Chemical Science Blog

All of the articles below are free to access until 14th May

Boron–boron J coupling constants are unique probes of electronic structure: a solid-state NMR and molecular orbital study
Frédéric A. Perras and David L. Bryce  
Chem. Sci., 2014, Advance Article
DOI: 10.1039/C4SC00603H, Edge Article

Disubstituted sialic acid ligands targeting siglecs CD33 and CD22 associated with myeloid leukaemias and B cell lymphomas
Cory D. Rillahan, Matthew S. Macauley, Erik Schwartz, Yuan He, Ryan McBride, Britni M. Arlian, Janani Rangarajan, Valery V. Fokin and James C. Paulson  
Chem. Sci., 2014, Advance Article
DOI: 10.1039/C4SC00451E, Edge Article

Solvatochromic AIE luminogens as supersensitive water detectors in organic solvents and highly efficient cyanide chemosensors in water
Yuping Zhang, Dongdong Li, Yi Li and Jihong Yu  
Chem. Sci., 2014, Accepted Manuscript
DOI: 10.1039/C4SC00721B, Edge Article

Catalytic enantioselective synthesis of 2-aryl-chromenes
Bi-Shun Zeng, Xinyi Yu, Paul W. Siu and Karl A. Scheidt  
Chem. Sci., 2014, Advance Article
DOI: 10.1039/C4SC00423J, Edge Article

All of the articles below are free to access until 13th April 

Turn-ON fluorescent affinity labeling using a small bifunctional O-nitrobenzoxadiazole unit
Takao Yamaguchi, Miwako Asanuma, Shuichi Nakanishi, Yohei Saito, Masateru Okazaki, Kosuke Dodo and Mikiko Sodeoka
Chem. Sci., 2014,5, 1021-1029
DOI: 10.1039/C3SC52704B, Edge Article  

DNAzyme-based 2:1 and 4:1 multiplexers and 1:2 demultiplexer
Ron Orbach, Francoise Remacle, R. D. Levine and Itamar Willner
Chem. Sci., 2014,5, 1074-1081
DOI: 10.1039/C3SC52752B, Edge Article  

Incorporation of electrically charged N-alkyl amino acids into ribosomally synthesized peptides via post-translational conversion
Takashi Kawakami, Toru Sasaki, Patrick C. Reid and Hiroshi Murakami
Chem. Sci., 2014,5, 887-893
DOI: 10.1039/C3SC52744A, Edge Article   

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Montelukast works by blocking the action of chemicals released by the body as part of allergic and inflammatory reactions

Scientists based in the US have devised a new way to make Montelukast, a drug used in the treatment of asthma and seasonal allergies.

Asthma is a chronic inflammatory disease of the airways which affects up to 300 million people worldwide and caused 250,000 deaths in 2011. Although there is no cure for asthma, symptoms can be managed through the use of fast-acting medication to treat acute attacks, and long-term control achieved using inhaled corticosteroids, sometimes in conjunction with a leukotriene antagonist, such as Montelukast.

Read the full article in Chemistry World»

Read the original journal article in Chemical Science – it’s free to access until 28th April:
Iron catalyzed enantioselective sulfa-Michael addition: a four-step synthesis of the anti-asthma agent Montelukast
James D. White and Subrata Shaw  
Chem. Sci., 2014, DOI: 10.1039/C4SC00051J

The self-assembled multivalent complexes (blue) can induce blood clotting by binding to heparin (green)

Recovering from operations could become easier thanks to a self-assembling multivalent heparin binding agent being developed by scientists in the UK, Italy and Spain. 

During some surgical procedures, heparin is given to patients to prevent blood clots from forming by thinning their blood. Protamine is then given following surgery to inactivate heparin and allow healing to begin. However, this drug can have dangerous side-effects, so is often only used in small doses but this can lead to bleeding and further surgery being required. Spending time at the hospital after his husband’s lung transplant gave David Smith at the University of York personal insight into the problems of using protamine and inspired him and his team to devise an alternative. 

The Self-Assembled Multivalent complexes they have created, called SAMul in honour of Smith’s husband, Sam, are made up of molecules containing an ionic heparin binding part and a hydrophobic part. In biological media, the hydrophobic section induces the individual molecules to aggregate into micelles, with multiple heparin binding sites exposed on the micelle surface. This multivalency increases the micelles’ ability to bind heparin. Incorporating an ester linker into the molecules mean they will slowly degrade via hydrolysis if an excess is used, minimising any side effects. 

