Light-driven ratcheted formation of
diastereomeric host-guest systems
Iago Neira, Chiara Taticchi, Federico Nicoli, Massimiliano Curcio, Marcos
D. Garcia, Carlos Peinador, Serena Silvi, Massimo Baroncini, Alberto Credi
Presented by: Florian Muster and Andrei Pavel
Abstract
Introduction to Host Guest Systems
Visible light was used to direct the self-assembly of azobenzene
axles with cyclodextrin in water, enabling the selective formation of
E
c
a high-energy host–guest complex. The study reveals a ratchet-like
Complex B
mechanism that shifts the system away from equilibrium and allows
ΔΔG‡
control over diastereomeric product distribution.
0
Complex A
Complexation analysis
Complex B
t
Complex A
− Cyclodextrin binding to non-symmetric
azobenzene axles.
Narrow rim
Cyclodextrin
− Kinetic vs. thermodynamic behavior of both
diastereomers.
− Light-induced shift toward the metastable
Wide Rim
complex.
UV-vis follows the formation
kinetics of A and B
1H NMR
distinguishes
complexes A and B
Effects of Substituents on
Host-Guest Systems
Complex A
Free E-Axle
Complex B
Unstable A
Free Z-Axle
Unstable B
E
E
E
E
E
ΔΔG‡
ΔΔG‡
ΔΔG‡
Light-driven
self-assembly
ΔΔG‡
E-1
0
0
0
0
0
E-3
E-2
Slow
E
Substituent
E-1
E-2
E-3
ΔΔG‡
kcal/mol
0.50
1.40
-1.00
E
Fast
Substitution mainly changes the
Fast
Fast
activation barriers, not the product
stability.
This
controls
0
whether
complex A or B forms faster.
0
Conclusion
References
[1]. I. Neira, C. Taticchi, F. Nicoli, M. Curcio, M. D. Garcia, C. Peinador, S. Silvi, M. Baroncini, A. Credi, Chem 2025,
11, 102375.
[2]. A. Harada, Acc. Chem. Res. 2001, 34, 456–464.
[3]. G. Ragazzon, L. J. Prins, Nat. Nanotechnol. 2018, 13, 882–889.
[4]. K. Das, L. Gabrielli, L. J. Prins, Angew. Chem. Int. Ed. 2021, 60, 20120–20143.
Visible light shifts the system away from equilibrium and
favors the metastable complex A in water. This strategy opens
perspectives for active supramolecular materials and artificial
molecular machines.