STRUCTURE AND SPECTRAL-LUMUINESCENT PROPERTIES OF LANTHANIDE-CONTAINING COMPLEXES WITH AZACROWN CALIXARENES

Lanthanide complexes with calix[4]arenes lower rim substituted with two azacrown ether fragments are reported. The size of the substituent cavity varied from 4 to 6 heteroatoms. The complexes were analyzed by means of IR, NMR, ESI mass spectroscopy. It is assumed that the coordination of Ln(III) ions occurs through the donor atoms of the lower rim; the counter anion and solvent molecule are also coordinated. Lanthanide-centered characteristic luminescence was observed in Eu(III), Tb(III) and Yb(III) complexes. The most efficient 4f-luminescence is observed for terbium-containing complexes with benzo-crown-derived ligands. The pathways of the sensitization of 4f-luminescence are discussed.

Synthesis of Aromatic and Aliphatic N-Heterocyclic Salts and Their Application as Organic Electrolyte Supporters in Electrochemical Capacitor

Aromatic and aliphatic N-heterocyclic chemical salts were synthesized by counter-anion-exchange reactions after substitution reactions in order to apply them as organic electrolyte supporters in an electrochemical capacitor (super capacitor). The aromatic N-heterocyclic salts were N-methylpyridinium tetrafluoroborate ([MPy]+[BF4]−), N-methylpyridinium hexafluorophosphate ([MPy]+[PF6]−), 1,3-dibuthylimidazolium tetrafluoroborate ([DI]+[BF4]−), 1,3-dibuthylimidazolium hexafluorophosphate ([DI]+[PF6]−), 1-buthyl-4-methyl-1,2,4-triazolium tetrafluoroborate ([BMTA]+[BF4]−), and 1-buthyl-4-methyl-1,2,4-triazolium hexafluorophosphate ([BMTA]+[PF6]−). The aliphatic N-heterocyclic salts were N,N-dimethylpiperilidium tetrafluoroborate ([DMP]+[BF4]−), N,N-dimethylpiperilidium hexafluorophosphate ([DMPy]+[PF6]−), N,N-dimethylpyrrolidium tetrafluoroborate ([DMPy]+[BF4]−) and N,N-dimethylpyrrolidium hexafluorophosphate ([DMPy]+[PF6]−), 1-ethyltriethamine tetrafluoroborate ([E-TEDA]+[BF4]−), and 1-ethyltriethamine hexafluorophosphate ([E-TEDA]+[PF6]−), respectively. We confirmed the successful synthesis of the aromatic and aliphatic N-heterocyclic chemical salts by 1H-NMR, FT-IR, and GC/MS analysis before conducting the counter-anion-exchange reactions. Then, we determined the electrochemical potential of vanadium acetylacetonate (V(acac)3) under acetonitrile in the presence of the N-heterocyclic chemical salts as energy-storage chemicals. By cyclic voltammetry, the maximum voltages with the N-heterocyclic chemical salts in acetonitrile reached 2.2 V under a fixed current value. Charge-discharge experiments were performed in the electrochemical capacitor with an anion-exchange membrane using a non-aqueous electrolyte prepared with a synthesized N-heterocyclic salt in acetonitrile.

Halides as versatile anions in asymmetric anion-binding organocatalysis

This review intends to provide an overview on the role of halide anions in the development of the research area of asymmetric anion-binding organocatalysis. Key early elucidation studies with chloride as counter-anion confirmed this type of alternative activation, which was then exploited in several processes and contributed to the advance and consolidation of anion-binding catalysis as a field. Thus, the use of the halide in the catalyst–anion complex as both a mere counter-anion spectator or an active nucleophile has been depicted, along with the new trends toward additional noncovalent contacts within the HB-donor catalyst and supramolecular interactions to both the anion and the cationic reactive species.

(4-Benzyl-1-methyl-1,2,4-triazol-5-ylidene)[(1,2,5,6-η)-cycloocta-1,5-diene](triphenylphosphane-κP)iridium(I) tetrafluoridoborate

A new triazole-based N-heterocyclic carbene iridium(I) cationic complex with a tetrafluoridoborate counter-anion, [Ir(C10H11N3)(C8H12)(C18H15P)]BF4, has been synthesized and structurally characterized. The cationic complex exhibits a distorted square-planar environment around the IrI ion. One significant non-standard hydrogen-bonding interaction exists between a hydrogen atom on the N-heterocyclic carbene ligand and a fluorine atom from the counter-ion, BF4 −. In the crystal, π–π stacking interactions are observed between one of the phenyl rings and the triazole ring. Both intermolecular and intramolecular C—H...π(ring) interactions are also observed.

[(1,2,5,6-η)-Cycloocta-1,5-diene](1-ethyl-3-isopropyl-1,3-imidazol-2-ylidene)(triphenylphosphane)rhodium(I) tetrafluoridoborate

A new N-heterocyclic cationic rhodium(I) complex with a tetrafluoridoborate counter-anion, [Rh(C8H14N2)(C8H12)(C18H15P)]BF4, has been prepared and structurally characterized. The cationic complex exhibits a distorted square-planar environment around the rhodium(I) ion. Two connections are made from rhodium(I) to the carbon atom of an N-heterocylic carbene ligand and to the phosphorus atom of a triphenylphosphane ligand. The remaining two coordination sites are made via a bidentate interaction from the two olefinic bonds of cyclooctadiene to the rhodium(I) ion. The compound includes an out-sphere tetrafluoridoborate counter-anion. Within the crystal of the compound exist several weak intermolecular C—H...F interactions.

Reversal of Enantioselectivity in the Conjugate Addition Reaction of Cyclic Enones with the CuOTf/Azolium Catalytic System

Hydroxyamide-functionalized azolium salt (NHC•HI 4) was evaluated for dual enantioselective control in a Cu-catalyzed asymmetric conjugate addition (ACA) reaction. This investigation was based on our previously reported ACA reaction catalyzed using CuOTf combined with NHC•AgI complex 1. It was revealed that the stereocontrol of the catalytic ACA reaction depended on the order of the addition of the substrates. Additionally, the chiral NHC ligand precursors, substrates, the relationship between the catalyst ee (eecat) and product ee (eepro), and halogen counter anion were completely evaluated. These results suggested that the catalytic performance of the CuOTf/4 system was comparable with that of the CuOTf/1 system. Furthermore, to gain knowledge of the Cu species generated using CuOTf and NHC ligand precursor, the reaction of CuOTf with 1 was investigated. Although obtaining the corresponding NHC•CuX species failed, the corresponding NHC•AuCl complex 11 could be synthesized by allowing 1 to react with AuCl•SMe2.