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A new Cu(II) complex, [Cu2(μ2-OH2)2(HSIP)2(H2O)6] (H3SIP = 5-sulfoisophthalic acid), has been synthesized and characterized by single crystal X-ray diffraction, EPR spectroscopy (X- (9.5 GHz) and Q-band (35 GHz)) and magnetic measurements. The solid state structure of the complex consists of coordination dimers [Cu2(μ2-OH2)2(HSIP)2(H2O)6] which are hydrogen bonded into 3D network. The neighbouring metal ions form a rare example of centrosymetric dinuclear core [Cu2(μ2-OH2)2] with equatorial – axial positions of the bridging ligands. The coordination dimers are organized into inorganic monolayers via water–sulfonate hydrogen bond intractions, and further linked in 3D structure via carboxylic–carboxylic hydrogen bond intractions. The magnetic properties and EPR spectra are discussed in terms of crystal structure features. The X- and Q-band EPR spectra exhibit fine structure signals due to S = 1 and the simulated parameters indicate small zero field splitting parameter Dexp (−0.035 cm−1) dominated by Ddip (−0.031 cm−1). A usually forbidden ΔMs = 2 line of lower intensity is observed in the half field region at about 150 mT. The susceptibility data have been analyzed using a spin–ladder model with both ferromagnetic (rungs) and antiferromagnetic (legs) coupling.

The reduction of chiral tetracyclic lactams 1 , 2 led to new functionalized derivatives 5 – 8 containing 3 or 5 stereogenic centers. Autoxidation of compound 5 was observed yielding an enantiopure peroxide 9 , which in turn slowly converted into tertiary alcohol 10 .

Several conditions need to be fulfilled for a photochemical reaction to proceed in crystals. Some of these conditions, for example, geometrical conditions, depend on the particular type of photochemical reaction, but the rest are common for all reactions. The mutual directionality of two neighbouring molecules determines the kind of product obtained. The influence of temperature on the probability of a photochemical reaction occurring varies for different types of photochemical reaction and different compounds. High pressure imposed on crystals also has a big influence on the free space and the reaction cavity. The wavelength of the applied UV light is another factor which can initiate a reaction and sometimes determine the structure of a product. It is possible, to a certain degree, to control the packing of molecules in stacks by using fluoro substituents on benzene rings. The crystal and molecular structure of 2,6-difluorocinnamic acid [systematic name: 3-(2,6-difluorophenyl)prop-2-enoic acid], C9H6F2O2, (I), was determined and analysed in terms of a photochemical [2 + 2] dimerization. The molecules are arranged in stacks along theaaxis and the values of the intermolecular geometrical parameters indicate that they may undergo this photochemical reaction. The reaction was carried outin situand the changes of the unit-cell parameters during crystal irradiation by a UV beam were monitored. The values of the unit-cell parameters change in a different manner,viz.cell lengthaafter an initial increase starts to decrease,bafter a decrease starts to increase,cincreases and the unit-cell volumeVafter a certain increase starts to decrease. The structure of a partially reacted crystal,i.e.containing both the reactant and the product, namely 2,6-difluorocinnamic acid–3,4-bis(2,6-difluorophenyl)cyclobutane-1,2-dicarboxylic acid (0.858/0.071), 0.858C9H6F2O2·0.071C18H12F4O4, obtainedin situ, is also presented. The powder of compound (I) was irradiated with UV light and afterwards crystallized [as 3,4-bis(2,6-difluorophenyl)cyclobutane-1,2-dicarboxylic acid toluene hemisolvate, C18H12F4O4·0.5C7H8] in a space group different from that of the crystal containing thein-situdimer.

