Janusz Lipkowski

Metal Complexes of Cinchonine as Chiral Building Blocks: A Strategy for the Construction of Nanotubular Architectures and Helical Coordination Polymers

The first chiral bipyridyl-type metalloligands based on aluminum derivatives of cinchonine (CN-H) were synthesized and characterized by single-crystal X-ray diffraction studies. These bischelate complexes, (CN)(2)AlX [X = Cl (1a), Me (1b)] were found to be effective building blocks for the preparation of novel helical nanotubular architectures as well as chiral bimetallic coordination polymers, as demonstrated by the rational synthesis of a helical structure formed by 1a and ZnCl(2). The applied methodology stands as an exemplary strategy for the rational synthesis of chiral metal-organic frameworks through self-organization driven by nonbonding interactions or coordination, which could potentially find applications in enantioselective separations and catalysis.

The Structure of Tetrabutylammonium Bromide Hydrate (C4H9)4NBr·21/3H2O

Abstract The results of the investigation using single crystal X-Ray diffraction analysis of tetrabutylammonium bromide hydrate structure (C4H9)4NBr·21/3H2O, which was discovered in the tetrabutylammonium bromide–water binary system within the range of concentrated solutions, are presented in this communication. The (C4H9)4NBr·21/3H2O compound is crystallized in the trigonal space group R3c, a=16.609(1) A, c=38.853(2) A. The structure is a packing of tetrabutylammonium cations and clusters composed of hydrogen-bonded water molecules and bromide anions. The change of water functions is discussed within one binary system tetrabutylammonium bromide–water. In the clathrate formation region water plays the role of the host, forming the water–anion host framework in clathrate polyhydrates, while in the region of concentrated solutions, in the case of (C4H9)4NBr·21/3H2O compound, water functions as a guest, forming water-anion guest particle.

Cucurbituril as a New Macrocyclic Ligand for Complexation of Lanthanide Cations in Aqueous Solutions

(Aqua)lanthanide complexes with cucurbituril {[Gd(NO3)(H2O)4](C36H36N24O12)}(NO3)2·7H2O (1), {[Gd(NO3)(C2H5OH)(H2O)3](C36H36N24O12)}(NO3)2·5.5H2O (2), {[Ho(NO3)(H2O)4](C36H36N24O12)}(NO3)2·7H2O (3), {[Yb(NO3)(H2O)4](C36H36N24O12)}(NO3)2·6H2O (4), {[La(H2O)6(SO4)](C36H36N24O12)}(NO3)·12H2O (5), {[Gd(H2O)4]2(C36H36N24O12)3}Br6·45H2O (6), and {[Ce(H2O)5]2(C36H36N24O12)2}Br6·26H2O (7) were obtained in high yield by reaction of cucurbituril with aqueous solutions of lanthanide(III) species. The crystal structures of the compounds show a packing of 1:1, 2:2, and 2:3 in the (cucurbituril)lanthanide complexes in which cucurbituril plays a bidentate ligand role, and water molecules of the (aqua)lanthanide complexes form hydrogen bonds with carbonyl groups of the cucurbituril molecule. The guest water molecule is situated in the cucurbituril molecule cavity of 2 and 5. The crystal structure of 6 is a packing of three-deck sandwiches, built from alternating cucurbituril molecules and Gd(H2O)43+ ions. The largest distance between outermost oxygen atoms in the sandwiches is 30.04 A. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Alkoxo-bridged binuclear copper(II) complexes as nodes in constructing extended structures

