Solar System: Life began on Mars - Boron and Molybdenum

New evidence has emerged which supports the long-debated theory that life on Earth may have started on Mars.

Professor Steven Benner will tell geochemists gathering today (Thursday 29 Aug) at the annual Goldschmidt conference that an oxidized mineral form of the element molybdenum, which may have been crucial to the origin of life, could only have been available on the surface of Mars and not on Earth.

"In addition", said Professor Benner "recent studies show that these conditions, suitable for the origin of life, may still exist on Mars."

"It's only when molybdenum becomes highly oxidized that it is able to influence how early life formed," explains Professor Benner, from The Westheimer Institute for Science and Technology in the USA.

"This form of molybdenum couldn't have been available on Earth at the time life first began, because three billion years ago the surface of the Earth had very little oxygen, but Mars did. It's yet another piece of evidence which makes it more likely life came to Earth on a Martian meteorite, rather than starting on this planet."

The research Professor Benner will present at the Goldschmidt conference tackles two of the paradoxes which make it difficult for scientists to understand how life could have started on Earth.

The first is dubbed by Professor Benner as the 'tar paradox'. All living things are made of organic matter, but if you add energy such as heat or light to organic molecules and leave them to themselves, they don't create life. Instead, they turn into something more like tar, oil or asphalt.

"Certain elements seem able to control the propensity of organic materials to turn into tar, particularly boron and molybdenum, so we believe that minerals containing both were fundamental to life first starting," says Professor Benner.

"Analysis of a Martian meteorite recently showed that there was boron on Mars; we now believe that the oxidized form of molybdenum was there too."

The second paradox is that life would have struggled to start on the early Earth because it was likely to have been totally covered by water.

Not only would this have prevented sufficient concentrations of boron forming – it's currently only found in very dry places like Death Valley – but water is corrosive to RNA, which scientists believe was the first genetic molecule to appear.

Although there was water on Mars, it covered much smaller areas than on early Earth.

"The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock," says Professor Benner.

"It's lucky that we ended up here nevertheless, as certainly Earth has been the better of the two planets for sustaining life. If our hypothetical Martian ancestors had remained on Mars, there might not have been a story to tell."

More information: goldschmidt.info/2013/

Hawaii Astrobiologists find Martian clay contains Chemical Organics

Electron microscope image showing the 700-million-year-old Martian clay veins containing boron (100 µm = one tenth of a millimeter).

Researchers from the University of Hawaii at Manoa NASA Astrobiology Institute (UHNAI) have discovered high concentrations of boron in a Martian meteorite.

When present in its oxidized form (borate), boron may have played a key role in the formation of RNA, one of the building blocks for life.

The work was published on June 6 in PLOS One.

The Antarctic Search for Meteorites team found the Martian meteorite used in this study in Antarctica during its 2009-2010 field season.

The minerals it contains, as well as its chemical composition, clearly show that it is of Martian origin.

Using the ion microprobe in the W. M. Keck Cosmochemistry Laboratory at UH, the team was able to analyze veins of Martian clay in the meteorite.

After ruling out contamination from Earth, they determined boron abundances in these clays are over ten times higher than in any previously measured meteorite.

"Borates may have been important for the origin of life on Earth because they can stabilize ribose, a crucial component of RNA. In early life RNA is thought to have been the informational precursor to DNA," said James Stephenson, a UHNAI postdoctoral fellow.

RNA may have been the first molecule to store information and pass it on to the next generation, a mechanism crucial for evolution.

Although life has now evolved a sophisticated mechanism to synthesize RNA, the first RNA molecules must have been made without such help.

One of the most difficult steps in making RNA nonbiologically is the formation of the RNA sugar component, ribose. Previous laboratory tests have shown that without borate the chemicals available on the early Earth fail to build ribose.

However, in the presence of borate, ribose is spontaneously produced and stabilized.

This work was born from the uniquely interdisciplinary environment of UHNAI. The lead authors on the paper, Stephenson, an evolutionary biologist, and Lydia Hallis, a cosmochemist who is also a UHNAI postdoctoral fellow, first came up with the idea over an after-work beer.

"Given that boron has been implicated in the emergence of life, I had assumed that it was well characterized in meteorites," said Stephenson.

"Discussing this with Dr. Hallis, I found out that it was barely studied. I was shocked and excited. She then informed me that both the samples and the specialized machinery needed to analyze them were available at UH."

More information: 
Stephenson, J. D., Hallis, L. J., Nagashima K., and Freeland, S. J. 2013, "Boron Enrichment in Martian Clay," PLoS ONE 8(6): e64624. dx.doi.org/10.1371/journal.pone.0064624

German team finds a way to link boron atoms with a triple bond

In the chemical world, there are few instances where atoms form triple bonds (where three electrons from an atom are bonded with the electrons from another atom). In fact other than triple bonds between carbon and nitrogen few examples exist at all. 

One instance that theory had predicted should work was with boron, mainly because of where it sits on the Periodic Table of Elements, but also of course because in its stable state it has just three electrons. Because of this, various chemists over the years have tried to figure out a way to form a compound made of triple bonded boron atoms. 

Now, it appears a team in Germany at the University of Würzberg, has succeeded. They have published a paper describing their results in the journal Science.

