Przemysław Starynowicz

Helical lanthanide(III) complexes with chiral nonaaza macrocycle.

The chiral nonaazamacrocyclic amine L, which is a reduction product of the 3 + 3 Schiff base macrocycle, wraps around the lanthanide(III) ions to form enantiopure helical complexes. These Ce(III), Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Er(III), Yb(III) and Lu(III) complexes have been isolated in enantiopure form and have been characterized by spectroscopic methods. X-ray crystal structures of the Ln(III) complexes with L show that the thermodynamic product of the complexation of the RRRRRR-isomer of the macrocycle is the (M)-helical complex in the case of Ce(III), Pr(III), Nd(III) and Eu(III). In contrast, the (P)-helical complex is the thermodynamic product in the case of Yb(III) and Lu(III). The NMR and CD spectra show that the (M)-helicity for the kinetic complexation product of the RRRRRR-isomer of the macrocycle is preferred for all investigated lanthanide(III) ions, while the preferred helicity of the thermodynamic product is (M) for the early lanthanide(III) ions and (P) for the late lanthanide(III) ions. In the case of the late lanthanide(III) ions, a slow inversion of helicity between the kinetic (M)-helical product and the thermodynamic (P)-helical product is observed in solution. For Er(III), Yb(III) and Lu(III) both forms have been isolated in pure form and characterized by NMR and CD. The analysis of 2D NMR spectra of the Lu(III) complex reveals the NOE correlations that prove that the helical structure is retained in solution. The NMR spectra also reveal large isotopic effect on the 1H NMR shifts of paramagnetic Ln(III) complexes, related to NH/ND exchange. Photophysical measurements show that L(RRRRRR) appears to favor an efficient 3pipi*-to-Ln energy transfer process taking place for Eu(III) and Tb(III), but these Eu(III)- and Tb(III)-containing complexes with L(RRRRRR) lead to small luminescent quantum yields due to an incomplete intersystem crossing (isc) transfer, a weak efficiency of the luminescence sensitization by the ligand, and/or efficient nonradiative deactivation processes. Circularly polarized luminescence on the MeOH solutions of Eu(III) and Tb(III) complexes confirms the presence of stable chiral emitting species and the observation of almost perfect mirror-image CPL spectra for these compounds with both enantiomeric forms of L.

Europium(II) complexes with unsubstituted crown ethers

Abstract Three Eu(II) complexes with crown ethers were obtained by electrochemical reduction. The complex with 12-crown-4 contains Eu bonded to four O crown atoms, three water molecules and a chloride anion, and shows luminescence at 429 nm at room temperature and at 410 nm at 77 K. The bis(15-crown-5)europium(II) cation has a sandwich structure with 10-coordinate metal ion. Its luminescence has the maximum at 433 nm at room temperature and at 417 nm at 77 K. The weakly luminescing (411.5 nm at 77 K) bisperchlorato(18-crown-6)europium(II) is also 10-coordinate; both perchlorate anions are bonded in a chelating bidentate fashion. The luminescence lifetimes and the excitation spectra are discussed.

Optical spectroscopy and structure of neodymium complexes with 2,6-pyridine-dicarboxylic acid in solution and single crystal at room and low temperatures

Abstract X-ray characterization of a compound reported as Na3[Nd(dpa)3]·15H2O by Albertsson was repeated and it was found to be a 14-hydrate. Absorption spectra of the crystal were measured along the a axis at room temperature and at 5 K. The results for the crystal were compared with those for Nd(III) aquoion and Nd(III)-dipicolinate solutions. Intensities of the f-f transitions were analyzed according to the Judd-Ofelt theory. The good correspondence between the values of oscillator strength of the hypersensitive transition for [Nd(dpa)3]3− complex in solution and in the crystal suggests an analogy between the coordination polyhedra; however, the crystal field splitting is different, best seen for the 4 I 9 2 → 2 P 1 2 transition. The contribution of polarization and electrostatic field mechanisms to the oscillator strengths is discussed.

