Isostructural Lanthanide Coordination Polymers with High Photoluminescent Quantum Yields by Effective Ligand Combination: Crystal Structures, Photophysical Characterizations, Biologically Relevant Molecular Sensing, and Anti-Counterfeiting Ink Application

Abstract

Characteristically strong photoluminescence with high quantum yield and long emission lifetime plays vital roles for the sensing performance of functional lanthanide complexes. To enhance the energy transfer efficiency through the ligand-field effect, three lanthanide-based coordination polymers formulated as {[Ln(H 2 O)(TPA)(ox)]•0.5H 2 O} n (Ln-CPs, Ln = Eu, Tb, and Gd) were solvothermally synthesized via employing 6-(1H-1,2,4-triazol-1-yl)pyridine-2-carboxylate (TPA) and oxalate (ox) as antenna and bridging ligands. These obtained Ln-CPs were structurally and photophysically characterized, and the sensing capacity and feasible application of two luminescent Ln-CPs were further investigated. The three Ln-CPs are crystallographically isostructural, exhibiting (4 4) layers assembled from centrosymmetric {Ln 2 (TPA) 2 } dimers and pairs of ditopic ox 2− linkages. Resulting from the conjugated TPA − chromophore and distorted Ln III coordination configuration, highly effective energy migration from the longer-lived triplet state of TPA − to Ln III is observed, endowing Eu-CP and Tb-CP to display bright red and green luminescence with an unexceptionable emission quantum yield up to 89% and 71%. Furthermore, the Tb-CP shows fast and effective responses toward the biomarkers of carcinoid cells with a strong Stern−Volmer quenching constant (K SV ) and low detection limit (LOD) of 8.95 × 10 3 M −1 and 0.72 μM for 5-hydroxy tryptamine as well as 1.18 × 10 4 M −1 and 0.95 μM for 5-hydroxy-3-indoleacetic acid. Instead, the red-emitting Eu-CP can differentiate quercetin effectively with K SV = 1.82 × 10 4 M −1 and LOD = 0.58 μM. Furthermore, luminescent ink with strong anti-counterfeiting ability and long-term stability is developed, representing the promising practice of Ln-CPs as functional materials.

Two luminescent film sensors constructed from new lanthanide coordination polymers for ratiometric detection of Zn2+ and NH3 in water and their white emission properties

“…The decay curves could be best fitted with a double exponential model to afford τ 1 = 0.423 ms and τ 2 = 1.121 ms for EuL , and τ 1 = 0.726 ms and τ 2 = 1.126 ms for TbL which are longer than or comparable to those previously reported. 31,32 In addition, the overall quantum yields of EuL and TbL were found to be 6.27% and 22.19% based on the absolute method.…”

A Water‐Stable Tb(III) Metal‐Organic Framework with Multiple Fluorescent Centers for Efficient Self‐Calibration Sensing Pesticides

“…Thus, the energy difference (ΔE) between E 1 ππ* and E 3 ππ* is 15499 cm −1 , indicative of effective intersystem crossing (ISC) process judging from the Reinhold's empirical rule (ΔE=E 1 ππ*−E 3 ππ*>5000 cm −1 ) [20] . Moreover, the energy gap within Tb(III) and T 1 of H 2 BDOA is 1153 cm −1 , which is less than 1700 cm −1 [21] . Part of the energy absorbed by the ligands is transferred to the lanthanide center.…”

“…[20] Moreover, the energy gap within Tb(III) and T 1 of H 2 BDOA is 1153 cm À 1 , which is less than 1700 cm À 1 . [21] Part of the energy absorbed by the ligands is transferred to the lanthanide center. The photogenerated electron moves via continuous intersystem crossing S 1 !T 1 and antenna T 1 !f transfer, and finally sensitizes f!f emissions of Tb(III) center (Figure 2).…”

NIR luminescent detection of quercetin based on an octanuclear Zn(ii)–Nd(iii) salen nanocluster

“…33)) of 1 to Que is obtained to be 2.5 mM, which is among the lowest ones reported for the uorescent detection of Que so far. [12][13][14][34][35][36][37] It is noticeable that, the shapes of NIR emission peaks of 1 are same before and aer the addition of Que (Fig. 4).…”