International audience; The synthesis of the new meso-porphyrin tetrakis[4-(benzoyloxy)phenyl]porphyrin (H2TPBP), the meso-_tetrakis[4-(benzoyloxy)phenyl]porphyrinato_zinc(II) starting material [Zn(TPBP)] (1), and the 1,4-diazabicyclo[2.2.2]octane (dabco), pyrazine (pyz), 4,4′-bipyridine (4,4′-bpy), 4,4′-diaminodiphenylmethane (4,4′-mda), and 4-cyanopyridine (4-CNpy) coordination compounds with [Zn(TPBP)] (2–7) are described. The preparation of the dabco derivative in chlorobenzene leads to a crystalline monomeric five-coordinate zinc porphyrin species (2), whereas the synthesis in dichloromethane gives a five-coordinate zinc metalloporphyrin dimer (3) in the solid state. The pyrazine derivative crystallizes as a bis-pyrazine six-coordinate zinc metalloporphyrin (4). Complex 5 in the solid state is a dimer with 4,4′-bpy as a bridging ligand, whereas the 4,4′-mda species (6) is a five-coordinated monomeric zinc derivative in the solid state. All of structures of 2–6 possess cavities with different dimensions in which solvent molecules are located. The solution UV/Vis spectra of 2–7 exhibit redshifted Soret bands that indicate that these derivatives are five-coordinate zinc(II) porphyrin complexes in solution. UV/Vis titrations show that the association constants of 2–7 are close to those of known five-coordinate zinc(II) meso-porphyrins. The 1H NMR spectra of these species confirm this deduction. The photophysical proprieties of 1–7 are similar to those of related zinc(II) meso-porphyrins. The cyclic voltammograms of the H2TPBP free base and 1–7 present a third one-electron reversible oxidation wave. Single-layer diode devices of the [iridium tin oxide/zinc porphyrin/aluminum] configuration show relatively low turn-on voltages. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The reaction of [Fe(TMP)(OClO[Formula: see text]], where TMP is the dianion of tetramesitylporphyrin, with a combination of a strong [Formula: see text]-acceptor ligand and a [Formula: see text]-donating imidazole can lead to the preparation of mixed-ligand complexes [Fe(Porph)(4-CNPy)(L)][Formula: see text] where L is imidazole itself or 1-acetylimidazole and 4-cyanopyridine is the strong [Formula: see text] acceptor ligand. The stability of the new mixed-ligand pair is the presumed result of synergic bonding between the two axial ligands. The molecular structure and other characterization of the new mixed axial ligand complex, [Fe(TMP)(4-CNPy)(HIm)]ClO4 is described. The axial ligands have a relative perpendicular arrangement with Fe–N(imidazole) = 1.945 Å and Fe–N(pyridine) = 2.021 Å. The average equatorial Fe–N[Formula: see text] distance is 1.963 Å, which is consistent with the S4-ruffled TMP core. Despite the relative perpendicular arrangement of axial ligands, the EPR spectrum of the complex is a rhombic signal and not a large gmax signal. The EPR g-values are [Formula: see text] 3.05, [Formula: see text] 2.07, and [Formula: see text] 1.22. A quadrupole doublet was seen in the Mössbauer spectrum with an isomer shift of 0.197 mm/s and quadrupole splitting of 1.935 mm/s. Two crystalline forms of [Fe(TMP)(4-CNPy)(HIm)]ClO4 have been characterized; the two forms differ only in the solvent content of the lattice. Crystal data for form A: [Formula: see text] 15.432 (12) Å, [Formula: see text] 20.696 (2) Å, [Formula: see text] 19.970 (5) Å, and [Formula: see text] 99.256 (14)[Formula: see text], monoclinic, space group P21/n, V [Formula: see text] 6295 (2) Å3, Z [Formula: see text] 4, formula FeCl3O4N8C[Formula: see text]H[Formula: see text], 8397 observed data, [Formula: see text] 0.086, [Formula: see text] 0.210, refinement on [Formula: see text]. Crystal data for form B: [Formula: see text]15.267 (3) Å, [Formula: see text]20.377 (6) Å, [Formula: see text] 19.670 (4) Å, and [Formula: see text] 98.14 (1)[Formula: see text], monoclinic, space group P[Formula: see text]/n, V = 6058 (4) Å3, Z = 4, formula C[Formula: see text]H[Formula: see text]Cl[Formula: see text]FeN8O4, 5464 observed data, [Formula: see text] 0.096, [Formula: see text] 0.112, refinement on F.

All 8,9-isomers of the 9-phenyl Cinchona alkaloids were obtained by autoxidation of 9-deoxy-9-phenyl-alkaloids and by the addition of Grignard reagents to the respective ketones. The diastereoselective addition of phenyl-, methyl-, and vinylmagnesium reagents to quinidinone and cinchoninone gave the corresponding (8R,9S)-products with acceptable yields and starting material recovery. The configurations of the compounds obtained were established by chemical correlations, NMR experiments, and were supported by DFT calculations and X-ray structures. Stereochemical models for both reactions were also devised and discussed.

