Iron(II)-8-quinolinol/MCM-41-catalyzed phenol hydroxylation and reaction mechanism

Iron(II)-8-quinolino/MCM-41 is prepared. Its catalysis is studied in phenol hydroxylation using H2O2 (30%) as oxidant. The experiment shows that Iron(II)-8-quinolinol/MCM-41 has good catalytic activity and desired stability. Based on cyclic voltammetry, ESR, and UV-visible spectra studies of iron(II)-8-quinolinol complex in liquid phase, a radical substitution mechanism is proposed and used to demonstrate the experimental facts clearly. (C) 1997 Academic Press.

Structural and spectroscopic characterization of 2,2 `-methylenedi-8-quinolinol dihydrochloride dihydrate

The crystal structure of the title compound, a promising ligand for chelatoterapies in the treatment of Alzheimer`s disease, has been determined by single crystal X-ray diffractometry. The compound crystallized in the monoclinic space group C2/c with Z = 4. The dimeric 8-quinolinol molecule is sited on a crystallographic twofold axis passing through the CH(2) carbon atom that links the symmetry related molecular halves, giving rise to a two-bladed propeller-like conformation. The (1)H and (13)C NMR as well as the IFT-IR and Raman spectra of the compound were also recorded and are briefly discussed. Some comparisons with spectra of related species are made. (C) 2008 Elsevier B.V. All rights reserved.

Comportamento térmico do 8-quinolinol e seus nitro-derivados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal decomposition of the magnesium, zinc, lead and niobium chelates derived from 8-quinolinol

Solid M-Ox compounds, where M represents Mg(II), Zn(II), Pb(II) and NbO(III), and Ox is 8-quinolinol, have been prepared. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) and infrared absorption spectra (IR) have been used to characterize and to study the thermal stability and thermal decomposition of these compounds. © 1997 Akadémiai Kiadó.

White organic electroluminescence based on a new boron complex

A bright blue boron complex BPh2(pybm) containing 2-(2-pyridyl)benzimidazole ligand was designed and synthesized by using N, N-bidentate ligand instead of N, O-bidentate one such as 8-quinolinol. For three-layer LED devices with the configuration of ITO/NPB/BPh2(pybm)/Alq(3)/LiF/Al, the white light emission covering the whole visible region from 400 to 750 nm with the maximum brightness of 110 cd/m(2) and the luminous efficiency of 0.8 cd/A was observed.

Vibrational spectroscopy of phthalocyanine and naphthalocyanine in sandwich-type (na)phthalocyaninato and porphyrinato rare earth complexes: Part 14. The infrared and Raman characteristics of phthalocyanine in “pinwheel-like” homoleptic bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] rare earth(III) double-decker complexes

The infrared (IR) spectroscopic data and Raman spectroscopic properties for a series of 13 “pinwheel-like” homoleptic bis(phthalocyaninato) rare earth complexes M[Pc(α-OC5H11)4]2 [M = Y and Pr–Lu except Pm; H2Pc(α-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine] have been collected and comparatively studied. Both the IR and Raman spectra for M[Pc(α-OC5H11)4]2 are more complicated than those of homoleptic bis(phthalocyaninato) rare earth analogues, namely M(Pc)2 and M[Pc(OC8H17)8]2, but resemble (for IR) or are a bit more complicated (for Raman) than those of heteroleptic counterparts M(Pc)[Pc(α-OC5H11)4], revealing the decreased molecular symmetry of these double-decker compounds, namely S8. Except for the obvious splitting of the isoindole breathing band at 1110–1123 cm−1, the IR spectra of M[Pc(α-OC5H11)4]2 are quite similar to those of corresponding M(Pc)[Pc(α-OC5H11)4] and therefore are similarly assigned. With laser excitation at 633 nm, Raman bands derived from isoindole ring and aza stretchings in the range of 1300–1600 cm−1 are selectively intensified. The IR spectra reveal that the frequencies of pyrrole stretching and pyrrole stretching coupled with the symmetrical CH bending of –CH3 groups are sensitive to the rare earth ionic size, while the Raman technique shows that the bands due to the isoindole stretchings and the coupled pyrrole and aza stretchings are similarly affected. Nevertheless, the phthalocyanine monoanion radical Pc′− IR marker band of bis(phthalocyaninato) complexes involving the same rare earth ion is found to shift to lower energy in the order M(Pc)2 > M(Pc)[Pc(α-OC5H11)4] > M[Pc(α-OC5H11)4]2, revealing the weakened π–π interaction between the two phthalocyanine rings in the same order.