Abstract Three new compounds exhibiting extended structures have been obtained by using alkoxo-bridged binuclear copper(II) complexes as nodes, and bis(4-pyridyl) derivatives as spacers: [Cu 2 (H 2 tea) 2 (bpe)](ClO 4 ) 2 ·(bpe)·H 2 O ( 1 ), [Cu 2 (Hdea) 2 (4,4′-bipy)](ClO 4 ) 2 ( 2 ), and [Cu 2 (ap) 2 (4,4′-bipy) 2 ](ClO 4 ) 3 ·(4,4′-bipy)·(H 2 ap)·(H 2 O) ( 3 ) (H 3 tea=triethanolamine, H 2 dea=diethanolamine, Hap=aminopropanol; bpe= trans -1,2-bis(4-pyridyl)ethylene, 4,4′-bipy=4,4′-bipyridine). The structure of 1 consists of infinite chains resulted by connecting the bis(alkoxo)-bridged unsymmetrical [Cu 2 (H 2 tea) 2 ] 2+ nodes with bis(4-pyridyl)ethylene rods. The Cu⋯Cu separations are of 2.924 and 13.402 A in an alternate mode. The noncoordinated bpe molecules bind the parallel coordination polymer chains, spread along b axis, through intermolecular H-bonds, resulting in a double zigzag ladder network. In crystal 2 , the 4,4′-bipy molecules connect centrosymmetric [Cu 2 (Hdea) 2 ] 2+ nodes, resulting in infinite chains. The parallel chains are disposed in planes which are parallel to the ab crystallographic plane. The chains directions, [110] or [1−10], alternate in adjacent planes. The stereochemistry of the copper(II) ion is distorted square-pyramidal. The alternate Cu⋯Cu distances within the chain are: 2.9880(5) and 11.0310(5) A. Compound 3 is a two-dimensional coordination polymer. There are two crystallographically independent centrosymmetric [Cu 2 (ap) 2 ] cores. The distances between the alkoxo-bridged copper atoms within the nodes are: 3.071(2) and 3.036(2) A. Each node is connected through four 4,4′-bipy bridges to four other nodes, resulting in a two-dimensional layer with rhombic meshes. The dimensions of the rhomboidal cells are 12.31 and 13.36 A, with an angle between the edges of 83.4°. The uncoordinated 4,4′-bipy and water molecules, the H 2 pa + (monoprotonated aminopropanol species) and perchlorate ions are interconnected through hydrogen bonds resulting in infinite chains. These hydrogen-bonded polymers fill the channels resulted through the stacking of the 2-D layers.

Oxygenation of a Me2Zn/α‐Diimine System: A Unique Zinc Methylperoxide Cluster and Evidence for Its Sequential Decomposition Pathways

Interest in the reaction of alkylzinc complexes with O2 has persisted for over 150 years since the pioneering studies by Frankland. The nature of the products, however, has been the subject of intense controversy. The widely accepted freeradical chain-reaction mechanism for these reactions, as found in the vast majority of text books, assumes the initiation by adventitious alkyl radicals (RC) followed by a cascade of fast reactions with little opportunity for the detection of intermediates. Recently, however, we provided unambiguous proof that R2Zn compounds, or their adducts with Lewis bases, have a marked tendency to undergo oxidation of only one alkyl group under controlled conditions with subsequent formation of RZnOOR or RZnOR species, and simultaneously structurally characterized the first examples of zinc alkylperoxides. We also proposed a plausible hypothesis for the mechanism of the reaction of alkylzinc complexes with O2. [5,6] In recent years there has been an increased interest in various radical additions initiated by the R2Zn/O2 system, especially regarding organic substrates which contain donor sites capable of forming the Lewis acid/base adducts with R2Zn that are actually involved in the reaction with O2. [7] This latter fact is usually ignored, and another assumption made in this field, which seems irrefutable, involves an alkyl radical RC (generated through the oxygenation reaction) acting as the chain carrier. Moreover, the most effective initiation systems involve Me2Zn, [7f,g] which, according to recent findings, can be selectively transformed into MeZnOMe without the generation of free MeC radicals. In light of this fact, as well as the lack of structurally characterized ZnOOMe species, it seemed reasonable to wonder how the oxygenated products participate in radical reactions. To gain a more in-depth view of both the role of the supporting ligands and the character of the radical species formed in the reactions of Me2Zn with O2, we have turned our attention to a-diimines, which have been widely used in fundamental coordination chemistry as noninnocent ligands. In the field of zinc chemistry, van Koten et al. have extensively studied the reactions of R2Zn compounds with 1,4-diazabutadiene (R-DAB) ligands and have demonstrated convincingly that this reaction system smoothly forms both paramagnetic and diamagnetic species. Herein we report the synthesis and structural characterization of a novel zinc oxo(methylperoxide) cubane along with the MeOC radical entrapped product, the formation of which involves ZnO OMe bond homolysis. Previous studies have demonstrated that the treatment of Me2Zn with tBu-DAB in diethyl ether at ambient temperature results in the formation of [Me2Zn(tBu-DAB)] (1). [11] According to the authors, the four-coordinate adduct 1 is rather stable under these reaction conditions and only upon heating above 35 8C does it undergo an inner-sphere single electron transfer to give the radical pair [MeZn(tBu-DABC)(MeC)], which subsequently dimerizes to the C C coupled dinuclear compound [{MeZn(tBu-DABC)}2] (2 ; Scheme 1). In light of these findings, we decided to modify the reaction system slightly and, in the first instance, stirred equimolar amounts of tBu-DAB andMe2Zn in toluene at 22 8C for 7 h. [12]

