Notes on the ‘ACS sesquicentennial’ crossword puzzle

 

It is a privilege to be invited to create a Sunday-size crossword puzzle for the March 2026 issue of C&EN, in commemoration of the 150th anniversary of the American Chemical Society. Because the crossword platform is necessarily terse, we elaborate below on some of the puzzle’s content, based on information on the ACS website, and in other authoritative sources referenced herein. First, the seven theme answers are arranged in chronological order of the ACS historical events or the ACS functions referred to. Second, we elaborate briefly, with documentation, on about a dozen scientifically relevant clues for non-theme answers found in the puzzle’s grid.

NEW YORK CITY

22-Across in the puzzle, clued as Gathering location for the 35 founding members of the ACS in 1876

Elaborating on the information in the clue, the American Chemical Society was founded on April 6, 1876, in a meeting at the College of Pharmacy of the City of New York. Seven months later, the first president of the newly formed society, John W. Draper (1811–1882), delivered his inaugural address at Chickering Hall in New York. In 2001, at a ceremony at New York University, the ACS designated John W. Draper and the founding of the American Chemical Society as a National Historic Chemical Landmark. For more historical information about the ACS, click here.

PRIESTLEY MEDAL

79-Across in the puzzle, clued as Most prestigious ACS award, named after the discoverer of oxygen

The Priestley Medal is the highest award bestowed by the American Chemical Society. The award, which recognizes distinguished service to chemistry and the chemistry community, includes a research grant (currently $20,000) and a gold medallion commemorating the life and legacy of Joseph Priestley. Since the establishment of the award in 1922, the medal has been awarded to 90 individuals, beginning with Ira Remsen (1848–1927), a renowned author and chemical educator who served as ACS president in 1902. The list of Priestley Medalists reads like a who’s who of eminent scientists, engineers, educators, and entrepreneurs, including 19 Nobel laureates. The most recent recipient, Jennnifer A. Doudna, appears on the cover of the March issue of C&EN which also features her award address.

Joseph Priestley (1733–1804), for whom the award is named, is an iconic figure not only in the history of chemistry but in the emerging role of science in the US. Well known to chemistry students across the world for discovering oxygen (which he called “de-phlogisticated air”) in 1774, Priestley emigrated to the US in 1794, fleeing religious and political persecution in his native England. He settled in Northumberland, Pennsylvania, where he continued his scientific research, founded an academy, and served as an inspiration to leading scientists and statesmen alike. In a letter to Priestley written in 1801, his friend Thomas Jefferson, then serving as US president, wrote, “Yours is one of the few lives precious to mankind, and for the continuance of which every thinking man is solicitous.”

In 1874, a group of 77 chemists gathered in Northumberland to celebrate the 100th anniversary of the discovery of oxygen. A proposal was made at this meeting to establish a national society of chemists in the US. Two years later, this proposal became a reality with the founding of the American Chemical Society in NEW YORK CITY (see above). The Priestley House in Northumberland was designated an National Historic Chemical Landmark in 1994 at a special celebration marking the bicentennial of the discovery of oxygen.

CHARTERED UNDER FDR

29-Across in the puzzle, clued as How ACS was granted federal incorporation by Congress and POTUS in 1937 in recognition of its role in public affairs

On Aug.25, 1937, President Franklin Delano Roosevelt (FDR) signed a bill titled An Act to Incorporate the American Chemical Society under Federal Charter, thus making it law. The bill was introduced in the Senate by Walter R. George (D-GA) and in the House of Representatives by Walter Chandler (R-TN). Before passage of the bill by the full House, the House Judiciary Committee had solicited the input and views of Cabinet members, including the secretaries of the War, Navy, Interior, Commerce, and Agriculture Departments. They responded that incorporating the ACS under federal charter served the national interest by providing for advice related to issues of national defense, supplying valuable information resources such as the Chemical Abstracts Service (now CAS), and ensuring a forum for technical discussions among chemists engaged in studies of the nation’s agricultural and mineral resources. Pursuant to these recommendations, the bill was enacted by Congress and signed into law. The act states that the object of incorporation under federal charter is to encourage the advancement of chemistry in all its branches, and thus to foster the public welfare, aid the development of the country’s industries, and increase the prosperity of its citizens.

