Ilona Turowska-Tyrk

Spectroscopic and magnetic studies of mixed lanthanide complexes: LnL3α,α′Dipy in solution and in solid

Abstract New monomeric complexes LnL3bip(1/2bip) were synthesized (Ln=Eu3+, Tb3+); L-phosphoro-azo derivative of β-diketone: CCl3C(O)NP(O)(OCH3)2 and bip-α,α′dipyridyl and single crystals were grown. X-Ray diffraction studies were done. The complexes crystallize in the triclinic system, space group P 1 . Magnetic susceptibility and magnetization of the crystals were investigated. High resolution absorption, luminescence and excitation spectra were measured for crystals at 293, 77 and 4 K in order to characterize their physical properties. Radiative and nonradiative processes were analyzed. The role of the ligand singlet and triplet states in energy-transfer as well as the charge-transfer states in emission quenching were studied.

Simple preparation of enantiomeric Michael adducts of thiophenol to chalcones: easily available new chiral building blocks

Abstract A facile and enantioselective method for the multigram preparation of the title compounds is described. The Michael addition of thiophenols to chalcones catalyzed by (+)-cinchonine, followed by crystallization, led to the corresponding adducts 2 in up to >95% e.e. The stereoselective Beckmann rearrangement of the oxime of (+)-1,3-diphenyl-3-phenylsulfanylpropan-1-one 2a gives the anilide of (R)-(+)-3-phenyl-3-phenylsulfanylpropanoic acid (as determined by X-ray analysis) and alcoholysis leads to the corresponding enantiomerically pure ethyl ester.

Synthesis of porphyrins tailored with eight facially-encumbering groups. An approach to solid-state light-harvesting complexes

Abstract Synthetic models of the photosynthetic antenna complexes must achieve long-range 3-dimensional order encompassing a large number of porphyrinic pigments with limited direct contact of the pigments. In order to develop solid-state antenna complexes, we have synthesized porphyrins bearing benzyloxy groups projecting over both faces and optionally also around the periphery of the porphyrin. Routes have been established for prefunctionalizing benzaldehydes with various benzyloxy groups. Reaction of 2,6-bis, 3,5-bis, or 2,4,6-tris-(benzyloxy)benzaldehydes with pyrrole via the room temperature two-step one-flask porphyrin reaction provides direct access to the facially-encumbered porphyrins. The benzyloxybenzaldehydes react as efficiently as methoxybenzaldehydes, indicating the utility of the -OCH2- unit for introducing large substituents near the face of the porphyrin. The octakis and dodecakis(benzyloxy)porphyrins exhibit characteristic porphyrin absorption and fluorescence properties in solution. The crystal structure of meso-tetrakis[2,6-bis(2,3,4,5,6-pentafluorobenzyloxy)phenyl]porphyrin has been determined. The pentafluorobenzyloxy substituents provide a cavity on each side of the porphyrin plane which has an approximate cylindrical shape with a diameter of ~ 7.5 A and a height of ≥ 4.5 A. The porphyrin core parameters are those obtained for free base derivatives in which the inner hydrogen atoms are ordered. Crystal data: a = 14.759 (1) A, b = 25.519 (2) A, c = 13.100 (1) A, α = 100.04 (1), β = 99.83 (1), γ = 88.25 (1), V = 4767.3 (6) A3, all measurements at 127 K, triclinic, space group P 1 , Z = 2 R1(F) = 0.097, for 10020 “observed” data, and wR2(F2) = 0.275 for 17761 total unique (all) data.

Spectra and details of the structure of europium aliphatic carboxylates with 1,10-phenanthroline derivatives

Abstract Luminescence, excitation of luminescence, IR and Raman spectra of a variety of carboxylates Eu(RCOO) 3 .Phen (Phen–1,10-phenanthroline) consisting of acetate, propionate, lactate, capronate compounds, and Eu(CH 3 COO) 3 .Ph (Ph–six 1,10-phenanthroline derivatives) were examined. Crystal field parameters for model compounds were calculated. The crystal structure of the europium acetate Eu(CH 3 COO) 3 .Phen was solved by X-ray method. Dependence of the spectroscopic characteristics on variation of both types of ligands, indicating details of the structure of compounds, was examined. Reciprocal influence of inequivalent ligands in europium carboxylates was analysed. It was demonstrated that steric factors are as significant as the donor–acceptor properties of the ligands in creation of the structure of compounds under investigation.

Monitoring structural transformations in crystals. 6. The [4 + 4] photodimerization of 9-methyl­anthracene

The structural changes in a crystal of 9-methylanthracene (1) during the [4 + 4] photodimerization were monitored by means of X-ray diffraction. This is the first example in the literature of such a study of a [4 + 4] photodimerization. The results obtained were compared with data for the [2 + 2] photodimerization. The shape of the product molecules and their preferred packing can explain the crystal disintegration. This was the reason that the reaction was monitored only to 28% completion. As far as could be determined the reaction proceeds with a constant rate. The cell volume increases at the beginning of the transformation and decreases afterwards. The product molecules do not assume a fixed position in the crystal during the photo-reaction, but move in a smooth way that includes a rotational component. The movements of the reactant are much smaller. Movements of molecules characterized by a rotational component were also observed in the case of the [2 + 2] photodimerization of 5-benzylidene-2-benzylcyclopentanone and 5-benzylidene-2-(4-chlorobenzyl)-cyclopentanone. The distance between the reacting atoms of the adjacent monomer molecules of (1) decreases with the degree of reaction completion, but more slowly than in the case of the [2 + 2] photodimerizations cited above. The orientation of the neighbouring monomer molecules changes during the phototransformation so that the monomer pair resembles the dimer product.