An effective deracemization of all trans -1,3-diphenyl-2,4-bis-[α-hydroxybenzyl]-cyclobutane 1 was achieved by the application of the ( R )-(−)- O -acylmandelic acid as a resolving agent, followed by the crystallization of the diastereomeric esters. The kinetic resolution was also observed in the esterification. Racemic 1 was transformed into bisphenylsulfanyl derivative 3 . Enantioselective oxidation of 3 with a VO(acac) 2 -chiral Schiff Base catalytic system led to a kinetic resolution, and highly enantiomerically enriched bissulfides/bissulfoxides were isolated. Assignment of the absolute configuration was made by spectroscopic methods and chemical correlation. Due to the rigid C 2 -symmetric framework, chiral compounds 1 and 3 have strong steric requirements and may be useful in chiral recognition.

The preparation and characterization of two π-cation radical derivatives of copper β-oxo porphyrins is described. [3,3,8,8,13,13,17,18-Octaethyl-(3H,8H,13H)-porphine-2,7,12-trionato (2-)] copper π-cation radical, [Cu(2,7,12-trioxoOEHP(.))](+), and [3,3,8,8,12,13,17,18-octaethyl-(3H,8H)-porphine-2,7-dionato(2-)] copper π-cation radical, [Cu(2,7-dioxoOEiBC(.))](+), have been prepared and characterized by single-crystal X-ray determinations, UV/vis/NIR, and IR spectroscopies. Both molecules have modest distortion from the planarity and show monomeric units in the solid state. [Cu(2,7-dioxoOEiBC(.))](+) shows a concentration dependent near-IR band at 1410 nm. Crystal data for [Cu(2,7,12-trioxoOEHP(.))][SbCl(6)]: tetragonal, space group P4(2)/n, a = 31.085 (14) Å, c = 9.410 (4) Å, V = 9093 Å(3), Z = 8, T = 127 K. Crystal data for [Cu(2,7-dioxoOEiBC(.))][SbCl(6)]: monoclinic, space group P2(1)/n, a = 9.655 (4) Å, b = 20.592 (8) Å, c = 43.347 (17) Åβ = 89.97(1)(°), V = 8618. Å(3), Z = 8, T = 100 K.

Polymorphism of N-benzyl-2-methyl-4-nitroaniline (BNA), a terahertz emitter and frequency doubler, was detected and the crystal structures of orthorhombic and monoclinic polymorphs have been determined at room temperature. The differential scanning calorimetry (DSC) studies revealed monotropic phase transition of the monoclinic BNA crystal system at 362 K and during re-heating, after the molten BNA cooling, the cold crystallization of the both polymorphs. The variable-temperature Raman spectra in the 700–1700 cm−1 range also evidenced the polymorphic transformation from the monoclinic to the orthorhombic, the latter stable in the wide temperature range, crystal system. The comparison of structures, DSC curves, FT-IR and Raman spectra of two forms enabled to recognize the N H···O hydrogen bond in the orthorhombic and C H···O hydrogen bond in the monoclinic one as well as other intermolecular interactions. The role of dynamic disorder, intra- and intermolecular charge transfers in the molecular mechanism of optical nonlinearity has been discussed.

Starting from (+)-3-carene 1, several chiral fragrant compounds with the bicyclo[3.1.0]hexane system were synthesized. These compounds were used as substrates for the biotransformation with lipases as biocatalysts. Pure diastereoisomers were obtained and their absolute configuration was confirmed by X-ray crystallography. The olfactory properties of new compounds were determined.

Phenyl sulfides derived from Cinchona alkaloids, 9-PhS-epi-CD, 9-PhS-epi-QN, 9-PhS-epi-QD, and 9-PhS-QN were oxidized into the corresponding sulfoxides. Regardless of the oxidation system used (NaIO4, TEMPO/NaOCl, VO(acac)2/chiral Schiff base/H2O2) a similar stereochemical outcome of the oxidation was observed. Four pure epimers of sulfoxides 9-PhSO-epi-CD and 9-PhSO-epi-QN were isolated and fully characterized (X-ray, CD, 1H NMR-pattern). The chiral sulfoxides as well as the corresponding sulfides and sulfones were tested in the Pd-catalyzed allylic alkylation of dimethyl malonate with rac-1,3-diphenyl-2-propenyl acetate. The sulfoxides obtained from Cinchona alkaloids bearing the additional stereogenic center gave the main product of configuration dependent on the chirality of alkaloid framework only. Similar ees (up to 60%) but significantly higher yields (90%) were obtained as compared to the reaction with the corresponding thioethers. The results were in agreement with nucleophilic attack directed at the allylic carbon located trans to the sulfur atom in the M-shaped intermediate η3-allylpalladium complex.

