Pasteur's Dissymmetry

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Long before chemists routinely drew molecules in three dimensions, Louis Pasteur encountered a puzzle in tartaric acid. In 1848, while examining salts of tartaric and racemic acids, he noticed that apparently identical crystals could occur in two forms that were mirror images of one another. He painstakingly separated the two kinds by hand and found that their solutions rotated polarized light in equal and opposite directions. It was a crucial early demonstration that molecules themselves could possess handedness.

Pasteur called this property dissymmetry. In two lectures delivered to the Chemical Society of Paris in 1860, he looked back over this work and became fascinated by a still deeper question: why did the chemistry of living things seem so strongly associated with molecular handedness?

The quotation on the back comes from that period of thought. Pasteur contrasted the molecular dissymmetry he encountered in natural products with the apparent symmetry of substances made artificially, and saw in that distinction a profound boundary between living chemistry and everything else.

Chemistry has moved well beyond Pasteur’s original formulation. We can, of course, synthesize chiral molecules today, but the mystery he identified remains fundamental. Living systems exhibit an extraordinary preference for particular molecular hands, and chirality now sits at the center of stereochemistry, biochemistry, and drug design.

The small stereocenter on the front shows the modern language for an idea Pasteur first glimpsed in crystals nearly two centuries ago.

Details

• Comfort Colors 1717 heavyweight T-shirt
• 100% ring-spun cotton
• 6.1 oz heavyweight fabric
• Garment-dyed and soft-washed
• Relaxed unisex fit
• Pre-shrunk
• Front and back printed design

Model images made with generative AI.