A Highly Symmetric Ionic Crystal Constructed by Polyoxoniobates and Cobalt Complexes for Preferential Water Uptake over Alcohols

An ionic crystal assembled by PNb₁₂O₄₀(VO)₆ and tris­(1,2-diaminopropane)­cobalt complexes was hydrothermally isolated and structurally characterized by routine methods. The compound exhibits three-dimensional channels with a pore size of 3.68 Å × 2.30 Å and composed of hydrophilic oxygen atoms of polyanions and hydrophobic −CH₃ groups of 1,2-diaminopropane ligands. With increasing vapor pressure, the compound shows preferable adsorption toward water over alcohols, and a gate-opening behavior was deduced from the water adsorption isotherm

Tuning the Luminescence of Metal–Organic Frameworks for Detection of Energetic Heterocyclic Compounds

Herein we report three metal–organic frameworks (MOFs), TABD-MOF-1, -2, and -3, constructed from Mg²⁺, Ni²⁺, and Co²⁺, respectively, and deprotonated 4,4′-((<i>Z</i>,<i>Z</i>)-1,4-diphenylbuta-1,3-diene-1,4-diyl)­dibenzoic acid (TABD-COOH). The fluorescence of these three MOFs is tuned from highly emissive to completely nonemissive via ligand-to-metal charge transfer by rational alteration of the metal ion. Through competitive coordination substitution, the organic linkers in the TABD-MOFs are released and subsequently reassemble to form emissive aggregates due to aggregation-induced emission. This enables highly sensitive and selective detection of explosives such as five-membered-ring energetic heterocyclic compounds in a few seconds with low detection limits through emission shift and/or turn-on. Remarkably, the cobalt-based MOF can selectively sense the powerful explosive 5-nitro-2,4-dihydro-3<i>H</i>-1,2,4-triazole-3-one with high sensitivity discernible by the naked eye (detection limit = 6.5 ng on a 1 cm² testing strip) and parts per billion-scale sensitivity by spectroscopy via pronounced fluorescence emission

Tuning the Luminescence of Metal–Organic Frameworks for Detection of Energetic Heterocyclic Compounds

Herein we report three metal–organic frameworks (MOFs), TABD-MOF-1, -2, and -3, constructed from Mg²⁺, Ni²⁺, and Co²⁺, respectively, and deprotonated 4,4′-((<i>Z</i>,<i>Z</i>)-1,4-diphenylbuta-1,3-diene-1,4-diyl)­dibenzoic acid (TABD-COOH). The fluorescence of these three MOFs is tuned from highly emissive to completely nonemissive via ligand-to-metal charge transfer by rational alteration of the metal ion. Through competitive coordination substitution, the organic linkers in the TABD-MOFs are released and subsequently reassemble to form emissive aggregates due to aggregation-induced emission. This enables highly sensitive and selective detection of explosives such as five-membered-ring energetic heterocyclic compounds in a few seconds with low detection limits through emission shift and/or turn-on. Remarkably, the cobalt-based MOF can selectively sense the powerful explosive 5-nitro-2,4-dihydro-3<i>H</i>-1,2,4-triazole-3-one with high sensitivity discernible by the naked eye (detection limit = 6.5 ng on a 1 cm² testing strip) and parts per billion-scale sensitivity by spectroscopy via pronounced fluorescence emission

Quasi-Living <i>trans</i>-1,4-Polymerization of Isoprene by Cationic Rare Earth Metal Alkyl Species Bearing a Chiral (<i>S</i>,<i>S</i>)‑Bis(oxazolinylphenyl)amido Ligand

A series of chiral mononuclear dialkyl complexes [(<i>S</i>,<i>S</i>)-BOPA]­Ln­(CH₂SiMe₃)₂ (<b>1</b>, <b>2</b>) (BOPA = (<i>S</i>,<i>S</i>)-bis­(oxazolinylphenyl)­amido; Ln = Sc (<b>1</b>); Ln = Lu (<b>2</b>)) and binuclear alkyl complexes [<i>ο</i>-(<i>S</i>)-OPA–C₆H₄–(CH₂SiMe₃)­CN–CH­(^<i>i</i>Pr)­CH₂–O]­Ln­(CH₂SiMe₃)}₂ (<b>3</b>,<b> </b><b>4</b>) (OPA = (oxazolinylphenyl)­amine; Ln = Y (<b>3</b>); Ln = Tm (<b>4</b>)) have been synthesized in moderate yields via one-pot acid–base reactions by use of the tris­(trimethylsilylmethyl) rare earth metal complexes with the chiral tridentate (<i>S</i>,<i>S</i>)-bis­(oxazolinylphenyl)­amine ligand. In the presence of activator with or without a small amount of Al^<i>i</i>Bu₃, the dialkyl complexes <b>1</b> and <b>2</b> exhibit very high activities (up to 6.8 × 10⁵ g mol_Ln^–1 h^–1) and <i>trans</i>-1,4-selectivity (up to 100%) in the quasi-living polymerization of isoprene, yielding the <i>trans</i>-1,4-PIPs with moderate molecular weights (<i>M</i>_n = (0.2–1.0) × 10⁵ g/mol) and narrow molecular weight distributions (<i>M</i>_w/<i>M</i>_n = 1.02–2.66)

