Catalytic deuterium exchange reactions with organics. XXIV. Electron spin resonance studies of adsorption on platinum oxide

1966 ◽  
Vol 19 (4) ◽  
pp. 529 ◽  
Author(s):  
IT Ernst ◽  
JL Garnett ◽  
WA Sollich-Baumgartner
Keyword(s):  
Transition Metal Oxides ◽  
Hydrogen Exchange ◽  
Platinum Oxide ◽  
Active Species ◽  
Paramagnetic Species ◽  
Charge Transfer Complexes ◽  
Severe Reaction ◽  
Exchange Reactions ◽  
Spin Resonance ◽  
Solid Liquid

The formation of paramagnetic species on catalyst surfaces at room temperature through the interaction of polynuclear aromatics in solid, liquid, or solute form with hydrated platinum oxide (PtO2,2H2O) is reported. The results are attributed to the formation of charge-transfer complexes, where the transferred electrons couple weakly, forming essentially a "diradicaloid" complex with a low-lying, thermally populated, triplet state. The effect of solvent, particle size, oxygen, water of crystallization, and temperature on the generation and stability of these e.s.r. active species has been investigated. The possible importance of these paramagnetic species in catalytic self-activation and hydrogen exchange reactions has been discussed. The following Group VIII transition metal oxides gave no e.s.r. spectra under relatively severe reaction conditions such as 1 hr at 120�: PdO; Ru02,2H20; RuO2; Rh2O3; IrO2,2H2O; ReO2; and NiO.

Catalytic deuterium exchange reactions with organics. XXVII. The alkylbenzenes on self-activated Group VIII transition metals

1966 ◽  
Vol 19 (12) ◽  
pp. 2299 ◽  
Author(s):  
BD Fisher ◽  
JL Garnett
Keyword(s):  
Transition Metal Oxides ◽  
Exchange Process ◽  
Kinetic Studies ◽  
Platinum Oxide ◽  
Activation Process ◽  
Group Viii ◽  
Exchange Reactions ◽  
Π Complex ◽  
Cis And Trans ◽  
In Cis

Exchange reactions between heavy water and the alkylbenzenes have been investigated on the following self-activated Group VIII transition metal oxides: PtO2,2H2O; PdO; Rh2O3; IrO2,2H2O; RuO2,H2O; ReO2; and Ni2O3. All oxides except Ni2O3 are self-activated by benzene up to 180�. Order of ease of self-activation is Pt > Pd > Rh, Ru, Ir > Re > Ni. Trends in deuteration rates of the alkylbenzenes on self-activated platinum oxide are generally similar to those obtained on hydrogen prereduced platinum. At 130�, some differences in reactivity are observed and these are attributed to reagent displacement effects from the presence of small percentages of dimer (1%) associated with the self-activation process. Compared with hydrogen prereduced catalysts, significant differences in isotope orientation are observed with certain alkylbenzenes on self-activated catalysts. Multiple deuteration effects which are accentuated on self-activated catalysts have been used to confirm isotope orientation and also the participation of a π-complex mechanism for the exchange process. Isomerization and exchange in cis- and trans-stilbenes on self-activated platinum have also been interpreted by the dissociative n-complex substitution mechanism. The advantages of self-activated catalysts in general deuterium and tritium labelling work have been evaluated. Possible correlations between exchange results and electron spin resonance data for charge-transfer adsorption on the above oxides are discussed. Preliminary kinetic studies with self-activation are also reported.

Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und n-Pentylbenzol in der Gasphase / Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes

1979 ◽  
Vol 34 (3) ◽  
pp. 495-501 ◽  
Author(s):  
C. Wesdemiotis ◽  
H. Schwarz ◽  
C. C. Van de Sande ◽  
F. Van Gaever
Keyword(s):  
Hydrogen Exchange ◽  
Closed Shell ◽  
Open Shell ◽  
Molecular Ions ◽  
Exchange Reactions ◽  
Intramolecular Exchange ◽  
Carbon Carbon Bond ◽  
Exchange Processes ◽  
Reaction Channels ◽  
Alkyl Benzenes

Abstract The investigation of several 13carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations.

