Giant intrinsic circular dichroism of prolinol-derived squaraine thin films

An International study, published in Nature Communications, has provided a new small molecular benchmark material for the development of organic thin film based chiroptics. Chirality is a fundamental symmetry property describing an object such as a molecule that is non-superimposable on its mirror image. Nature has evolved with single handedness meaning that essentially all biological processes are intrinsically chiral. This is well recognized for instance in pharmacological applications, but however, the enantiopure, i.e. homochiral, synthesis of drugs remains a challenge for chemists. Combination of molecular chirality and the inherently connected circular dichroism (CD) with semiconducting properties offers great potential for chiral opto-electronics. Researchers in this work, in which Oriol Arteaga from Department of Applied Physics and IN2UB, University of Barcelona participated, assessed the temperature-controlled assembly of enantiopure prolinol functionalized squaraines with opposite handedness into intrinsically circular dichroic, molecular J-aggregates in spincasted thin films (see Figure). The results presented in this work, provide a new small molecular benchmark material for the development of organic thin film based chiroptics with a uniquely high CD rooted in a large oscillator strength of the J-type excitonic optical transitions and not to mesoscopic structural ordering.


Fig. Thickness normalized circular dichroic properties of ProSQ-C16 thin films



· Magnetically tunable bidirectional locomotion of a self-assembled nanorod-sphere propeller. José García-Torres, Carles Calero, Francesc Sagués, Ignacio Pagonabarraga & Pietro Tierno. Nature Communications.

· Change in the magnetic configurations of tubular nanostructures by tuning dipolar interactions. H. D. Salinas, J. Restrepo & Òscar IglesiasScientific Reports.




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