Golden nanocrown

May 14, 2008

Chinese researchers have recently made a "golden crown" with a diameter of only a few nanometers. It is a large ring-shaped molecule containing 36 gold atoms. The lords of the ring, a team of researchers from the Universities of Beijing, Hong Kong, and Nanjing report their unusual compound in the journal Angewandte Chemie: the molecular ring structure is held together exclusively by gold-gold bonds and is thus the largest ring system made of gold atoms produced to date.

Large molecular rings have fascinated chemists for over 40 years--ever since the discovery of crown ethers in 1967. The pioneers in this area, C. J. Pederson, J.-M. Lehn, and D. J. Cram received the Nobel Prize in Chemistry for their discovery in 1987. In the meantime, large molecular ring systems have played an important role in the search for new functional materials and in nanotechnology. The synthesis of ring systems held together exclusively by metal-metal bonds has remained a challenge.

Small rings made of positively charged gold atoms have been know for some time, but only recently could the Chinese team make a ring containing 16 gold atoms. Now, the researchers, led by Shu-Yan Yu, Yi-Zhi Li, and Vivian Wing-Wah Yam, have introduced a new representative of this class of compounds, the biggest gold ring to date that is held together by means of gold-gold bonds: a ring system containing 36 univalent gold atoms.

The researchers started their synthesis with a ring system containing six gold atoms. Three of the gold atoms are linked into a triangle. Each of these gold atoms is attached to another gold atom that sticks out from the corner of the triangle. Three organic ligands are then bound to this flat double triangle to form a molecule that resembles a three-blade propeller.

Six such "propellers" can be linked into a larger ring by means of a self-assembly process. Within this ring system, the gold atoms are arranged into a shape that resembles a crown: six double triangles are each bound to each other by two corners. The free double-corners point outward in a pattern that alternates above and below the plane of the ring.
-end-
Author: Shu-Yan Yu, Renmin University of China, Beijing (China), http://chem.ruc.edu.cn/readnews.asp?newsid=338
Title: Au36 Crown: A Macrocyclization Directed by Metal-Metal Bonding Interactions
Angewandte Chemie International Edition 2008, 47, No. 24, doi: 10.1002/anie.200801001

Wiley

Related Gold Articles from Brightsurf:

The "gold" in breast milk
Breast milk strengthens a child's immune system, supporting the intestinal flora.

From nanocellulose to gold
When nanocellulose is combined with various types of metal nanoparticles, materials are formed with many new and exciting properties.

Research brief: 'Fool's gold' may be valuable after all
In a breakthrough new study, scientists and engineers at the University of Minnesota have electrically transformed the abundant and low-cost non-magnetic material iron sulfide, also known as 'fool's gold' or pyrite, into a magnetic material.

Water molecules are gold for nanocatalysis
Nanocatalysts made of gold nanoparticles dispersed on metal oxides are very promising for the industrial, selective oxidation of compounds, including alcohols, into valuable chemicals.

As electronics shrink to nanoscale, will they still be good as gold?
As circuit interconnects shrink to nanoscale, will the pressure caused by thermal expansion when current flows through wires cause gold to behave more like a liquid than a solid -- making nanoelectronics unreliable?

Peppered with gold
Terahertz waves are becoming more important in science and technology.

No need to dig too deep to find gold!
Why are some porphyry deposits rich in copper while others contain gold?

An 18-carat gold nugget made of plastic
ETH researchers have created an incredibly lightweight 18-carat gold, using a matrix of plastic in place of metallic alloy elements.

What happens to gold nanoparticles in cells?
Gold nanoparticles, which are supposed to be stable in biological environments, can be degraded inside cells.

Turning 'junk' DNA into gold
Mining the rich uncharted territory of the genome or genetic material of a cancer cell has yielded gold for Princess Margaret scientists: new protein targets for drug development against prostate cancer.

Read More: Gold News and Gold Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.