Dalton Transactions Blog

Combining the properties of transition metals with the dynamic properties of mechanically interlocked molecules has the potential to create chemical systems with a variety of unique applications, the scope of which, are just beginning to be explored. However, the synthesis of such sophisticated ligands and their transition metal complexes still present a major challenge for synthetic inorganic chemists.

In their Dalton Transactions Hot Article Stephen Loeb and Darren Mercer introduce a practical method of incorporating inert metal ions directly into an interlocked species by constructing a ligand that is itself a permanently interlocked rotaxane. Read more about this clever synthesis in their Dalton Transactions Hot Communication:

Complexes of a [2]rotaxane ligand with terminal terpyridine groups
Darren J. Mercer and Stephen J. Loeb
Dalton Trans., 2011, 40, 6385-6387DOI: 10.1039/C1DT10569H

In this Dalton Transactions Hot Article, a team from the University of Florence, and Annie Powell from Karlsruhe Institute of Technology carried out a single crystal EPR study on a molecular nanomagnet (MNM).

The study was aimed at confirming the nature of the ground spin state and the fine determination of the magnetic anisotropy of an Fe₁₉ cluster.

Fe-based MNMs like the one reported in this study can be used as models for natural systems and provide clues for understanding the growth of inorganic cores in proteins.

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Single crystal EPR study at 95 GHz of a large Fe based molecular nanomagnet: toward the structuring of magnetic nanoparticle properties
L. Castelli, M. Fittipaldi, A. K. Powell, D. Gatteschi and L. Sorace
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10311C, Paper

In this Dalton Transactions Hot Article, Fenghua Chen and colleagues prepared multifunctional nanoparticles composed of a Fe₃O₄–Au nanocomposite core and a porous silica shell.

The aim of the synthesis was to maintain the magnetic and optical properties of the nanocomposite while ensuring stability.

The catalytic activity of the product was tested on reduction of o-nitroaniline to benzenediamine by NaBH₄. The core/shell nanoparticles showed improved activity compared to Fe₃O₄–Au composite nanoparticles alone.

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Multifunctional nanocomposites constructed from Fe₃O₄–Au nanoparticle cores and a porous silica shell in the solution phase
Fenghua Chen, Qingtao Chen, Shaoming Fang, Yu’an Sun, Zhijun Chen, Gang Xie and Yaping Du
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10374A, Paper

In this HOT article, Ian Dance examines afresh the relationships between CO and H on nitrogenase cofactors following the recent finding that vanadium nitrogenase and modified molybdenum nitrogenase reduce CO to hydrocarbons. In order to assist the interpretation of kinetic infrared spectral data, vibrational frequencies and modes have been calculated for a variety of possible structures in which FeMo-co bears H atoms, or CO ligands, or both.

Fe–H stretching frequencies occur in the same spectral window as the C–O stretching frequencies, with lesser intensity, and both stretches are strongly coupled in some structures. Symmetrical bridging of CO between two Fe atoms of FeMo-co is destabilised by the presence of other ligands on Fe, and the reason for this is evident. Two results for bound formyl, HCO, are reported. These calculations of reference structures allow some interpretation of existing experimental spectra, but, perhaps more significantly, they suggest further kinetic infrared experiments to elucidate the chemical mechanism of catalysis by nitrogenase under normal turnover conditions.

Read more about nitrogenase mechanisms for FREE until 22nd June at:

Calculated vibrational frequencies for FeMo-co, the active site of nitrogenase, bearing hydrogen atoms and carbon monoxide
Ian Dance
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10505

In this HOT article, Wu and Yamauchi et al., reported the synthesis of highly ordered mesoporous alumina thin films existing both as P6₃/mmc and Fm-3m mesostructures by using triblock copolymer Pluronic P123 as a structure-directing agent and their framework crystallization to γ-alumina phase at 1000 °C. During the crystallization process, large uniaxial shrinkage occurred along the direction perpendicular to the substrate with the retention of horizontal mesoscale periodicity, thereby forming vertically oriented nanopillars on the film surface.

The well-ordered arrangement of the nanopillars can produce vertical mesoporosity in the films.This porosity can be regarded as “inverse mesospace” of a 2D hexagonal structure with “mesochannels” running perpendicular to the substrate.  This vertical mesoporosity in films is very exciting as it can enhance pore accessibility broadening the potential applications of these already much studied mesoporous metal oxides.

Read more about these exciting developments for FREE until 22nd June at:

Synthesis of highly ordered mesoporous alumina thin films and their framework crystallization to gamma-alumina phase
Xiangfen Jiang, Hamid Oveisi, Yoshihiro Nemoto, Norihiro Suzuki, Kevin C.-W. Wu and Yusuke Yamauchi
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10166H

In their Dalton Transactions Hot Article, Lauren Huffman and Shannon Stahl investigate an unusual trans C–N reductive elimination reaction from a square-planar aryl-CuIII complex. Their research provides valuable fundamental insights into the emerging area associated with the organometallic chemistry of copper(III).

Available to read for free until the 12th June – strike while the articles hot!

Mechanistic analysis of trans C–N reductive elimination from a square-planar macrocyclic aryl-copper(III) complex
Lauren M. Huffman and Shannon S. Stahl
Dalton Trans., 2011, DOI: 10.1039/C1DT10463B, Paper

Christopher F. Blanford’s group from the University of Oxford have solved the x-ray structure for bilirubin oxidase from the plant pathogen Myrothecium verrucaria. This enzyme efficiently catalyses the oxidation of bilirubin to biliverdin, and can be used in O₂ reduction.

The authors look at the environment of the copper in the enzyme, to better understand and improve its stability  when is attached to the carbon surface of a pyrolytic graphite electrode. When attached to an electrode it can act as a cathode catalyst, and this enhanced electrocatalytic response of the material is an important step in developing viable low-temperature bio-fuel cells.

Read the full article for FREE to find out more about bilirubin oxidase…

Bilirubin oxidase from Myrothecium verrucaria: X-ray determination of the complete crystal structure and a rational surface modification for enhanced electrocatalytic O2 reduction
James A. Cracknell, Thomas P. McNamara, Edward D. Lowe and Christopher F. Blanford
Dalton Trans., 2011, DOI: 10.1039/C0DT01403F