An international team led by researchers from the University of Geneva (UNIGE), Switzerla

nd,  has  designed  a  family  of  molecules capable of binding to metal ions present in the 

surrounding environment and providing an easily detectable light signal during binding. Th

is new type of sensor forms a 3-D structure whose molecules are chiral, that is to say, 

structurally identical but not superimposable, like the left and right hands. These molecules 

consist of a ring and two luminescent arms that emit a particular type of light in a process 

called Circular Polarized Luminescence (CPL), and selectively detect ions such as sodium. 

This research has been published in Chemical Science.

"The  luminescent  arms  of  our molecules function like light bulbs that light up or turn off 

depending on the presence of a positively charged ion, a metal cation," explains Jérôme 

Lacour, Dean of the Faculty of Science at UNIGE and Ordinary Professor in the Department 

of Organic Chemistry. These molecules can be compared to small locks. When they are 

ready to operate and detect the presence of metals, they emit a particular type of light 

(circularly polarized). When a metal ion is inserted, it acts on them like a key, the lock 

geometry changes and the light disappears.

These "locks" are made up of two parts: a ring (a crown ether) that can encircle metal ions 

such as sodium, and two twisted arms that extend from the rim and act like light bulbs, allo

wing researchers to detect whether metal ions are present or not. In the absence of metal 

ions, the two arms are close together and emit intense polarized luminescence. When a metal 

ion is inserted, the molecule changes geometry. The arms move apart and stop emitting light.