Organic & Biomolecular Chemistry Blog

Molecular self-assembly is an area of research that has spectacularly grown during the last two decades. The design of macromolecules that can adopt specific shapes and can act as receptors or host other molecules through non-covalent interactions has attracted particular attention.

One of the most popular building blocks in self assembly is calixarenes.  However, although calix-[4]-arenes have been widely studied in the field of molecular recognition, calix-[6]-arenes have not received as much attention due to the flexibility of their skeleton. The design of calix-[6]-arenes is still a challenging task.

In this paper, Stephane Le Gac, Ivan Jabin and co-workers take advantage of the versatility of the calix[6]arene functionalization together with the flexibility of its skeleton to create additional host-guest and host-host interactions. The resulting supramolecular receptors are unique since these additional interactions are reminiscent of intra-protein interactions in biological receptors.

If you want to find out more about these unique supramolecular receptors, download this HOT paper which is free to access until 23rd March.

Allosterically driven self-assemblies of interlocked calix[6]arene receptors
Stéphane Le Gac, Jean-François Picron, Olivia Reinaud and Ivan Jabin
Org. Biomol. Chem., 2011
DOI: 10.1039/C0OB01020K

Paul-Alain Jaffrès et al. from the Université de Brest report the synthesis of cationic lipo-phosphoramidates and lipo-thiophosphoramidates possessing the capacity to compact and transfect plasmid DNA. They investigated the effect of different functional groups on the physico-chemical properties of the lipids and found that they could fine tune the fluidity and fusogenicity of the liposomes. The best of the thiophosphoramidates synthesised provided highly efficient transfection—even at low charge levels, in contrast to the older phosphoramidates—demonstrating that a minor modification of the chemical structure of the cationic lipids may have a direct impact on their gene transfection ability.

As all our HOT articles, this is free to access for 4 weeks (until 23rd March).

Cationic lipo-thiophosphoramidates for gene delivery: synthesis, physico-chemical characterization and gene transfection activity – comparison with lipo-phosphoramidates
Aurore Fraix, Tristan Montier, Nathalie Carmoy, Damien Loizeau, Laure Burel-Deschamps, Tony Le Gall, Philippe Giamarchi, Hélène Couthon-Gourvès, Jean-Pierre Haelters, Pierre Lehn and Paul-Alain Jaffrès
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C0OB00981D

Computational tools for predicting the viability of reactions are invaluable for making synthetic chemists’ lives easier, and this latest study makes another valuable addition to the metaphorical toolbox.

It is assumed that microwave irradiation assists organic reactions, such as Diels-Alder reactions, by rapid heating of the reactants.  However, to date there are no computational studies which explain the role of microwaves on the course of these reactions.

Now, Maria Pilar Prieto and co-workers from the University of Castilla-La Mancha have used DFT to rationalise the activation of intramolecular Diels-Alder cycloaddition reactions under microwave conditions.  They  found that the activation energy of the reaction and the polarity of the stationary points on the reaction surface are good indicators of whether or not a reaction can be improved by microwave irradiation.

Read the full details of their findings online – the article is free to access for four weeks:

“In silico” mechanistic studies as predictive tools in microwave-assisted organic synthesis
A. M. Rodriguez, P. Prieto, A. de la Hoz and A. Díaz-Ortiz
Org. Biomol. Chem., 2011, Advance Article
DOI: 10.1039/C0OB01037E

Deazapurines are bicyclic heterocycles derived from purine where one nitrogen atom is replaced by a carbon. Although they have been widely studied in recent years, the mechanistic understanding of the biosynthesis of 7-deazapurines has always been intriguing.

There is a question that inevitably arise when looking at the biosynthetic pathway of deazapurines: Where does N-7 go? 

Now, Professor Moody and his group at University of Nottingham have solved this mystery by using a doubly labelled purine-adenine and following it up by NMR spectroscopy and mass spectrometry.
Their conclusions are supported and support a recent study published in Biochemistry.

If you want to find out more about the fate of this nitrogen and the mechanistic understanding of the biosynthesis of deazapurines, read this HOT paper which is free to access until 16th March.

7-Deazapurine biosynthesis: NMR study of toyocamycin biosynthesis in Streptomyces rimosus using 2-13C-7-15N-adenine
Ugo Battaglia, Jed E. Long, Mark S. Searle and Christopher J. Moody
Org. Biomol. Chem., 2011
DOI: 10.1039/C0OB01054E