Weird water: Discovery challenges long-held beliefs about water's special ...( Beyond its role as the elixir of all...)

Beyond its role as the elixir of all life, water is a very unusual substance: Scientists have long marveled over counter-intuitive properties that set water apart from other solids and liquids commonly found in nature.

The simple fact that water expands when it freezes -- an effect known to anyone whose plumbing has burst in winter -- is just the beginning of a long list of special characteristics. (Most liquids contract when they freeze.)

That is why chemical engineer Pablo Debenedetti and collaborators at three other institutions were surprised to find a highly simplified model molecule that behaves in much the same way as water, a discovery that upends long-held beliefs about what makes water so special.

The conventional wisdom is that water is unique, said Debenedetti, the Class of 1950 Professor in Engineering and Applied Science. And here we have a very simple model that displays behaviors that are very hard to get in anything but water. It forces you to rethink what is unique about water.

While their water imitator is hypothetical -- it was created with computer software that is commonly used for simulating interactions between molecules -- the researchers discovery may ultimately have implications for industrial or pharmaceutical research. I would be very interested to see if experimentalists could create colloids (small particles suspended in liquid) that exhibit the water-like properties we observed in our simulations, Debenedetti said. Such laboratory creations might be useful in controlling the self-assembly of complex biomolecules or detergents and other surfactants. .

More fundamentally, the research raises questions about why oil and water dont mix, because the simulated molecule repels oil as water does, but without the delicate interactions between hydrogen and oxygen that are thought to give water much of its special behavior.

The researchers published their findings Dec. 12 in the Proceedi
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