Tag Archives: University of Oregon

A new, stable open-shell carbon molecule from Oregon

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This discovery could one day make organic solar cells more efficient than silicon ones. Researchers at the University of Oregon announced their discovery in a June 9, 2016 news item on ScienceDaily,

University of Oregon chemists have synthesized a stable and long-lasting carbon-based molecule that, they say, potentially could be applicable in solar cells and electronic devices.

The molecule changes its bonding patterns to a magnetic biradical state when heated; it then returns to a fully bonded non-magnetic closed state at room temperature. That transition, they report, can be done repeatedly without decomposition. It remains stable in the presence of both heat and oxygen.

A June 9, 2016 University of Oregon news release on EurekAlert, which originated the news item, provides more detail,

 

Biradical refers to organic compounds, known as open-shell molecules, that have two free-flowing, non-bonding electrons. Producing them using techniques to control their electron spin, and thus provide semiconducting properties, in a heated state has been hampered by instability since the first synthetic biradical hydrocarbon was made in 1907.

“Potentially our approach could help to make organic solar cells more efficient than silicon solar cells, but that’s probably far in the future,” said UO doctoral student Gabriel E. Rudebusch, the paper’s lead author. “Our synthesis is rapid and efficient. We easily can make a gram of this compound, which is very stable when exposed to oxygen and heat. This stability has been almost unheard of in the literature about biradical compounds.”

The four-step synthesis of the compound — diindenoanthracene, or DIAn — and how it held up when tested in superconducting materials were detailed in a proof-of-principle paper published online May 23 by the journal Nature Chemistry. The UO team collaborated with experts in Japan, Spain and Sweden.

The molecular framework for the new molecule involves the hydrocarbon anthracene, which has three linearly fused hexagonal benzene rings, in combination with two five-membered pentagonal rings.

“The big difference between our new molecule and a lot of other biradical molecules that have been produced is those five-membered rings,” said co-author Michael M. Haley, who holds the UO’s Richard M. and Patricia H. Noyes Professorship in Chemistry. “They have the inherent ability to accept electrons or give up electrons. This means DIAn can move both negative and positive charges, which is an essential property for useful devices such as transistors and solar cells. Also, we can heat up our molecule to 150 degrees Celsius, bring it back to room temperature and heat it up again, repeatedly, and we see no decomposition in its reaction to oxygen. The unique features of DIAn are essential if these molecules are to have a use in the real world.”

Haley’s lab is now seeking to develop derivatives of the new molecule to help move the technology forward into potential applications.

Here’s a link to and a citation for the paper,

Diindeno-fusion of an anthracene as a design strategy for stable organic biradicals by Gabriel E. Rudebusch, José L. Zafra, Kjell Jorner, Kotaro Fukuda, Jonathan L. Marshall, Iratxe Arrechea-Marcos, Guzmán L. Espejo, Rocío Ponce Ortiz, Carlos J. Gómez-García, Lev N. Zakharov, Masayoshi Nakano, Henrik Ottosson, Juan Casado & Michael M. Haley. Nature Chemistry (2016)  doi:10.1038/nchem.2518 Published online 23 May 2016

This paper is behind a paywall.

There is another June 9, 2016 University of Oregon news release by Jim Barlow about this discovery. It covers much of the same material but focuses more closely on Rudebusch’s perspective.

Metallic nanoflowers produce neuron-like fractals

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I was a bit surprised to find that this University of Oregon story was about a patent. Here’s more from a July 28, 2015 news item on Azonano,

Richard Taylor’s vision of using artificial fractal-based implants to restore sight to the blind — part of a far-reaching concept that won an innovation award this year from the White House — is now covered under a broad U.S. patent.

The patent goes far beyond efforts to use the emerging technology to restore eyesight. It covers all fractal-designed electronic implants that link signaling activity with nerves for any purpose in animal and human biology.

