Crystal structure of tetra-phenyl phosphate tetra-kis-[dimethyl (2,2,2-tri-chloro-acet-yl)phos-pho-ramidato]lutetium(III), PPh4[LuL4].

A lutetium(III) complex based on the anion of the ligand dimethyl (2,2,2-tri-chloro-acet-yl)phospho-ramidate (HL) and tetra-phenylphosphonium, of composition PPh4[LuL 4] (L = CAPh = carbacyl-amido-phosphate), or (C24H20)[Lu(C4H6Cl3NO4P)4], has been synthesized and structurally characterized. The X-ray diffraction study of the compound revealed that the lutetium ion is surrounded by four bis-chelating CAPh ligands, forming the complex anion [LuL 4]- with a coordination number of 8[O] for LuIII, while PPh4 + serves as a counter-ion. The coordination geometry around the Lu3+ ion was determined to be a nearly perfect triangular dodeca-hedron. The complex crystallizes in the monoclinic crystal system, space group P21/c, with four mol-ecules in the unit cell. Weak hydrogen bonds O⋯HC(Ph), Cl⋯HC(Ph) and N⋯HC(Ph) are formed between the cations and anions. For a comparative study, HL-based structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed. A Hirshfeld surface analysis was also performed.

A Novel Bisquaternary Ammonium Compound as an Anion Sensor-ESI-MS and Fluorescence Study.

Electrospray ionization mass spectrometry (ESI-MS) analysis is frequently associated with noncovalent adduct formation, both in positive and negative modes. Anion binding and sensing by mass spectrometry, notably more challenging compared to cation binding, will have major research potential with the development of appropriate sensors. Here, we demonstrated identification of stable bisquaternary dication adducts with trifluoroacetate (TFA-), Cl- and HSO4- in positive-mode ESI-MS analysis. The observed adducts were stable in MS/MS mode, leading to the formation of characteristic fragment ions containing a covalently bound anion, which requires bond reorganization. This phenomenon was confirmed by computational methods. Furthermore, given that anion detection and anion sensor chemistry have gained significant prominence in chemistry, we conducted an analysis of the fluorescent properties of bisquaternary ammonium compound as a potential anion sensor.

Eu3+ and Tb3+ coordination compounds with phenyl-containing carbacylamidophosphates: comparison with selected Ln3+ ß-diketonates.

Materials based on Eu3+ and Tb3+ coordination compounds are of great interest due to their strong red and green luminescence. Appropriate selection of ligands plays a huge role in optimizing their photophysical properties. Another very helpful instrument for such optimization is theoretical modelling, which permits the prediction of the emissive properties of materials through intramolecular energy transfer analysis. The ligands that allow for achieving high efficiency of Eu3+ and Tb3+ emissions include carbacylamidophosphates (CAPh, HL). In this brief review, we summarize recent research for lanthanides CAPh-based coordination compounds of general formulas Cat[LnL]4, [LnL3Q] and [Ln(HL)3(NO3)3], where Cat+ = Cs+, NEt4+, PPh4 + and Q = 1,10-phenanthroline, 2,2-bipyridine or triphenylphosphine oxide, involving the use of thermal gravimetric analysis, X-ray analysis, and absorption and luminescence spectroscopy. We carried out a comparison with selected Ln3+ ß-diketonates. Possibilities and developments of theoretical calculations on energy transfer rates are also presented.

New Luminescent Lanthanide Tetrakis-Complexes NEt4 [LnL4 ] Based on Dimethyl-N-Benzoylamidophosphate.

New lanthanide dimethyl-N-benzoylamidophosphate (HL) based tetrakis-complexes NEt4 [LnL4 ] (Ln3+ =La, Nd, Sm, Eu, Gd, Tb, Dy) are reported. The complexes are characterized by means of NMR, IR, absorption, and luminescent spectroscopy as well as by elemental, X-Ray, and thermal gravimetric analyses. The phenyl groups of the four ligands of the complex anion are directed towards one side, while the methoxy groups are directed in the opposite side, which makes the complexes under consideration structurally similar to calixarenes. The effect of changing the alkali metal counterion to the organic cation NEt4+ on the structure and properties of the tetrakis-complex [LnL4]- is analyzed. The complexes exhibit bright characteristic for respective lanthanides luminescence. Rather high intensity of the band of 5 D0 →7 F4 transition, observed in the luminescence spectrum of NEt4 [EuL4 ], is discussed based on theoretical calculations.

