Okayama University


A Colorimetric Sensor that Changes Its Color in Response to Cu2+ Concentration Developed

August 02, 2013

S. Enomoto, S. Kamino and their colleagues in the collaborative research group of Okayama University and RIKEN have developed a colorimetric sensor that allows determination of changes in Cu2+ concentration by spectrophotometry and the naked eye.

The findings were published online on July 10, 2013 in the journal Chemistry–An Asian Journal.

Colorimetric sensors using functional dyes are widely applied for detection of ions and molecules in the environment and human bodies. However, there are no functional dyes that change their colors in response to ion and molecule concentrations.

Previously, the research group has synthesized a new class of rhodamine dyes (one of functional dyes) that are called aminobenzopyranoxanthene (ABPX) dyes. The dyes change their color when a pair of spilolactone benzen in ABPX changes their form in response to the concentration of hydrogen ions. In this study, to apply this reaction, the group synthesized ABPX-hydrazide (ABPX−hy) that has high binding affinity to Cu2+. The ABPX-hy solution is colorless; when Cu2+ is added, the color of solution turns red. The color then changes from red to purple when the Cu2+ concentration increases further. The determination of changes in Cu2+ concentration can be done not only by the naked eye but also quantitatively by spectrophotometry.

It is expected that the ABPX dyes could lead the development of new environmental monitoring devices and diagnostic devices by modifying the spilobenzen structure in response to various ions and molecules.

Contact Information:
Mototaka Senda, Ph.D.
US Representative
Intellectual Property Office, Organization for Research Promotion and Collaboration, Okayama University
Fremont, California USA
TEL: 1-510-797-0907
Email: takasenda@okayama-u.ac.jp

Shuichi Enomoto, Ph.D.
Next-generation Imaging Team Leader
Center for Life Science Technology, RIKEN, Kobe, Japan
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences,
Okayama University, Okayama, Japan