Chemical Science Advances: Molecular Dynamics and Quantum Chemistry


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Tri-nitrobenzene may be a worry of the distant past for travelers if current research succeeds.

Tri-nitrobenzene may be a worry of the distant past for travelers if current research succeeds. Molecule image by John Jaksich, all rights reserved.

In Chemistry news of interest this week, developments in molecular dynamics and education show the chemical sciences advancing the potential to protect individuals, and further the understanding of quantum chemistry.

Explosive Detection: Forensic Research News

According to research appearing in the British Royal Society of Chemistry journal, Polymer Chemistry; workers from Germany and China have invented better way to detect explosives.

In an explosion, a chemical reaction expands faster than the expansion volume. In short, the rapid release of gas causes the explosion to occur.

The method these workers found enabled them to detect TNT through a method similar to which litmus paper detects an acidic solution. A strip of paper with an embedded amount of ‘detecting material’ will change its color (hue) to a deeper shade if TNT is near.

Here’s how the chemical reactions behind this detection method works:

When using trinitro-benzene (TNT) as the explosive test material, researchers utilized tetraphenylethylene-substituted polycarbazoles.

We know the polycarbazole molecule reacts with molecules similar TNT, (but without explosive consequences). It forms a ‘loosely associated pair’ with TNB.

This loose association is known in chemical phenomena as a ‘charge-transfer-complex.’ No chemical bonds are broken or formed—but a pair of molecules will associate with one another.

The chemistry behind the methodology is in the research phase. If further research proves the methods safe and reliable—the days of airport security problems may eventually be a problem of the past, at least as far as explosive devices are concerned.

Quantum Chemical Methods

In quantum mechanics, the Uncertainty Principle successfully predicts that we cannot locate a particle such as a molecule without losing information of its structural parameters—most stable structure (or its truest chemical state).

Werner Heisenberg realized that molecules could not be discerned in the same manner as their larger cousins-an aggregate of molecules such as a football could be fully characterized. However, when that aggregate becomes the size of Buckminster Fullerene, C60—the ability to fully discern it is next to impossible. The point where size is an issue is also known as the Planck scale—it corresponds to the numerical value of approximately 10⁻⁸ meters or 1 angstrom. (The diameter of C60 is approximately 10 angstroms.)

In a novel methodology developed by researchers in Europe and the United States, the scientists showed that they could study an individual molecule, in principle, by using X-Ray diffraction while aligned with a m0lecular beam. Diffraction is what happens when light bends, as it passes through a slit or around a corner.

The researchers aligned a molecule, 2,5-diiodobenzonitrile, with a free-electron laser and submitted it to measurements with X-Rays to understand the molecule as it moved freely within the laser field. Researchers have studies molecules like this in the past for its rotational characteristics-it bears the potential for future implementation in nanotechnology.

Chemistry and Education

A high school student has the distinction of being included in a research level publication.

Simon D. Kaschock-Marenda proposed feeding natural and artificial sugars to fruit flies to his father’s research group at Drexel University when he was just 12 years old.

As a sixth grader, Kaschock-Marenda performed the experiment in a science fair experiment; he successfully showed that the sweetener, Truvia, (a combination of stevia and erithrytol) was toxic to fruit flies. He also found that feeding table sugar (sucrose) to the fruit flies made them survive 10 times longer. His father continued and elaborated on Simon’s project, and his research appears in the open access journal, PLOS One.

Molecules Make Life Interesting

Molecules make life interesting — from the detection of explosives to single molecule detection methods and discernment of a novel insecticide, humanity has utilized its propensity to explore with chemistry to astonishing results.

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