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

Structural Diversity of Diosgenin Hydrates: Effect of Initial Concentration, Water Volume Fraction, and Solvent on Crystallization

Four hemihydrates (HH-I, HH-II, HH-III, and HH-IV) and two monohydrates (MH-I, MH-II) of diosgenin, a steroid sapogenin, have been prepared. Hydrates HH-I, HH-III, HH-IV, MH-I, and MH-II have been thoroughly characterized by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. Although in these cases diosgenin has a similar conformation, hydrogen bonding interactions connect diosgenin and the lattice water molecule into different supermolecular structures. More importantly, three controlling factors, including initial concentration, water volume fraction, and solvent, have been investigated in the crystallization of diosgenin hydrates. The control experiments in ethanol display that as the initial concentration increases, HH-III, HH-I, and HH-II appear in order, and with the increase of water content, HH-I, HH-III, MH-I, and MH-II are obtained correspondingly. When acetone is used as solvent, HH-IV was synthesized. Moreover, we observed that stick-like crystals of HH-III gradually transform to plate-like ones of MH-I in solution at ambient conditions. This transformation is prevented by lowering temperature and is accelerated by adding water

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

Three Candesartan Salts with Enhanced Oral Bioavailability

Three new salts, [H₃N­(CH₂)₂NH₃]­[can]·2H₂O (<b>1</b>), [H₃N­(CH₂)₃NH₃]­[can]·2H₂O (<b>2</b>), and [NH₄]­[Hcan] (<b>3</b>), of the minimally soluble antihypertensive drug, Candesartan (H₂can), have been prepared by solvent-assisted grinding. Salts <b>1–3</b> also have been thoroughly characterized by single-crystal X-ray diffraction, powder X-ray diffraction, Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance, thermogravimetry, and differential scanning calorimetry. In the case of <b>1</b> and <b>2</b>, two protons of carboxyl and tetrazole groups of Candesartan transfer to the diamine, resulting in salts where both hydrogen bonding and electrostatic interactions that link the Candesartan and diamine (diammonium) units into a one-dimensional supramolecular ribbon. However, unlike the case in <b>1</b> and <b>2</b>, only one proton from the carboxyl group of Candesartan transfers to ammonia in <b>3</b> and ionic components now assemble into a three-dimensional supramolecular network. Dissolution studies indicate that both the apparent solubility and dissolution rate of salts <b>2</b> and <b>3</b> in phosphate buffer are dramatically improved compared to those of the original active pharmaceutical ingredient (API). Furthermore, to evaluate the absorption effect of salts <b>1–3</b> <i>in vivo</i>, pharmacokinetic studies were performed in rats. It is notable that the oral bioavailability of salts <b>1–3</b> is enhanced by 1.3, 2.5, and 3.1 times, respectively, compared to that of the API

Self-Assembly of Ln(III)-Containing Tungstotellurates(VI): Correlation of Structure and Photoluminescence

The generation of five types of Ln­(III)-containing tungstotellurates­(VI), dimeric (DMAH)₁₂­Na₂[H₁₀(WO₂)­{Ln­(H₂O)₅­(TeW₁₈O₆₅)}₂]­·<i>n</i>H₂O (abbreviated as {Ln₂Te₂W₃₇}; Ln = Eu, Gd, or Tb; DMAH = dimethylammonium), tetrameric (DMAH)₂₁­Na₇[H₁₆­{Ln­(H₂O)₅­(TeW₁₈O₆₄)}₄]­·<i>n</i>H₂O (abbreviated as {Ln₄Te₄W₇₂}, Ln = Eu or Gd), 2:2 dimeric (DMAH)₁₂­[H₆{Tb­(H₂O)₃­(TeW₁₇O₆₁)}₂]­·25H₂O (abbreviated as {Tb₂Te₂W₃₄}), 1:1 monosubstituted (DMAH)₇­Na₂[H₂Tb­(H₂O)₄­(TeW₁₇O₆₁)]­·21H₂O (abbreviated as {TbTeW₁₇}), and three-dimensional polymer (DMAH)₂­[HTb­(H₂O)₄­{TeW₆O₂₄}]­·14H₂O (abbreviated as {TbTeW₆}_<i>n</i>), provides insight into the rich condensation chemistry of lacunary and other Dawson-type polyoxometalates. The pH and the type of Ln³⁺ source both dictate which of these new complexes form. To our knowledge, {Ln₄Te₄W₇₂} is the highest-nuclearity tungstotellurate to date, and {Tb₂Te₂W₃₄} and {TbTeW₁₇} contain the first lacunary {TeW₁₇O₆₁}. Electrospray ionization mass spectra analyses indicate that the Dawson-like building blocks, {TeW₁₈O₆₅} and {TeW₁₇O₆₁}, found in solid structures are also present in solution. The intense photoluminescence (characteristic green emission) of {TbTeW₆}_<i>n</i>, 100× greater than those of {Tb₂Te₂W₃₇}, {Tb₂Te₂W₃₄}, and {TbTeW₁₇}, is explained by analysis of all 4 X-ray structures and multiple structure-intensity correlations