Incorporation of the American Chemical Society under federal charter remains vital and central to the mission of the ACS in the 21st century. The society renews its commitment to serving the public interest annually with programs such as its Public Policy Fellowships and Science Policy Fellowships, established in 1974 and 1986, respectively. As expressed by Jeanette M. Van Emon of the ACS Board of Directors in the C&EN commentary cited above, “the ACS will continue our mission to advance scientific knowledge, empower a global community, and champion scientific integrity for our legacy and our future.”

PETROLEUM RESEARCH FUND

63-Across in the puzzle, clued as ACS-administered trust supporting fundamental science

As summarized in this historical account, the Petroleum Research Fund (PRF) was originally established as a trust by seven major oil companies in 1944, and its assets were transferred to the American Chemical Society in 2000. The mandate to support “advanced scientific education and fundamental research in the petroleum field” has been interpreted generously, and many academic chemists secured essential PRF support early in their careers, as recounted here. In addition, the PRF supports research at primarily undergraduate institutions and offers seed funding to established chemists who are shifting fields. All told, ACS allocates on the order of $15 million–$20 million annually.

BETTER TOMORROW

48-Across in the puzzle, clued as “Maker of a ___” (tagline on the first day cover for an ACS commemorative stamp issued in 1951)

In 1951, the US Post Office Department issued a 3-cent stamp commemorating the 75th anniversary of the founding of the American Chemical Society. The central design element of the maroon stamp is the then-official emblem of ACS, created in 1908 by Tiffany and Co. (The ACS logo was streamlined and modernized in 1987 to make it more reproducible in a variety of formats.) In the horizon, the background of the stamp features a stylized chemical skyline depicting both laboratory and industrial chemistry. Recognizable “landmarks” in the skyline include a hydrometer, a three-neck round-bottom distillation flask, and a trio of industrial chemical towers—a catalytic cracking plant, a butadiene reactor, and a fractionating unit.

As the clue indicates, the phrase “Maker of a Better Tomorrow” appears on a first day cover envelope bearing the newly issued ACS commemorative stamp. The cover shown in the photo below is addressed to Roger Adams (1889–1971) of the University of Illinois. Adams, member of a celebrated American family and a Priestley Medalist in 1946, served as president of the ACS in 1935 and was chairman of the ACS Board of Directors from 1946 to 1950. The prestigious Roger Adams Award in Organic Chemistry is a biennial national award from the ACS named in his honor.

PROJECT SEED

107-Across in the puzzle, clued as ACS summer internship program created in 1968 to provide opportunities for high school students

Drawing on information from the Project SEED website, a 2018 address by former C&EN editor and ACS Executive Director Madeleine Jacobs, and a recent C&EN article by Nina Notman, we can tell a truly inspirational story. It begins on April 4, 1968, an otherwise dark day marked by the assassination of Martin Luther King Jr. The ACS Council passed a resolution “to take the appropriate steps to ease the problems of underprivileged segments of the nation’s population, particularly in relation to lack of education and unemployment.” Thus, Project SEED (originally summer experiences for the economically disadvantaged) was born.

More than half a century later, Project SEED has grown to provide hands-on summer research experiences of 8–10 weeks and virtual summer camps; it has served approximately 14,000 students in most US states and territories. Each year, 350-plus high school students are given generous stipends and matched with mentors in academia, industry, or government labs. The virtual camps focus on college and lab readiness, professional development, and exposure to chemistry-related career paths.

One notable Project SEED alumna is Dr. Kizzmekia S. Corbett-Helaire. Currently assistant professor of immunology and infectious diseases at Harvard University, she played a pivotal role in the development of messenger RNA–based vaccines that helped the world emerge from the COVID-19 pandemic. While still in high school, Corbett-Helaire spent two summers conducting research at the University of North Carolina, Chapel Hill, as a Project SEED Scholar. In an interview with ACS in 2020, she described how the program had sparked her interest in becoming a scientist, and she offered advice to students considering careers in science.