The geometrical parameters governing the potential for the photocyclization reaction occurring in crystals of 2,3,4,5,6-pentamethylbenzophenone, C(18)H(20)O, (I), 1,3-diphenylbutan-1-one, C(16)H(16)O, (II), and 2,4,6-triisopropyl-4'-methoxybenzophenone, C(23)H(30)O(2), (IV), have been evaluated. Compound (IV) undergoes photocyclization but (I) and (II) do not, despite the fact that their geometrical parameters appear equally favourable for reaction. The structure of the partially reacted crystal of the photoactive compound, i.e. 2,4,6-triisopropyl-4'-methoxybenzophenone-3,5-diisopropyl-7-(4-methoxyphenyl)-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-ol (9/1), 0.90C(23)H(30)O(2).0.10C(23)H(30)O(2), (III), was also determined, providing structural evidence for the reactivity of the compound. It has been found that the carbonyl group of the photoactive compound reacts with one of the two o-isopropyl groups. The study has shown that the intramolecular geometrical parameters are not the only factors influencing the reactivity of compounds in crystals.

An unexpected stereoselective direct dimerization occurred when 9-quinine halide was treated with butyllithium. The reaction of either (9S)- or (9R)-chloroquinine gave the same C2-symmetric dimer with 9R configuration (X-ray structure). A tentative mechanism involving radical recombination is discussed. This highly congested dimer forms two atropisomers, and their reversible interconversion was studied by NMR. Another C2-symmetric (9S)-quinine dimer connected solely by carbon-carbon bonds was obtained by the stereoselective coupling of bis(arylbromomagnesium) derivative with (9S)-chloroquinine.

Polarized FT-IR, Raman, neutron scattering (IINS), and UV-Vis-NIR spectra of 2-methyl-4-nitroaniline (MNA) crystal plates, powder, and solutions were measured in the 10–50 000 cm −1 range. The FT-IR spectrum of deuterated MNA (DMNA) in KBr pellet, the Raman spectrum of the DMNA powder as well as the EPR spectrum of the MNA powder were also recorded. Complete assignments of bands to normal vibrations have been proposed. Density functional theory (DFT) calculations of wavenumbers and potential energy distribution (PED) have been performed to strengthen the assignments. The analysis of vibrational and electronic spectra has revealed vibronic couplings in MNA molecules in solutions and in crystals. In the polarized FT-IR spectra of the crystal five unusually large bands are observed in MIR and NIR regions. Their origin is discussed in terms of N–H ··· O, C–H ··· O, C–H ··· H–N hydrogen bonds, intermolecular charge transfers, electrostatic interactions, and ion radicals formation in the crystal. The role of a methyl group introduction to 4-nitroaniline is analyzed. The crystal structure of MNA at the room temperature was re-investigated. Copyright  2008 John Wiley & Sons, Ltd.

The photophysical properties of two europium(III) complexes: EuL3bpy(1/2bpy) (1) [M. Borzechowska, V. Trush, I. Turowska-Tyrk, W. Amirkhanov, J. Legendziewicz, J. Alloys Compd. 341 (2002) 98] and EuL3bpy (2) (L = CCl3C(O)NP(O)(OCH3)2, bpy = 2,2′-bipyridine) were investigated with the aim of finding new interesting optical materials. X-ray studies of both compounds have shown some structural similarities. The lattice consists of discrete mononuclear units EuO6N2 with the same coordination modes of ligands. Additionally, the crystal structure of the complex (1) comprises non-coordinated molecules of 2,2′-bipyridine, what causes a change of coordination polyhedron geometry around Eu(III) ion. High resolution emission and excitation of emission spectra and also lifetimes of both europium(III) complexes in solid state as well as in methanol solution have been measured at 77 and 300 K. On the basis of optical studies we have proven efficient sensitised luminescence and proposed the probable energy transfer mechanism. Observed considerable differences in luminescence spectra confirm structural distinction between two investigated compounds. It is to our knowledge the first reported structural and spectroscopic characteristics of a pair of europium(III) complexes from which one comprises inner and outer sphere 2,2′-bipyridine but the second inner sphere only. It was proved that the presence of non-coordinated 2,2′-bipyridine molecule influences spectroscopic properties of the complex (1) very much.

