Near-Infrared Luminescence and Inner Filter Effects of Lanthanide Coordination Polymers with 1,2-Di(4-pyridyl)ethylene

Abstract

A series of 12 lanthanide coordination polymers was synthesized from anhydrous LnCl 3 and 1,2-di(4-pyridyl)ethylene (dpe) under solvothermal conditions in either thiazole (thz) or pyridine (py). The reactions yielded ∞ 1 [Ln 2 Cl 6 (dpe) 2 (thz) 4 ]•dpe with Ln = Ce (1), Nd (2), ∞ 1 [LnCl 3 (dpe)(py) 2 ]•(dpe/py) with Ln = Gd (3), Er (4), and ∞ 1 [LnCl 3 (dpe) (thz) 2 ](dpe/thz) with Ln = Sm (5), Gd (6), Tb (7), Dy (8), Er (9), Yb (10), as well as ∞ 1 [HoCl 3 (dpe)(thz) 2 ]•thz (11) and ∞ 2 [La 2 Cl 6 (dpe) 3 (py) 2 ]•dpe ( 12). One-dimensional coordination polymers (CPs) and a two-dimensional network of five different constitutions are formed by connection of LnCl 3 units via dpe molecules. As free ligand, dpe shows an excimer effect that is reduced in the coordination polymers. In addition, dipyridylethylene proves to be a suitable sensitizer for the photoluminescence of lanthanides in the near-infrared region (NIR) only. Thereby, dpe differs from the related ligand 1,2-di(4-pyridyl)ethane. For the compounds presented, four different luminescence effects were detected: luminescence based on fluorescence of the linker dpe is observed in the visible region, whereas ligand-sensitized 4f−4f NIR emission is dominating for trivalent Nd, Er, and Yb. The Er-containing CPs show an inner-filter effect of Er 3+ , which is based on reabsorption of emission of dpe triggering the erbium NIR emission.

Two Series of Lanthanide Coordination Polymers and Complexes with 4′‐Phenylterpyridine and their Luminescence Properties

“…Quantum yields of the Dy 3+ , Pr 3+ , Ho 3+ , and Tm 3+ products obtained could not be determined reliably due to low intensity of emission in the visible, and of Nd 3+ and Yb 3+ products due to emission in the NIR. However, the respective metal ion based emission lifetimes were also successfully determined for the Dy 3+ , Pr 3+ , Ho 3+ , Tm 3+ , and Yb 3+ products (Table ), which are also close to the values presented in the literature , …”

Thiazole- and Thiadiazole-Based Metal–Organic Frameworks and Coordination Polymers for Luminescent Applications

“…The polymers with Tb and Er show intense luminescence with a strong sensitizer effect of the ligands that can be observed by dominant ligand excitation and exclusive metal emission for VIS and NIR. Thiazole, as such, has been exploited as a solvent in the synthesis of a series of lanthanide CPs from anhydrous LnCl3 and 1,2-bis(4-pyridyl)ethylene (dpe) under solvothermal conditions by the group of Müller-Buschbaum (Wurzburg, DEU) [61]. The obtained polymers of general formula [LnCl3(dpe)(thiazole)2]∞ are 1D or 2D, and the connections between adjacent metal ions in the crystal structures are guaranteed by the dpe bridging linker.…”

Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr2(SO4)3

“…This contribution allows evaluating the composition boundaries of the existence of monoclinic structure in anhydrous sulfates Ln 2 (SO 4 ) 3 . As is known, praseodymium, due to its peculiar electronic structure, may be in different valence states and exhibits various coordination environments in the crystal lattice [49][50][51][52][53][54][55]. Praseodymium ions are able to accept an oxygen deficiency in oxide systems, thereby causing the photocatalytic activity of Pr-containing compounds [55][56][57][58][59][60][61].…”