3d-4f Coordination Research Articles

Self-assembly of 3-D 4d–4f coordination frameworks based on pyridine-3,5-dicarboxylic acid: Syntheses, crystal structures and luminescence

The hydrothermal reactions of H 2PDC, AgNO 3 with Eu 2O 3 or Tb(NO 3) 3·6H 2O gave rise to two novel three-dimensional 4d–4f heterometallic metal–organic coordination polymers, AgEu(PDC) 2 ( 1) and AgTb(PDC) 2 ( 2) (H 2PDC = pyridine-3,5-dicarboxylic acid), and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. Complexes 1 and 2 crystallize in the monoclinic system, P2/ c space group; the structure determination reveal that both of them are isostructural and feature an unusual three-dimensional heterometallic network structure in which infinite lanthanide-carboxylate chains are linked by [Ag(PDC) 2] 3− metalloligands to form a mixed-metal coordination network. Moreover, the luminescent properties of two complexes have also been investigated at room temperature.

3D Ln–Ag (Ln=Nd; Eu) coordination polymers based on isonicotinate and oxalate ligands: Synthesis, crystal structures and luminescence

Abstract The self-assembly of isonicotinic acid with metal salts under hydrothermal conditions obtained two new 4d–4f coordination polymers, LnAg(OX)(IN)2·H2O (Ln = Nd (1); Eu (2), OX = oxalic acid, IN = isonicotinic acid). The 3D isostructural complexes 1 and 2 are constructed by the assembly of 2D layers, which are built by carboxylate groups of isonicotinic acid and oxalate ligands coordinating to metal centers, with 1D linear linkers completed by silver ions. Furthermore, the luminescent property of complex 2 was investigated.

Metal-directed assembly of two 2-D 4d–4f coordination polymers based on elliptical triple-deck cylinders hinged by meso-double helical chains

Two 2-D 4d–4f coordination polymers based on elliptical triple-deck cylinders hinged by meso-helical chains containing an isonicotinate ligand, namely, {[Ag2Ln(IN)4(H2O)2]·(NO3)·(H2O)}n (Ln = Sm and Eu, IN− = isonicotinate), have been successfully constructed through the transformation of a single-crystal to single-crystal (SC-SC) or different metal–organic polymer units, in which the recognition between the organic ligand and two types of metal ions direct the formation of the final productions.

Construction of three isostructural 3d–4f microporous coordination frameworks based on mixed nicotinate and oxalate ligands

The self-assembly of nicotinic acid and sodium oxalate with mixed 3d–4f metal salts under hydrothermal conditions gave three isostructural 3D 3d–4f coordination polymers, [LnCu(nic) 2(ox)] · xH 2O [Ln = La, x = 1 ( 1); Ln = Eu, x = 2 ( 2); Ln = Gd, x = 2 ( 3)] [ox = oxalate, nic = nicotinate]. All three structures exhibit same unusual 3D microporous heterometallic coordination frameworks that are built up by rare tetranuclear Ln 2Cu 2 clusters and mixed ox and nic linkers. Furthermore, the luminescent property of complex 2 has also been investigated.

A novel three-dimensional heterometallic coordination polymer: poly[[hexaaquabis[μ3-3,5-dicarboxylatopyrazolato-κ5O3,N2:N1,O5:O5′](μ2-oxalato-κ4O1,O2:O1′,O2′)copper(II)dierbium(III)] trihydrate

The title novel heterometallic 3d-4f coordination polymer, {[CuEr(2)(C(5)HN(2)O(4))(2)(C(2)O(4))(H(2)O)(6)].3H(2)O}(n), has a three-dimensional metal-organic framework composed of two types of metal atoms (one Cu(II) and two Er(III)) and two types of bridging anionic ligands [3,5-dicarboxylatopyrazolate(3-) (ptc(3-)) and oxalate]. The Cu(II) atom is four-coordinated in a square geometry. The Er(III) atoms are both eight-coordinated, but the geometries at the two atoms appear different, viz. triangular dodecahedral and bicapped trigonal prismatic. One of the oxalate anions is located on a twofold axis and the other lies about an inversion centre. Both oxalate anions act as bis-bidentate ligands bridging the latter type of Er atoms in parallel zigzag chains. The pdc(3-) anions act as quinquedentate ligands not only chelating the Cu(II) and the triangular dodecahedral Er(III) centres in a bis-bidentate bridging mode, but also connecting to Er(III) centres of both types in a monodentate bridging mode. Thus, a three-dimensional metal-organic framework is generated, and hydrogen bonds link the metal-organic framework with the uncoordinated water molecules. This study describes the first example of a three-dimensional 3d-4f coordination polymer based on pyrazole-3,5-dicarboxylate and oxalate, and therefore demonstrates further the usefulness of pyrazoledicarboxylate as a versatile multidentate ligand for constructing heterometallic 3d-4f coordination polymers with interesting architectures.

