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

Abstract

Two series of trivalent lanthanide and group 3 metal coordination polymers with 4′‐phenyl‐2,2′:6′,2′′‐terpyridine (ptpy) of the composition 1∞[MCl3(ptpy)] (1, M = La, Ce, Pr, Nd) and the complexes [MCl3(ptpy)(py)] (2, M = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y) have been synthesized and characterized. For europium, the complex [Eu2Cl6(ptpy)2] (3) was obtained as single crystals, its dimeric structure providing potential insight into the coordination polymer formation from monomeric entities. Product series 1 and 2 were photophysically investigated in the solid state at room temperature and 77 K. Alongside with standard ion‐specific 4f–4f trivalent lanthanide luminescence in the visible and NIR (of emitters such as europium, terbium, dysprosium, neodymium, etc.), visible range emission of praseodymium, holmium, erbium, and thulium was observed, which is rarely reported for coordination compounds. It occurs in addition to their characteristic NIR emission. For complexes of series 1, an exciplex based luminescence was observed originating from ligand π‐stacking in the crystal packing.

Similarities of Coordination Polymer and Dimeric Complex of Europium(III) with Joint and Separate Terpyridine and Benzoate

“…We have obtained the dimeric complex [Eu 2 Cl 4 (bc) 2 (ptpy) 2 ] ( 1 ), which has two separate ligands with different coordination sites: 4'‐phenyl‐2,2':6',2''‐terpyridine (ptpy) and benzoate (bc – ), in two synthetic pathways (Scheme 1). Starting from the complex [EuCl 3 (ptpy)(py)], [ 15 ] in which terpyridine is already coordinated to the metal center, we substituted one chloride anion with benzoate under solvothermal conditions – resulting in formation of single crystals of [Eu 2 Cl 4 (bc) 2 (ptpy) 2 ] ( 1 ) (see Scheme 1, route I). In addition, 1 was also obtained directly from trivalent europium chloride hexahydrate in a reaction with ptpy and Hbc in good yield (67 %, Scheme 1, route II).…”

“…[ 5–8,13 ] The emission lifetime is mainly based on the transitions of Eu 3+ in 1 being 1.493(1) ms (λ ex = 360 nm, λ em = 624 nm), and is typical for trivalent europium [ 34–37 ] and coordination compounds with terpyridine and its derivatives. [ 5,6,8,13,15,38 ] Upon cooling to 77 K the emission lifetime of 1 rises to 1.649(1) ms, as the thermal quenching of the luminescence decreases. Mono‐exponential decay character of the emission decay at both RT and 77 K indicates that two central europium atoms in 1 are spectroscopically equivalent.…”

“…[ 1–4 ] Since then, a number of publications presented coordination compounds of Eu 3+ with terpyridine itself or its derivatives. [ 5–18 ] In these compounds, trivalent europium as 4f‐4f emitter is influenced by the chemical environment rather in the intensity of 4f‐4f transitions than in nature of the transitions. [ 19–21 ] In addition, terpyridine and its derivatives are good sensitizers of trivalent Eu 3+ photoluminescence properties.…”

“…The resulting materials show good absorption of high energy photons and emission in the red region of the visible spectrum with overall quantum yields reaching higher than 50 %. [ 5–8,13,15 ]…”

Synthesis of Samarium OxysulfateSm2O2SO4 in the High-Temperature Oxidation Reaction and Its Structural, Thermal and Luminescent Properties

“…As it is known from the reported results, the initial material granules, under certain conditions, are able to maintain the original shape and size in the thermal decomposition process [28][29][30]. At the same time, the compounds with the stoichiometric lanthanide ion content attract attention in order to find efficient luminescent materials with low concentration quenching and to investigate specific mechanisms of luminescence quenching in them [31][32][33][34][35][36][37][38][39][40]. At the same time, the consideration of lanthanide-containing materials cannot be restricted only by their luminescent properties.…”