Upper rim substituted thiacalix[4]arenes

Abstract The synthesis and structure of new tetrahydroxythiacalix[4]arenes, existing in the cone conformation and possessing reactive bromide, chloromethyl or diorganylphosphoryl groups on the upper rim of the macrocycle are described. The molecular structure of tetrakis(diisopropoxyphosphorylmethyl)thiacalix[4]arene was examined by X-ray crystallography.

Crystallography of supramolecular compounds

Preface G. Tsoucaris, et al. 1. An Introduction to the Crystallography of Supramolecular Compounds J.L. Atwood. 2. Association of Helical Peptides and Ion Channels I.L. Karle. 3. On Molecular Recognition in Fullerene Chemistry H.B. Buergi. 4. Long Range Order in Organized Monolayers D. Mobius. 5. Applications of the Cambridge Structural Database in the Study of Non-covalent Interactions F.H. Allen. 6. Solvent and Dynamic Effects on the structure of Alkali Cation Complexes of the t-butyl-calyx[4]arene Anion: MD and FEP Computer Investigations on the Na+ / Cs+ Binding Affinity A. Varnek, et al. 7. Solid State NMR in Inclusion Compounds J.A. Ripmeester, C.I. Ratcliffe. 8. The Single Crystal as a Super Molecule C. Pascard. 9. New Layered and Pillared-Type Compounds, their Intercalation Chemistry and Applications G. Alberti, et al. 10. Molecular Tectonics X. Delaigue, et al. 11. Symmetry in Spheroalcanes, Fullerenes, Tubules and Other Column-Like Aggregates A. Rassat. 12. Stability, Solvent Patterns and Molecular Recognition in Cyclodextrins G. Tsoucaris. 13. Constitution and Stability of Clathrate Hydrates Yu.A. Dyadin. 14. Cyclodextrins and Fragments of Starch and Cellulose: Crystal Structures, Self-Assembly and Hydrogen Bonding W. Saenger, et al. 15. Clathration and Solvation of Molecules J. Lipkowski. 16. Inclusion Compounds: Relating Structure to Kinetics and Thermodynamics L.R. Nassimbeni. 17. The Self- Assembly of Guanosine Derivatives and Folic Acid G. Gottarelli, et al. 18. Recognition at Crystal Interfaces. Self Organization and Transfer of Structural Information from 2-D Monolayers to 3-D Single Crystals M. Lahav. 19. Synthetic Receptors: A Modular Approach to Large Structures I. Higler, et al. 20. Structural Models of Biological Significance from Supramolecular Systems J.L. Atwood. 21. How DNA is Recognized by Proteins W. Saenger. 22. Catalytic Antibodies: An Intriguing Host-Guest System B.S. Green. 23. Supramolecular Organization of Keratinized Tissue J.-L. Leveque. 24. Molecular Recognition: The Lipocalins E. Eliopoulos. 25. Supramolecular Photochemical Reactions of Organic Molecules Adsorbed on Porous Crystalline Zeolites N.J. Turbo. 26. Topics in Supramolecular Chemistry J.-M. Lehn. Appendix. Tutorials on Molecular Modelling. 1. Introduction to Conformational Analysis with the Macromodel Software A. Varnek, G. Wipff. 2. Display of Dynamic Structures from Molecular Dynamics Simulations in Aqueous/Non-aqueous Solutions. Comparison with X-Ray Structures A. Varnek, et al. 3. The Cambridge Structural Database F. Allen, O. Johnson. 4. Harmony: the Supramolecular Database Management System M. Bailly, et al. 5. Molecular Graphics Approaches in Structure Prediction and Determination E. Eliopoulos, I.M. Mavridis. 6. Tutorial Available on a PC Floppy Disk: Display of Supramolecular Structures E. Eliopoulos, I.M. Mavridis. Index.

