Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > In water as in love, likes can attract

This model of the guanidinium chloride salt (blue and silver) in solution shows carbon (yellow) and water (green) surrounding the cations and demonstrates cation-cation pairing.
This model of the guanidinium chloride salt (blue and silver) in solution shows carbon (yellow) and water (green) surrounding the cations and demonstrates cation-cation pairing.

Abstract:
At some point in elementary school you were shown that opposite charges attract and like charges repel. This is a universal scientific truth - except when it isn't. A research team led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, working at the Advanced Light Source (ALS), has shown that, when hydrated in water, positively charged ions (cations) can actually pair up with one another.

In water as in love, likes can attract

Berkeley, CA | Posted on September 19th, 2013

"Through a combination of X-ray spectroscopy, liquid microjets and first principles' theory, we've observed and characterized contact pairing between guanidinium cations in aqueous solution," Saykally says. "Theorists have predicted this cation-to-cation pairing but it has never been definitively observed before. If guanidinium cations can pair this way, then other similar cation systems probably can too."

Guanidinium is an ionic compound of hydrogen, nitrogen and carbon atoms whose salt - guanidinium chloride - is widely used by scientists to denature proteins for protein-folding studies. This practice dates back to the late 19th century when the Czech scientist Franz Hofmeister observed that cations such as guanidinium can pair with anions (negatively charged ions) in proteins to cause them to precipitate. The Hofmeister effect, which ranks ions on their ability to "salt-out" proteins, became a staple of protein research even though its mechanism has never been fully understood.

In 2006, Kim Collins of the University of Maryland proposed a "Law of Matching Water Affinities" to help explain "Hofmeister effects". Collins's proposal holds that the tendency of a cation and anion to form a contact pair is governed by how closely their hydration energies match, meaning how strongly the ions hold onto molecules of water. Saykally, who is a faculty scientist in Berkeley Lab's Chemical Sciences Division and a professor of chemistry at the University of California Berkeley, devised a means of studying both the Law of Matching Water Affinities and Hofmeister effects. In 2000, he and his group incorporated liquid microjet technology into the high-vacuum experimental environment of ALS beamlines and used the combination to perform the first X-ray absorption spectroscopy measurements on liquid samples. This technique has since become a widely used research practice.

"The XAS spectrum is generally sensitive to the changes in the local solvation environment around each atom, including potential effects of ion-pairing," Saykally says. "However, the chemical information that one can extract from such experimental data alone is limited, so we interpret our spectra with a combination of molecular dynamics simulations and a first principles theory method."

Development of this first principles theory method was led by Prendergast, a staff scientist in the Theory of Nanostructures Facility at Berkeley Lab's Molecular Foundry. Computational resources were provided by the National Energy Research Scientific Computing Center (NERSC). The Molecular Foundry and NERSC, as well as the ALS, are all U.S. Department of Energy national user facilities hosted at Berkeley Lab.

With the liquid microjet technology, a sample rapidly flows through a fused silica capillary shaped to a finely tipped nozzle with an opening only a few micrometers in diameter. The resulting liquid beam travels a few centimeters in a vacuum chamber and is intersected by an X-ray beam then collected and condensed out. In analyzing their current results, which were obtained at ALS Beamline 8.0.1, the Berkeley Lab researchers concluded that the counterintuitive cation-cation pairing observed is driven by water-binding energy, as predicted by theory.

Orion Shih, a recent graduate of Saykally's research group, is the lead author of a paper describing this study in the Journal of Chemical Physics. The paper is titled "Cation-cation contact pairing in water: Guanidinium." Saykally is the corresponding author. Other co-authors are Alice England, Gregory Dallinger, Jacob Smith, Kaitlin Duffey, Ronald Cohen and Prendergast.

"We found that the guanidinium ions form strong donor hydrogen bonds in the plane of the molecule, but weak acceptor hydrogen bonds with the pi electrons orthogonal to the plane," Shih says. "When fluctuations bring the solvated ions near each other, the van der Waals attraction between the pi electron clouds squeezes out the weakly held water molecules, which move into the bulk solution and form much stronger hydrogen bonds with other water molecules. This release of the weakly interacting water molecules results in contact pairing between the guanidinium cations. We believe our observations may set a general precedent in which like charges attract becomes a new paradigm for aqueous solutions."