To get two boron atoms to triple bond with one another, you can’t just shove them together and hope they will stick because they are too stable in their current state. In other words, they’ll just ignore one another. To get them to bond some external force must be introduced.

Prior researchers had tried using a laser as a force, but only succeeded in creating a triple bound that could exist at eight degrees above absolute zero. At room temperature it vaporized.

The German team took another approach, instead of trying to push the atoms into bonding, they coaxed them together by slowly filling the places that the three electrons can exist around the nucleus with something else, essentially leaving them no choice but to bond with the electrons from another boron atom.

To do that, they introduced a molecule that contained carbon and nitrogen atoms, called a N-heterocyclic carbine (NHC) in a sterile vacuum chamber.

The idea is that because main-group elements such as boron are most stable when surrounded by eight electrons, creating an environment where the boron atoms could share two electrons from the NHC would leave three openings for electrons from one boron atom to be shared with those of another.

Thus, the three electrons from each would form bonds with each other naturally to create the full complement of eight electrons. To make it happen they induced a boron-boron double bond as a first step, and then a triple bond in the second.

The result is a green crystal that will exist at room temperature indefinitely in the absence of air or water.

Because the discovered process and resultant material is still so new, scientists don’t really know if it might be useful for anything, but the fact that the team has finally solved the riddle of how to get boron to triple bound, will assure them a place in the history books.

More information: Ambient-Temperature Isolation of a Compound with a Boron-Boron Triple Bond, Science, 15 June 2012: Vol. 336 no. 6087 pp. 1420-1422. DOI: 10.1126/science.1221138

Boron and the Hope Diamond

The 45.52 carat Hope Diamond is in a platinum setting surrounded by sixteen white pear-shaped and cushion-cut diamonds designed by Pierre Cartier in about 1910.

Boron is also responsible for the colour of the world's most famous blue diamond, the 46-carat, ironically named, Hope Diamond.

In comparison, the Bulgari Blue diamond, which is currently for sale at Christie's is the diameter of a quarter and weighs in at just 11 carats.

In addition, the boron and carbon matrix in the Hope actually has a real scientific puzzle hanging over it. When irradiated with ultraviolet light, the diamond glows a fierce orange, like the world's most expensive charcoal briquette.

The effect lasts for several minutes. Other blue diamonds also phosphoresce, but none in quite the same way, and scientists don't know why there's so much variability.

There is a legend that this passionate orange colour is linked to the curse of the hope diamond and the alleged beheadings, drownings, stabbings, suicides, overthrown monarchs and various other misfortunes attributed to the Hope Diamond, but that is the stuff of legends and film makers.

Boron - A Girl's Best Friend's best friend

What is a girl's best friend? A "fancy, vivid" diamond, of course and there's a Bulgari Blue two stone diamond ring going up for auction at Christie's this week. It contains a spectacular blue diamond and is expected to fetch $12 to $15 million.

What makes this diamond so valuable?
Boron. On a submicro scale, pure diamond is billions of billions of carbon atoms bonded to one another. If you shrunk yourself down and stood inside the diamond, you'd see nothing but carbon in a perfect pattern in every direction.

Carbon atoms have four electrons available to form bonds with four other atoms, and because there's nothing else but carbon to bond with inside a diamond, each of the four bonds is equally strong, leaving no weak spots in any direction. This gives diamonds their proverbial hardness, but also leaves them transparent.

Light interacts primarily with electrons, and when all the electrons are tied up in bonds, visible light streams right through.

The Hope Diamond at the Smithsonian's Instutute

Periodic table
Boron is carbon's neighbour on the periodic table, which means it can do a passable carbon impression and wriggle its way into the matrix of a diamond but it has one fewer electron, so it can't quite form the same four perfect bonds.

This different distribution of electrons doesn't weaken the diamond appreciably, but it does free up electrons to interact with visible light. Because boron absorbs lower-energy red light, the light that streams through has a blue hue.

The price of diamonds can vary greatly depending on size, cut, color, and other factors, including whether they have a history, but because of the rarity of blue boron diamonds, they often fetch more money than gems of similar quality. So remember this when you are in the jewellers with your partner to be.

What's Tougher Than Girl's Best Friend? Diamonds versus Boron

You don't often break a diamond. So when in 2003 Dave Mao cracked a tooth of his diamond anvil, he knew something extraordinary must have happened.

Together with his daughter Wendy and other colleagues at the Geophysical Laboratory of the Carnegie Institution for Science in Washington DC, he was using the device to test materials at pressures many millions of times higher than those at the Earth's surface - higher even than in our planet's core - by squeezing them between two tiny diamond jaws.

Behind the glitz, diamond is just a form of carbon. It is, however, by common consent the hardest material known. The substance in the Maos' test cell had also begun as pure carbon.

It was plain old graphite - the soft, slippery stuff that is used for pencil leads and lubricants. Clearly, something had happened in the anvil cell to make it awesomely hard.

It seemed the Maos might accidentally have succeeded where many before had failed. Had they made the first superhard material that matched or even surpassed diamond? Probably not, as it turned out.

Six years and several twists later, though, that feat might at last have been achieved, though not with pure carbon. If the latest reports are right, the hardness crown has changed hands at last.