Read the full article in Chemistry World» 

Read the original journal article in Chemical Science – it’s free to download until 26th March:
Nanoscale self-assembled multivalent (SAMul) heparin binders in highly competitive, biologically relevant, aqueous media
Stephen M. Bromfield, Paola Posocco, Ching W. Chan, Marcelo Calderon, Scott E. Guimond, Jeremy E. Turnbull, Sabrina Pricl and David K. Smith  
Chem. Sci., 2014, Advance Article, DOI: 10.1039/C4SC00298A, Edge Article

An international team of scientists have made a material capable of both piezoelectric and ferromagnetic behaviour. The discovery opens up the possibility of a new class of polarisable and magnetic compounds, and could lead to better devices for storing electronic information.

New data storage techniques are in demand to meet the ever-increasing use of digital information. Present methods rely on the writing and reading of computer bits by electricity, and require a high electrical current. This generates heat so the amount of data that can be stored on a drive is limited by how efficiently the device can be cooled.

The alternating layers of YFeO3 and LaFeO3 give the structure its unusual polarisation properties

One possible solution is to read the bits electronically but write them magnetically, thereby removing the need for high electrical currents and cooling mechanisms. This method requires a material in which the electrical polarisation can be controlled by changing the magnetic field, but so far no such materials have been discovered.

A crucial first step is to find materials that can display both electrical polarisation and magnetisation at the same time, known as multiferroic materials. Multiferroic materials are challenging to make as there is often competition between their electronic structure requirements, which give rise to each property, and they also have strict symmetry conditions for the overall crystal structure of the material, which must be fulfilled.

Electrical polarisation is impossible in materials with a centre of inversion, so breaking the inversion symmetry of the material is crucial for electrical polarisation to occur. As this is a very common property of many materials’ crystal structures, this limits the number of potential compounds capable of showing multiferroic behaviour, and remains a barrier to the possibility of magnetic data writing.

However, the new approach described by Matthew Rosseinsky, from the University of Liverpool in the UK, and colleagues, side-steps this problem by showing how two centrosymmetric perovskite materials can be combined in such a way as to break the inversion symmetry of the whole material. Depositing alternating layers of yttrium iron oxide (YFeO₃) and lanthanum iron oxide (LaFeO₃) using a laser produces a larger heterostructure in which the alternating layers of Y³⁺ and La³⁺ cations combine with the tilting of the FeO₆ octahedra to remove the centre of inversion symmetry.

Read the full article in Chemistry World»

Read the original journal article in Chemical Science – it’s free to download until 25th March:
Engineered spatial inversion symmetry breaking in an oxide heterostructure built from isosymmetric room-temperature magnetically ordered components
J. Alaria, P. Borisov, M. S. Dyer, T. D. Manning, S. Lepadatu, M. G. Cain, E. D. Mishina, N. E. Sherstyuk, N. A. Ilyin, J. Hadermann, D. Lederman, J. B. Claridge and M. J. Rosseinsky  
Chem. Sci., 2014, Advance Article, DOI: 10.1039/C3SC53248H, Edge Article

The vaccine ingredients self-assemble into a liposome

A Streptococcus pneumonia vaccine with fewer sugar units and no antigenic protein is not only easier to produce but could also induce a superior immune response to the vaccine currently in clinical use.

Cells are sugar coated; bacteria, parasite and tumour cells often have different carbohydrates to host cells on their surface. Since the immune system recognises these, vaccines can be made of carbohydrates. However, to gain long-term immunity, a protein that provokes an immune response by activating T cells is usually included too. The protein is covalently attached to the carbohydrate, but synthesis of such vaccines can be tricky.

Shenglou Deng, of Brigham Young University in Utah, US, and co-workers, made two main changes with their new vaccine: instead of using the whole sugar on the pathogen’s coat they took a small section of it – an oligosaccharide – and instead of joining this to a protein, they combined it with a lipid that targets only one type of T cell – natural killer T (NKT) cells. Two long chain lipids, to give the vaccine structure, were also added to the vaccine’s ingredients.

Read the full article in Chemistry World»

Read the original journal article in Chemical Science – it’s free to access until 19th March:
A peptide-free, liposome-based oligosaccharide vaccine, adjuvanted with a natural killer T cell antigen, generates robust antibody responses in vivo
S. Deng, L. Bai, R. Reboulet, R. Matthew, D. A. Engler, L. Teyton, A. Bendelac and P. B. Savage  
Chem. Sci., 2014, Advance Article, DOI: 10.1039/C3SC53471E