Towards a New Family of Photoluminescent Organozinc 8- Hydroxyquinolinates with a High Propensity to Form Noncovalent Porous Materials

We report on investigations of reactions of tBu(2)Zn with 8-hydroxyquinoline (q-H) and the influence of water on the composition and structure of the final product. A new synthetic approach to photoluminescent zinc complexes with quinolinate ligands was developed that allowed the isolation of a series of structurally diverse and novel alkylzinc 8-hydroxyquinolate complexes: the trinuclear alkylzinc aggregate [tBuZn(q)](3) (1(3)), the pentanuclear oxo cluster [(tBu)(3)Zn(5)(μ(4) -O)(q)(5)] (2), and the tetranuclear hydroxo cluster [Zn(q)(2)](2)[tBuZn(OH)](2) (3). All compounds were characterized in solution by (1)H NMR, IR, UV/Vis, and photoluminescence (PL) spectroscopy, and in the solid state by X-ray diffraction, TGA, and PL studies. Density functional theory calculations were also carried out for these new Zn(II) complexes to rationalize their luminescence behavior. A detailed analysis of the supramolecular structures of 2 and 3 shows that the unique shape of the corresponding single molecules leads to the formation of extended 3D networks with 1D open channels. Varying the stoichiometry, shape, and supramolecular structure of the resulting complexes leads to changes in their spectroscopic properties. The close-packed crystal structure of 1(3) shows a redshifted emission maximum in comparison to the porous crystal structure of 2 and the THF-solvated structure of 3.

Cinchona Alkaloid-Metal Complexes: Noncovalent Porous Materials with Unique Gas Separation Properties**

The most common andeffective approach to design and prepare metal–organicframeworks (MOFs) or porous coordination polymers(PCPs) of desired topology and functionality is based oncoordination-driven self-assembly, and both the correctchoice of metal centers and the engineering of the ligandsfeatures, such as size, flexibility, and directionality of bindingcenters, play a decisive role.

Green synthesis of a natrolite zeolite/palladium nanocomposite and its application as a reusable catalyst for the reduction of organic dyes in a very short time

A natrolite zeolite/palladium (natrolite zeolite/Pd) nanocomposite has been successfully synthesized applying a simple in situ reduction method using an aqueous extract of fruits of Piper longum as a reducing and stabilizing agent. The natrolite zeolite/Pd nanocomposite is characterized using Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM) equipped with an energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The crystal structure of natrolite zeolite is determined by single-crystal X-ray diffraction analysis. The catalytic activity of the natrolite zeolite/Pd nanocomposite is excellent for organic dye reduction at room temperature and remains the same for several cycles. The present strategy gives a promising way to prepare heterogeneous nanocatalysts composed by metal nanoparticles for broad applications in catalysis and organic transformations.