Fractals are objects with irregular curves or shapes. “They are a trademark building block of nature,” said Taylor, a professor of physics and director of the Materials Science Institute at the University of Oregon [UO]. “In math, that property is self-similarity. Trees, clouds, rivers, galaxies, lungs and neurons are fractals. What we hope to do is adapt the technology to nature’s geometry.”

Named in U.S. patent 9079017 are Taylor, the UO, Taylor’s research collaborator Simon Brown, and Brown’s home institution, the University of Canterbury in New Zealand.

A July 28, 2015 University of Oregon news release (also on EurekAlert) by Jim Barlow, which originated the news item, continues the patent celebration,

“We’re very delighted,” Taylor said. “The U.S. Patent and Trademark Office has recognized the novelty and utility of our general concept, but there is a lot to do. We want to get all of the fundamental science sorted out. We’re looking at least another couple of years of basic science before moving forward.”

The patent solidifies the relationship between the two universities, said Charles Williams, associate vice president for innovation at the UO. “This is still in the very early days. This project has attracted national attention, awards and grants.

“We hope to engage the right set of partners to develop the technology over time as the concept moves into potentially vast forms of medical applications,” Williams added. “Dr. Taylor’s interdisciplinary science is a hallmark of the creativity at the University of Oregon and a great example of the international research collaborations that our faculty engage in every day.”

Here’s an image illustrating the ‘fractal neurons’,

FractalImplant

Caption: Retinal neurons, outlined in yellow, attach to and follows branches of a fractal interconnect. Such connections, says University of Oregon physicist Richard Taylor, could some day help to treat eye diseases such as macular degeneration. Credit: Courtesy of Richard Taylor

The news release goes on to describe the ‘fractal approach’ to eye implants which is markedly different from the implants entering the marketplace,

Taylor raised the idea of a fractal-based approach to treat eye diseases in a 2011 article in Physics World, writing that it could overcome problems associated with efforts to insert photodiodes behind the eyes. Current chip technology doesn’t allow sufficient connections with neurons.

“The wiring — the neurons — in the retina is fractal, but the chips are not fractal,” Taylor said. His vision, based on research with Brown, is to grow nanoflowers seeded from nanoparticles of metals that self assemble in a natural process, producing fractals that mimic and communicate with neurons.

It is conceivable, Taylor said, that fractal interconnects — as the implants are called in the patent — could be shaped so they network with like-shaped neurons to address narrow needs, such as a feedback loop for the sensation of touch from a prosthetic arm or leg to the brain.

Such implants would overcome the biological rejection of implants with smooth surfaces or those randomly patterned that have been developed in a trial-and-error approach to link to neurons.

Once perfected, he said, the implants would generate an electrical field that would fool a sea of glial cells that insulate and protect neurons from foreign invaders. Fractal interconnects would allow electrical signals to operate in “a safety zone biologically” that avoids toxicity issues.

“The patent covers any generic interface for connecting any electronics to any nerve,” Taylor said, adding that fractal interconnects are not electrodes. “Our interface is multifunctional. The primary thing is to get the electrical field into the system so that reaches the neurons and induces the signal.”

Taylor’s proposal for using fractal-based technology earned the top prize in a contest held by the innovation company InnoCentive. Taylor was honored in April [2015] at a meeting of the White House Office of Science and Technology Policy.

The competition was sponsored by a collaboration of science philanthropies including the Research Corporation for Science Advancement, the Gordon and Betty Moore Foundation, the W.M. Keck Foundation, the Kavli Foundation, the Templeton Foundation and the Burroughs Wellcome Fund.

You can find out more about InnoCentive here. As for other types of artificial eye implants, the latest here is a June 30, 2015 post titled, Clinical trial for bionic eye (artificial retinal implant) shows encouraging results (safety and efficacy).

