Science + Technology

UCLA Chemists Make Molecular Rings in the Shape of King Solomon’s Knot, a Symbol of Wisdom

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UCLA chemists have made, atthe nanoscale, a molecular compound of interlocked rings that has theshape of the ancient King Solomon's knot, a symbol of wisdom that is thousandsof years old and is widely used in architecture and works of art. The Bible portrays Solomon as great inwisdom, wealth and power.

"King Solomon, according to Italian legend, was on a hilland was charged by God with protecting a village from large boulders that weregoing to roll down and destroy the village," said UCLA chemistry graduatestudent Cari Pentecost, lead author of the Solomon'sknot research, which was published in this year's first issue of the Germanchemistry journal Angewandte Chemie."King Solomon was holding three large boulders and took a rope and devised thisknot to support the boulders and protect the town."

"Our research is amarriage of nanoscience, mathematics and art,"Pentecost added.

The Solomon's knot is composed of two rings that interlaceeach other four times, with alternating crossing points that go over, under,over and under as one traces around each of the rings. Pentecost's nano-version is roughly 2 nanometers high — about 1,000times smaller than a red blood cell and 10,000 times smaller than the diameterof a human hair — by 1.2 nanometers wide.

Pentecost conducts research in the laboratory of J. Fraser Stoddart, director of the California NanoSystemsInstitute (CNSI), who holds UCLA's Fred Kavli Chairin Nanosystems Sciences and who last December wasawarded a knighthood by Queen Elizabeth II of Britain for his work in chemistryand nanotechnology. The Solomon's knot research is federally funded by theNational Science Foundation.

Pentecost produced the molecular Solomon's knot whileperforming experiments on molecular Borromean rings,which are comprised of three interlocked rings that form an inseparable unionsuch that cutting any one ring results in the other two falling apart. Stoddart's research team developed this mechanicallyinterlocked Borromean compound in 2004, and theresearch was published in the May 28, 2004, issue of Science.

Pentecost decided to change the recipe for making molecular Borromean rings ever so slightly. With the knowledge thatif she used either zinc or copper ions as the template for a particularchemical reaction, she would get only the molecular Borromeanrings, Pentecost instead used equal amounts of zinc and copper ions, and theresult was crystals of the molecular Solomon's knot 10 out of 10 times.

"Synthetic chemistry is ready to make substantial inroadsinto some quite exotic molecules in the shape of knots and links," said Stoddart, who believes the molecular Borromeanrings and the Solomon's knot are likely to have future applications. "There isoftentimes a connection between the beauty and elegance of a chemical structureand its potential usefulness, and this Solomon knot structure is quitebeautiful and elegant."

The Solomon's knot is carved,painted, sculpted, stitched, crocheted, knitted, inlaid and beaded in culturalrelics from Europe, the Middle East andelsewhere, according to Lois Rose Rose, authorof "Seeing Solomon's Knot"and a UCLA graduate. The design, which is found in numerous buildings,can be seen in the floor tiles and on the wooden ceilings of UCLA's PowellLibrary and on the outside architecture of UCLA's Haines Hall and Moore Hall.

"Here I am, making molecules of these Solomon's knots, andeverywhere I go on the campus, they are staring me in the face or I am walkinginto them," Pentecost said.

Speaking of the excitement of nanoscience,Stoddart said, "We have to try to rediscover thespirit of the Renaissance, when there were no boundaries. Nanoscienceis a replay of previous industrial revolutions. In the 21st century, peoplewill start to appreciate what a nanoparticle or nanowire is, just as in the past they embraced theinvention of the wheel or the highway."

Stoddart said that making themolecular counterparts of Borromean rings andSolomon's knots is a form of chemical evolution on the nanoscale.

"In the making of these exotic compounds, chemical bonds arebeing broken just as fast as they are being formed, until the compound thatfeels most comfortable emerges as the final product," he said. "A kind ofDarwinian selection process is going on in a playful kind of way in the 'roomat the top.' Cari Pentecost's contribution was tofind, accidentally, the particular set of keys that opens the combination lockto the door to yet another of these rooms at the top."

Co-authors on the research are former UCLA postdoctoral scholarsKelly Chichak and Andrea Peters, both of whom workedin Stoddart's research group; GarethCave, an X-ray crystallographer at Nottingham Trent University;and Stuart Cantrill, a former research associate in Stoddart's research group.

The CNSI, a jointenterprise between UCLA and the University of California, Santa Barbara, isexploring the power and potential of organizing and manipulating matter toengineer "new integrated and emergent systems and devices, by starting down atthe nanoscale level, that will aid and abetinformation technology, energy production, storage and saving, environmentalwell-being, and the diagnosis, prevention and treatment of chronic anddegenerative diseases with an impact that far outstretches our comprehension oflife to date," Stoddart said.

When Stoddart was appointed director of the CNSIin 2003, he also assumed the Fred Kavli Chair of NanoSystems Sciences. Previously, Stoddartheld UCLA's Saul Winstein Chair in Organic Chemistry,having succeeded Donald J. Cram, the 1987 Nobel laureate in chemistry. The Winstein Chair will be held in abeyance while Stoddart serves as director of the CNSI. For moreinformation about Stoddart's research, please see http://stoddart.chem.ucla.edu.

About the Kavli Foundation

Dedicated to the advancement of science for thebenefit of humanity, the Kavli Foundation supportsscientific research, honors scientific achievement, and promotes publicunderstanding of scientists and their work. The foundation focuses on scienceof both the greatest and the smallest physical dimensions, as well as thescience of the human brain. Its mission is implemented through an internationalprogram of research institutes, prizes, professorships and symposia in the fieldsof astrophysics, nanoscience and neuroscience.

About the CNSI

Established inDecember 2000 by the state of California asone of the University of California's four Institutes of Science andInnovation, the CNSI forges partnerships with private industry as a means toaccelerate technological advances for the people of California and society in general. Theinstitute represents an interdisciplinary collaboration between UCLA and UCSanta Barbara faculty from the life and physical sciences, engineering, andmedicine. In 2007, the CNSI at UCLA will relocate to a new 180,000-square-footfacility housing a 260-seat theater, wet and dry laboratories, fully outfittedconference rooms and classrooms, and three floors of core facilities includingelectron microscopes, atomic-force microscopes, X-ray diffractometers,optical microscopies and spectroscopies,and high-throughput robotics. In addition, UCLA is funding 15 jointly-hiredCNSI faculty to ensure that the institute will possessthe expertise necessary to make rapid progress in nanoscienceand nanotechnology amid fierce international competition. For more about theCNSI, please visit http://www.cnsi.ucla.edu.

 

About UCLA

California's largest university, UCLA enrolls approximately38,000 students per year and offers degrees from the UCLA College of Lettersand Science and 11 professional schools in dozens of varied disciplines. UCLAconsistently ranks among the top five universities and colleges nationally intotal research-and-development spending, receiving more than $820 million ayear in competitively awarded federal and state grants and contracts. For every$1 state taxpayers invest in UCLA, the university generates almost $9 ineconomic activity, resulting in an annual $6 billion economic impact on theGreater Los Angeles region. The university's health care network treats 450,000patients per year. UCLA employs more than 27,000 faculty and staff, has morethan 350,000 living alumni and has been home to five Nobel Prizerecipients.

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