Spectroscopic aspects for the Yb3+ coordination compound with a large energy gap between the ligand and Yb3+ excited states.

We present the experimental and theoretical results that made it possible to propose the energy transfer mechanism for a Yb complex with a large energy gap between the ligand and Yb excited states using a theoretical model and experimental data. Absorption and emission spectroscopy in the 300-4 K range is used for the study of the Yb3+ compound with N-phosphorylated sulfonamide (Na[YbL4]), which, despite the large energy gap, is characterized by high emission sensitization efficiency (ηsens = 40%) and relatively long Yb3+ emission lifetime (27 µs). The crystal structure of Na[YbL4], radiative lifetime (930 µs), refractive index (1.46), intrinsic (3.0%), and overall (1.3%) emission quantum yield were determined. To obtain the electronic properties of the Na[YbL4], a time-dependent density functional theory (TD-DFT) was performed. The intramolecular energy transfer (IET) rates from the excited states S1 and T1 to the Yb3+ ion as well as between the ligand and the ligand-to-metal charge transfer (LMCT) states were calculated. Once the intersystem crossing S1 â†’ T1 is not so effective due to a large energy gap between S1 and T1 (≈10000 cm-1), it has been shown that the LMCT state acts as an additional channel to feed the T1 state. Then, the T1 can transfer energy to the Yb3+ 2F5/2 energy level (WT), where WT is dominated by the exchange mechanism. Based on IET and a rate equation model, the overall emission quantum yield QLLn was simulated with and without the LMCT, this also confirmed that the pathway S1 â†’ LMCT â†’ T1 â†’ Yb3+ is more likely than the S1 â†’ T1 â†’ Yb3+ one.

Structures and Spectral and Magnetic Properties of a Series of Carbacylamidophosphate Pentanuclear Lanthanide(III) Hydroxo Complexes.

A series of pentanuclear lanthanide complexes Ln5L6(µ-L)4(µ3-OH)4(µ4-OH) (LnIII = Nd, Dy, Ho, Er, Yb; L- = dimethyl N-benzoylamidophosphate ion, [C6H5C(O)-N-P(O)(OCH3)2]-) was obtained by the reaction of sodium dimethyl N-benzoylamidophosphate with the corresponding lanthanide nitrates. The pentanuclear cores formed as a result of self-arrangement and their composition did not depend on the lanthanide ion. The complexes and sodium dimethyl N-benzoylamidophosphate have been characterized by single-crystal X-ray diffraction. The absorption spectra of the complexes were measured at 300 and 4 K. The dysprosium and ytterbium complexes exhibited weak emission in the visible and IR regions, respectively. Temperature dependences of magnetic susceptibility (χM) of the dysprosium, holmium, and erbium compounds were studied. It was found that χM vs T dependences were governed by the crystal field splitting effects with the Δ parameter being in the range 5-17 cm-1. Slow magnetic relaxation was found for the dysprosium complex by ac magnetic measurements, while no significant out-of-phase signals were detected for holmium and erbium complexes.

Contribution of Energy Transfer from the Singlet State to the Sensitization of Eu3+ and Tb3+ Luminescence by Sulfonylamidophosphates.

