Three-Dimensional Extended Frameworks Constructed from Dinuclear Lanthanide(III) 1,4-Naphthalenedicarboxylate Units with Bis(2,2′-biimidazole) Templates: Syntheses, Structures, and Magnetic and Luminescent Properties

Eight unprecedented Ln-NDC coordination polymers with BBI as templates {[HBBI]­[Ln­(NDC)₂(H₂O)]·H₂O [Ln = La (<b>1</b>), Pr (<b>2</b>)], [HBBI]₂[Sm­(NDC)₂(H₂O)]₂·1/2H₂O (<b>3</b>), and [HBBI]­[Ln­(NDC)₂(H₂O)] [Ln = Eu (<b>4</b>), Gd (<b>5</b>), Tb (<b>6</b>), Dy (<b>7</b>), Er (<b>8</b>)] [Ln = lanthanide, H₂NDC = 1,4-naphthalenedicarboxylic acid, BBI = bis­(2,2′-biimidazole)]} have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. Complexes <b>1</b>–<b>8</b> crystallize in the monoclinic space group <i>P</i>2₁/<i>c</i> and display similar (8,8)-connected 3-D frameworks with different dinuclear Ln secondary building units due to the effect of Ln contraction and diverse coordination modes of NDC^2– ligands. As the ionic radii of Ln ions decrease, the coordination numbers of Ln ions decrease from 10, to 9, to 8. The variable-temperature magnetic properties of <b>2</b>–<b>8</b> have been investigated. The strong fluorescent emissions of <b>4</b> demonstrate that ligand-to-Eu^III energy transfer is efficient. In addition, thermogravimetric analyses and optical diffuse reflectance spectra of these compounds are also described

Three-Dimensional Extended Frameworks Constructed from Dinuclear Lanthanide(III) 1,4-Naphthalenedicarboxylate Units with Bis(2,2′-biimidazole) Templates: Syntheses, Structures, and Magnetic and Luminescent Properties

Eight unprecedented Ln-NDC coordination polymers with BBI as templates {[HBBI]­[Ln­(NDC)₂(H₂O)]·H₂O [Ln = La (<b>1</b>), Pr (<b>2</b>)], [HBBI]₂[Sm­(NDC)₂(H₂O)]₂·1/2H₂O (<b>3</b>), and [HBBI]­[Ln­(NDC)₂(H₂O)] [Ln = Eu (<b>4</b>), Gd (<b>5</b>), Tb (<b>6</b>), Dy (<b>7</b>), Er (<b>8</b>)] [Ln = lanthanide, H₂NDC = 1,4-naphthalenedicarboxylic acid, BBI = bis­(2,2′-biimidazole)]} have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. Complexes <b>1</b>–<b>8</b> crystallize in the monoclinic space group <i>P</i>2₁/<i>c</i> and display similar (8,8)-connected 3-D frameworks with different dinuclear Ln secondary building units due to the effect of Ln contraction and diverse coordination modes of NDC^2– ligands. As the ionic radii of Ln ions decrease, the coordination numbers of Ln ions decrease from 10, to 9, to 8. The variable-temperature magnetic properties of <b>2</b>–<b>8</b> have been investigated. The strong fluorescent emissions of <b>4</b> demonstrate that ligand-to-Eu^III energy transfer is efficient. In addition, thermogravimetric analyses and optical diffuse reflectance spectra of these compounds are also described

Anion Effects on Lanthanide(III) Tetrazole-1-acetate Dinuclear Complexes Showing Slow Magnetic Relaxation and Photofluorescent Emission

Three types of lanthanide complexes based on the tetrazole-1-acetic acid ligand and the 2,2′-bipyridine coligand were prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses; the formulas of these complexes are [Ln₂(1-tza)₄(NO₃)₂(2,2′-bipy)₂] (Ln = Sm (<b>1</b>), Eu (<b>2</b>), Gd (<b>3</b>), Tb (<b>4</b>), Dy (<b>5</b>)), [Dy₂(1-tza)₄Cl₂(2,2′-bipy)₂] (<b>6</b>), and [Yb₂(1-tza)₄(NO₃)₂(2,2′-bipy)₂] (<b>7</b>) (1-tza = tetrazole-1-acetate and 2,2′-bipy = 2,2′-bipyridine). They are dinuclear complexes possessing similar structures but different lanthanide­(III) ion coordination geometries because of the distinction of peripheral anions (such as NO₃^– and Cl^–) and the effect of lanthanide contraction. The variable-temperature magnetic susceptibilities of <b>1</b>–<b>6</b> were measured. Both Dy^III complexes (<b>5</b> and <b>6</b>) display field-induced single-molecule magnet behaviors. Ab initio calculations revealed that the Dy^III complex <b>6</b> possesses a more anisotropic Dy^III ion in comparison to that in <b>5</b>. The room-temperature photoluminescence spectra of Sm^III (<b>1</b>), Eu^III (<b>2</b>), Tb^III (<b>4</b>), and Dy^III (<b>5</b> and <b>6</b>) complexes exhibit strong characteristic emissions in the visible region, whereas the Yb^III (<b>7</b>) complex shows near-infrared (NIR) luminescence