Search

A new coordination polymer (CP), namely, poly[[diaquatris[μ2‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]bis[μ6‐4‐(2,4‐dicarboxylatophenoxy)phthalato]tetracobalt(II)] hexahydrate], {[Co4(C16H6O9)2(C12H10N4)3(H2O)2]·6H2O}n, has been synthesized by solvothermal reaction. The CP was fully characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, and powder and single‐crystal X‐ray diffraction. It presents a three‐dimensional (3D) structure based on tetranuclear CoII secondary building units (SBUs) with a tfz‐d net and point symbol (43)2(46·618·84). The 4‐(2,4‐dicarboxyphenoxy)phthalic acid (H4dcppa) ligands are completely deprotonated and link {Co4(COO)4}4− SBUs into two‐dimensional (2D) layers. Furthermore, adjacent layers are connected by 1,4‐bis(1H‐imidazol‐1‐yl)benzene (bib) ligands, giving rise to a 3D supramolecular architecture. Interestingly, there are numerous elliptical cavities in the CP where isolated unique discrete hexameric water clusters have been observed. The results of thermogravimetric and magnetic analyses are described in detail. [ABSTRACT FROM AUTHOR]

Six two‐dimensional (2D) coordination polymers (CPs), namely, poly[{μ5‐3,3‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ6O1:O1′:O3,O3′:O5:O5′}bis(N,N‐dimethylformamide‐κO)lanthanide(III)], [Ln(C21H11O8)(C3H7NO)2]n, with lanthanide/Ln = cerium/Ce for CP1, praseodymium/Pr for CP2, neodymium/Nd for CP3, samarium/Sm for CP4, europium/Eu for CP5 and gadolinium/Gd for CP6, have been prepared by solvothermal methods using the ligand 3,3′‐[(5‐carboxy‐1,3‐phenylene)bis(oxy)]dibenzoic acid (H3cpboda) in the presence of Ln(NO3)3. The complexes were characterized by single‐crystal X‐ray and powder diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis (TGA). All the structures of this family of lanthanide CPs are isomorphous with the triclinic space group P and reveal that they have the same 2D network based on binuclear LnIII units, which are further extended via interlayer C—H...π interactions into a three‐dimensional supramolecular structure. The carboxylate groups of the cpboda3− ligands link adjacent LnIII ions and form binuclear [Ln2(RCOO)4] secondary building units (SBUs), in which each binuclear LnIII SBU contains four carboxylate groups from different cpboda3− ligands. Moreover, with the increase of the rare‐earth Ln atomic radius, the dihedral angles between the aromatic rings gradually increase. Magnetically, CP6 shows weak antiferromagnetic coupling between the GdIII ions. The solid‐state luminescence properties of CP2, CP5 and CP6 were examined at ambient temperature and CP5 exhibits characteristic red emission bands derived from the Eu3+ ion (CIE 0.53, 0.31), with luminescence quantum yields of 22%. Therefore, CP5 should be regarded as a potential optical material. [ABSTRACT FROM AUTHOR]

Four manganese (II) compounds are obtained by the reaction of manganese salts, triazole-derivatives and auxiliary reagents in aqueous solution or mix-solvents by routine or hydrothermal reactions. X-ray crystal structure analyses reveal that a neutral 0D compound [Mn(Hmctrz) 2 (H 2 O) 2 ] ( 1 ) (H 2 mctrz = 1 H -1,2,4-triazole-3-carboxylic acid) displays a centro-symmetric mononuclear octahedral entity with two Hmctrz − anions and two water molecules; two neutral 2D clusters [Mn(Hdctrz)(H 2 O) 2 ] n ( 2 ) (H 3 dctrz = 1 H -1,2,4-triazole-3,5-dicarboxylic acid) and [Mn 2 (pbtrz)(btca)] n ·4nH 2 O ( 3 ) (pbtrz = 1,3-bis(1,2,4-triazol-1-yl)-propane&H 4 btca = benzene-1,2,4,5-tetracarboxylic acid) possess layer structures with Hdctrz 2 − linkers ( 2 ) and Mn(II)-pbtrz-Mn(II) building blocks periodically extended by μ -btca 4 − connectors ( 3 ); [Mn(pbtrz)] n ·nOAc·nOH ( 4 ) shows a 3D diamond-shaped cationic framework with the anion void volume of 49.2%. Nitrogenous bases are used as the auxiliary ligand in compound 3 and the temple ligand in compounds 1 , 2 , and 4 . Compounds 1 – 4 show antiferromagnetic coupling that has been fitted by different models with the molecular field approximate with D = − 0.129(1) cm −1 for 1 , J = − 0.354(4) cm −1 for 2 and J = − 0.696(6) cm −1 for 3 , respectively. The magnetic differences can be related to different superexchange interactions transmitted by the crystal lattice and/or the zero field splitting (ZFS) of the 6 A 1g single-ion states of 1 and the syn-anti -COO − of 2 as well as the mixed magnetic bridges of μ 1 -O and μ -pbtrz- μ -COO − of 3 . [ABSTRACT FROM AUTHOR]