Structural changes proceeding in a crystal during the Yang photocyclization of the salt 6,6-diethyl-5-oxo-5,6,7,8-tetrahydronaphthalene-2-carboxylate with (1S)-1-(4-methylphenyl)ethylamine were monitored by means of X-ray structure analysis. The course of the photoreaction was evaluated on the basis of the geometrical parameters for the pure reactant crystal. Variations in the cell constants, the product content, the geometry of the reaction centre, the orientation of molecular fragments and the geometry of hydrogen bonds were described and analyzed. It was found that the cell volume increased until 56% product content and decreased thereafter. The distance between the directly reacting C atoms was constant, ∼ 3.0 Å, until ∼ 75% reaction progress. Analysis of the distance between atoms that would participate in the formation of the second (unobserved) enantiomorph excluded the formation of such an isomer. Molecular fragments varied their orientation during the photoreaction, and the largest change was observed for the carboxylate group despite its participation in strong hydrogen bonds. The geometry of the hydrogen bonds changed during the photoreaction. The largest change was 0.17 Å for the D...A distance and 13° for the D—H...A angle. A comparison of the intra- and intermolecular parameters for the studied salt with data for other compounds undergoing the Yang photocyclization in crystals revealed a diversity of structural changes brought about by this type of photochemical reaction.

Structural changes taking place in a crystal during an intramolecular photochemical reaction [the Yang photocyclization of the α-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.

The single crystal-to-single crystal retro-Claisen photorearrangement of the salt of 7-(4-carboxybenzoyl)norbornene with (S)-(−)-1-cyclohexylethylamine was studied. Although this reaction is an ionic chiral auxiliary-mediated asymmetric synthesis, which normally affords highly enantio-enriched products, the enantiomeric excess in this case is a relatively low 60% (80% of one enantiomer, 20% of the other). X-ray structure analysis was used in order to describe changes in the reaction centers and the behavior of molecules during the photoreaction and to understand the formation of two enantiomers. It was discovered that the conformation of the reactant molecules changes during the photoreaction to one that enables the formation of the minor enantiomer. This was seen clearly at ca. 30% reaction progress. The variations in the cell constants as a function of reaction progress are also presented. The structural changes taking place during the retro-Claisen photorearrangement are compared to the changes observed for other intra- and intermolecular photoreactions in crystals.

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 .

Optically active (3R,1RS)-3-aryl-1-phenyl-3-phenylsulfanyl-1-propanols were easily dehydrated forming mainly rac-cis-2-aryl-4-phenylthiochroman, and rac-cis-4-aryl-2-phenylthiochroman along with the corresponding trans-isomers. The observed reaction outcome (rearrangement and racemisation) apparently results from the SEAr reaction involving the unusual 1,3-phenylsulfanyl group migration. This interpretation is supported by the results of theoretical studies (DFT) on the supposed intermediates.

The preliminary results of high-pressure X-ray diffraction studies of the intramolecular photochemical Norrish–Yang reaction in single crystals of the salt of 6,6-diethyl-5-oxo-5,6,7,8-tetrahydronaphthalene-2-carboxylic acid and (1S)-1-(4-methylphenyl)ethylamine are presented. The photo-induced changes in the cell parameters at high pressure along with the time of UV irradiation and the changes in the cell parameters along with pressure are discussed. The percentage change in the cell parameters brought about by the photochemical reaction at high pressure is similar to that at normal pressure. The cell volume decreases non-linearly with increasing pressure. The crystals lose their crystallinity above 2 GPa. This is the first paper in scientific literature on monitoring photochemical reactions in crystals at high pressure by X-ray diffraction.

The cooperative effects were monitored in 2-benzyl-5-benzylidenecyclopentanone single crystals by the use of X-ray diffraction methods. The remarkable changes take place in the reciprocal lattice of the crystal after UV irradiation, indicating that the cooperative effects work and the crystal transformation proceeds. The mutual position of the substrate molecules and their internal geometry change with the reaction progress. This is explained in terms of the chemical pressure caused by the product molecules in the crystal.

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.

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.

Products with three new stereogenic centers were generated via sequential asymmetric dihydroxylation and sulfoxidation of homoallylic sulfides. The non-racemic homoallylic sulfoxides were prepared using chiral, vanadyl-based catalytic system with e.e. of up to 85%. Subsequently, these compounds were dihydroxylated with AD-mix system and gave products of low d.e.s (up to 40%). Recrystallization of l -diastereomers furnished both enantiomerically pure 1-phenyl-4-phenylsulfinylbutane-1,2-diols (X-ray), which are new and useful chiral building blocks. Further oxidation at sulfur produced the corresponding enantiomers of 1-phenyl-4-phenylsulfonylbutane-1,2-diol.

