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Two novel calix[4]arene macrocyclic ligands functionalized with four 1,3-diketone groups at the upper and hydroxyl ( 3 ) or propyloxy-groups ( 6 ) at the lower rims were synthesized and characterized using NMR, IR spectroscopy, mass spectrometry, and elemental analysis. UV–vis spectrophotometry and ESI mass spectrometry studies indicate 1:1 complex formation of ligands 3 and 6 with Ln(III) (Ln=Tb, Yb) in alkaline DMF solutions resulted from coordination of Ln(III) with 1,3-diketonate groups. Luminescence study of Ln(III) complexes with 3 and 6 reveals significant difference in antenna effects of their deprotonated forms on both Tb(III)- and Yb(III)-centered luminescence. Comparison of ligand-centered emission for ligands 3 and 6 points to the latter as more efficient antenna for Tb(III) and Yb(III). Different conformational behavior of ligands 3 and 6 in alkaline media is assumed as a reason for the experimentally observed difference in sensitization pathways in Ln(III) complexes with 3 and 6 . [ABSTRACT FROM AUTHOR]

• In situ Dimethylammonium by mild solvothermal. • In situ solvents generation can be tuned for preferred topologies. • Single crystal XRD and DFT computation. • Larger values of HOMO-LUMO energy gap is responsible for less reactive of complex. A new ytterbium(III) complex, (DMAH 2) 3 [Yb(Pydc) 3 ].4H 2 O (1) {Pydc = Pyridine-2,6-dicarboxylate anion, DMAH 2 = Dimethylammonium} has been prepared under mild solvothermal conditions and characterized by elemental analysis, IR spectroscopy, thermal analysis and single crystal X-ray diffraction. The DMAH 2 molecules in 1 , generated in situ from hydrolysis of N,N -dimethylformamide are responsible to assemble 2D coordination polymer through N-H···O and O-H···O hydrogen bonding. Magnetic susceptibility measurements indicate that the complex (1) obeys the Curie Weiss law and the overall magnetic behavior is typical for the presence of weak antiferromagnetic exchange coupling interactions. Theoretical data for geometrical parameters of complex 1 agree well with the experimental data. Large HOMO-LUMO energy gap of 4.33 eV has provided kinetic stability to the complex 1. NBO analysis reflects that intramolecular charge transfer occurred between ligand and metal orbitals with the highest stabilization energy of 1024.04 kcal/mol. The negative electrostatic potential at the nitrogen and dianionic pyridine-2,6-dicarboxylate regions confirms that these are dynamic locations for Yb(III) binding. : [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The new styryl substituted pyrazinoporphyrazine complex has been synthesised for the first time. The spectral properties of the ytterbium complex have been studied. The introduction of the styryl fragments in the cycle leads to bathochromatic shift of the Q-band. It can be explained by the stabilisation of LUMO. [Copyright &y& Elsevier]

Abstract: The axially substituted monophthalocyanine complexes of lanthanides are not enough investigated in comparison with sandwich-type phthalocyanine complexes of lanthanides because of their much lower stability in comparison with sandwich-type complexes. In this work, the new methods of obtaining monolithic silica blocks doped with acetato substituted Yb(III) monophthalocyanine complex are reported. The spectroscopic properties of this complex were measured and the results were compared for solution, solid state and xerogels dotted with PcYb(OAc). Besides of the usually observed emission of the phthalocyanines, the emission of the Yb3+ ion in IR region after excitation in phthalocyanine band (674nm) for Yb(III) complex incorporated in silica gel was observed first time. Thus, this result confirms energy transfer in the system under study. The mechanism of energy transfer was proposed. It is worth to notice, that Yb(III) emission was not observed for complex in solution and at solid state. The IR and Raman spectra of ytterbium ion in phthalocyanine complexes are reported and discussed. [ABSTRACT FROM AUTHOR]

Abstract: The ytterbium(III) extraction kinetics by 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP) in the presence of isooctanol have been investigated using constant interfacial cell with laminar flow. The stoichiometry of the complex formation reaction between the ytterbium(III) and HEHEHP in the presence of isooctanol had been evaluated. The extraction kinetics data had been analyzed in terms of pseudo-first order constants. From the temperature dependence of rate measurement, the values of Ea, ΔH and ΔS were calculated and it was found that the extraction process was a diffusion-controlled kinetics process with an interfacial reaction. The rate-determining step was made by predictions derived from interfacial reaction models, and through the approximate solutions of the flux equation, diffusion parameters and thickness of the diffusion film have been calculated. [Copyright &y& Elsevier]