A new chiral one-dimensional gadolinium coordination polymer [Gd(HDTTA)3(CH3OH)3]n (1) (D-H2DTTA = (+)-Di-p-toluoyl-D-tartaric acid) was synthesized at room temperature, and fully structurally characterized by Infrared (IR), elemental analysis (EA), single-crystal and powder X-ray diffraction (PXRD). The structure analysis shows that complex 1 belongs to the trigonal system with R3 space group and displays an infinite chain structure along the c axis. In 1, each Gd3+ cation is in the tri-capped trigonal prism geometry, and neighboring Gd3+ cations are connected by three partly deprotonated HDTTA− ligands with the Gd···Gd distance of 7.686(1) Å. The circular dichroism (CD) spectrum demonstrates the chirality of the complex. Magnetic studies reveal that complex 1 displays weak antiferromagnetic interactions between Gd3+ cations and it exhibits a small magnetic entropy change (−ΔSm = 7.26 J kg−1 K−1 with ΔH = 7 T and T = 2.5 K) because of long Gd···Gd distance and relatively low magnetic density. [ABSTRACT FROM AUTHOR]

A new mononuclear europium complex incorporating the (+)‐di‐p‐toluoyl‐d‐tartaric acid (d‐H2DTTA) ligand, namely, catena‐poly[tris{μ2‐3‐carboxy‐2,3‐bis[(4‐methylphenyl)carbonyloxy]propanoato}tris(methanol)europium(III)], [Eu(C20H17O8)3(CH3OH)3]n, (I), has been synthesized and characterized by IR spectroscopy, elemental analysis, powder X‐ray diffraction and single‐crystal X‐ray diffraction analysis. The structure analysis indicates that complex (I) crystallizes in the trigonal space group R3 and exhibits an infinite one‐dimensional chain structure, in which the Eu3+ ion is surrounded by six O atoms from six d‐HDTTA− ligands and three O atoms from three coordinated methanol molecules, thus forming a tricapped trigonal prism geometry. The d‐H2DTTA ligand is partially deprotonated and adopts a μ1,6‐coordination mode via two carboxylate groups to link adjacent Eu3+ ions, affording an infinite one‐dimensional propeller‐shaped coordination polymer chain along the c axis, with an Eu...Eu distance of 7.622 (1) Å. Moreover, C—H...π interactions lead to the formation of helical chains running along the c axis and the whole structure displays a snowflake pattern in the ab plane. The circular dichroism spectrum confirms the chirality of complex (I). The solid‐state photoluminescence properties were also investigated at room temperature and (I) exhibits characteristic red emission bands derived from the Eu3+ ion (CIE 0.63, 0.32), with a reasonably long lifetime of 0.394 ms, indicating effective energy transfer from the ligand to the metal centre. In addition, a magnetic investigation reveals single‐ion magnetic behaviour. The spin‐orbit coupling parameter (λ) between the ground and excited states is fitted to be 360 (2) cm−1 through Zeeman perturbation. Therefore, complex (I) may be regarded as a chiral optical‐magneto bifunctional material. [ABSTRACT FROM AUTHOR]

Careful investigation of the effects of metal ions and pH value resulted in five multi-dimensional metal−organic complexes, [Co 5 ( μ 3 -OH) 2 ( α -bptc) 2 (H 2 O) 6 ] n ( 1 ), {(H 3 O) 2 [Co 4 ( μ 3 -O)( α -bptc) 2 (H 2 O)]·4H 2 O} n ( 2 ), {K 2 [Zn 4 ( μ 3 -OH) 2 ( α -bptc) 2 (H 2 O) 3 ]} n ( 3 ), [Zn 4 ( α -bptc) 2 (H 2 O) 3 ] n ( 4 ), and {[Cd 4 ( α -bptc) 2 (H 2 O) 7 ]·2H 2 O} n ( 5 ) ( α - H 4 bptc = 2,3,3 ' ,4 ' - biphenyl tetracarboxylic acid). The complexes consisted of different highly connected secondary building units (SBUs) assembled via hydrothermal in situ routes. The pH value as well as the kinds of metal ions influenced the coordination modes of α -H 4 bptc and also introduced the hydroxyl ligand at high pH value, resulting in the diversity of SBUs and dimensionality. Variable temperature magnetic measurements indicated the antiferromagnetic behavior in the Co 5 core in 1 , and the intra - chain ferrimagnetic behavior in complex 2 . Moreover, the luminescent properties of the complexes 3 − 5 indicated the existence of intra - ligand charge transfer. [ABSTRACT FROM AUTHOR]