HISTORIC LANDMARKS

96-Across in the puzzle, clued as Achievements recognized by an ACS program created in 1992 to celebrate the central science

The American Chemical Society established its National Historic Chemical Landmarks program in 1992, to “enhance public appreciation for the contributions of the chemical sciences to modern life in the United States and to encourage a sense of pride in their practitioners for chemistry’s rich history.” Through 2025, 105 seminal advances in the history of chemistry have been granted landmark status. Such landmark designations may include scientific discoveries, individuals, and institutions, as well as historic sites that have influenced and advanced the role of chemistry in transforming everyday life. Advances ranging from the invention of the first plastic to the discovery of penicillin, from the deciphering of the genetic code to the exploration of Mars, richly illuminate the breadth and depth of chemical exploration and discovery.

An ACS website features a complete directory of National Historic Chemical Landmarks, as well as an interactive timeline and a map of discoveries. These resources, augmented by first-person accounts, stories, and historic photos, allow users to appreciate the landmarks’ cultural and historic context. The website is an especially valuable resource for educators, providing lesson plans, teacher guides, student handouts, and classroom activities.

Several National Historic Chemical Landmarks are referenced in the ‘ACS sesquicentennial’ crossword puzzle and in these annotations. They include the New York City site where the society was founded (see NEW YORK CITY); the Priestley House and the discovery of oxygen (see PRIESTLEY MEDAL); the Noyes Laboratory at the University of Illinois, led by Roger Adams from 1926 to 1954 (see BETTER TOMORROW); the development of magnetic resonance imaging (see MRI) by Paul Lauterbur; and the University of California, Berkeley building where Glenn Seaborg and others discovered plutonium (see AEC).

Reflections on selected chemically relevant nontheme answers and their clues

Beyond the 7 theme answers discussed above, the crossword puzzle contains 30 or so answer words that have been clued in ways that refer to the chemical sciences, as broadly defined. In the highly selective listing that follows, the order is numerical, with the Across answers preceding the Down answers.

Spool

18-Across in the puzzle, clued as Collect nylon on a stir rod, e.g.

The nylon rope trick is a classic polymer chemistry demonstration. In the original version, the formation of nylon 6,6 occurs at the interface of two immiscible liquids: an aqueous solution of hexamethylenediamine, and a hydrocarbon solution containing adipoyl chloride. The synthetic polyamide can be collected by inserting a glass stirring rod into the interface and spooling the fiber onto the rod or another type of roller. Other, less hazardous diacid chlorides can be substituted to make different polyamides, such as nylon 6,10, using sebacoyl chloride.

Another classic spooling experiment involves DNA extraction from fruits such as bananas and strawberries. This reference has a detailed protocol and accompanying photos.

Excitable

24-Across in the puzzle, clued as Like electrons in the valence band of a semiconductor

This ChemMatters article provides a useful explanation of how valence band electrons are excited to conduction bands in semiconductors and how they are harnessed in microchip technology.

Tobias

38-Across in the puzzle, clued as Douglas (UC Irvine) who received an award in theoretical chemistry in 2014

Professor Douglas J. Tobias, of the University of California, Irvine, received the ACS Physical Chemistry Division’s 2014 Award in Theoretical Chemistry for research into novel behavior of ions at interfaces and in membrane-bound proteins, with corresponding implications for atmospheric and biological chemistry, respectively.

Onion

69-Across in the puzzle, clued as When cut, a source of syn-propanethial S-oxide, a strong lachrymator

The fact that cutting onions induces tearing is common knowledge. The compound referred to in the clue was the ACS Molecule of the Week on Jan. 22, 2013. Even more information can be found at this Molecule of the Month (September 2007) site and in Eric Block’s book Garlic and Other Alliums: The Lore and the Science.

Heck

91-Across in the puzzle, clued as 2010 Nobelist with an eponymous organometallic cross-coupling reaction

Richard F. Heck (1931–2015) shared the 2010 Nobel Prize in Chemistry with Ei-Ichi Negishi (1935–2021) and Akira Suzuki (b. 1930) for the development and applications of palladium-catalyzed cross-couplings in organic synthesis. C&EN recently highlighted this work for its impact on green chemistry. Notably, the eponymous Heck reaction, and others like it, can now be performed in aqueous media or under solvent-free, solid-state conditions. These advances exemplify two of the core principles of green chemistry—the use of safer solvents and auxiliaries, and catalysis.