8-Ammonionaphthalene-2-sulfonate monohydrate : the zwitterionic hydrate of 1,7-Cleve's acid

The structure of 8-amino-2-naphthalenesulfonic acid monohydrate (1,7-Cleve's acid hydrate), C10H9NO3S.H2O, shows the presence of a sulfonate-aminium group zwitterion, both groups and the water molecule of solvation giving cyclic R3/3(8) intermolecular hydrogen-bonding interactions forming chains which extend down a axis of the unit cell. Additional peripheral associations, including weak aromatic ring pi-pi interactions [centroid-centroid distance 3.6299(15)A], result in a two-dimensional sheet structure.

Raman spectroscopic study of the uranyl sulphate mineral jáchymovite (UO2)8(SO4)(OH)14•13H2O

Raman spectra of jáchymovite, (UO2)8(SO4)(OH)14•13H2O, were studied, complemented with infrared spectra, and compared with published Raman and infrared spectra of uranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6] •6H2O. Bands related to the stretching and bending vibrations of (UO2)2+, (SO4)2-, (OH)- and water molecules were assigned. U-O bond lengths in uranyl and O-H…O hydrogen bond lengths were calculated from the Raman and infrared spectra.

Year 8, 9 and 10 students’ understanding and access of percent knowledge

This paper reports on Years 8, 9 and 10 students’ knowledge of percent problem types, use of diagrams, and type of solution strategy. Non- and semi-proficient students displayed the expected inflexible formula approach to solution but proficient students used a flexible mixture of estimation, number sense and trial and error instead of expected schema based methods.

A comparison of executive function in very preterm and term infants at 8 months corrected age

Executive function (EF) emerges in infancy and continues to develop throughout childhood. Executive dysfunction is believed to contribute to learning and attention problems in children at school age. Children born very preterm are more prone to these problems than their full-term peers.

Crystallographic characterization of the first reported crystalline form of the potent hallucinogen (R)-2-amino-1-(8-bromobenzo[1,2-b;5,4-b']difuran-4-yl)propane or `bromodragonfly': the 1:1 anhydrous proton-transfer compound with 3,5-dinitrosalicylic acid

The 1:1 proton-transfer compound of the potent substituted amphetamine hallucinogen (R)-1-(8-bromobenzo[1,2-b; 4,5-b']difuran-4-yl)-2-aminopropane (common trivial name 'bromodragonfly') with 3,5-dinitrosalicylic acid, 1-(8-bromobenzo[1,2-b;4,5-b']difuran-4-yl)-2-mmoniopropane 2-carboxy-4,6-dinitrophenolate, C13H13BrNO2+ C7H3N2O7- forms hydrogen-bonded cation-anion chain substructures comprising undulating head-to-tail anion chains formed through C(8) carboxyl O-H...O(nitro) associations and incorporating the aminium groups of the cations. The intra-chain cation-anion hydrogen-bonding associations feature proximal cyclic R33(8) interactions involving both a N+-H...O(phenolate) and the carboxyl O--H...O(nitro)associations. Also present are aromatic pi-pi ring interactions [minimum ring centroid separation, 3.566(2)A; inter-plane dihedral angle, 5.13(1)deg]. A lateral hydrogen-bonding interaction between the third aminium proton and a carboxyl O acceptor link the chain substructures giving a two-dimensional sheet structure. This determination represents the first of any form of this compound and confirms that it has the (R) absolute configuration. The atypical crystal stability is attributed both to the hydrogen-bonded chain substructures provided by the anions, which accommodate the aminium proton-donor groups of the cations and give cross-linking, and to the presence of cation--anion aromatic ring pi-pi interactions.