Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A molecular thread

04.12.2014

Flexible metal–organic frameworks with a range of pore sizes are made by threading through molecular ligands

The ability to ‘thread’ a molecular ligand through a metal–organic framework (MOF) to alter the pore size of the material — and yet allow the MOF to retain its crystallinity and principal structural features — has been demonstrated in a new study by A*STAR[1].


A three-dimensional metal–organic framework with interpenetrating bridging ligands and guest molecules denoted as large balls (color codes: cadmium, dark magenta; chlorine, green; oxygen, red; nitrogen, blue; carbon, black). © 2014 A*STAR Institute of Materials Research and Engineering

MOFs are three-dimensional, coordination networks comprising metal ions and organic molecules and usually are crystalline, porous materials with many applications including storage of gases such as hydrogen and carbon dioxide. While ‘threaded’ MOFs have been synthesized in the past, they remain challenging to easily and reliably produce.

Inclusion of molecular ligands creates a flexible, interpenetrated MOF — similar to stitching a thread through fabric to make a new pattern. Use of bridging ligands of varying lengths potentially could lead to materials with many different properties in terms of gas adsorption, gas separation and catalysis.

Now, Andy Hor and colleagues at the A*STAR Institute of Materials Research and Engineering and the National University of Singapore show how solvate molecules adhering to the surface of the channels on a cadmium-based coordination polymer can be replaced with nitrogen-containing ligands that form a bridge between two metal ions of the MOF. These dipyridyl ligands of lengths varying from 0.28 to 1.10 nanometers are then threaded through the pores of the framework to form flexible MOF structures with different porosities (see image).

A surprise for the researchers came when long dipyridyl ligands that were expected to cause structural collapse of the framework were accommodated by slippage of two-dimensional layers within the structure. “Our observation that within these crystals, two side-by-side layers can slip or slide across to create space for guests suggests that these MOFs are actually smarter than we thought because they can respond to external stimuli without losing their crystallinity,” says Hor.

The researchers used the solvent diethylformamide (DEF), rather than the less bulky dimethylformamide solvate, to create cadmium-based double layers with large enough channels to permit the dipyridyl ligands to thread through. They also replaced other DEF solvates within the structure with water to minimize congestion.

“We hope to apply a similar approach to other MOFs — using a range of metals and organic molecules — and to test the boundaries for creating adaptable three-dimensional materials,” says Hor. “We could introduce different functional organic moieties to the present MOF and create materials with magnetic, electronic and photonic functionalities.” Also, the dynamic nature of these MOFs makes them attractive candidates for selective gas adsorption materials.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering. More information about the group’s research can be found at the Porous Materials Laboratory webpage.

Reference:
[1] Zhang, Z.-X. Ding, N.-N., Zhang, W.-H., Chen, J.-X., Young, D. J. & Hor, T. S. A. Stitching 2D polymeric layers into flexible interpenetrated metal–organic frameworks within single crystals. Angewandte Chemie International Edition 53, 4689–4632 (2014).

A*STAR Research | ResearchSEA
Further information:
http://www.research.a-star.edu.sg/research/7116
http://www.researchsea.com

More articles from Materials Sciences:

nachricht New concept for structural colors
18.05.2018 | Technische Universität Hamburg-Harburg

nachricht Saarbrücken mathematicians study the cooling of heavy plate from Dillingen
17.05.2018 | Universität des Saarlandes

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>