molybdenum sulfates [66,67].…”

“…While it is known that chiral components are useful in the formation of new noncentrosymmetric materials [62][63][64][65][66][67][68], researchers often value compounds that crystallize in polar space groups more highly. Of the twenty-one noncentrosymmetric crystal classes, only the ten polar crystal classes contain permanent dipole moments, which enables the possibility of ferroelectricity [2] and pyroelectricity.…”

Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][MII(H2O)6](SO4)2, (MII = Mn, Fe, Co, Ni)

“…Such disorders are founded in the related gallium fluorophosphates. 26 Counterpoints to the role of template disorder in these compounds can be found in related systems based upon the templated copper sulfate compound. [C 5 The structural aspects of 1-4 are reminiscent of another group of compounds with the formula A 2 M(H 2 O) 6 (XO 4 ) 2 (A = monovalent cation, M = divalent cation, X = hexavalent cation), popularly referred to as Tutton's salts.…”