An Eye for Colour

 

What´s your favourite colour?

Blue? What kind of blue?

Navy blue? Sky blue? Cyan?

Dr Sally Brooker can answer that question without thinking – for her, it´s royal blue. It´s not just a matter of personal taste, as much of the chemistry professor´s current research is informed by careful discrimination of colour. So much so that a set of British Paint colour charts are taped to the laboratory walls where Sally and her team are monitoring the finer points of colour change as an indicator of changes in molecular environments.

“In coordination chemistry the metal ions are all colourful and there are subtle colour changes which are very informative,” explains Brooker, adding cheerfully “I love the pretty colours!”

A globe of glassware full of a port-coloured solution is being gently agitated on a bench, with a tawny-orange precipitate forming a fine coating on the bottom. The orange colour tells the researchers that the new molecular environment supports iron in its high spin state – if it had turned a deep red-purple, that would have indicated that the new molecular environment had caused it to go low spin. Those differences are critical.

Such reactions intrigue and excite Brooker, not least because some of the resulting molecules can switch between one state and another. That switching, from high spin to low spin, can be caused by a host of factors, including temperature, pressure and irradiation. While the basic nature of the research has its own fascination, there is also the potential for the on-off switching to be used as the binary basis for tiny molecular computers or highly accurate temperature sensors.

That means finding ways of controlling the switching through careful selection and manipulation of the various materials and environments involved. Brooker´s team has become adept at building molecules that form a stable ring with the metal ions on the inside. Their ability to build such “designer” molecules has been attracting increasing attention from researchers around the world intrigued by the possibilities inherent in what sounds like very esoteric chemistry.

“Our many international collaborators, who are experts in characterising molecules, love our designer molecules – so everyone is able to enjoy doing what they do best,” Brooker declares.

“Brooker´s Bunch”, as the team are known, are at the forefront of fundamental research into the synthesis and properties of these compounds. It´s work that has been featured on the cover of highly respected professional journals and brought both post-graduates and professors from places as far-flung as Germany, England, China, Ethiopia, Australia and Mexico to collaborate with the Dunedin-based group.

“We´re very fortunate to attract very talented group members,” says Sally. At 8 to 12 people, the team is large by New Zealand research standards. Currently, a BSc(Hons), MSc, RA and fi ve PhD students fill the lab, funded by different bodies with support from the MacDiarmid Institute, the Marsden Fund, the University of Otago and a TEC Top Achiever PhD Scholarship.

“PhD students are the key to doing research at universities, especially in New Zealand.”

One recent change Sally has very much welcomed has been the dropping of fees for international post-graduate students. “Now we can potentially gain these intelligent, well-motivated people from all around the world as well as from our own backyard”. Group members who subsequently head overseas further the network of ties, as well as the international standing of the group.

Within Brookers Bunch there´s a good deal of teamwork, supervision and mentoring, and strong encouragement to pass on skills and maintain continuity of knowledge. Brooker would dearly like to add a permanent Research Fellow to help deal with the huge management and training workload that the research entails, but is also realistic about the shoe-string budgets of New Zealand science making this highly unlikely.

There are always experiments on the go, the trying of different compounds and approaches to see what new information can be gleaned.

“You´re doing work at the cutting edge and most stuff doesn´t work, so that means you need to do another experiment and another experiment, learning from each,” notes Brooker. “Just get on with it – that´s my philosophy.”

Brooker believes strongly in the importance of the team approach, having found enormous benefi t in her own experience as a post-doctoral fellow in Germany following on from her graduation from the University of Canterbury. Her current position as Professor of Chemistry at the University of Otago is a far cry from her original intention of becoming a secondary school teacher, and a role she fi nds immensely satisfying.

“I get to teach and research, and I´ve always enjoyed doing both.”

There is also the awareness that a research team, no matter how good it is, cannot do everything. Brooker discovered by accident that the Industrial Research superconductor group headed by Professor Jeff Tallon had some of the highly complex equipment that she needed, and they have since made joint applications for more equipment. She freely confesses that she´s not interested in the machines per se, but in what information they can provide on the complex materials and constructions that her group make, so she is more than happy to collaborate with the experts at IRL for these studies.

Brooker credits the MacDiarmid Institute with helping both in funding equipment and in strengthening the connections that makes such research attainable within New Zealand, despite stretched research budgets and the small size of the relevant research communities.

“In New Zealand, it´s unrealistic to do it all in one group, especially with the equipment being so expensive.”

Both groups need million-dollar machines such as the Superconducting Quantum Interference Device (SQUID) used to measure extremely small magnetic fi elds, or a Mössbauer spectrometer which uses gamma radiation to provide information about the chemical environment of a sample, or a PPMS, a physical properties measurement system. It makes sense to spread both the costs and the expertise among the groups. Brooker hopes to get funding to support a post-doc to develop protocols for using this MacDiarmid-funded equipment in the specialist applications she needs.

In the past, the researchers have sent tiny fragile crystals to other departments for analysis of their structure, and the crystals haven´t always survived the journey. Thankfully this is no longer the case, as Otago now has its own X-ray diffractometer so her group does their own structural analyses. Quite apart from their potential utility and scientifi c fascination, the crystals are aesthetically pleasing, with deep colours and faceted edges making them look jewel-like.

“These crystals can be spectacular,” says Brooker,” and I get a lot of pleasure out of that.”