Synthesis, Crystal Structure, and Luminescence Properties of the Iso-Reticular Series of Lanthanide Coordination Polymers Synthesized from Hexa-Lanthanide Molecular Precursors.

Microwave-assisted reactions in DMSO, between a hexa-lanthanide octahedral complex ([Ln 6 (μ 6 -O)(μ 3 -OH) 8 (NO 3 ) 6 (H 2 O) 12 ·2NO 3 ·2H 2 O] with Ln = Nd-Yb plus Y) and either 3-halogenobenzoic acid (hereafter symbolized by 3- x bH with x = f or c for fluoro or chloro, respectively) or 4-halogenobenzoic acid (hereafter symbolized by 4- x bH with x = f, c, or b for fluoro, chloro, or bromo, respectively), lead to 1D lanthanide coordination polymers. These coordination polymers are almost iso-reticular. The crystal structure is described on the basis of the coordination polymer with chemical formula [Tb(4-fb) 3 (DMSO)(H 2 O) 2 ·DMSO] ∞ obtained from 4-fluorobenzoic acid (4-fbH) and the Tb 3+ -based octahedral complex: It crystallizes in the triclinic system, space group P 1̅ (n°2), with the following cell parameters: a = 9.8561(9) Å, b = 10.5636(9) Å, c = 15.1288(15) Å, α = 100.840(3)°, β = 95.552(3)°, γ = 110.482(3)°, V = 1426.4(3) Å 3 , and Z = 2. It can be described on the basis of 1D molecular chains. Luminescence properties of the Tb and Eu derivatives have been measured and compared vs the halogeno-function and its position ( meta or para ). Some molecular alloys have also been prepared to estimate the strength of the intermetallic energy transfers. To confirm that the hexa-nuclear complexes (and not the halogenated ligand) have a structuring effect for the formation of the straight chain-like molecular motif, another coordination polymer with chemical formula [Tb(4-npa) 3 DMSO·DMSO·H 2 O] ∞ where 4-npaH symbolizes 4-nitro-phenyl-acetic acid has been prepared. It crystallizes in the triclinic system, space group P 1̅ (n°2) with the following cell parameters: a = 7.8784(8) Å, b = 14.8719(16) Å, c = 15.2753(17) Å, α = 73.612(4)°, β = 86.406(4)°, γ = 83.104(4)°, V = 1703.8(3) Å 3 , and Z = 2. Its crystal structure can be described on the basis of a molecular motif that is similar to the one observed in the five previous crystal structures which confirms the structuring effect of the hexa-nuclear complexes.