Single crystals of [Ln(2,2′-bipyridine-1,1′-dioxide)4](ClO4)3 (Ln = Nd, Lu) have been obtained and the crystal structures determined. By comparison with previous structural determinations, it is demonstrated that steric crowding associated with the decreasing lanthanide ions radius causes changes of the angles between the rings of the ligand. This leads to a deformation of the coordination polyhedron from an almost ideal cube (La, Ce) to a dodecahedron distorted towards a square antiprism (for Nd and heavier lanthanides), and slightly distorted square antiprism for Lu. Electronic absorption spectra of Nd(bpyO2)43+ and Eu(bpyO2)43+ (bpyO2 = 2,2′-bipyridine-1,1′-dioxide) at room temperature and 4 K were measured in CH3CN and CH3NO2 and in the solid state. Emission and excitation spectra, and lifetime measurements of Tb(bpyO2)43+ at 293 and 77 K are presented and used to characterize the excited state photophysics of this species. Comparisons are made to previous results, and generalizations concerning molecular and electronic structure for the series of complexes are presented.

Herein we describe the changes in the packing patterns and discuss the structural modifications in guanidinium carboxybenzenesulfonates G·CBS [C(NH2)3]+[XC6H4SO3]− (where X is the carboxylic group) compared with those in guanidinium benzenesulfonate G·BS. Generally, the one-dimensional arrangements in all three crystals comprise the same ribbon formations. However, the further organization of the ribbons is significantly different in G·CBS. We analyse the donor and acceptor efficacy of the additional functional group to disrupt some of the basic hydrogen bonds between the guanidinium and the sulfonium portions in G·BS. Since the carboxylic group introduces a mismatching of the sites on the counter ions, the changes in the symmetry relations essentially depend upon the topology of the substituent X, which results in modified packing patterns. All engineering peculiarities are analysed with respect to the symmetry constraints and geometrical demands of the packing forces.

The high resolution emission spectrum of the Eu 3+ ion in the compound Eu(bpyO 2 ) 4 (ClO 4 ) 3 , where bpyO 2 =2,2'-bipyridine-1,1'-dioxide, has been previously studied in solid state and frozen solution. The compound crystallizes in the monoclinic P2, space group with the cell parameters a=14.730(1) A, b=13.585(1) A, c=22.967(2) A and β=91.46(1)°. The coordination polyhedron can be described as a distorted cube into a square antiprism with symmetry close to D 2 . The experimental emission quantum yield (q) was measured according to a method previously described and a q-value of 15% was obtained. By using the structural crystallographic data a theoretical ligand field and intensity analysis was carried out, and the sparkle model was applied to obtain the electronic structure of the organic part of the compound. From these results, intramolecular energy transfer rates were evaluated according to a recently developed model. An appropriate set of rate equations for the normalized populations of the levels involved was solved numerically, by using the 4th order Runge-Kutta method, and a theoretical q-value could be obtained (19.6%), which is in good agreement with experiment. A relevant aspect is that the reason for this rather low q-value could be explained in terms of the relative position of the lowest ligand triplet energy level with respect to the 5 D 1 and 5 D 0 levels of the Eu 3 ion. The theoretical analysis has also shown that, in this compound, a slight decrease in the energy of the ligand triplet level is sufficient to quench almost completely the Eu 3 luminescence.

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.

N-(4-butyryl-3-hydroxyphenyl)acetamide monohydrate, (I), and 4-(4-chlorophenyl)-2-methyl-4-oxobutanoic acid, (II), are photochemically inert, which is a result of their conformation. The geometrical parameters describing the molecular conformation and possibilities of the Yang photocyclization in crystals have been calculated and discussed. Compound (I) forms double ribbons along the a axis, stabilized by hydrogen bonds and π⋯π interactions. Compound (II) forms dimers. (I): triclinic, space group $$ {\text{P}}\bar{1} $$ , a = 6.9291(12) A, b = 7.5736(16) A, c = 13.0528(18) A, α = 79.643(17)°, β = 85.818(15)°, γ = 63.97(2)°, Z = 2. (II): monoclinic, space group P21/c, a = 11.904(2) A, b = 9.6508(12) A, c = 10.666(2) A, β = 110.64(2)°, Z = 4. The analysis of the geometrical parameters explains photochemical inertia of the presented compounds.

Investigations of crystal structure, electronic and vibrational absorption spectra and electron spin resonance of the complex of the fullerene C 70 with chloro(triphenylphosphine)gold have been performed. Optical anisotropy, in particular the anisotropy of normal vibrations of the donor, has been observed and discussed. It was stated that the C 70 ·2[(Ph 3 P)AuCl] complex undergoes a first-order phase transition at ∼160 K and shows an anomaly between 225 and 250 K. The role of the shape of C 70 molecule in the structural organization and physical properties of the electron donor–acceptor complex is emphasized.

