Tunable Thermochromism of Multifunctional Charge-Transfer-Based Supramolecular Materials Assembled in Water

Abstract

Stimuli-responsive materials, such as thermochromics, have found mass usage and profitability in manufacturing and process control. Imparting charge-transfer-based functional supramolecular materials with tunable thermochromism emerges as an ideal strategy to construct optically responsive multifunctional assemblies. Herein, the authors report a new series of thermochromic charge-transfer-based supramolecular materials assembled in water. These assemblies are composed of a bis-bipyridinium-derived acceptor and a series of commercially available donorsnamely, the neurotransmitter melatonin and its analogue bioisosteres. When the chemical structure of the donors are tailored, the strength of the charge-transfer interactions can be tuned. Thermochromic aerogels and inks of these materials are prepared, with a large selection of colors, in environment-friendly solvents and demonstrate tunable thermochromic transition temperatures ranging from 45 to 105 °C. Favorable compatibility of these materials with commercial inks and inkjet printers afford excellent pattern quality with extended color options. Mechanistic studies reveal that the two types of water molecules were bound to the supramolecular complexes with differing strengths, and that the more weakly bound water is responsible for the thermochromic transitions.

Colloidally Stable Monolayer Nanosheets with Colorimetric Responses

“…Furthermore, inkjet printing has attracted tremendous attention owing to the facile construction of light‐weight, flexible, and disposable devices, especially the defined deposition of functional materials . The aqueous stable chromogenic PDA‐EDMA‐TMG nanosheet can reach a concentration as high as 20 mg mL −1 (≈33 × 10 −3 m , according to the diacetylene monomer), which affords a great opportunity for inkjet printing.…”

Bis‐Bipyridinium Gemini Surfactant‐Based Supramolecular Helical Fibers and Solid State Thermochromism

“…In our previous work, we discovered that bipyridinium‐based surfactants, which had been joined together with a biphenyl bridge, formed bundled helical fibrillar networks leading to hydrogelation upon molecular templation with the neurotransmitter melatonin and other π‐electron‐rich donors . This ability to form long self‐assembled fibers leading to gelation ultimately proved to be a crucial property, which facilitated the material processing of the surfactants to form functional xerogel films and aerogels.…”

“…Recently, we developed a new class of thermochromic supramolecular materials, which are comprised of a π‐electron‐deficient bis‐bipyridinium gemini surfactant acceptor with halogen counterions and a π‐electron‐rich guest, namely di(ethylene glycol)‐disubstituted 1,5‐dihydroxynaphthalene . In aqueous solution, the bis‐bipyridinium amphiphile engages in donor–acceptor charge‐transfer (CT) π‐π stacking interactions with the naphthalene derivative.…”

Assembly and Chiral Memory Effects of Dynamic Macroscopic Supramolecular Helices

“…Higher concentrations of the donor and acceptor led to gelation of the aqueous solution, which was reversible under thermal treatment (Figure S2). The hydrogel matrix was comprised of highly‐entangled supramolecular fibers, similar to those formed by 1 ⋅4Br and other achiral donors . In contrast to the racemic amount of left‐handed (M) and right‐handed (P) helical fibers formed with achiral donors, a dominating presence of M helices was observed [Figure b (center) and c (top)] by scanning electron microscopy (SEM).…”