Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe

Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe

Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe

Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties

An isomorphous family of mixed 3d–4f dodenuclear aggregates, {[Mn^III₈Ln₄(Clshi)₈(OAc)₆(μ₃-OCH₃)₂(μ₃-O)₂(CH₃OH)₁₂(H₂O)₂]·4CH₃OH·<i>x</i>H₂O)} (where Ln = Eu^III (<b>1</b>), Gd^III (<b>2</b>), Tb^III (<b>3</b>), and Dy^III (<b>4</b>); ClshiH₃ = 5-chlorosalicylhydroxamic acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> = 2 for <b>4</b>), were synthesized and characterized. They were obtained from the reaction of ClshiH₃ with Mn­(OAc)₂·4H₂O and Ln­(NO₃)₃·6H₂O. These isomorphous mixed 3d–4f compounds represent a family of novel structures with lanthanide ions in the metallacrown (MC) ring. Each dodecanuclear aggregate contains two offset stacked 14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M connectivity to capture one Ln^III ion in the core of each MC. Two 14-MC-5 units are connected through O ions with four Mn ions and six O atoms arranged in a double Mn₄O₆ cubane. Magnetic measurement indicates that antiferromagnetic interactions are present between the metal ions. The Dy^III analogue with high anisotropy and large spin shows slow magnetization relaxation at a direct-current field of 2 kOe

Solvent and pH Dependences of Mixing Enthalpies of <i>N</i>‑Glycylglycine with Protocatechuic Acid

Protocatechuic acid (PA) is a natural phenolic compound which has been proven to have chemopreventive property against chemically induced carcinogenesis. The mixing enthalpies of PA with <i>N</i>-glycylglycine in sodium phosphate and potassium phosphate buffer solutions with different pH values have been investigated by mixing-flow isothermal microcalorimetry at <i>T</i> = 298.15 K. The heterotactic enthalpic interaction coefficients (<i>h</i>_<i>xy</i>) in the pH range of phosphate buffer solution from 3.0 to 8.0 have been calculated according to the McMillan–Mayer theory. Trends of the enthalpic pairwise interaction coefficients (<i>h</i>_<i>xy</i>) with increasing pH in both phosphate buffer solutions were obtained. The solvent and pH dependence of the <i>h</i>_<i>xy</i> were discussed in terms of molecular interactions between solvated solute molecules