Dynamic Covalent Hydrazone Supramolecular Polymers toward Multiresponsive Self-Assembled Nanowire System

Abstract

Stimuli-responsive polymeric systems are of considerable interest due to their potential applications in environment-adaptive technologies such as smart surfaces. Traditionally, such systems can be constructed either by dynamic noncovalent (supramolecular) or dynamic covalent chemistry, but the use of both chemistries in one system may offer unique opportunities for structural diversity and various controllability. Herein, we report that hydrazone–pyridinum conjugates, which can be dynamically exchanged by transimination, assemble to form one-dimensional nanowires due to direct intermolecular interactions (without metal-ion coordination). The self-assembly process can be controlled not only by dynamic covalent chemistry but also by pH adjustment. The hydrazone–pyridinum conjugates are transformed to merocyanine-type dyes of distinctive negative solvatochromism via deprotonation, which also affects their self-assembly. Such a dual control of the dynamic molecular assembly will provide unique way to develop diverse smart nanomaterials with multistimuli-responsiveness.

Additive-free photo-mediated oxidative cyclization of pyridinium acylhydrazones to 1,3,4-oxadiazoles: solid-state conversion in a microporous organic polymer and supramolecular energy-level engineering

“…4 ), which exhibited a stimuli-responsive helical wire-type self-assembly by direct intermolecular interactions such as dipole–dipole, π–π, CH–π, and van der Waals interactions. 14 We tested whether BH1 made an inclusion complex with CB7 ( Fig. 4a ) and its effect on the photo-mediated oxidative cyclization.…”

“…Pyridinium hydrazone conjugates, H1 and BH1 were prepared following the published procedures. 14 Cucurbit [7]uril (CB7) was purchased from CBTECH (Pohang, Korea). 1-Adamantanamine, benzohydrazide, 4-pyridinecarboxaldehyde, p-xylene dibromide, and iodomethane were commercially available and used as received.…”

“…1b ). In our previous report, 14 bis- p -pyridinium benzoyl hydrazone (BH1, a cationic guest molecule) showed pH-dependent supramolecular assembly and dynamic covalent exchange reactions (transamination). Initially, we tested the effect of inclusion complexation of BH1 with cucurbit[7]uril (CB7) to stimuli-responsiveness and self-assembly.…”

A novel aggregation-induced enhanced emission aromatic molecule: 2-aminophenylboronic acid dimer

“…To the best of our knowledge, this is the first example of dynamic covalent system with both B-N and B-O bonds, which provides a new avenue for construction of molecular architectures for advanced materials applications such as CO2 detection (Fig. S28), nanogating, saccharide recognition and separation, 51 chemo/bio-sensing, 52 self-healing, 53 supramolecular self-assembly 54 and controlled drug release. 55 In the following, a CO2-responsive nanogating system by using 2-APBA dimer was presented.…”

Tuning the Dynamics of Boronic Acid Hydrazones and Oximes with pH and Redox Control

“…[1][2][3] One of the most commonly used DCBs are hydrazones and oximes, formed from an aldehyde or ketone and a hydrazine or alkoxyamine, respectively. [4][5][6][7][8][9][10][11] As a result of their broad availability, ease of incorporation into more complex (macro)molecules, and ability to exchange, hydrazones and oximes have been used…”