A series of stable lanthanide complexes Na[Ln(L)4 ] (Ln=La3+ , Eu3+ , Gd3+ , Tb3+ , with L=dimethyl(4-methylphenylsulfonyl)amidophosphate and dimethyl-2-naphthylsulfonylamidophosphate) were synthesized. The compounds were characterized by single-crystal X-ray diffraction, IR, absorption, and emission spectroscopy at 293 and 77 K. In contrast to the usual and well-known dominant role of the ligand triplet state in intramolecular energy transfer processes in Ln complexes, in this particular new class of Ln compounds with sulphonylamidophosphate ligands, strong experimental and detailed theoretical evidence suggest a dominant role is played by the ligand first excited singlet state. The importance of the role played by the 7 F5 level in the case of the Tb3+ compound in this process is shown. The theoretical approach for the energy transfer rates was successfully applied to the rationalization of the experimental data. The higher-lying excited levels of Eu (5 DJ , 5 LJ , 5 GJ ) and Tb (5 DJ , 5 GJ , 5 LJ , 5 HJ , 5 FJ , 5 IJ ) were included in the calculations for the first time. Both the multipolar and exchange mechanisms were taken into account. The experimental intensity parameters (Ωλ ), emission lifetimes (τ), radiative (Arad ) and non-radiative (Anrad ) decay rates, and quantum yields (theoretical and experimental) were determined and are discussed in detail.

Lanthanide mixed-ligand complexes of the [Ln(CAPh)3(Phen)] and [LaxEu1-x(CAPh)3(Phen)] (CAPh = carbacylamidophosphate) type. A comparative study of their spectral properties.

A series of complexes Ln(Pip)3(Phen) (Ln(iii) = La, Ce-Nd, Sm-Lu, Y; HPip (CAPh type ligand) = 2,2,2-trichloro-N-(dipiperidin-1-yl-phosphoryl)acetamide, Phen = 1,10-phenanthroline) has been synthesized. The lanthanum(iii) doped europium(iii) complexes ([LaxEu1-x(Pip)3(Phen)], x = 0.99, 0.95, 0.50) have been obtained by the co-crystallization method. The complexes have been characterized by means of X-ray diffraction, IR, (1)H and (31)P-NMR and absorption spectroscopy. Emission and excitation luminescence spectra were recorded at 295 and 77 K. The lifetime values (τ) for the emission of all europium complexes were determined. The (5)D0 luminescence quantum efficiency is 73-89%. The symmetries of the nearest europium surrounding in pure and doped complexes were evaluated from the Stark splitting of (5)D0-(7)FJ transitions. Crystal structures of [Ln(Pip)3(Phen)] (Ln = Nd (1), Eu (2) and Tb (3)) have been determined. Lattice parameters of the [Ln(Pip)3(Phen)] (Ln = Tb, Yb) and the doped [LaxEu1-x(Pip)3(Phen)] (x = 0.99, 0.95, 0.50) complexes have been measured. The presence of four polymorphs within a number of rare earth elements has been estimated: two in triclinic (Ln1 = La, Nd; Ln2 = Eu), one in the monoclinic (Ln3 = Tb) and one in the rhombic (Ln4 = Tb, Yb) symmetry. Complex 3 can be obtained in two crystal modifications: monoclinic and orthorhombic ones.

Experimental and theoretical study of the photophysics and structures of europium cryptates incorporating 3,3'-bi-isoquinoline-2,2'-dioxide.

A detailed photophysical study of [Eu within (biqO2.2.2)(CF3SO3)](CF3SO3)2. CH3CN.H2O (Eu within 1) and two other types of cryptates incorporating three 3,3'-biisoquinoline-2,2'-dioxide units has been performed. Structural crystallographic data of Eu within 1, electronic structure calculations and theoretical models were used to obtain the intramolecular energy transfer rates and the appropriate set of rate equations, which was solved numerically. Quantum yields and decay lifetimes were obtained from these results and compared to the experimental data. The role of the ligand-to-metal charge transfer (LMCT) states was ascertained. A theoretical ligand field and intensity analysis was carried out and the results agree very well with the emission spectra. The molecular structures of the lanthanide cryptates were successfully modelled by the YIII ion using the restricted Hartree-Fock (RHF) method, with the advantage of dealing with closed-shell systems. These molecular structures were used to explain the drastic differences in the photophysics of the three EuIII cryptates.