Aggregate

105-Across in the puzzle, clued as Clump of misfolded proteins, as in amyloid

Amyloid fibrils, clumped aggregates of misfolded proteins, are of intense scientific interest because of their putative role in the development of neurodegenerative diseases. Understanding how these aggregates form may provide a key to unlocking future treatments for Alzheimer’s disease and chronic traumatic encephalopathy.

Chou

112-Across in the puzzle, clued as Codeveloper, with Fasman, of an algorithm to predict protein secondary structure

Peter Y. Chou was the first author, along with his mentor Gerald D. Fasman (1925–2003) of Brandeis University, of a widely cited 1974 paper in the ACS journal Biochemistry, entitled “Prediction of protein conformation.” Each genetically encoded amino acid was scored for its statistical propensity to be found in helix, strand, or turn secondary structural elements of proteins. The resultant Chou-Fasman rules could be used to generate influential hypotheses about conformational changes being determinants of protein structure. Such approaches informed discoveries about prion biology (1997) and about in silico protein folding (2024) that were recognized by Nobel prizes.

MRI

8-Down in the puzzle, clued as 3D-scanning technique developed by 2003 Nobelist Paul Lauterbur

As detailed here, ACS designated the development of magnetic resonance imaging (MRI) by Paul Lauterbur (1929–2007) as a National Historic Chemical Landmark at Stony Brook University, on March 8, 2011. The text of the plaque commemorating the development reads

On this site, in the early 1970s, Paul C. Lauterbur demonstrated that nuclear magnetic resonance (NMR) could be used to generate images of macroscopic objects. In the years following, magnetic resonance imaging (MRI) has been refined as a technique for the detailed resolution of internal structures. Lauterbur’s invention thus created a powerful diagnostic tool for the non-invasive examination of body tissues such as the brain, heart, and muscles. It allows for the early detection of cancer and other diseases. Lauterbur shared the 2003 Nobel Prize in Physiology or Medicine for his role in the development of MRI.

Amazingly, Lauterbur’s proof-of-concept experiments were conducted using a simple Varian A-60 instrument. Read more about his Nobel Prize (shared with Peter Mansfield, 1933–2017) at the Nobel website.

Elise

49-Down in the puzzle, clued as Full first name of nuclear fission pioneer Meitner

Crossword puzzle constructors generally clue ELISE with reference to a very familiar classical piano standard by Beethoven (the link is to a performance by 43-Down, Claudio ARRAU). We chose a different route by paying homage to Elise Meitner (1878–1968), normally known as Lise Meitner, who by all accounts should have shared the 1944 Nobel Prize in Chemistry with Otto Hahn (1879–1968). In 1997, Meitner was immortalized with element number 109 in the periodic table, meitnerium (Mt). In an ironic twist, element number 105 was informally known as hahnium (Ha) before its official name, dubnium (Db), was announced, also in 1997.

AEC

60-Down in the puzzle, clued as Nuclear agcy. once led by Nobelist Glenn Seaborg

The clue points to the Atomic Energy Commission (AEC), which grew out of the Manhattan Project and whose functions were eventually subsumed by the Department of Energy. The focus of the clue, though, is the remarkable scientific and administrative career of Glenn T. Seaborg (1912–1999), recipient of the 1951 Nobel Prize in Chemistry for the discovery of plutonium and several other transuranium elements. Seaborg was chair of the AEC from 1961 to 1971, ACS president during its centennial year of 1976, and the 1979 Priestley Medalist. His academic career was almost entirely at the University of California, Berkeley, except for his participation in the Manhattan Project at the University of Chicago (1942–46) and his stint at the AEC. In 1997, seaborgium (Sg), element number 106 in the periodic table, was named in his honor. Gilman Hall at the University of California, Berkeley, where Seaborg and others worked on the identification and production of plutonium, has been designated a National Historic Chemical Landmark. Finally, the Glenn T. Seaborg Award for Nuclear Chemistry, an ACS annual national award, is dedicated in his honor.

Poppy

63-Down in the puzzle, clued as Source of the opium alkaloids morphine and codeine

Morphine is the most important alkaloid in opium, an extract of the poppy Papaver somniferum.