19-Tungstodiarsenate(III) Functionalized by Organoantimony(III) Groups: Tuning the Structure–Bioactivity Relationship

A family of three discrete organoantimony­(III)-functionalized heteropolyanions[Na­{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}­As^III₂W₁₉O₆₇(H₂O)]^10– (<b>1</b>), [{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}₂As^III₂W₁₉O₆₇(H₂O)]^8– (<b>2</b>), and [{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}­{WO₂(H₂O)}­{WO­(H₂O)}₂(<i>B</i>-β-As^IIIW₈O₃₀)­(<i>B</i>-α-As^IIIW₉O₃₃)₂]^14– (<b>3</b>)have been prepared by one-pot reactions of the 19-tungstodiarsenate­(III) precursor [As^III₂W₁₉O₆₇(H₂O)]^14– with 2-(Me₂NCH₂)­C₆H₄SbCl₂. The three novel polyanions crystallized as the hydrated mixed-alkali salts Cs₃KNa₆[Na­{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}­As^III₂W₁₉O₆₇(H₂O)]·43H₂O (<b>CsKNa-1</b>), Rb_2.5K_5.5[{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}₂As^III₂W₁₉O₆₇(H₂O)]·18H₂O·Me₂NCH₂C₆H₅ (<b>RbK-2</b>), and Rb_2.5K_11.5[{2-(Me₂HN⁺CH₂)­C₆H₄Sb^III}­{WO₂(H₂O)}­{WO­(H₂O)}₂(<i>B</i>-β-As^IIIW₈O₃₀)­(<i>B</i>-α-As^IIIW₉O₃₃)₂]·52H₂O (<b>RbK-3</b>), respectively. The number of incorporated {2-(Me₂HN⁺CH₂)­C₆H₄Sb^III} units could be tuned by careful control of the experimental parameters. Polyanions <b>1</b> and <b>2</b> possess a dimeric sandwich-type topology, whereas <b>3</b> features a trimeric, wheel-shaped structure, representing the largest organoantimony-containing polyanion. All three compounds were fully characterized in the solid state via single-crystal X-ray diffraction (XRD), infrared (IR) spectroscopy, and thermogravimetric analysis, and their aqueous solution stability was validated by ultraviolet–visible light (UV-vis) and multinuclear (¹H, ¹³C, and ¹⁸³W) nuclear magnetic resonance (NMR) spectroscopy. Effective inhibition against six different types of bacteria was observed for <b>1</b> and <b>2</b>, and we could extract a structure–bioactivity relationship for these polyanions

Tetra-Antimony(III)-Bridged 18-Tungsto-2-Arsenates(V), [(LSb^III)₄(<i>A</i>‑α-As^VW₉O₃₄)₂]^10– (L = Ph, OH): Turning Bioactivity On and Off by Ligand Substitution

Two tetra-antimony­(III)-bridged, sandwich-type 18-tungsto-2-arsenates­(V), [(LSb^III)₄(<i>A</i>-α-As^VW₉O₃₄)₂]^10– (L = Ph (<b>1</b>), OH (<b>2</b>)), were prepared and fully characterized in the solid state and in solution. Both polyanions are stable in aqueous physiological medium for at least 24 h (at concentrations ≥2.5 × 10^–6 M). Despite the presence of an isostructural tetra-antimony­(III) motif in <b>1</b> and <b>2</b>, distinctly different antibacterial activity was observed for both polyanions. The minimum inhibitory concentrations (MIC) of <b>1</b> (7.8–62.5 μg/mL) is lower than for any other organoantimony­(III)-containing polyoxometalate reported to date

Tetra-Antimony(III)-Bridged 18-Tungsto-2-Arsenates(V), [(LSb^III)₄(<i>A</i>‑α-As^VW₉O₃₄)₂]^10– (L = Ph, OH): Turning Bioactivity On and Off by Ligand Substitution

Two tetra-antimony­(III)-bridged, sandwich-type 18-tungsto-2-arsenates­(V), [(LSb^III)₄(<i>A</i>-α-As^VW₉O₃₄)₂]^10– (L = Ph (<b>1</b>), OH (<b>2</b>)), were prepared and fully characterized in the solid state and in solution. Both polyanions are stable in aqueous physiological medium for at least 24 h (at concentrations ≥2.5 × 10^–6 M). Despite the presence of an isostructural tetra-antimony­(III) motif in <b>1</b> and <b>2</b>, distinctly different antibacterial activity was observed for both polyanions. The minimum inhibitory concentrations (MIC) of <b>1</b> (7.8–62.5 μg/mL) is lower than for any other organoantimony­(III)-containing polyoxometalate reported to date

Synthesis and Biological Activity of Organoantimony(III)-Containing Heteropolytungstates

Three discrete organoantimony­(III)-containing heteropolytungstates [(PhSb^III)₄(<i>A</i>-α-Ge^IVW₉O₃₄)₂]^12– (<b>1</b>), [(PhSb^III)₄(<i>A</i>-<i>α</i>-P^VW₉O₃₄)₂]^10– (<b>2</b>), and [{2-(Me₂NCH₂C₆H₄)­Sb^III}₃(<i>B</i>-α-As^IIIW₉O₃₃)]^3– (<b>3</b>) have been synthesized in one-pot reactions in aqueous medium using the appropriate lacunary heteropolyanion precursor and organoantimony­(III) source. Polyanions <b>1</b>–<b>3</b> were isolated as hydrated salts, (NH₄)₁₂[(PhSb^III)₄(<i>A</i>-α-Ge^IVW₉O₃₄)₂]·20H₂O (<b>1a</b>), Rb₉Na­[(PhSb^III)₄(<i>A</i>-α-P^VW₉O₃₄)₂]·20H₂O (<b>2a</b>), and Rb₃[{2-(Me₂NCH₂C₆H₄)­Sb^III}₃(<i>B</i>-α-As^IIIW₉O₃₃)]·7H₂O (<b>3a</b>). The compounds <b>1a</b>–<b>3a</b> were fully characterized in the solid state using infrared (IR) spectroscopy, single-crystal XRD, and thermogravimetric and elemental analyses. The stability of <b>1</b>–<b>3</b> in aqueous solution was confirmed by multinuclear NMR (¹H, ¹³C, ³¹P, and ¹⁸³W) spectroscopy. Preliminary studies on the biological activity of <b>1</b>–<b>3</b> showed that all three compounds might act as potent antimicrobial agents