Dynamic Transformation of a Ag⁺-Coordinated Supramolecular Nanostructure from a 1D Needle to a 1D Helical Tube via a 2D Ribbon Accompanying the Conversion of Complex Structures

Abstract

We report a unique dynamic morphology transformation of a Ag +coordinated supramolecular nanostructure accompanying the conversion of complex structures in aqueous solution. In the presence of AgNO 3 (1.0 equiv), the achiral bipyridine-based ligand 1G, possessing hydrazine and glycine moieties, preferentially generated a 1D needle-like structure (nanostructure I) based on the 1GAgNO 3 complex (1G:Ag + = 1:1) as a metastable product. Nanostructure I was then transformed into nanostructure II, which was composed of the 1G 3 Ag 2 (NO 3 ) 2 complex (1G:Ag + = 3:2) as the thermodynamically stable product. This nanostructure exhibited a 1D helical tubular structure with a uniform diameter via a 2D ribbon as an intermediator, which led to the generation of a circular dichroism (CD) signal with right-handed (P-type) helicity. The observed dynamic transformation was attributed to formation of the thermodynamically favored helical 1G 3 Ag 2 (NO 3 ) 2 complex. In addition, the helical 1G 3 Ag 2 (NO 3 ) 2 complex acted as an initiator in the transformation from the 1D needle-like structure to the 1D helical tube via a 2D ribbon. The enhanced ΔG°value of nanostructure II compared to that of nanostructure I confirmed that nanostructure II is thermodynamically stable. More importantly, the transformation of supramolecular nanostructure I to nanostructure II occurred via an "on" pathway, even though the 1GAgNO 3 complex was converted to the 1G 3 Ag 2 (NO 3 ) 2 complex, which did not involve dissociation from nanostructure I into the monomeric 1GAgNO 3 complex species. In the kinetic study, the NO 3 − anion was found to act as an accelerator for the dynamic transformation from nanostructure I to nanostructure II. This result provides the first example of a dynamic transformation of a 1D needle-like structure into a 1D tubular structure via a 2D ribbon structure, accompanied by the conversion of a complex structure and the generation of a large CD signal for the metallosupramolecular nanostructure. This study may open up new avenues to the understanding of a dynamic morphology transformation process in biological systems.

Circularly Polarized Luminescence Active Supramolecular Nanotubes Based on PtIIComplexes That Undergo Dynamic Morphological Transformation and Helicity Inversion

“…Various pitch lengths and angles of the righthanded helical ribbons were observed, indicating that the right-handed ribbons were generated by the "closing pitch model" and "growing width model". [22] After aging for 25 minutes, to our surprise, the partially right-handed ribbons were transformed to the tubes with left-handed helical scroll marks (Figure 2D). We also observed some single strands, each of which has two half segments with different morphologies and handedness; a right-handed ribbon and a left-handed tube (Figure 2E).…”

“…(Figures 2C and S1). Various pitch lengths and angles of the right‐handed helical ribbons were observed, indicating that the right‐handed ribbons were generated by the “closing pitch model” and “growing width model” [22] . After aging for 25 minutes, to our surprise, the partially right‐handed ribbons were transformed to the tubes with left‐handed helical scroll marks (Figure 2D).…”

Isomerism and Silver Ion-Regulated Triterpenoid-Based Nanostructures for In Situ Synthesis of Ag Nanoparticles with Plasmonic Chirality

“…Silver­(I) ions (Ag + ) tend to adopt diverse coordination geometries in supramolecular chemistry and have a considerable binding strength to N atoms. , Inspired by the fabrication of various supramolecular architectures by Ag + and pyridyl ligands, − assembly of p -Py-BL was chosen for Ag + (used as AgNO 3 ) coordination to further regulate supramolecular chirality. Not surprisingly, p -Py-BL showed striking changes on CD spectra and morphologies after addition of Ag + .…”

Supramolecular Nanotubes Functioning as Morphology Regulators for Fluid-State Molecular Assemblies

“…The helical fibrous morphology and the tubular morphology can be classified as a similar morphology, because both the morphologies had not only the bilayer membrane structures based on the tilted and twisted molecular packing of the phospholipid and the surfactants but also the chirality induced by confinement in the nanotubes. In fact, helical fibrous morphologies are often observable as intermediates of tubular morphologies. ,,− …”