Catalytic deuterium exchange reactions with organics. XIII. Characteristic reactions of the Group VIII transition metals

1965 ◽  
Vol 18 (7) ◽  
pp. 1003 ◽  
Author(s):  
JL Garnett ◽  
WA Sollich
Keyword(s):  
Transition Metal ◽  
Hydrogen Exchange ◽  
Deuterium Oxide ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Group Viii ◽  
Exchange Reactions ◽  
Substitution Mechanism ◽  
Π Complex ◽  
Complex Adsorption

Activation procedures and hydrogen exchange reactions with six Group VIII transition metal catalysts (Pt, Pd, Ru, Rh, Ir, Ni) are reported for three characteristic reaction systems: (i) deuterium oxide/benzene, (ii) deuterium oxide/naphthalene, and (iii) deuterium oxide/n-octane. Results of these exchange reactions indicate that both π-complex adsorption and the dissociative π-complex substitution mechanism previously established for platinum are applicable to other Group VIII transition metal catalysts. For general catalytic labelling with isotopic hydrogen, platinum was found to be the most efficient of the catalysts investigated.

An all-in-one approach for synthesis and functionalization of nano colloidal gold with acetylacetone

2021 ◽  
Author(s):  
Li Zhang ◽  
Hongcen Zheng ◽  
Yonghai Gan ◽  
Bingdang Wu ◽  
Zhihao Chen ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Ligand Exchange ◽  
Fold Increase ◽  
Charge Transfer Complexes ◽  
Photochemical Property ◽  
Exchange Reactions ◽  
Ligand Exchange Reaction ◽  
Enhanced Photoluminescence ◽  
Good Imaging ◽  
Imaging Probes

Abstract Controllable synthesis, proper dispersion, and feasible functionalization are crucial requirements for the application of nanomaterials in many scenarios. Here, we report an all-in-one approach for the synthesis and functionalization of gold nanoparticles (AuNPs) with the simplest β-diketone, acetylacetone (AcAc). With this approach, the particle size of the resultant AuNPs was tunable by simply adjusting the light intensity or AcAc dosage. Moreover, owing to the capping role of AcAc, the resultant AuNPs could be stably dispersed in water for a year without obvious change in morphology and photochemical property. Formation of ligand to metal charge transfer complexes was found to play an important role in the redox conversion of Au with AcAc. Meanwhile, the moderate complexation ability enables the surface AcAc on the AuNPs to undergo ligand exchange reactions. With the aid of Ag+, the AuNPs underwent ligand exchange reaction with glutathione and exhibited enhanced photoluminescence (PL) with a maximum of 22-fold increase in PL intensity. The PL response was linear to the concentration of glutathione in the range of 0~500 μM. Such a ligand exchange reaction makes the obtained AuNPs being good imaging probes. To the best of our knowledge, this is the first work on illustrating the roles of AcAc as a multifunctional ligand in fabrication of NPs, which sheds new light on the surface modulation in synthesis of nanomaterials.

Applications of ESR to Carbonaceous Materials

1982 ◽  
Vol 36 (1) ◽  
pp. 52-57 ◽  
Author(s):  
L. S. Singer ◽  
I. C. Lewis
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Low Temperature ◽  
Electron Spin ◽  
Paramagnetic Species ◽  
Carbonaceous Materials ◽  
Conduction Electrons ◽  
Spin Resonance ◽  
Higher Temperature ◽  
Low Temperature Pyrolysis

The applications of electron spin resonance (ESR) to carbonaceous materials are reviewed. The stable paramagnetic species observed in the products of low-temperature pyrolysis are odd-alternate neutral free radicals, whereas the unpaired spins of higher temperature carbons and graphites are primarily conduction electrons. The variety of ESR properties and phenomena requires special attention to techniques of measurement and interpretations of results. The relevance to the carbonization process of the free radicals observed by ESR is also discussed.

Magnetic resonance studies of metal–olefin complexes. I. Electron spin resonance spectra of γ-irradiated silver perchlorate cycloalkene complexes

1970 ◽  
Vol 48 (17) ◽  
pp. 2740-2744 ◽  
Author(s):  
D. R. Gee ◽  
K. E. Russell ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Magnetic Resonance ◽  
Spin Density ◽  
Room Temperature ◽  
Paramagnetic Species ◽  
Magnetic Resonance Studies ◽  
Silver Perchlorate ◽  
Spin Resonance ◽  
The Stability ◽  
Polycrystalline Silver

Paramagnetic species have been detected in γ-irradiated polycrystalline silver perchlorate – cycloalkene complexes at room temperature and identified as Ag+ cycloalkenyl radicals, with spin density on Ag decreasing from 4.6 to 1.5% with increasing size of the cycloalkenyl ring. The extent of the spin density on Ag increases with the stability of the parent complexes.

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