Dalton Transactions Blog

The formation of peptide or protein aggregates is a common feature of many different forms of neurodegenerative disorders including Alzheimer’s disease, Parkinson’s disease and prion diseases. It is also widely accepted that various metal ions can play a significant role in the conformational changes of these peptides/proteins.

In this HOT article, Kállay and co-workers report on the synthesis and study of the copper complexes of rIAPP fragments. First of all the terminally protected tridecapeptide rIAPP(17–29) was investigated in which the potentially metal binding amino acid residues are located in the N-terminus. The surprisingly high affinity of this peptide towards complexation with copper(II) promoted a systematic study on the shorter fragments including rIAPP(17–22) (Ac-VRSSNN-NH₂), rIAPP(17–20) (Ac-VRSS-NH₂), its mutant peptides (Ac-VASSNH₂ and Ac-VRAA-NH₂) and rIAPP(19–22) (Ac-SSNN-NH₂). The peptides can be classified into two different categories: (i) the tetrapeptides Ac-VRSS-NH₂, Ac-VASS-NH₂ and Ac-VRAA-NH₂ can interact with copper(II) only under strongly alkaline conditions (pH > 10.0) and the formation of only one species with four amide nitrogen coordination can be detected; (ii) the peptides Ac-VRSSNNLGPVLPP-NH₂, Ac-VRSSNN-NH₂ and Ac-SSNN-NH₂ can form complexes above pH 6.0 with the major stoichiometries [CuH₋₂L], [CuH₋₃L]⁻ and [CuH₋₄L]²⁻. The data supports the idea that  rIAPP(17–29) can interact with copper(II) ions under physiological conditions and the SSNN tetrapeptide fragment can be considered as the shortest sequence responsible for metal binding.

Read more for FREE until 21st September at:
Copper(II) complexes of rat amylin fragments
Csilla Kállay, Ágnes Dávid, Sarolta Timári, Eszter Márta Nagy, Daniele Sanna, Eugenio Garribba, Giovanni Micera, Paolo De Bona, Giuseppe Pappalardo, Enrico Rizzarelli and Imre Sóvágó
Dalton Trans., 2011, Advance Article
DOI: 10.1039/C1DT10835B

Peter G. Edwards and colleagues from Cardiff University and the University of Southampton investigate P3 and As3 macrocycles on an iron template in this Dalton Transactions Hot article.

The authors look at 9-membered triphospha- and triarsamacrocycles with unsaturated benzo-backbones that they make using a [Cp^RFe]⁺ template.

The complexes from an interesting ‘cup-shaped’ cavity, which could potentially accommodate anions.

Read the full article for FREE until 21st September to find out more…

Iron(II) template synthesis of benzannulated triphospha- and triarsamacrocycles
Thomas Albers, Julia Baker (neé Johnstone), Simon J. Coles, Peter G. Edwards, Benson Kariuki and Paul D. Newman
Dalton Trans., 2011, DOI: 10.1039/C0DT01724H

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A new system, using a solid state catalyst, to remove impurities from petroleum has been developed by US scientists.

With current oil consumption levels high, light crude oil reserves will be exhausted, giving way to heavy and extra heavy bitumen refinery feeds. These contain a higher proportion of large polycyclic hydrocarbons, together with N- and S-heteroaromatics, which need to be removed or transformed, without catalyst poisoning. Current methods to do this require high temperatures and pressures.

The catalyst made by the researchers, composed of ruthenium nanoparticles immobilised on a polymer, hydrogenates aromatic compounds under moderate conditions with no poisoning.

Hydrogenation of arenes and N-heteroaromatic compounds over ruthenium nanoparticles on poly(4-vinylpyridine): a versatile catalyst operating by a substrate-dependent dual site mechanism
Minfeng Fang, Nataliya Machalaba and Roberto A. Sánchez-Delgado
Dalton Trans., 2011, DOI: 10.1039/C1DT10801H

Read this Dalton Transactions Hot article to find out about how uranium can reductively couple carbon monoxide, an interesting reaction in Fischer-Tropsch chemistry.

Jennifer Green and co-workers at Oxford University use density functional theory to look at the reductive di- tri- and tetramerization of CO. They look at the linear yne diolate complex which forms if there is no further CO to react with the dimeric C₂O₂ reaction intermediate, amongst other intermediates. With the insight provided by this computational study a better understanding can be gained of Fischer-Tropsch chemistry.

Read the full article for FREE until 15th September to find out more…

Reductive coupling of carbon monoxide by U(III) complexes—a computational study
Georgina Aitken, Nilay Hazari, Alistair S. P. Frey, F. Geoffrey N. Cloke, O. Summerscales and Jennifer C. Green
Dalton Trans., 2011, DOI: 10.1039/C1DT10692A

Read Leonard Lindoy’s latest supramolecular host-guest formation research in this Dalton Transactions Hot article.

Lindoy’s group make helicates and tetrahedral Ni and Fe host complexes from quaterpyridine ligand derivatives, and look how they can control which products they get. They are particularly interested in the cavity volumes of the tetrahedral cages they make, and hope in the future to look at the host-guest chemistry of the cages with the largest cavities.

Read the full article for FREE to find out more…

New nickel(II) and iron(II) helicates and tetrahedra derived from expanded quaterpyridines
Christopher R. K. Glasson, George V. Meehan, Cherie A. Motti, Jack K. Clegg, Peter Turner, Paul Jensen and Leonard F. Lindoy
Dalton Trans., 2011, DOI: 10.1039/C1DT10667H

This manuscript will be part of the issue celebrating the 40th Anniversary of Dalton Transactions. Click on the 40th Anniversary link on the right hand side to find out what else we are doing.

Radostina Stoyanova and co-workers have carried out detailed analysis of the zero-field splitting parameters (ZFS) of Mn⁴⁺ and Fe³⁺ ions in LiAlO₂ with a layered structure are analyzed both experimentally and theoretically by using high-frequency electron paramagnetic resonance spectroscopy, Neuman superposition model (NSM), DFT and multiconfigurational calculations and reported their work in the recent Dalton Transactions Hot Article.

But why are they doing this analysis you might ask? Well, oxide-based materials, like doped layered LiAlO₂, are important components of lithium ion batteries. In order to optimise materials like this for energy storage applications it is necssary to look at their atomic arrangement on a very small scale as Stoyanova and colleagues successfully carry out and report in this paper, which you can read for free until the 5th September.

Local structure of Mn⁴⁺ and Fe³⁺ spin probes in layered LiAlO₂ oxide by modelling of zero-field splitting parameters
Radostina Stoyanova, Anne-Laure Barra, Meglena Yoncheva, Elitza Kuzmanova and Ekaterina Zhecheva
Dalton Trans., 2011, DOI: 10.1039/C1DT10929D

In this Dalton Transactions Hot article Andrew Burrows and Frank Marken and colleagues from the University of Bath make MOFs of zinc^II and aluminium^III dicarboxylate frameworks with covalently attached ferrocene functional redox groups.

Burrows uses post-synthetic modification to attach the ferrocenyl groups to the frameworks using an amine to amide functional group interconversion. The metal-organic frameworks they made were found to have novel redox active properties, which is an interesting development in the search for designer-electocatalysts.

Read the full article for FREE to find out more, until 30th August…

Metal–organic frameworks post-synthetically modified with ferrocenyl groups: framework effects on redox processes and surface conduction
Jonathan E. Halls, Alberto Hernán-Gómez, Andrew D. Burrows and Frank Marken
Dalton Trans., 2011, DOI: 10.1039/C1DT10734H

Read more about Andrew Burrows’ research by visiting his University of Bath homepage.