Joint meeting of the
Royal Australian Chemical Institute, NSW Branch
and the
Royal Society of New South Wales
Art, Architecture and Engineering at the Molecular Level
Professor Len LindoySchool of Chemistry, University of Sydney
Date: Wednesday, 4th August, 1999
Venue: Faculty of Science, University of Technology, Sydney.
ABSTRACT
Since prehistoric times, our species has been driven to undertake artistic and engineering endeavours on a human (or macro) scale. However, dating from the beginnings of modern chemistry around two hundred years ago, it has become increasingly possible to undertake similar creative activities at the molecular level.
A major part of the current activity is occurring in the field of supramolecular chemistry - an area that tends to mimic nature's way of doing things. The lecture will address the recent rise of supramolecular chemistry with emphasis on its potential for "art, architecture and engineering" at the molecular level.
Enquiries: A/Prof. Tony Baker
Phone: 9514 1764
email: Tony.Baker@uts.edu.au
Open to members and visitors - all welcome
Molecular Trains and Computers
A report on the 1083rd General Monthly Meetingby Dr Edmund Potter
Humans have built monumental structures over millennia, maybe for vanity or respect for gods and perhaps just because the technology was available. Projects such as Stonehenge and the great cathedrals of Europe represent huge investments of human labour. These macrostructures are fine achievements of the architects, engineers and builders of their time. Modern chemistry, defined in terms of having control at a molecular level, is still less than two centuries old. This science, now thought of as mature, has provided many challenges to the creativity of humankind. One way the challenge has been interpreted has been to design structures that, to some extent, mimic the great architectural creations though on the nanoscale.
Some of the creations of chemists include dendrimers where a large molecule grows from a nucleus that contains in its functional groups and their disposition information about how the dendrimer can grow. The growth of the molecule is ultimately limited by clashes between groups at the periphery. Professor Lindoy referred to these molecules as "molecular macrame" because the structural formula represented in two dimensions looks like an intricate doily.
Fraser Stoddart, now at UC Berkeley, and his co-workers have made some wonderful molecular systems including rotaxanes. In these systems a linear molecular with two end-stops passes through a large cyclic molecule. These are no linking covalent or coordinate bonds but the relationship between the molecules is tightly defined. In a further elaboration of such systems extremely large (by chemists" standards) cyclic molecules have been synthesised and interlinked with a smaller cyclic molecule. The smaller molecule (train) can be located at favoured positions (stations) on the larger ring. The systems can be excited so that the smaller molecule shuttles from one station to the next. This is the molecular train set. Another "train set" has two trains and four stations (marketed for the better-off children) and it has been observed that the trains move so that there is always one unoccupied station between the trains (molecular safe working).
Other structures discussed include double-helical metal complexes that can be used as a base to prepare molecular trefoil knots, interlocking rings or big macrocycles, depending on what further linking is done.
Professor Lindoy also discussed some work from his own group involving the preparation of a cage-like ligand that has three bipyridine metal-binding sites. The molecule itself is not inherently chiral but binding of a metal ion causes twisting of the three "bars" of the cage leading to a chiral complex.
Jean-Marie Lehn has developed complex ions that have 9 cations arranged in a 3x3 matrix. If these sites could be addressed and changed between states (eg. spin states or oxidation states) then such devices could be elements of memory for a molecular computer. Other components that have been developed include molecular wires that even have insulation surrounding the conducting core. How long until we see molecular computers containing the most miniaturised electronics we can imagine?
The meeting, which was held in conjunction with the NSW Branch of the Royal Australian Chemical Institute, was well attended with over 35 members and guests present. Professor Mick Wilson (UTS) proposed the vote of thanks. The Department of Chemistry, Materials and Forensic Science provided the pre-meeting catering (Era Koirala and Alex Rubel are thanked for assistance). Fourteen members and guests attended dinner with the speaker at the Malaya on George restaurant.