Relations between Structural and Luminescence Properties of Novel Lanthanide Nitrate Complexes with Bis-phosphoramidate Ligands

New lanthanum (III) complexes containing azaphosphor β-diketon and diimine ligands: Synthesis, crystallography, morphology properties, DNA binding, DNA cleavage, and DFT calculation

Two octa-coordinated lanthanum (III) complexes of deprotonated azaphosphor β-diketon and diimine ligands, [LnL3Q] (L = [Cl2CHC(O)NP(O)(NC6H12)2], Q = Phen (C1) and Bipy (C2)), were synthesized and characterized by elemental analysis, IR, and NMR spectra. X-ray crystallography revealed a distorted tetragonal antiprism LaO6N2 coordination geometry around the lanthanum atom in both compounds. Nano-sized complexes (Ć1 and Ć2) were synthesized via a sonochemical process and analyzed using SEM and XRPD. TGA-DTA analysis were performed on complexes in both bulk and nano scales. Redox behavior was also examined by cyclic voltammetry. The interaction between the complexes and calf thymus DNA (ct-DNA) was investigated using UV-Vis spectroscopy, fluorescence titration, viscosity measurements, and gel electrophoresis. C2 and Ć2 likely intercalate between DNA base pairs through van der Waals forces and hydrogen bonding, whereas C1 and Ć1 interact with DNA via groove binding. Further, result indicated the apparent association constant (Kapp) in the range of 4.53 × 104 M-1-26.86 × 104 M-1 with the highest value for nanocomplex Ć2. Fluorescence studies revealed dynamic and static quenching for C1, while the other compounds followed a static quenching process. Hirshfeld surface analysis and the NCI method were employed to demonstrate how non-covalent interactions influence the crystal packing through intermolecular interactions.

Luminescent lanthanide complexes based on 4,5-di(3,5-dicarboxylphenoxy)phthalic acid as enhanced fluorescence probes for highly selective detection of lead(II) ions in water

Six novel lanthanide complexes ([Nd2(L)(H2O)6]n·4.58n(H2O) (1), [Ln(H3L)(H2O)]n·0.5n(H2O), Ln = Sm (2), Eu (3), Gd (4), Tb (5), Eu0.18Gd0.62Tb0.20 (6)) have been hydrothermally synthesized based on the ligand 4,5-di(3,5-dicarboxylphenoxy)phthalic acid (H6L). Single crystal X-ray diffraction reveals that complexes 1-6 are 2D structures, where 2-6 are isomorphic. Complexes 3 and 5 exhibit the characteristic fluorescence of Eu(III) and Tb(III) ions respectively, while complex 4 shows blue-green light emission based on the ligand. In particular, the ternary Eu/Gd/Tb complex 6 shows white light emission with a CIE (Commission International del'Eclairage) chromaticity coordinate of (0.330, 0.339) and hence close to pure white light emission. Moreover, complexes 3 and 5 display specific fluorescence-enhanced detection performance for Pb2+ ions: The interaction between Pb2+ ions and the ligand enhances the charge transfer efficiency between the ligand and the Eu(III) and Tb(III) ions and thus leads to fluorescence enhancement of complexes 3 and 5. More importantly, complex 3 exhibits the lowest detection limit of 4.72 nM for Pb2+ ions among the existing complex fluorescent probes. In addition, both complexes 3 and 5 show good performance for recycling and for the detection of Pb2+ in real water samples.