13,000 year old nanodiamonds and a scientific controversy about extinction

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It took scientists from several countries and institutions seven years to reply to criticism of their 2007 theory which posited that a comet exploded over the earth’s surface roughly 13,000 years ago causing mass extinctions and leaving nano-sized diamonds in a layer of the earth’s crust. From a Sept. 1, 2014 news item on Azonano,

Tiny diamonds invisible to human eyes but confirmed by a powerful microscope at the University of Oregon are shining new light on the idea proposed in 2007 that a cosmic event — an exploding comet above North America — sparked catastrophic climate change 12,800 years ago.

In a paper appearing online ahead of print in the Journal of Geology, scientists from 21 universities in six countries report the definitive presence of nanodiamonds at some 32 sites in 11 countries on three continents in layers of darkened soil at the Earth’s Younger Dryas boundary.

The scientists have provided a map showing the areas with nanodiamonds,

The solid line defines the current known limits of the Younger Dryas Boundary field of cosmic-impact proxies, spanning 50 million square kilometers. [downloaded from http://www.news.ucsb.edu/2014/014368/nanodiamonds-are-forever#sthash.FtKG6WwS.dpuf]

The solid line defines the current known limits of the Younger Dryas Boundary field of cosmic-impact proxies, spanning 50 million square kilometers. [downloaded from http://www.news.ucsb.edu/2014/014368/nanodiamonds-are-forever#sthash.FtKG6WwS.dpuf]

 An Aug. 28,, 2014 University of Oregon news release, which originated the Azonano news item, describes the findings and the controversy,

The boundary layer is widespread, the researchers found. The miniscule diamonds, which often form during large impact events, are abundant along with cosmic impact spherules, high-temperature melt-glass, fullerenes, grape-like clusters of soot, charcoal, carbon spherules, glasslike carbon, heium-3, iridium, osmium, platinum, nickel and cobalt.

The combination of components is similar to that found in soils connected with the 1908 in-air explosion of a comet over Siberia and those found in the Cretaceous-Tertiary Boundary (KTB) layer that formed 65 million years ago when a comet or asteroid struck off Mexico and wiped out dinosaurs worldwide.

In the Oct. 9, 2007, issue of Proceedings of the National Academy of Sciences, a 26-member team from 16 institutions proposed that a cosmic impact event set off a 1,300-year-long cold spell known as the Younger Dryas. Prehistoric Clovis culture was fragmented, and widespread extinctions occurred across North America. Former UO researcher Douglas Kennett, a co-author of the new paper and now at Pennsylvania State University, was a member of the original study.

In that [2007] paper and in a series of subsequent studies, reports of nanodiamond-rich soils were documented at numerous sites. However, numerous critics refuted the findings, holding to a long-running theory that over-hunting sparked the extinctions and that the suspected nanodiamonds had been formed by wildfires, volcanism or occasional meteoritic debris, rather than a cosmic event.

The University of Oregon news release goes on to provide a rejoinder from a co-author of both the 2007 paper and the 2014 paper. as well as. a discussion of how the scientists gathered their evidence,

The glassy and metallic materials in the YDB layers would have formed at temperatures in excess of 2,200 degrees Celsius and could not have resulted from the alternative scenarios, said co-author James Kennett, professor emeritus at the University of California, Santa Barbara, in a news release. He also was on the team that originally proposed a comet-based event.

In the new paper, researchers slightly revised the date of the theorized cosmic event and cited six examples of independent research that have found consistent peaks in the creation of the nanodiamonds that match their hypothesis.

“The evidence presented in this paper rejects the alternate hypotheses and settles the debate about the existence of the nanodiamonds,” said the paper’s corresponding author Allen West of GeoScience Consulting of Dewey, Arizona. “We provide the first comprehensive review of the state of the debate and about YDB nanodiamonds deposited across three continents.”

West worked in close consultation with researchers at the various labs that conducted the independent testing, including with co-author Joshua J. Razink, operator and instrument manager since 2011 of the UO’s state-of-the-art high-resolution transmission electron microscope (HR-TEM) in the Center for Advanced Materials Characterization in Oregon (CAMCOR).

