A Series of Lanthanide Frameworks with a Flexible Ligand, N,N′-Diacetic Acid Imidazolium, in Different Coordination Modes

Abstract

Compounds 1 and 2 both contain the same 2D corrugated layers bridged by DAMwith different bridging modes to form different 3D structures, exhibiting tcs and (4,6)connected topologies, respectively. The structural differences of 1 and 2 lie in the linkages of DAMbetween the layers. Compound 3 also possesses a 3D architecture with an ant net, which is pillared by 2D (4,4) fan-shaped layers in an -ABABsequence. Compounds 4-6 contain similar 2D layers to 1 and 2. The analogous cationic structures 4 and 5 show a 4-connected sql net and 6 presents a (4,5)-connected network, resulting from the different modes of flag-like DAMabove and below the layers. Compound 7 with identical molecular formula to 6 displays a 2D double-layer, consisting of a couple of (4,4) rectangular grid layers. It exhibits a (3,6)connected network. Additionally, IR and UV-visible spectroscopy, the luminescent properties, and thermogravimetric analyses are discussed.

Elaboration of Luminescent and Magnetic Hybrid Networks Based on Lanthanide Ions and Imidazolium Dicarboxylate Salts: Influence of the Synthesis Conditions

“…The Nd-O distances range from 2.413(3) Å to 2.731(3) Å (and from 2.385(4) to 2.716(3) Å for the compound [Sm(L)(ox)(H2O)]•H2O). These bond lengths are comparable to those observed in similar compounds [26,34]. Nd-Nd distances are equal to 4.221(1) Å (4.189(1) Å for Sm-Sm) through the O3 di-oxo bridge and 6.285(1) Å (6.234(1) Å for Sm-Sm) through the oxalate ligand.…”

“…These carboxylate functions are involved in a bidentate chelate coordination mode through O3 and O4 and in a bridging bidentate coordination mode through O4 ( Figure 5). As for the nitrate anions, one is coordinated to Nd1 in a bidentate chelate mode, while the second is free as previously reported for the compound [Nd(L)2(H2O)2][NO3].3H2O [26]. The bidentate chelate coordination mode of the nitrate anion is often reported in the literature [35,36].…”

“…Figure 10, while the assignments of the bands are reported on Table 2. The three spectra show a common band centered at 220 nm due to the intraligand π-π* transition of the imidazolium ligand [26,31,38] Figure 11. The excitation spectra (monitored for λ em = 404 nm) show seven peaks corresponding to the transitions from the ground state of the Sm 3+ ion, 6 Figure 12.…”

Four cluster-based coordination polymers built on a semirigid tripod tricarboxylate ligand

“…More new coordination polymers based on H 3 L could be prepared by varying the synthetic conditions. 10 …”

Metal–organic frameworks containing N-heterocyclic carbenes and their precursors

“…Owing to the degree of flexibility and conformational freedom, the ligand N,N -diacetic acid imidazolium was used by Chai et al [153] with lanthanide ions to synthesize a series of MOFs with different topological structures, as shown in Fig. 19.…”