W przypadku tytulowego związku di-{bis(tri-tert-butoksysilanotiolano-S)(dimetylformamid-O)kadm(II)}-μ-trans-1,2-di-4-pirydyloeten [Cd(C12H27O3SSi)4(C3H7NO)2(C12H10N2)], centralny atom kadmu jest skoordynowany z czterema atomami donorowymi, tworząc rdzen typu CdNOS2. Jest to pierwszy kompleks Cd(II) o tego typu centrum i ze wzgledu na obecnośc dwoch reszt tiolanowych, N- i O-donora moze on sluzyc za model centrum katalitycznego wątrobowej dehydrogenazy alkoholowej.

Molecules of the title compound, C28H30OSi2, are centrosymmetric, with the O atom lying on an inversion centre. The ethyl substituents are placed trans along the strictly linear Si—O—Si fragment.

Lanthanide ions are widely applied as spectroscopic probes in studies of biomolecular structures. However, in all known crystal structures of lanthanide complexes with amino acids and peptides, dimers and polymers are formed with one or more symmetry sites of the metal ions; this strongly affects the spectroscopic properties. In order to explain the role of the type of amino acid, the Ln/ligand ratio and ligand chirality in the structure, two types of Eu(lII) complexes with L-proline of formulae [Eu 2 (C 5 H 9 O 2 N) 4 (H 2 O) 8 ](ClO 4 ) 6 .4H 2 O (I) and [Eu(C 5 H 9 O 2 N) 3 (H 2 O) 3 ](ClO 4 ) 3 (II) were obtained and characterised by X-ray and electron spectroscopic methods. Compound I crystallizes in a tetragonal space group (P42,2) and forms dimers with two nonequivalent europium sites, with square antiprism polyhedra. Compound II (triclinic P1) forms polymeric chains in a crystal lattice, with two coordination modes of the proline molecules (mono- and bridging bidentate) and with dodecahedron polyhedra. Moreover, differences in the Eu-O bond lengths between two crystallographically nonequivalent metal ions are smaller in structure II. High resolution absorption, excitation and emission spectra of the compounds were measured at 4-293 K and analysed in order to explain how subtle structural changes affect the intensity of the electronic transitions, splitting of levels and vibronic coupling.

In the title compound, [Cd(C12H27O3SiS)2(C10H8N2)], the CdII atom has a distorted octa­hedral coordination formed by two N atoms of the bipyridine ligand and two pairs of S and O atoms from two S,O-chelating tri-tert-butoxy­silanethiol­ate ligands. The O atoms occupy axial positions and the two halves of the mol­ecule are related by a twofold axis which passes through the Cd atom.

The coexistence in solution of at least two conformers of (meso-tetraphenylporphinato)nickel(II) [Ni(TPP)] is inferred from solution and single-crystal resonance Raman spectra obtained at different temperatures (170 − 297 K) and excitation wavelengths (413.1 and 457.9 nm). The shapes of the structure-sensitive Raman lines ν8 and ν2 are clearly asymmetric and change with temperature. These broad lines can be decomposed into at least two sublines, a low-frequency (LF) and a high-frequency (HF) component. In contrast, the corresponding single-crystal Raman lines of the nonplanar structure of Ni(TPP) in the crystal are narrow and symmetric. For the line ν2, the broad LF subline results from nonplanar conformers and the narrow HF subline arises from a more planar conformer. This assignment is consistent with the observation that the LF subline of ν2 is more enhanced upon changing the excitation wavelength from 413.1 to 457.9 nm. The selective resonance enhancement is caused by the red shifts of the UV−visible ...

The structure of (porphinato)nickel(II) [Ni(P)] has been determined by X-ray diffraction and inferred from a combination of single-crystal and solution resonance Raman measurements. The crystal structure reveals a planar porphyrin macrocycle with a π−π dimer packing configuration exhibiting a small lateral shift. This group S crystallographic packing arrangement has been suggested to give strong π−π interactions between the porphyrin rings on the basis of the small interplanar spacing (3.355 A) and lateral shift (1.528 A) between the porphine planes. Strong π−π interactions are usually associated with geometrically inequivalent structural parameters such as different metal−nitrogen bond distances, but this is not observed for Ni(P). The average nickel−nitrogen bond distance is 1.951 A, consistent with planar nickel porphyrins. The root-mean-square out-of-plane displacement from the mean plane of the macrocyclic atoms is 0.019 A, consonant with the observed very slight ruffling of the macrocycle. A salient...