Razink was provided with samples previously cited in many of the earlier studies, as well as untested soil samples delivered from multiple new sites. The samples were placed onto grids and analyzed thoroughly, he said.

“These diamonds are incredibly small, on the order of a few nanometers and are invisible to the human eye and even to an optical microscope,” Razink said. “For reference, if you took a meter stick and cut it into one billion pieces, each of those pieces is one nanometer. The only way to really get definitive characterization that these are diamonds is to use tools like the transmission electron microscope. It helps us to rule out that the samples are not graphene or copper. Our findings say these samples are nanodiamonds.”

In addition to the HR-TEM done at the UO, researchers also used standard TEM, electron energy loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDS), selected area diffraction (SAD), fast Fourier transform (FFT) algorithms, and energy-filtered transmission electron microscopy (EFTEM).

“The chemical processing methods described in the paper,” Razink said, “lay out with great detail the methodology that one needs to go through in order to prepare their samples and identify these diamonds.”

The University of California at Santa Barbara (UCSB) produced an Aug. 28, 2014 news release about this work and while there is repetition, there is additional information such as a lede describing some of what was made extinct,

Most of North America’s megafauna — mastodons, short-faced bears, giant ground sloths, saber-toothed cats and American camels and horses — disappeared close to 13,000 years ago at the end of the Pleistocene period. …

An Aug. 27, 2014 news item (scroll down to the end) on ScienceDaily provides a link and a citation to the latest paper.

Transmetalation, substituting one set of metal atoms for another set

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Transmetalation bears a resemblance of sorts to transmutation. While the chemists from the University of Oregon aren’t turning lead to gold through an alchemical process they are switching out individual metal atoms, aluminum for indium. From a July 21, 2014 news item on ScienceDaily,

The yield so far is small, but chemists at the University of Oregon have developed a low-energy, solution-based mineral substitution process to make a precursor to transparent thin films that could find use in electronics and alternative energy devices.

A paper describing the approach is highlighted on the cover of the July 21 [2014] issue of the journal Inorganic Chemistry, which draws the most citations of research in the inorganic and nuclear chemistry fields. [emphasis mine] The paper was chosen by the American Chemical Society journal as an ACS Editor’s Choice for its potential scientific and broad public interest when it initially published online.

One observation unrelated to the research, the competition amongst universities seems to be heating up. While journals often tout their impact factor, it’s usually more discreetly than in what amounts to a citation in the second paragraph of the university news release, which originated the news item.

The July 21, 2014 University of Oregon news release (also on EurekAlert), describes the work in more detail,

The process described in the paper represents a new approach to transmetalation, in which individual atoms of one metal complex — a cluster in this case — are individually substituted in water. For this study, Maisha K. Kamunde-Devonish and Milton N. Jackson Jr., doctoral students in the Department of Chemistry and Biochemistry, replaced aluminum atoms with indium atoms.

The goal is to develop inorganic clusters as precursors that result in dense thin films with negligible defects, resulting in new functional materials and thin-film metal oxides. The latter would have wide application in a variety of electronic devices.

“Since the numbers of compounds that fit this bill is small, we are looking at transmetelation as a method for creating new precursors with new combinations of metals that would circumvent barriers to performance,” Kamunde-Devonish said.

Components in these devices now use deposition techniques that require a lot of energy in the form of pressure or temperature. Doing so in a more green way — reducing chemical waste during preparation — could reduce manufacturing costs and allow for larger-scale materials, she said.

“In essence,” said co-author Darren W. Johnson, a professor of chemistry, “we can prepare one type of nanoscale cluster compound, and then step-by-step substitute out the individual metal atoms to make new clusters that cannot be made by direct methods. The cluster we report in this paper serves as an excellent solution precursor to make very smooth thin films of amorphous aluminum indium oxide, a semiconductor material that can be used in transparent thin-film transistors.”