Structural Transformations in a Crystal during the Photochemical Reaction of 2‐Benzyl‐5‐benzylidenecyclopentanone

The studies presented are the first example in which the substrate and product molecules were monitored separately over many stages during the chemical reaction progress in a crystal to understand the reaction path of the molecules in detail during the whole transformation. The BBCP, 2-benzyl-5-benzylidenecyclopentanone, single crystal was irradiated without any destruction over several steps. After each of step the X-ray structure with a different substrate/product ratio and with a disorder was determined. The study revealed that the photochemical [2+2]-cycloaddition reaction of BBCP in a crystal does not exhibit cooperative character and can be regarded as of the first-order. During the transformation the product molecules do not adopt the position of the molecules in the final pure dimer crystal, but move gradually and smoothly in this direction. The movement of the molecules was also observed for the substrate. This remarkable behaviour of the product and reactant molecules bears a rotational component. The distance between reaction centres of adjacent BBCP substrate molecules decreases fluently with the progress of the reaction, but it does not get smaller than a sum of van der Waals radii.

Monitoring structural transformations in crystals. 8. Monitoring molecules and a reaction center during a solid-state Yang photocyclization

Structural changes taking place in a crystal during an intramolecular photochemical reaction [the Yang photocyclization of the alpha-methylbenzylamine salt with 1-(4-carboxybenzoyl)-1-methyladamantane] were monitored step-by-step using X-ray structure analysis. This is the first example of such a study carried out for an intramolecular photochemical reaction. During the photoreaction, both the reactant and product molecules change their orientation, but the reactant changes more rapidly after the reaction is about 80% complete. The distance between directly reacting atoms in the reactant molecule is almost constant until about 80% reaction progress and afterwards decreases. The torsion angle defined by the reactant atoms that form the cyclobutane ring also changes in the final stages of the photoreaction. These phenomena are explained in terms of the influence of many product molecules upon a small number of reacting molecules. The adamantane portion shifts more than the remaining part of the anionic reactant species during the reaction, which is explained in terms of hydrogen bonding. The structural changes are accompanied by changes in the cell constants. The results obtained in the present study are compared with analogous results published for intermolecular reactions.

Monitoring structural transformations in crystals. 5. A topotactic [2 + 2]-photodimerization reaction

The structural changes in a crystal of 5-benzylidene-2-(4-chlorobenzyl)cyclopentanone during [2 + 2]-photodimerization were monitored by means of X-ray diffraction. It was observed that the monomers moved gradually from the position occupied in the crystal at the initial stage of the photoreaction and the dimers moved towards the position assumed at the final step. The movements of the molecules possess a rotational component. Moreover, with the progress of the phototransformation the monomers in the reacting pair gradually move closer and change their relative orientation to resemble more the product molecule. The behaviour of the molecules and also the variation of the cell constants for the studied compound were compared with data for 5-benzylidene-2-benzylcyclopentanone.

Crystallographic studies of intra- and intermolecular interactions. Part 4. A comparative study of the effect of through-resonance on the geometry of p-nitro- and p-nitrosophenolate anions

The VB- and the HOSE-model calculations carried out on the basis of an experimental geometry of p-nitro- and p-nitrosophenolate anions revealed that the NO2 group is a much weakerπ-electron acceptor than the NO group. The STO-3G ab initio calculation with optimization of the geometry supported this view. Electrochemical study in an aprotic solvent (DMF) yielded estimates of electron affinity for nitro- and nitrosobenzene and indicated a much lower value for the latter, supporting stronger electron accepting properties of the NO group in p-X-Ph-NO systems with X-electron donating substitutents. п-electron distribution in p-nitrosophenolate anions depends strongly on H-bonding interactions in a crystal lattice as deduced directly from the HOSE-model and the VB calculations for the experimental geometry.

Monitoring structural transformations in crystals. Part 4. Monitoring structural changes in crystals of pyridine analogs of chalcone during [2 + 2]-photodimerization and possibilities of the reaction in hydroxy derivatives

Abstract We studied the [2+2]-photodimerization in crystals of pyridine analogs and hydroxy derivatives of chalcone using the X-ray structure analysis. The mutual orientation of adjacent molecules in the crystals was analyzed in a quantitative way and the results were compared with data for known photoactive crystals undergoing the [2+2]-photodimerization. In the case of one pyridine analog, we processed the single-crystal-to-single-crystal photodimerization and determined the structure for the mixed crystal containing both the substrate and the product. We also explained a role of hydrogen bonds in the [2+2]-photodimerization in the case of the hydroxy derivatives of chalcone. C5H4N–CO–CHCH–C6H5: a=6.0885(7) A , b=13.1022(14) A , c=13.7197(17) A , β=91.318(10)°, monoclinic, P2 1 /n, Z=4 . The irradiated crystal of the above analog: a=6.1502(7) A , b=12.9740(13) A , c=13.7964(15) A , β=91.870(10)°, monoclinic, P2 1 /n, Z=4 . C6H5–CO–CHCH–C5H4N: a=23.907(6) A , b=4.6709(10) A , c=21.199(6) A , β=110.01(3)°, monoclinic, C2/c, Z=8 . C6H5–CO–CHCH–C6H4(o-OH): a=13.295(6) A , b=5.659(2) A , c=16.144(8) A , β=109.73(5)°, monoclinic, P2 1 /n, Z=4 . C6H5–CO–CHCH–C6H4(p-OH): a=5.3446(7) A , b=12.9304(18) A , c=17.134(2) A , orthorhombic, P2 1 2 1 2 1 , Z=4 .