Zhengtao Li

Water-Soluble Pillar[7]arene: Synthesis, pH-Controlled Complexation with Paraquat, and Application in Constructing Supramolecular Vesicles

By the introduction of 14 anionic carboxylate groups at its two rims, a water-soluble pillar[7]arene (WP7) was synthesized. Its pH-controlled complexation with paraquat G1 in water was investigated. Host WP7 and guest G1 formed a 1:1 [2]pseudorotaxane with a high association constant of (2.96 ± 0.31) × 10(9) M(-1) in water. Furthermore, we took advantage of this novel molecular recognition motif to fabricate a supra-amphiphile based on WP7 and an amphiphilic paraquat derivative G2. The morphologies and sizes of self-assemblies of G2 and WP7⊃G2 were identified by transmission electron microscopy and dynamic light scattering.

Fluorescent Supramolecular Polymeric Materials

Fluorescent supramolecular polymeric materials are rising stars in the field of fluorescent materials not only because of the inherent optoelectronic properties originating from their chromophores, but also due to the fascinating stimuli-responsiveness and reversibility coming from their noncovalent connections. Especially, these noncovalent connections influence the fluorescence properties of the chromophores because their state of aggregation and energy transfer can be regulated by the assembly-disassembly process. Considering these unique properties, fluorescent supramolecular polymeric materials have facilitated the evolution of new materials useful for applications in fluorescent sensors, probes, as imaging agents in biological systems, light-emitting diodes, and organic electronic devices. In this Review, fluorescent supramolecular polymeric materials are classified depending on the types of main driving forces for supramolecular polymerization, including multiple hydrogen bonding, electrostatic interactions, π-π stacking interactions, metal-coordination, van der Waals interactions and host-guest interactions. Through the summary of the studies about fluorescent supramolecular polymeric materials, the status quo of this research field is assessed. Based on existing challenges, directions for the future development of this field are furnished.

Reversible Iodine Capture by Nonporous Pillar[6]arene Crystals

Here we report that easily obtained per-ethylated pillar[6]arene (EtP6) is a new adsorbent for iodine capture with high chemical and thermal stability. Nonporous EtP6 solids are shown to capture not only volatile iodine in the air but also iodine dissolved in an organic solvent and aqueous solution. Uptake of iodine leads to a structural transformation of EtP6 in the solid state. In the single crystal structure of iodine-doped EtP6 (I2@EtP6), each adsorbed iodine molecule is located between two adjacent EtP6 molecules to form a linear supramolecular polymer. Iodine is released spontaneously from I2@EtP6 solids when they are immersed in cyclohexane. These EtP6 solids can be reused many times without losing iodine capture capacity.

Construction of a pillar[5]arene-based linear supramolecular polymer and a photo-responsive supramolecular network

A linear supramolecular polymer has been constructed from self-assembly of two complementary homoditopic monomers, an azobenzene-bridged pillar[5]arene dimer and a bisammonium salt, at high concentration based on the pillar[5]arene/secondary ammonium salt molecular recognition motif. This supramolecular polymer exhibited photo and pH dual-responsiveness. Polymer–oligomer and polymer–monomer transitions were reversibly regulated by UV/vis light irradiation and changing the solution pH, respectively. Furthermore, a photo-responsive supramolecular crosslinked liquid-crystalline polymer network based on the host–guest interactions between the azobenzene-bridged pillar[5]arene dimer and a secondary ammonium salt-functionalized poly(methyl acrylate) was fabricated.

A water-soluble pillar[10]arene: synthesis, pH-responsive host–guest complexation, and application in constructing a supra-amphiphile

A water-soluble pillar[10]arene was prepared. Its pH-responsive host–guest complexation with paraquat and application in constructing a supra-amphiphile were investigated.

Chemically-Responsive Complexation of A Diquaternary Salt with Bis(m-phenylene)-32-Crown-10 Derivatives and Host Substituent Effect on Complexation Geometry

A chemically responsive diquaternary salt with π-extended surface was made. The host-guest complexation with chemo-responsiveness between three bis(m-phenylene)-32-crown-10 (BMP32C10) derivatives and this diquaternary salt guest was studied through the sequential addition of basic and acidic reagents (diethylamine and trifluoroacetic acid, respectively). Furthermore, the host-substituent effect on the complexation geometries of these three host-guest complexes, from taco to taco-type threaded to threaded structures by changing the substituent on BMP32C10 as shown by crystal structures, was also addressed.

Pillar[10]arene-based host–guest complexation promoted self-assembly: from nanoparticles to uniform giant vesicles

A novel host–guest recognition motif between a water-soluble pillar[10]arene and pyrene derivative was established and applied in the fabrication of a pH-responsive supra-amphiphile. Furthermore, the host–guest complexation induced morphology change of the self-assembly was investigated.

Preparation of a white-light-emitting fluorescent supramolecular polymer gel with a single chromophore and use of the gel to fabricate a protected quick response code

We report here a novel yet facile approach to prepare white-light-emitting fluorescent polymeric materials resulting from the aggregation of a single fluorescent chromophore. This aggregation resulted from the energetically favorable self-assembly of the polymer through intermolecular quadruple hydrogen bonding. This advanced material was shown to be an ideal candidate for constructing intelligent information display/storage devices. A protected quick response code was fabricated by using this white-light-emitting fluorescent supramolecular gel, which was shown to hide the information under natural light yet to display it under UV light. Therefore, the code was protected and only readable under a specific condition. Furthermore, due to the dynamic nature of hydrogen bonds, the supramolecular polymer gel and the resulting quick response code showed self-healing abilities, which is crucial for their applications. The information of an intentionally damaged QR code was incomplete and could not be read out under UV light irradiation, but we were able to mend the code, based on the interfacial self-assembly of the gels through multiple hydrogen bonding, and then recover the protected information.

Two novel supramolecular metallogels constructed by platinum(II) coordination and pillar[5]arene-based host–guest interactions

Two architecturally controlled supramolecular metallogels have been fabricated by unifying the themes of coordination-driven self-assembly and pillararene-based molecular recognition.

Dual-pH responsive host–guest complexation between a water-soluble pillar[9]arene and a 2,7-diazapyrenium salt

The host–guest complexation between a water-soluble pillar[9]arene and a 2,7-diazapyrenium salt not only can be controlled by the sequential addition of an acid and a base (HCl and NaOH, respectively) but also can be switched through the sequential addition of a base and an acid (hexylamine and TFA, respectively).