Construction of isostructural Ln–Ag (Ln = Eu; Tb; Dy) nano-channel heterometallic coordination frameworks based on pyrazine-2-carboxylate and oxalate ligands

The self-assembly of pyrazine-2-carboxylate and oxalate with mixed-metal salts under hydrothermal conditions gave three isostructural 3D 4d-4f coordination polymers, LnAg(ox)(2-pzc) 2 · H 2O [Ln = Eu ( 1); Tb ( 2); Dy ( 3)] [ox = oxalate, 2-pzc = pyrazine-2-carboxylate]. All three structures exhibit same unusual 3D nanoporous heterometallic coordination frameworks constructed by zigzag lanthanide–oxalate chains and Ag(2-pzc) 2 units. Furthermore, the luminescent properties of complexes 1 and 2 are discussed.

Heterometallic 3d–4f coordination polymers: Synthesis, characterization and magnetic properties of 1D zigzag chains containing samarium and terbium

Reaction of the copper precursor [Cu(MeOsaltn)(H 2O)] (H 2MeOsaltn = N, N′-bis(3-methoxysalicylidene)-1,3-diaminopropane) with Ln(NO 3) 3·6H 2O (Ln = Sm and Tb) and pyrazine-2,3-dicarboxylic acid (H 2pyrdic) results in the formation of 1D zigzag chains with the general formula of [Cu(MeOsaltn)Ln(NO 3)(pyrdic)] n · nDMF. X-ray crystal structures reveal that the samarium and terbium compounds are isostructural and crystalize in the orthorhombic space group Pbcn. The chains are composed of heterodinuclear copper–lanthanide building blocks which are linked by the pyrazine-2,3-dicarboxylate bridging units. Temperature-dependent susceptibility measurements indicate antiferromagnetic exchange interactions for the samarium–copper chain whereas for the terbium–copper compound ferromagnetic interactions are observed.

3D Ln–Ag (Ln = Nd; Eu) coordination polymers based on N- and O-donor ligands: Synthesis, crystal structures and luminescence

The self-assembly of isonicotinic acid with metal salts under hydrothermal conditions gave two isostructural 3D 4d–4f coordination polymers, Ln 2Ag 4(OX)(IN) 6(H 2O) 1.5 · 2(ClO 4) [Ln = Nd ( 1); Eu ( 2), OX = oxalic acid, IN = isonicotinic acid]. Compounds 1 and 2 are 3D coordination frameworks via 2D layers built by carboxylate groups of isonicotinic acid and oxalate ligands coordinating to metal centers and completing the linear linker by silver ions. Furthermore, the luminescent properties of complex 2 have also been investigated.

Self-assembly of 3-D 4d–4f coordination frameworks based on 1-D inorganic heterometallic chains and linear organic linkers

Four novel 4d–4f heterometallic coordination polymers, namely, LnAg(pydc)2(Hnic)0.5 [Ln = Nd (1), Eu (2); H2pydc = pyridine-3,4-dicarboxylic acid, Hnic = nicotinic acid], and LnAg(inic)2(nicO)·0.5H2O [Ln = Nd (3), Eu (4); Hinic = isonicotinic acid, H2nicO = 2-hydroxynicotinic acid], have been synthesized and characterized. Compounds 1 and 2 exhibit three-dimensional (3-D) coordination frameworks constructed by one-dimensional (1-D) inorganic heterometallic chains and linear pydc linkers. The 1-D channels occupied by disordered Hnic molecules emerge. To our knowledge, both compounds represent the first examples of 3-D open-framework 4d–4f heterometallic coordination frameworks. Compounds 3 and 4 display 3-D covalent frameworks composed of 1-D inorganic heterometallic chains joined by inic ligands, representing the first examples of 3-D 4d–4f coordination frameworks constructed by inorganic heterometallic chain and mixed linear and nonlinear ligands with same donors. Furthermore, the luminescent properties of 2 and 4 were studied.

Impact of linkers on the structural diversity of 3d-4f coordination polymers

3d-4f oligonuclear complexes are very attractive building blocks in designing novel solid-state architectures because they combine the electronic and stereochemical peculiarities of both 3d and 4f metal ions. The building-blocks we use are stable biand trinuclear complexes [CuiLn] (i=1, 2), the metal ions being held together by a Schiff base ligand derived from o-vanilline. The versatility of such building-blocks allows their sequential association by a selective interaction of the metal ions with various linkers, thus yielding supramolecular systems with interesting magnetic properties. The building principle is based on the employment of spacers which are able to recognize either the oxophilic rare-earth cation, or the borderline acid which is copper(II) [1]. The heterobinuclear [CuLn] complexes are also good candidates for the synthesis of polymetallic systems with three different spin carriers 3d-3d’-4f. The third metal ion arises from metalloligands, such as the hexacyanometallate anions [M(CN)6] (M = Cr, Fel.s., Col.s.) [2].

{[GdAg 2(dtpa)(H 2O)] · 3H 2O} n: the first 2D Gd–Ag coordination polymer with Ag–Ag interaction

A novel 4d–4f coordination polymer {[GdAg 2(dtpa)(H 2O)] · 3H 2O} n ( 1) (dtpa = diethylenetriamine pentaacetate) was synthesized and characterized by magnetic and EPR studies. Its one-dimensional Gd–Ag ladder-like chains built upon tetranuclear rings are further connected by Ag–O bonds and Ag–Ag interactions to form a lamellar 2D packing.