Smart Nanocages as a Tool for Controlling Supramolecular Aggregation

Abstract

An important aspect in the field of supramolecular chemistry is the control of the composition and aggregation state of supramolecular polymers and the possibility of stabilizing out-of-equilibrium states. The ability to freeze metastable systems and release them on demand, under spatiotemporal control, to allow their thermodynamic evolution toward the most stable species is a very attractive concept. Such temporal blockage could be realized using stimuli-responsive “boxes” able to trap and redirect supramolecular polymers. In this work, we report the use of a redox responsive nanocontainer, an organosilica nanocage (OSCs), for controlling the dynamic self-assembly pathway of supramolecular aggregates of a luminescent platinum compound (PtAC ). The aggregation of the complexes leads to different photoluminescent properties that allow visualization of the different assemblies and their evolution. We discovered that the nanocontainers can encapsulate kinetically trapped species characterized by an orange emission, preventing their evolution into the thermodynamically stable aggregation state characterized by blue-emitting fibers. Interestingly, the out-of-equilibrium trapped Pt species (PtAC@OSCs) can be released on demand by the redox-triggered degradation of OSCs, re-establishing their self-assembly toward the thermodynamically stable state. To demonstrate that control of the self-assembly pathway occurs also in complex media, we followed the evolution of the supramolecular aggregates inside living cells, where the destruction of the cages allows the intracellular release of PtAC aggregates, followed by the formation of microscopic blue emitting fibers. Our approach highlights the importance of “ondemand” confinement as a tool to temporally stabilize transient species which modulate complex self-assembly pathways in supramolecular polymerization.

Heteroleptic copper(i) complexes bearing functionalized 1H-pyrazole-bipyridine ligands: synthesis, photophysical properties, crystal structures, and applications in halogen sensing

“…Over the past few decades, well-defined metal–organic or organometallic supramolecular architectures with fluorescence properties have been the subject of keen interest 1–3 because of their novel structures and wide applications in the fields of bioimaging, chemo- or bio-sensors, organic light-emitting devices, catalysis, light harvesting etc . 4–13…”

“…Over the past few decades, well-defined metal-organic or organometallic supramolecular architectures with fluorescence properties have been the subject of keen interest [1][2][3] because of their novel structures and wide applications in the fields of bioimaging, chemo-or bio-sensors, organic light-emitting devices, catalysis, light harvesting etc. [4][5][6][7][8][9][10][11][12][13] Their applications depend on the presence of fluorophores with optoelectronic properties but may also benefit from stimuli-responsive non-covalent interactions. 7,12,13 Anions play a critical role in a range of biological processes, and are implicated at various levels in a number of diseases, ranging from fluorosis to cystic fibrosis.…”

“…[42][43][44] Inspired by these developments, we decided to design a series of new ligands 5-pzbpy (L 1 ), 4,4 0 -pz 2 bpy (L 2 ), 5,5 0 -pz 2 bpy (L 3 ), and 3,8-pz 2 phen (L 4 ), bearing anion-binding 1H-pyrazole units (hydrogen bond proton donors), and to study their ability to form fluorescent pyrazole-based metallo-supramolecules. Six luminescent 1H-pyrazole functionalized Cu(I) complexes (1)(2)(3)(4)(5)(6) (5), and [Cu(L 2 )-(dppp)](BF 4 ) (6) supported by these novel ligands and by a diphosphine ligand (POP/dppp) were successfully synthesized and fully characterized. The results indicate that the halogen ions can effectively tune the emission intensity of these Cu(I) complexes by hydrogen bonds or by proton transfer with the participation of the 1H-pyrazole N-H groups supported by the experimental data and theoretical calculations.…”

A Dual‐Kinetic Control Strategy for Designing Nano‐Metamaterials: Novel Class of Metamaterials with Both Characteristic and Whole Sizes of Nanoscale

“…[ 8 ] It means that a many‐dimensional parameter space of processing variables provides opportunities for creating a wide diversity of non‐equilibrium structures in a T eff (w) ‐constant system. [ 9 ] As a conceptual model for regulating dynamic processes, we developed a novel dual‐kinetic control strategy, in which two kinetic pathways, block copolymers (BCP) self‐assembly and droplet self‐emulsifying, were controlled simultaneously (Scheme 1b ). On the basis of manipulating two different kinetic processes, an unusual dual‐phase separation occurred, including nonsolvent‐induced microphase separation and osmotically driven macrophase separation.…”

Supramolecular Self‐Assembly in Living Cells

“…In supramolecular chemistry,m acromolecules are made from two or more chemical components based on noncovalent intramolecular forces.These forces include hydrophobic interactions,h ydrogen bonding,e lectrostatic interactions, p-p interactions,a nd van der Waals forces,and underlie key mechanisms,such as host-guest chemistry,s elf-assembly,a nd molecular recognition in applications ranging from material science to biochemistry. [8,66] Recently,t he combination of supramolecular chemistry and biology has provided innovative methods of intracellular modification for protein bioimaging and polyamine extraction through the use of host-guest inclusion interactions. [9] Furthermore,c ontrolled intracellular self-assembly induced by external/internal stimuli leads to the selfassembly of nanoaggregates with different topologies for cancer cell apoptosis.…”