Chemistry—the science of the properties, composition, structure, and reactions of substances—has always been an integral part of mankind’s everyday life. Long before chemistry was a recognized field of science and even before recorded history, chemistry yielded numerous useful discoveries to inquisitive minds. Even common materials and everyday activities offer opportunities for new discoveries and a deeper understanding of the chemical processes that impact our lives and the world around us. Nothing dramatizes this point more than the use of fire, one of the four ancient elements, the others being air,earth, and water. In Greek mythology, Prometheus stole fire from the gods and gave it to mankind. While fire presented many dangers, over thousands of years it provided mankind with light, warmth, and numerous other benefits. Even the by-products of incomplete combustion such as charcoal and carbon black found uses. Yet it was not until the 1980s that modern chemists discovered that soot, from combustion of organic matter, contained a symmetrical, soccer-ball-shaped molecule composed of 60 carbon atoms, named buckminster fullerene in honor of the architect Buckminster Fuller, a leading proponent of the geodesic dome that it resembled. The serendipitous discovery of this ancient and ubiquitous third allotrope of the element carbon led to an explosion in new research with wide-ranging applications from anticancer drugs to nanotechnology. Fire was also essential for mankind’s discovery and exploitation of the elements of copper, gold, silver, tin, lead, iron, and mercury, and, by trial and error, their alloys such as bronze (copper and tin), pewter (tin and lead), and steel (iron and carbon). Since the 18th century, scientists have discovered more exotic metals and created novel alloys, some of which are important industrial catalysts—accelerators of chemical reactions. Two of the largest scale uses of catalysts are petroleum cracking, optimization of fuel production, and hydrogenation of vegetable oils (hardening) for oleomargarines. Other alloys act as semiconductors used in integrated circuits and superconductors such as those used in magnets for medical magnetic resonance imaging (MRI). Oils and fats have been important throughout human history not only for food, but also as lubricants, polishes, ointments, and fuel. The reaction of oils and fats with alkali (saponification) produces soap (salts of fatty acids) and glycerin. This chemical process was known to the Romans and continues to be of significant commercial importance. Today, tens of thousands of tons of soap are produced annually from tallow and plant oils. Tallow is a by-product of the meat industry, while the principal plant oils are dependent on extensive plantations—palm and palm kernel oils from Indonesia, Malaysia, and India, and coconut oil from the Philippines and Brazil. Twentieth-century chemists designed more effective synthetic, crude-oil-based surface-active agents (surfactants, e.g., sodium linear alkylbenzenesulfonate or LAS) for fabric, household, and industrial cleaning applications, and specialty surfactants to meet the needs of consumer products industry such as milder skin and hair cleansers. The surface-active properties of dissolved soaps and surfactants are attributed to their amphipathic structure, having both hydrophilic (water liking) and hydrophobic (water disliking) parts. In solution, surfactants condense at interphases, with the hydrophilic end in solution and with their hydrophobic tails aligned away from the solution. As a result, surfactants change the solution surface properties, lowering the surface tension and improving wetting and spreading. Early studies of surfactant monolayers provided insights into the surfactant molecule size and shape and the intermolecular forces that influence molecular packing. In the bulk solution, surfactants aggregate to form microscopic micelles when the so-called critical micelle concentration (CMC) is exceeded. Typically, the micelles initially assume consistent spherical aggregates. As the concentration of surfactants increases, the micelles may also assume the shape of rods and plates or disks. Under the proper conditions, some surfactants may form vesicles, cell-like spherical structures consisting of a surfactant bilayer “skin” separating an internal phase from the surrounding bulk solution. Chemists design special surfactants and control formulation compositions in order to exploit these phenomena in a broad range of novel products and applications. Scientists have long recognized that specific molecular interactions and aggregation phenomena are crucial in biological systems. Lipid bilayers are essential for forming the complex cell membrane, while hydrogen-bonding interactions between nucleic-acid base pairs give rise to the double helical or twisted ladder structure of DNA, arguably the most important discovery of the 20th century. More importantly, the specific hydrogen bonding in DNA is also responsible for the ability of multiplying cells to precisely reproduce their genetic code. Modern scientists have learned how to mimic the cell’s ability to replicate DNA, a technique now commonly used in forensics for DNA matches. Molecular interactions also determine the three-dimensional structure of enzymes and other biologically important proteins and thereby their function. Pharmaceutical chemists have long designed drugs that target proteins in disease-causing organisms to cure infections. Recently, scientists discovered that short-chain proteins, called prions, can catalyze the protein misfolding that causes BSE or “mad cow disease.” They now hope that further research may lead to a cure for BSE and other ailments caused by misfolded proteins such as Alzheimer’s and Parkinson’s. Chemists are now venturing to exploit their knowledge about molecular interactions to design molecules that can be controlled to self-assemble into novel structures. Some scientists hope to create a set of molecular building blocks to construct “molecular machines,” while others are designing nanostructures with electrical properties useful for creating the next generation of computer chips. A few scientists even dare to attempt to create “artificial life.” The world of chemistry is all around us. Modern science has deciphered many of nature’s chemical mysteries, but there are still many more to be discovered, sometimes in the most common but overlooked places. These few offer only a glimpse at the important role chemistry plays in science, its contributions to mankind, and the opportunities available to the curious.
—Karl F. Moschner, Ph.D.,is an organic chemistry and scientific computing consultant in Troy, New York.