As I have written in previous posts, the nano scale provides us with many different physical characteristics. Although hard to get your head round, taking particles 10000000000 times smaller than a metre can drastically change what we would thing are usual. For example, gold nanoparticles appear red or purple due to the difference in light wavelength that they interact with.
Well now theres a shape memory polymer! Research carried out in China has developed a polymer that can become tangled but returns to its original shape when put into water. This polymer has combined the advantages of the macro and nano scale. It is made from chitosan (a linear polysaccharide) and picks up surrounding nanoparticles in solution through electrostatic bonds after it has been shaped by a mould and ice has pushed the chitosan chains into a fixed structure.
This discovery can be used with a wide range of nanoparticles, giving many functions. If you then immerse the polymer in water it remains to its original shape - amazing!
September 11, 2013
August 15, 2013
Agostic isomerism - myth or reality?
We've all seen the colourful solids that organometallics can produce but what about two-tone crystals?!
A breakthrough in organometallic chemistry has shown that agostic isomers do, indeed, exist! An agostic interaction is one of a coordinatively unsaturated transition metal (a 16-electron complex, rather than the 18-electron norm) and a carbon-hydrogen bond. This is possible since the two electrons from the hydrogen atom enter the empty d-orbital of the transition metal.
As you may know, organometallics is a particularly useful area of chemistry when it comes to catalysis. This was how they were discovered. Scientists in the US carried out a catalytic run and recorded possible evidence of a 16-electron complex. We know these would be unstable and therefore extremely difficult to isolate. However, the agostic interactions stable this intermediate and the scientists were able to isolate the species as a crystal since interconversion between the isomers happened much slower than it would in solution.
Interesting stuff, and a real breakthrough!
A breakthrough in organometallic chemistry has shown that agostic isomers do, indeed, exist! An agostic interaction is one of a coordinatively unsaturated transition metal (a 16-electron complex, rather than the 18-electron norm) and a carbon-hydrogen bond. This is possible since the two electrons from the hydrogen atom enter the empty d-orbital of the transition metal.
As you may know, organometallics is a particularly useful area of chemistry when it comes to catalysis. This was how they were discovered. Scientists in the US carried out a catalytic run and recorded possible evidence of a 16-electron complex. We know these would be unstable and therefore extremely difficult to isolate. However, the agostic interactions stable this intermediate and the scientists were able to isolate the species as a crystal since interconversion between the isomers happened much slower than it would in solution.
Interesting stuff, and a real breakthrough!
July 2, 2013
Thalidomide's comeback!
Back in the 1950s, thalidomide was introduced as a sleeping pill and was also well known for relieving symptoms of morning sickness in pregnant women. Thalidomide was taken off the shelves in 1962 when it was tragically discovered that thalidomide caused birth defects.
However, thalidomide is now back on the scene with a team mate - turmeric (the spice!). It has been discovered that this team can help fight multiple myeloma which is the second most common type of blood cancer.
Thalidomide works by disturbing tumour cells in the bone marrow however the drug disintegrates when in the body. Curcumin, the pigment that gives turmeric it's yellow colour, has also been found to be active against cancer but has poor water solubility. Combining these together to make a hybrid compound has improved water solubility, does not disintegrate in the body and is even more active against myeloma. Win win!
However, thalidomide is now back on the scene with a team mate - turmeric (the spice!). It has been discovered that this team can help fight multiple myeloma which is the second most common type of blood cancer.
Thalidomide works by disturbing tumour cells in the bone marrow however the drug disintegrates when in the body. Curcumin, the pigment that gives turmeric it's yellow colour, has also been found to be active against cancer but has poor water solubility. Combining these together to make a hybrid compound has improved water solubility, does not disintegrate in the body and is even more active against myeloma. Win win!
June 24, 2013
The secret of mercury's liquidity
Mercury's most famous property is that it is the only metal that is a liquid under standard conditions. Why is this?
An exceptionally low boiling and melting point for a heavy d-block element has always been explained by relativity but no hard evidence has been found to back this theory up. Until now!
Quantum mechanics were used by a team in New Zealand to calculate the heat capacity of mercury with and without considering relativity. The result of these calculations showed that when considering relativity, the melting point matched almost exactly on the experimental value of -39 degrees Celsius.
Now you may ask, what exactly is relativity?
The theory of relativity, by Albert Einstein, considers that in atoms, the velocity of the innermost electron is related to the nuclear charge. As nuclear charge increases, the atoms must move faster in order to prevent the innermost electrons from 'falling' into it. Going down the periodic table, this theory is shown as the electrons within the 1s orbital move faster and faster meaning that the element becomes heavier and the atomic radius decreases. This effect can stabilise orbitals or destabilise them (again by the theory of relativity).
In the case of mercury, bonds are not formed between surrounding atoms, the outer electrons stay within their orbital and do not become associated with other mercury atoms, forming weaker van der Waals bonds and therefore giving mercury a lower melting point than we would expect.
An exceptionally low boiling and melting point for a heavy d-block element has always been explained by relativity but no hard evidence has been found to back this theory up. Until now!
Quantum mechanics were used by a team in New Zealand to calculate the heat capacity of mercury with and without considering relativity. The result of these calculations showed that when considering relativity, the melting point matched almost exactly on the experimental value of -39 degrees Celsius.
