Structural and Luminescence Properties of Anthracene- and Biphenyl-Based Lanthanide Bisphosphonate Ester Coordination Polymers

Abstract

Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M­(NO3)3]­L} n or {[M­(NO3)3]2(L1)3} n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.

Functionalised phosphonate ester supported lanthanide (Ln = La, Nd, Dy, Er) complexes

“…Nonetheless, both angles are nearly identical classifying this interaction as a type I halogen bond. 35 In comparison to related bis-phosphonate esters (anthracene-based I, 9 and tetra-fluorophenyl-based II 36 ), ligands L3 and L6 show comparable structural features ( Table 1, vide infra). The P1-C1 and P1-O1 distances differ only marginally between 1.79-1.81 Å and 1.46-147 Å, respectively.…”

“…The 31 P-NMR shifts of L1-L6 are in-between 19.0 ppm (L6) and 24.4 ppm (L5) ( Table 2) and are located within the range of related compounds found in the literature. [7][8][9] Lanthanide complexes 1-32…”

“…Despite of the phosphonate esters L1-L6 being potential three-dentate chelate ligands, all obtained lanthanide complexes exhibit only a mono-dentate coordination by the oxygen atom of the P + -O − moieties like it is observed in related structures. [7][8][9] Except for the L4and L5-supported complexes 21 and 25, the 31 P-NMR signal of the free ligands experiences a 0.1-0.4 ppm shift to higher field upon complex formation with the lanthanum chloride precursors ( Table 2). This effect is even more pronounced upon com-plexation with the lanthanum nitrates causing a high-field shift of 1.1 ppm (1) and 1.3 ppm (9), respectively.…”

“…6 Our group has focussed on this topic during the last years preparing a variety of efficiently luminescent lanthanide based MOFs. [7][8][9] Moreover, different poly-fluoroaryl substituted mono- 10,11 and bis-phosphanes, 12 and phosphinic acids 13 with enhanced rigidity have been prepared and investigated in terms of reactivity and coordination behaviour. Now, to obtain distinct molecular lanthanide complexes with enhanced excited state lifetimes in the context of a future attachment to semiconductor surfaces, our research focusses on preparation of aryl-sub-stituted mono phosphonate ester ligands.…”

1D and 2D hybrid polymers based on zinc phenylphosphates: synthesis, characterization and applications in electroactive materials

“…These compounds are regarded as a useful platform for the synthesis of new metal-organic frameworks with improved air stability and high-temperature resistance. 10,32,33 Moreover, due to the presence of aromatic groups in the phosphate ligands, these materials exhibit some interesting magnetic 34 and optical [35][36][37] properties that can be utilized in future applications.…”