Using Chemistry to Create Smart Materials

NYUAD student Selbi Nuryyeva, Class of 2015, under the supervision of Assistant Professor of Chemistry Ali Trabolsi, conducts her first research on the synthesis and characterization of molecular switches.

NYU Abu Dhabi rising senior Selbi Nuryyeva (Class of 2015), from Turkmenistan, is a busy undergraduate with a packed schedule. For two years, she has spent summers and semesters as a research assistant intern in both Abu Dhabi and New York, and has published two papers and presented her work at international conferences. "Research is important because no matter how thick the textbooks are, there is still a huge chunk of science that remains unknown and undiscovered," Nuryyeva said.

Under the supervision of NYUAD Assistant Professor of Chemistry Ali Trabolsi, Nuryyeva conducted her first research on the synthesis and characterization of molecular switches — molecules that can reversibly switch between two states, "off" and "on," under external stimuli based on the viologen moities.

Viologens are known to be electrochromic — they change color upon the application of a small electric current. The HV molecule Nuryyeva synthesized is transparent and known as "off" state. But by reducing the molecule by one electron, it turns the molecule to an "on" state, changing the color to a dark purple. In this reduced form, the HV also absorbs ultraviolet light.

This led Nuryyeva and her colleagues to construct a device that sandwiched the HV between two glass slides. They then applied an electric current and discovered that the HV was still able to exhibit a reversible color change within the device. "Such findings serve as proof for the possibility of a smart window application where the color of the window can be controlled by a switch or a button. The application has the potential to limit the heat entering the buildings, reducing energy consumption from air conditioners," Nuryyeva explained.

Nuryyeva also analyzed the dimerization and complex formation of HV with an organic macrocycle. Besides changing color, upon one electron reduction of HV, viologen on each branch becomes a radical cation — an ion, atom, or a molecule that has an unpaired electron. Dimerization occurs when one radical attracts another, forming a dimer through strong interactions.

Besides dimerization, viologen groups are also known to form a molecular complex with cucurbituril[7] (CB7), a water-soluble organic macrocycle. The hydrophobic interaction between CB7 and the viologen group is a stronger preferred intermolecular force compared to dimerization. But experiments done by Nuryyeva's team came up with a case where dimerization force is stronger than hydrophobic interactions.

A molecular switch like that could be used in nanomechanical systems, such as memory chips and in drug delivery, where release of the drug is required as a response to an external stimulus. Such a drug would resemble the structure of the HV and could be released upon electron reduction.

Nuryyeva's work on synthesis and characterization of molecular switches conducted in Abu Dhabi resulted in two papers. The research on the synthesis of HV and its characterization was the cover story of the Journal of Material Chemistry, while the other paper on HV forming a complex with CB7 was accepted by Chemistry — A European Journal. Nuryyeva also presented this work at the International Union of Pure and Applied Chemistry's 44th World Chemistry Congress in Istanbul, at the American Chemical Society Northeast Regional Meeting in New Haven, Connecticut, and at NYUAD's Annual Research Conference.

Nuryyeva sees her passion for research in chemistry as a way of helping others and plans to do new research with Trabolsi for her senior Capstone project next year. "From the small scale of referencing other people's papers to the big scale of attending and exchanging ideas with other scientists in international conferences, research is a unifying bond between countries, eliminating all the borders," she said.

This article originally appeared in NYUAD's 2013-14 Research Report (13MB PDF).