Abstract: The coordination chemistry of bisphosphonates with Yb3+ was investigated to evaluate the potential of the UV–vis based detection method using the Yb3+–pyrocatechol complexation reaction as a sensor for bisphosphonates. The complexation chemistry of Yb3+ with phosphate and ATP analogs was previously described (E. Gaidamauskas, K. Saejueng, A.A. Holder, S. Bharuah, B.A. Kashemirov, D.C. Crans, C.E. McKenna, J. Biol. Inorg. Chem. 13 (2008) 1291–1299), and we here studied the complexation chemistry of bisphosphonates in this system. The spectrophotometric assay yields direct evidence for formation of a 4:3 metal to ligand complex at neutral pH. Direct evidence for Yb3+:methylenebis(phosphonate) complexes with 1:1 and 1:2 stoichiometry was also obtained by potentiometry at acidic and basic pH. Direct evidence for complex formation was obtained using 1H NMR spectroscopy although the stoichiometry was not accessed at neutral pH. Our results suggest that the spectroscopic observation of the YbPV complex can be used to conveniently measure concentrations of bisphosphonates down to 2–3μM. [Copyright &y& Elsevier]

Abstract: A selective and fast method has been developed for the determination of phosphates by measuring the formation of ytterbium(III) phosphate through the variation of the light scattering intensity with time. The low solubility of this compound causes an efficient dispersion of the radiation at 490nm, which is measured at 980nm using the second-order grating effect. This approach minimizes potential background signals from the sample matrix. The initial rate of the system is automatically obtained in only 0.5s by stopped-flow mixing technique. The variable optimization study has been carried out using univariate and multivariate methods. The dynamic range of the calibration graph is 0.09–7.9mmolL−1 (Pearson''s correlation coefficient=0.9999) and the detection limit is 0.03mmolL−1. The precision of the method, expressed as relative standard deviation, is 2.3%. The study of the potential interference of different inorganic anions showed that arsenate is the main interferent, although it is tolerated in a molar ratio of 5.5. The method has been satisfactorily applied to the determination of soluble phosphates in tap, ground and river water using a previous preconcentration step with a Dowex 1 (1×4–400) anionic resin. A 500-fold concentration has been achieved, which has allowed to decrease the detection limit up to 60mmolL−1. The recovery range is 97.5–102.5%. The results obtained are consistent with those obtained with the standard molybdenum blue method. [Copyright &y& Elsevier]

Abstract: The transamination of anionic homoleptic amido ytterbium complex, LiYb[N(i-Pr)2]4 with aryloxo-functionalized N-heterocyclic carbene (NHC) precursor, HO-4,6-di- t Bu-C6H2-2-CH2{CH[i-Pr-NCHCHN]}Cl (H2LCl) 1 and HO-4,6-di- t Bu-C6H2-2-CH2{CH[Me-NCHCHN]}Cl (H2L′Cl) 2, and BuLi in 1:2:1 molar ratio in THF at 0°C afforded the first bisaryloxo- NHC monoamido ytterbium complexes, L2Yb [N(i-Pr)2] 3 and , respectively. The same reactions in the molar ratio of 1:1 without BuLi yields also the complex 3 and 4, not the bis-amido mono aryloxo-NHC complex {LYb[N(i-Pr)2]2} and {L′Yb[N(i-Pr)2]2}. The in situ low-temperature reaction of 2 with two equivalents of BuLi, followed by addition of one equivalent of YbCl3 in THF does not afford the expected LYbCl2, instead, [Li(DME)3][YbCl4(DME)] 5 and a dimeric imidazole-aryloxo lithium {[O-4,6-di- t Bu-C6H2-2-CH2{CH(MeNCHCHNH)}]Li(THF)}2 6 which results from the 1,2-benzyl migration in N-heterocyclic carbene, are obtained. Complexes 3, 4, 5 and 6 have been characterized by elemental analysis and X-ray crystallography, and by NMR spectroscopy for 6. [Copyright &y& Elsevier]

Abstract: Studies have been made on the kinetics of ytterbium(III) with bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272, HA) in n-heptane using a constant interfacial cell with laminar flow. The stiochiometry and the equilibrium constant of the extracted complex formation reaction between Yb3+ and Cyanex 272 are determined. The extraction rate is dependent of the stirring rate. This fact together with the E a value suggests that the mass transfer process is a mixed chemical reaction–diffusion controlled at lower temperature, whereas it is entirely diffusion controlled at higher temperature. The rate equations for the ytterbium extraction with Cyanex 272 have been obtained. The rate-determining step is also made by predictions derived from interfacial reaction models, and through the approximate solutions of the flux equation, diffusion parameters and thickness of the diffusion film have been calculated. [Copyright &y& Elsevier]