Structural Mapping and Framework Interconversions in 1D, 2D, and 3D Divalent Metal R,S-Hydroxyphosphonoacetate Hybrids

Abstract

Reactions of divalent cations (Mg(2+), Co(2+), Ni(2+), and Zn(2+)) with R,S-hydroxyphosphonoacetic acid (HPAA) in aqueous solutions (pH values ranging 1.0-4.0) yielded a range of crystalline hydrated M-HPAA hybrids. One-dimensional (1D) chain compounds were formed at room temperature whereas reactions conducted under hydrothermal conditions resulted in two-dimensional (2D) layered frameworks or, in some cases, three-dimensional (3D) networks incorporating various alkaline cations. 1D phases with compositions [M{HO(3)PCH(OH)CO(2)}(H(2)O)(2)].2H(2)O (M = Mg, Co, and Zn) were isolated. These compounds were dehydrated in liquid water to yield the corresponding [M{HO(3)PCH(OH)CO(2)}(H(2)O)(2)] compounds lacking the lattice water between the 1D chains. [M{HO(3)PCH(OH)CO(2)}(H(2)O)(2)] (M = Mg, Ni, Co, Zn) compounds were formed by crystallization at room temperature (at higher pH values) or also by partial dehydration of 1D compounds with higher hydration degrees. Complete dehydration of these 1D solids at 240-270 degrees C led to 3D phases, [M{HO3PCH(OH)CO(2)}]. The 2D layered compound [Mg{HO(3)PCH(OH)CO(2)}(H(2)O)(2)] was obtained under hydrothermal conditions. For both synthesis methods, addition of alkali metal hydroxides to adjust the pH usually led to mixed phase materials, whereas direct reactions between the metal oxides and the hydroxyphosphonoacetic acid gave single phase materials. On the other hand, adjusting the pH with acetate salts and increasing the ratio M(2+)/HPAA and/or the A(+)/M(2+) ratio (A = Na, K) resulted in 3D networks, where the alkali cations were incorporated within the frameworks for charge compensation. The crystal structures of eight new M(II)-HPAA hybrids are reported herein and the thermal behavior related to dehydration/rehydration of some compounds are studied in detail.

Chapter 14. Structural Diversity in Metal Phosphonate Frameworks: Impact on Applications

“…123 In the 1D Zn-HPAA material the Zn-O distance is 2.042(2) Å . 109 In the 1D material Ni-HPAA the Ni-O distance is 2.0322(18) Å . 124 In 3 Cl] Á 3.5py (py ¼ pyridine), 1.913(9) Å to 1.964(5) Å .…”

“…An identical trend is observed for the series M-HPAA materials (M ¼ Mg, Ca, Sr, Ba), as shown in Figure 14.19. 98,99,109 Bond distances versus ionic radii of the first row divalent transition metal ions are plotted in Figure 14.20. It is obvious that there is no discernible trend.…”

High-Throughput Synthesis of Pillared-Layered Magnesium Tetraphosphonate Coordination Polymers: Framework Interconversions and Proton Conductivity Studies

“…Synthesis conditions were screened by high-throughput methodology with a system previously reported [31,32]. The aluminum autoclave block contains 36 Teflon-lined reaction chambers of 5 mL volume.…”

The crystallisation of copper(ii) phenylphosphonates

“…[6][7][8][9] The materials can be used as proton conductors and for the modification of surfaces because of their polar pores and different organic groups. [10][11][12][13][14][15][16] Zirconium(IV) phenylphosphonate was one of the first described metal phosphonates. 17 Cunningham et al showed different syntheses of divalent metal phenylphosphonates with the general formula M(II)(O 3 PC 6 H 5 )•H 2 O.…”