Now you may ask, what exactly is relativity?
The theory of relativity, by Albert Einstein, considers that in atoms, the velocity of the innermost electron is related to the nuclear charge. As nuclear charge increases, the atoms must move faster in order to prevent the innermost electrons from 'falling' into it. Going down the periodic table, this theory is shown as the electrons within the 1s orbital move faster and faster meaning that the element becomes heavier and the atomic radius decreases. This effect can stabilise orbitals or destabilise them (again by the theory of relativity).
In the case of mercury, bonds are not formed between surrounding atoms, the outer electrons stay within their orbital and do not become associated with other mercury atoms, forming weaker van der Waals bonds and therefore giving mercury a lower melting point than we would expect.
April 14, 2013
The key to storing hydrogen?
As we all know, processes which will improve the 'greenness' of the Earth are becoming more and more important in the chemistry industry. Some UK scientists have now developed an electrolysis system which is able to split up water as it oxidises water into oxygen.
So how exactly is this 'green'? Well, normally in electrolysis like this, the hydrogen would be released as hydrogen gas just as the oxygen is released in it's diatomic form. However, scientists in Glasgow have found that using a phosphomolybdate anion, the hydrogen ions are able to be stored. This means that the next step in the electrolysis can be postponed until whenever! This could act as a renewable energy store for hydrogen fuel made by water electrolysis. The idea was to try to reverse the electrolysis process, giving pure hydrogen rather than pure oxygen. If this is developed then this could crack the renewable energy problem as well as improving the carbon footprint of the world!
So how exactly is this 'green'? Well, normally in electrolysis like this, the hydrogen would be released as hydrogen gas just as the oxygen is released in it's diatomic form. However, scientists in Glasgow have found that using a phosphomolybdate anion, the hydrogen ions are able to be stored. This means that the next step in the electrolysis can be postponed until whenever! This could act as a renewable energy store for hydrogen fuel made by water electrolysis. The idea was to try to reverse the electrolysis process, giving pure hydrogen rather than pure oxygen. If this is developed then this could crack the renewable energy problem as well as improving the carbon footprint of the world!
April 4, 2013
What makes you, you? The contents of your breath??
A recent study has shown that the metabolites (basically, the chemicals present) in exhaled breath could be just as useful to medics as the chemicals found in urine and blood when diagnosing illness. Exhaling breath is a great method - it's non-invasive and gives instant results.
So why is this the case? Studies have shown that there is a precise type of bacteria which cause lung infections exhaled in the breath as well as those in the presence of stomach cancer!
Could this really be as effective as a fingerprint? Are the chemicals present in the population's breath really that varied? I'm not too sure, as from first-hand experience i'm sure we can all say that after we've drank a cup of coffee or eaten some garlic bread, the contents of our breath does noticeably change.
However a study was done where the breath of some volunteers was repeatedly taken over a week or so. Mass spectroscopy was used to analyse the samples. Obviously there were some compounds present in all samples such as carbon dioxide and water vapour, however compounds which appeared to be unique to each volunteer remained constant throughout the study. I guess this means that we might all have a unique composition of breath, right?
This is really an interesting idea and I hope that it really goes somewhere as I think it could really improve the efficacy of diagnostic methods.
So why is this the case? Studies have shown that there is a precise type of bacteria which cause lung infections exhaled in the breath as well as those in the presence of stomach cancer!
Could this really be as effective as a fingerprint? Are the chemicals present in the population's breath really that varied? I'm not too sure, as from first-hand experience i'm sure we can all say that after we've drank a cup of coffee or eaten some garlic bread, the contents of our breath does noticeably change.
However a study was done where the breath of some volunteers was repeatedly taken over a week or so. Mass spectroscopy was used to analyse the samples. Obviously there were some compounds present in all samples such as carbon dioxide and water vapour, however compounds which appeared to be unique to each volunteer remained constant throughout the study. I guess this means that we might all have a unique composition of breath, right?
This is really an interesting idea and I hope that it really goes somewhere as I think it could really improve the efficacy of diagnostic methods.
April 2, 2013
Water of life!
One of the main reasons for bad health in third world countries is the lack of freshwater, making the need to purify water increasingly important.
Scientists from South Korea have been working on a method called capacitive deionisation to tackle this problem by desalinating water on a large scale. Capacitive deionisation uses an electric field as a sort of magnet to draw out the anions and cations present in water. You may be familiar with this method on a small scale, using electrodes. Capacitive deionisation is effectively the same method but on a much larger scale - scaling it up by increasing the flow of electrons in the system.
This idea holds great potential and although very simple I think it will be a breakthrough in tackling bad health in undeveloped countries, which really is great.
Scientists from South Korea have been working on a method called capacitive deionisation to tackle this problem by desalinating water on a large scale. Capacitive deionisation uses an electric field as a sort of magnet to draw out the anions and cations present in water. You may be familiar with this method on a small scale, using electrodes. Capacitive deionisation is effectively the same method but on a much larger scale - scaling it up by increasing the flow of electrons in the system.
This idea holds great potential and although very simple I think it will be a breakthrough in tackling bad health in undeveloped countries, which really is great.
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