The synthesis and characterization of isocyanide complexes of (porphyrinato)iron(III) species, [(Porph)Fe(t-BuNC)2]ClO4, Porph = OEP, TPP, are reported. The crystal structures of [(TPP)Fe(t-BuNC)2]...

Crystals of the 1-chloroanthracene photodimer, viz. trans-bi(1-chloro-9,10-dihydro-9,10-anthracenediyl), C(28)H(18)Cl(2), were obtained from the solid-state [4+4]-photodimerization of the monomer, C(14)H(9)Cl, followed by recrystallization. The symmetry of the product molecules is defined by the orientation of the reactant molecules in the crystal. The mutual orientation parameters calculated for adjacent monomers explain the reactivity of the compound. The molecules in the crystal of the monomer and the recrystallized photodimer pack differently and the photodimer has crystallographically imposed inversion symmetry.

The crystal and molecular structure of four-coordinate (octaethylporphinato)cobalt(II) has been determined at 127 K from X-ray diffraction data collected on an area detector. Crystals of Co(OEP) are isomorphous with Fe(OEP), one crystalline form of Ni(OEP), and Cu(OEP); the porphinato core in the series are all planar. The M-N p bond distance order in the series is Fe>Co>Ni

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.

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.

The crystal structures of 2-oxo-2-phenyl-N-[(R)-1-phenylethyl]acetamide, C16H15NO2, (I), and N,N-dimethyl-2-(1-naphthyl)-2-oxoacetamide, C14H13NO2, (II), were determined in an attempt to understand the reason for the lack of Yang photocyclization in their respective crystals. In the case of (I), the long distance between the O atom of the carbonyl group and the gamma-H atom, and between the C atom of the carbonyl group and the gamma-C atom, preclude Yang photocyclization. For (II), the deviation of the gamma-H atom from the plane of the carbonyl group and interactions between the naphthalene rings are regarded as possible reasons for the chemical inertia. The two independent molecules of (I) differ in their conformation. N-H...O hydrogen bonds link molecules of (I) into chains extended along the b axis.

The crystal and molecular structure of 2,6-diphenyl-4- (4- N , N -dimethylaminophenyl)pyrylium perchlorate has been determined by X-ray diffraction methods given R=0.061 and mean esd for bond lengths 0.006 A and bond angles 0.3°. NMe 2 -substitution in the para position causes a strong through-resonance effect with the positively charged pyrylium ring. As a result, (i) a shortening of internal bond length with maintaining coplanarity, and (ii) a decrease of aromatic character of the pyrylium ring due to localization of two π-CC bonds, are observed.

The crystal and molecular structure of 2,6-diphenyl-4-(4-nitrophenyl)pyrylium perchlorate nitromethane solvate was solved with R =0.067 for 2827 reflections and mean esd for bond lengths 0.005A and bond angles 0.4°. Phenyl rings attached to positions 2,4 and 6 of the pyrylium ring exhibit a strong deformation of angular geometry indicating enhanced electronegativity of carbon atoms 2,4 and 6 due to the positive charge on them. Exocyclic valence angles at carbon atoms 2 and 6 of the pyrylium ring are strongly deformed from 120° due to the strongly electronegative oxygen atom with partial positive charge, STO-3G, 3-21G and 6-31G * ab initio calculations support this interpretation.

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.

The analysis of the crystal structures of rac-3-benzoyl-2-methylpropionic acid, C(11)H(12)O(3), (I), morpholinium rac-3-benzoyl-2-methylpropionate monohydrate, C(4)H(10)NO(+).C(11)H(11)O(3)(-).H(2)O, (II), pyridinium [hydrogen bis(rac-3-benzoyl-2-methylpropionate)], C(5)H(6)N(+).(H(+).2C(11)H(11)O(3)(-)), (III), and pyrrolidinium rac-3-benzoyl-2-methylpropionate rac-3-benzoyl-2-methylpropionic acid, C(4)H(10)N(+).C(11)H(11)O(3)(-).C(11)H(12)O(3), (IV), has enabled us to predict and understand the behaviour of these compounds in Yang photocyclization. Molecules containing the Ar-CO-C-C-CH fragment can undergo Yang photocyclization in solvents but they can be photoinert in the crystalline state. In the case of the compounds studied here, the long distances between the O atom of the carbonyl group and the gamma-H atom, and between the C atom of the carbonyl group and the gamma-C atom preclude Yang photocyclization in the crystals. Molecules of (I) are deprotonated in a different manner depending on the kind of organic base used. In the crystal structure of (III), strong centrosymmetric O...H...O hydrogen bonds are observed.