Seven Ln(III) coordination polymers with two kinds of geometric coordination but the same 3D topological property: luminescence sensing and magnetic property

Two series of seven lanthanide metal coordination polymers (Ln-CPs) formulated as {[Ln(dttpa)_1.5(H₂O)₂]·H₂O}_n [Ln = La³⁺ (1), Ce³⁺ (2), Nd³⁺ (3), Sm³⁺ (4) and Eu³⁺ (5)] and {[Ln (dttpa)_1.5(H₂O)]·xH₂O}_n [Ln = Tb³⁺ (6) and Er³⁺ (7), x = 0.75] have been successfully constructed using Ln³⁺ ions and 2,5-di(1H-1,2,4-triazol-1-yl)terephthalic acid (H₂dttpa) via a hydrothermal method. Their 3D structures are fully characterised by Fourier transform infrared (FT-IR) spectroscopy, X-ray single-crystal analyses, powder diffraction analyses (PXRD), elemental analyses (EAs) and thermogravimetric analyses (TGAs). All Ln-CPs display the same topological property with the point symbol of {4²·8⁴}{4⁴·6²}₂{4⁹·6⁶}₂, and crystallize in the triclinic space group P1̄. Interestingly, Eu-CP (5) effectively sensitizes the visible emission of Tb³⁺ and shows high selectivity and stable response with the lowest detection limit of 9.88 nM. Furthermore, Tb-CP (6) acts as a good luminescence sensor to detect nitrobenzene (NB) with a detection limit of 12.5 nM. In addition, the magnetic susceptibility measurement for Er-CP (7) further shows that compounds constructed by dttpa^2- are a kind of promising functional material.

Synthesis, characterization, cytotoxicity studies, theoretical approach of adsorptive removal and molecular calculations of four new phosphoramide derivatives and related graphene oxide

In this study, four novel phosphoramide ligands (L1-L4) are synthesized and characterized by ³¹PNMR, ¹HNMR, MASS, and FT-IR spectroscopies. In vitro cell growth inhibition is studied by the MTT assay to evaluate the cytotoxicity of ligands against MCF-7 cell line; the result of the assay demonstrates that all ligands significantly suppress the proliferation of breast cancer cells in a concentration-dependent manner. The calculated IC₅₀ values are in the range of 3.6-10.77 µg ml^-1, of which the lowest value is attributed to L1. Then a facile approach was developed to functionalize graphene oxide (GO) surface by L1. The data which are obtained by XRD, FT-IR, and EDX analysis confirmed the deposition of phosphoramide on the surface of GO. The cell viability of GO-L1 compound at different concentrations is investigated in 24 h experiment. Excellent synergistic antitumor effects of GO and L1 lead to a decrease in IC₅₀ value up to 2.13 μg ml^-1. The Quantum calculations of compounds are used to study energies and HOMO and LUMO values, dipole moments (µ), global hardness (η), global softness (σ), and electrophilicity index (ω) using DMol³ module in Material studio2017. The docking calculations are performed to describe the mode of the binding to DNA and DNA polymerase IIα. Adsorption calculations of ligands (L1-L4) on GO sheet in the presence of water showed that L1 and L2 were located on GO via π electrons of anisole ring. While, L3 and L4 were located on GO by π - π interactions of aniline ring.

Photoluminescence of LaI3 switched on and off by association and dissociation of non-luminescent tetrahydrofuran

Although luminescent lanthanide-containing molecular complexes are well-known, it is not the case for La³⁺ with no 4f or 5d electrons, and the few luminescent complexes of La³⁺ contain luminescent ligands. Herein, we report an unexpected photoluminescence phenomenon of the LaI₃(THF)₄ complex that was easily prepared by immersing commercial anhydrous LaI₃ in THF. Strong blue emission was observed when LaI₃(THF)₄ was subjected to UV irradiation at 254 nm, which contrasts the non-luminescence character of either LaI₃ or THF. The absolute emission quantum yield was determined to be 50.5%. The observed luminescence of LaI₃(THF)₄ results from metal-to-ligand charge transition (MLCT) which differs from the known charge transition types for lanthanum complexes according to DFT/TDDFT calculations. The photoluminescence of LaI₃ can be switched on and off by reversible THF association and dissociation. THF concentrations as low as 0.1 vol% in n-hexane and 0.5 vol% in the gas phase can be detected, indicating the capability of anhydrous LaI₃ as a sensor for convenient and rapid THF detection.