Chiral macrocyclic Nd(III) and Tm(III) complexes

Abstract The two new chiral macrocyclic complexes obtained in a template condensation of R,R-1,2-diaminocyclohexane and 2,6-diformylpyridine, [NdL](NO3)3 and [TmL](NO3)3, have been synthesized and their X-ray crystal structures have been determined. The lanthanide(III) ions in both complexes are coordinated by a helically twisted hexadentate macrocycle and two bidentate nitrate anions. The [NdL](NO3)3 and [TmL](NO3)3 complexes have been studied also by 1H and 13C NMR spectroscopy. The signal assignment was based on COSY, NOESY and HMQC measurements. The spectra of the investigated compounds in methanol–chloroform solution confirm the D2-symmetrical helical conformation of the ligand.

Synthesis and crystal structure of europium(II) dihydrogen bis(sulfosalicylate) pentahydrate [Eu(C7H5O6S)2(H2O)5]∞

The crystals of the title compound are composed of a polymeric network composed of europium(II) cations, hydrogen sulfosalicylate (2-hydroxy-5-sulfonatobenzoate) anions and coordinated water molecules. The first coordination sphere of the metal cation is composed of two carboxylic oxygen atoms, two sulfonate ones and five water molecules. The simultaneous coordination of sulfosalicylate moiety through carboxylate and sulfonate groups results in a very long b axis.

Structure and spectroscopy of diaqua(μ3-acetato)(acetato-O)(acetic acid-O)europium(II), [Eu(OAc)2(AcOH)(H2O)2]

Abstract The crystal structure and absorption spectrum of the title compound are presented. The crystals are isomorphic with those of the analogous strontium compound. The spectrum shows a shift of the f-d transitions towards longer wavelengths as compared with EuII halogenide systems.

Synthesis and Crystal Structure of Europium(II) Tartrate Tetrahydrate, [Eu(C4H4O6)(H2O)2](H2O)2

Single crystals of [Eu(C4H4O6)(H2O)2](H2O)2 were obtained from the combination of solutions of EuCl2, previously obtained by electrolysis of an aqueous solution of EuCl3, and tartraric acid, neutralized by LiOH. The crystal structure (orthorhombic, P212121, Z = 4, a = 948.9(1), b = 954.6(1), c = 1098.4(1) pm; R(F) = 0.0242 and Rw(F2) = 0.0585 for I > 2σ(I); R(F) = 0.0256 and Rw(F2) = 0.0592 for all data) is isotypic with [Ca(C4H4O6)(H2O)2](H2O)2 and [Sr(C4H4O6)(H2O)2](H2O)2 exhibiting a three-dimensional structure. The divalent cations (Eu2+, Ca2+, Sr2+) are eight-coordinate by oxygen atoms that originate from carboxylate and hydroxyl groups of the tartraric dianion and two of the four water molecules.

Structure and optical spectroscopy of holmium(III) triethylenetetraaminehexaacetate in single crystal and in solution

The crystal structure of [C(NH2)3]3[Ho(ttha)]·3H2O (H6ttha=triethylenetetraaminehexaacetic acid) has been determined. The coordination environment of the HoIII ion is composed of five carboxylate oxygen atoms and four nitrogen atoms. Electronic absorption spectra of a [C(NH2)3]3[Ho(ttha)]·3H2O single crystal were measured at room and liquid helium temperatures and compared with those of the HoIII–ttha (1:1) complex in solution. The results suggest that a species of coordination geometry similar to that of the [Ho(N4O5)]3− type found in the crystal exists predominantly in solution at pH>5. At lower pH values, as for other LnIII–ttha complexes, coordination equilibria are observed.

Charge density distribution in aminomethylphosphonic acid.

The experimental charge density distribution in aminomethylphosphonic acid has been determined from X-ray diffraction and its topological features have been analyzed. The results have shown that the P-O bonds are highly polarized, moreover the P-OH bond is weaker than the bonds to unprotonated O atoms. These facts have been confirmed by theoretical density functional theory (DFT) calculations, which have shown that the single, strongly polarized bonds within the phosphonate group are modified by hyperconjugation effects.

Synthesis and structure of bis(triethanolamine)europium(II) diperchlorate

The crystal structure of the title compound was determined at 293 and 100 K. The structure contains bis(triethanolamine)europium(II) cations, and perchlorate anions. The metal ion coordination environment is composed of two N and six O atoms. At room temperature, all triethanolamine molecules are partially disordered. On going to 100 K, the disorder partially disappears, giving rise to a commensurate modulation of the structure.