Transmetalation normally involves a reaction done in organic chemistry in which the substitution of metal ions generates new metal-carbon bonds for use in catalytic systems and to synthesize new metal complexes.

“This is a new way to use the process,” Kamunde-Devonish said, “Usually you take smaller building blocks and put them together to form a mix of your basic two or three metals. Instead of building a house from the ground up, we’re doing some remodeling. In everyday life that happens regularly, but in chemistry it doesn’t happen very often. We’ve been trying to make materials, compounds, anything that can be useful to improve the processes to make thin films that find application in a variety of electronic devices.”

The process, she added, could be turned into a toolbox that allows for precise substitutions to generate specifically desired properties. “Currently, we can only make small amounts,” she said, “but the fact that we can do this will allow us to get a fundamental understanding of how this process happens. The technology is possible already. It’s just a matter of determining if this type of material we’ve produced is the best for the process.”

Here’s a citation for and a link to the paper,

Transmetalation of Aqueous Inorganic Clusters: A Useful Route to the Synthesis of Heterometallic Aluminum and Indium Hydroxo—Aquo Clusters by Maisha K. Kamunde-Devonish, Milton N. Jackson, Jr., Zachary L. Mensinger, Lev N. Zakharov, and Darren W. Johnson. Inorg. Chem., 2014, 53 (14), pp 7101–7105 DOI: 10.1021/ic403121r Publication Date (Web): April 18, 2014

Copyright © 2014 American Chemical Society

This paper appears to be open access (I was able to view the HTML version when I clicked).

Stabilizing or destabilitizing gold nanoparticles

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Every once in a while I stumble across a ‘nanotechnology’ news release from Oregon (either Oregon State University or the University of Oregon) and as I recall it’s always environment-focused. The latest in an almost complete change-of-pace is, a Dec. 9, 2013 University of Oregon news release (also on EurekAlert) profiling some work on gold nanoparticles and nanoelectronics,

University of Oregon chemists studying the structure of ligand-stabilized gold nanoparticles have captured fundamental new insights about their stability. The information, they say, could help to maintain a desired, integral property in nanoparticles used in electronic devices, where stability is important, or to design them so they readily condense into thin films for such things as inks or catalysts in electronic or solar devices.

The news release goes on to detail the work,

They focused on nanoparticles less than two nanometers in diameter — the smallest studied to date — to better understand structural stability of these tiny particles being engineered for use in electronics, medicine and other materials. Whether a nanoparticle needs to remain stable or condense depends on how they are being used. Those used as catalysts in industrial chemical processing or quantum dots for lighting need to remain intact; if they are precursors for coatings in solar devices or for printing ink, nanoparticles need to be unstable so they sinter and condense into a thin mass.

For their experiments, Smith and Hutchison produced gold nanoparticles in four well-controlled sizes, ranging from 0.9 nanometers to 1.5 nanometers, and analyzed ligand loss and sintering with thermogravimetric analysis and differential scanning calorimetry, and examined the resulting films by scanning electron microscopy and X-ray photoelectron spectroscopy. As the nanoparticles were heated at 5 degrees Celsius per minute, from room temperature to 600 degrees Celsius, the nanoparticles began to transform near 150 degrees Celsius.

The researchers found that smaller nanoparticles have better structural integrity than larger-sized particles that have been tested. In other words, Hutchison said, they are less likely to lose their ligands and bind together. “If you have unstable particles, then the property you want is fleeting,” he said. “Either the light emission degrades over time and you’re done, or the metal becomes inactive and you’re done. In that case, you want to preserve the function and keep the particles from aggregating.”The opposite is desired for Hutchison and others working in the National Science Foundation-funded Center for Sustainable Materials Chemistry, a multi-universities collaboration led by the UO and Oregon State University. Researchers there are synthesizing nanoparticles as precursors for thin films.

“We want solution precursors that can lead to inorganic thin films for use in electronics and solar industries,” said Hutchison, who also is a member of the UO Materials Science Institute.

