José Ramón Romero, PhD student under the supervision of Prof. Pau Ballester (ICIQ) has defended his PhD Thesis entitled
“Interlocked Architectures Based on a Bis-Calixpyrrole Macrocycle for Ion-Pair Recognition”‘ (assigned to the Analytical and Organic Chemistry Department of the Universitat Rovira i Virgili) publicly on March 24th at the ICIQ Auditorium.
The members of the evaluation committee were: Prof. Christopher Hunter (University of Cambridge), Prof. Arjan W. Kleij (ICIQ) and Prof. Vanesa Marcos Algaba (University of Manchester)
This doctoral thesis deals with the synthesis of mechanically interlocked molecules featuring a rotaxane topology. We report the synthesis of a rotaxane based on a bis-calixpyrrole macrocycle and a 3,5-bis-amidepyridil-N-oxide axle in a remarkable 50% yield through an optimized “in situ” capping strategy using copper(I)-catalysed azide-alkyne cycloaddition reaction. During the optimization studies we concluded that the use of anion templation was detrimental not only for the isolation of the pure rotaxane but also for the good performance of the catalytic reaction. We determined the thermodynamic parameters of the binding process of the rotaxane with different tetraalkylammonium ion-pairs in two different solvents (i.e. chloroform and acetone) and we could identify different binding geometries in the binding process (1:1 and 2:1 complexes). We have also studied the influence of the stopper size in the synthesis of the interlocked structure. We concluded that the use of smaller stoppers mainly leads to the recovery of non-interlocked components from the reaction mixture: free macrocycle and linear component. Moreover, we could identify traces of a new species that we attributed to a hypothetical rotaxane structure after a complete set of characterization analysis. The studies carried out in this doctoral thesis provided deeper knowledge on the synthesis of interlocked structures. Moreover, they can be considered and important first step towards the application of this kind of structures as molecular machines.