####

For more information, please click here

Contacts:
Lynn Yarris

510-486-5375

Copyright © DOE/Lawrence Berkeley National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

For more about Richard Saykally and his research group go here:

For more about Berkeley Lab’s Advanced Light Source go here:

For more about Berkeley Lab’s Molecular Foundry go here:

For more about NERSC go here:

Related News Press

News and information

Collaboration yields discovery of 12-sided silica cages June 20th, 2018

JPK talks with Dr Frank Lafont, Director of the BioImaging Center Lille (BICeL) about the use of the NanoWizard® AFM together with fluorescence microscopy in the study of living cells June 19th, 2018

Powering the 21st Century with Integrated Photonics: UCSB-Led Team Selected for Demonstration of a Novel Waveguide Platform Which is Transparent Throughout the MWIR and LWIR Spectral Bands June 19th, 2018

Executives Explore Key Megatrends and Innovations in MEMS, Sensors, Imaging Tech at SEMI-MSIG European Summits: Speakers to share developments in smart automotive, smart cities, smart industrial, biomedical, consumer and IoT, September 19-21, 2018 in Grenoble, France June 19th, 2018

Carbon nanotube optics poised to provide pathway to optical-based quantum cryptography and quantum computing: Researchers are exploring enhanced potential of carbon nanotubes for unique applications June 18th, 2018

Laboratories

Carbon nanotube optics poised to provide pathway to optical-based quantum cryptography and quantum computing: Researchers are exploring enhanced potential of carbon nanotubes for unique applications June 18th, 2018

Tripling the Energy Storage of Lithium-Ion Batteries: Scientists have synthesized a new cathode material from iron fluoride that surpasses the capacity limits of traditional lithium-ion batteries June 14th, 2018

Evidence for a new property of quantum matter revealed: Electrical dipole activity detected in a quantum material unlike any other tested June 11th, 2018

Building nanomaterials for next-generation computing: Scientists recently developed a blueprint to fabricate new nanoheterostructures using 2D materials June 1st, 2018

Physics

Evidence for a new property of quantum matter revealed: Electrical dipole activity detected in a quantum material unlike any other tested June 11th, 2018

Chemistry

Quantum Interference May Be Key to Smaller Insulators: Breakthrough could jumpstart further miniaturization of transistors June 6th, 2018

Density gradient ultracentrifugation for colloidal nanostructures separation and investigation June 5th, 2018

From Face Recognition to Phase Recognition: Neural Network Captures Atomic-Scale Rearrangements: Scientists use approach analogous to facial-recognition technology to track atomic-scale rearrangements relevant to phase changes, catalytic reactions, and more May 31st, 2018

Govt.-Legislation/Regulation/Funding/Policy

Collaboration yields discovery of 12-sided silica cages June 20th, 2018

Powering the 21st Century with Integrated Photonics: UCSB-Led Team Selected for Demonstration of a Novel Waveguide Platform Which is Transparent Throughout the MWIR and LWIR Spectral Bands June 19th, 2018

Carbon nanotube optics poised to provide pathway to optical-based quantum cryptography and quantum computing: Researchers are exploring enhanced potential of carbon nanotubes for unique applications June 18th, 2018

Camouflaged nanoparticles used to deliver killer protein to cancer June 17th, 2018

Discoveries

Collaboration yields discovery of 12-sided silica cages June 20th, 2018

Carbon nanotube optics poised to provide pathway to optical-based quantum cryptography and quantum computing: Researchers are exploring enhanced potential of carbon nanotubes for unique applications June 18th, 2018

Camouflaged nanoparticles used to deliver killer protein to cancer June 17th, 2018

Squeezing light at the nanoscale: Ultra-confined light could detect harmful molecules June 17th, 2018

Announcements

Collaboration yields discovery of 12-sided silica cages June 20th, 2018

JPK talks with Dr Frank Lafont, Director of the BioImaging Center Lille (BICeL) about the use of the NanoWizard® AFM together with fluorescence microscopy in the study of living cells June 19th, 2018

Powering the 21st Century with Integrated Photonics: UCSB-Led Team Selected for Demonstration of a Novel Waveguide Platform Which is Transparent Throughout the MWIR and LWIR Spectral Bands June 19th, 2018

Executives Explore Key Megatrends and Innovations in MEMS, Sensors, Imaging Tech at SEMI-MSIG European Summits: Speakers to share developments in smart automotive, smart cities, smart industrial, biomedical, consumer and IoT, September 19-21, 2018 in Grenoble, France June 19th, 2018

Water

Making quantum puddles: Physicists discover how to create the thinnest liquid films ever June 13th, 2018

Engineered polymer membranes could be new option for water treatment May 6th, 2018

Rice U.'s one-step catalyst turns nitrates into water and air: NSF-funded NEWT Center aims for catalytic converter for nitrate-polluted water January 5th, 2018

A new way to mix oil and water: Condensation-based method developed at MIT could create stable nanoscale emulsions November 8th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project