“In this case, we want to know how to keep our nanoparticles or other precursors stable enough in solution so that we can work with them, using just a tiny amount of additional energy to make them unstable so that they condense into a film — where the property that you want comes from the extended solid that is generated, not from the nanoparticles themselves.”

The research, Hutchison said, identified weak sites on nanoparticles where ligands might pop off. If only a small amount do so, he said, separate nanoparticles are more likely to come together and begin the sintering process to create thin films.

“That’s a really stabilizing effect that, in turn, kicks out all these ligands on the outside,” he said. “The surface area decreases quickly and the particles get bigger, but now all the extra ligands gets excluded into the film and then, over time, the ligands vaporize and go away.”

The coming apart, however, is a “catastrophic failure” if protecting against sintering is the goal. It may be possible to use the findings, he said, to explore ways to strengthen nanoparticles, such as developing ligands that bind in at least two sites or avoiding volatile ligands.

The process, as studied, produced porous gold films. “A next step might be to study how to manipulate the process to get a more dense film if that is desired,” Hutchison said. Understanding how nanoparticles respond to certain conditions, such as changing temperatures, he added, may help researchers reduce waste in the manufacturing process.

As I hinted earlier, this work retains an ‘environment focus’,

“Researchers at the University of Oregon are re-engineering the science, manufacturing and business processes behind critical products,” said Kimberly Andrews Espy, vice president for research and innovation and dean of the UO Graduate School. “This research analyzing the structural stability of nanoparticles by Dr. Hutchison and his team has the potential to improve the engineering of electronics, medicine and other materials, helping to foster a sustainable future for our planet and its people.” [emphasis mine]

Here’s a link to and a citation for the paper,

Transformations during Sintering of Small (Dcore < 2 nm) Ligand-Stabilized Gold Nanoparticles: Influence of Ligand Functionality and Core Size by Beverly L. Smith and James E. Hutchison. J. Phys. Chem. C, 2013, 117 (47), pp 25127–25137 DOI: 10.1021/jp408111v Publication Date (Web): October 24, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall.

Nanoparticle size doesn’t matter

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Does size matter when regulating nanomaterials? As I’ve noted (more than once), I waffle on this issue. Earlier this week, I featured my thoughts on Health Canada’s definition of nanomaterial (Oct. 24, 2011)  and posted an interview with Dr. Andrew Maynard (Oct. 24, 2011) where he expressed reservations about basing nanomaterial regulations on definitions which rely on  nanoparticle size.

Hours after posting my thoughts and the interview with Andrew, I came across this Oct. 24, 2011 news item on Nanowerk titled, Nanoparticles and their size may not be big issues. From the news item,

If you’ve ever eaten from silverware or worn copper jewelry, you’ve been in a perfect storm in which nanoparticles were dropped into the environment, say scientists at the University of Oregon.

Since the emergence of nanotechnology, researchers, regulators and the public have been concerned that the potential toxicity of nano-sized products might threaten human health by way of environmental exposure.

Now, with the help of high-powered transmission electron microscopes, chemists captured never-before-seen views of miniscule metal nanoparticles naturally being created by silver articles such as wire, jewelry and eating utensils in contact with other surfaces. It turns out, researchers say, nanoparticles have been in contact with humans for a long, long time. [emphasis mine]

…

“Our findings show that nanoparticle ‘size’ may not be static, especially when particles are on surfaces. For this reason, we believe that environmental health and safety concerns should not be defined — or regulated — based upon size,” said James E. Hutchison, who holds the Lokey-Harrington Chair in Chemistry. [emphasis mine] “In addition, the generation of nanoparticles from objects that humans have contacted for millennia suggests that humans have been exposed to these nanoparticles throughout time. Rather than raise concern, I think this suggests that we would have already linked exposure to these materials to health hazards if there were any.”

This discussion is becoming quite interesting.