Regulating supramolecular interactions in dimeric macrocycles.

Supramolecular behavior is highly dependent on many factors, including complicated microenvironments and weak interactions. Herein, we describe tuning supramolecular architectures of rigid macrocycles by synergistic effects of their geometric configurations, sizes, and guests. Two paraphenylene-based macrocycles are anchored onto different positions in a triphenylene derivative, resulting in dimeric macrocycles with different shapes and configurations. Interestingly, these dimeric macrocycles show tunable supramolecular interactions with guests. In solid state, a 2 : 1 host-guest complex was observed between 1a and C60/C70, while an unusual 2 : 3 host-guest complex 3C60@(1b)2 can be observed between 1b and C60. This work expands the scope of the synthesis of novel rigid bismacrocycles and provides a new strategy to construct different supramolecular systems.

Selective synthesis and (chir)optical properties of binaphthyl-based chiral carbon macrocycles.

Herein, we report the selective synthesis, characterization, and photophysical properties of two novel chiral carbon macrocycles. Non-planar (S)-2,2'-bis(methoxymethoxy)-1,1'-binaphthalene was introduced into the scaffold of oligo-paraphenylenes to achieve the chirality in these macrocycles. Their photophysical properties were investigated by steady-state and time-resolved spectroscopies, as well as circular dichroism and circularly polarized luminescence spectroscopies. We demonstrate that the emission maxima of the chiral macrocycles are redshifted compared to chiral binaphthyl units and that macrocycles show chiroptical properties (|glum| > 1.0 × 10-3).

Tuning the (Chir)Optical Properties and Squeezing out the Inherent Chirality in Polyphenylene-Locked Helical Carbon Nanorings.

Distorting linear polyaromatic hydrocarbons (PAHs) out of planarity affects their physical properties and breaks their symmetry to induce inherent chirality. However, the chirality cannot be achieved in large distorted PAHs-based macrocycles due to a low racemization barrier for isomerization. Herein, we report the precise synthesis and tuning size-dependent (chir)optical properties of a new class of chiral PAHs-containing conjugated macrocycles (cyclo[n]paraphenylene-2,6-anthrylene, [n]CPPAn2,6 ; n=6-8). Their inherent chiralities were squeezed out in small anthrylene-based macrocycles. Efficient resolutions for chiral enantiomers with (P)/(M)-helicity of small [6-7]CPPAns were achieved by HPLC. Interestingly, these macrocycles showed enriched size-dependent physical, chiral, and (chir)optical properties. Theoretical calculations indicate that these macrocycles have high strain energy (Estrain =60.8 to 73.4 kcal/mol) and very small Egap (∼3.0 eV). Notably, these enantiomers showed strong chiroptical properties and dissymmetry factors (|gabs | and |glum |∼0.01 for an enantiomer of [6]CPPAn2,6 ), which can give them potential applications in optically active materials.

Precise membrane separation of nanoparticles using a microporous polymer containing radially π-conjugated molecular carbocycles.

Herein, we report the synthesis of a novel porous polymer, PS2, containing radially π-conjugated carbocycles and a linear phenylene backbone. The PS2-based membrane has a distinct small size cutoff (ca. 2.6 nm) and a major size at ∼1.5 nm for the size-selective separation of nanoparticles.

A supramolecular polymeric heterojunction composed of an all-carbon conjugated polymer and fullerenes.

Herein, we design and synthesize a novel all-carbon supramolecular polymer host (SPh) containing conjugated macrocycles interconnected by a linear poly(para-phenylene) backbone. Applying the supramolecular host and fullerene C60 as the guest, we successfully construct a supramolecular polymeric heterojunction (SPh⊃C60). This carbon structure offers a means to explore the convex-concave π-π interactions between SPh and C60. The produced SPh was characterized by gel permeation chromatography, mass spectrometry, FTIR, Raman spectroscopy, and other spectroscopies. The polymeric segment can be directly viewed using a scanning tunneling microscope. Femtosecond transient absorption and fluorescence up-conversion measurements revealed femtosecond (≪300 fs) electron transfer from photoexcited SPh to C60, followed by nanosecond charge recombination to produce the C60 triplet excited state. The potential applications of SPh⊃C60 in electron- and hole-transport devices were also investigated, revealing that C60 incorporation enhances the charge transport properties of SPh. These results expand the scope of the synthesis and application of supramolecular polymeric heterojunctions.

Fully physically cross-linked double network hydrogels with strong mechanical properties, good recovery and self-healing properties.

Combining a hydrophobic interaction crosslinked curdlan as the first network and hydrophobic interaction crosslinked polyacrylamide as the second network, we have fabricated a curdlan/HPAAm double network (DN) hydrogel using a one-pot method. The resulting DN hydrogel exhibited good mechanical properties, i.e. an elastic modulus of 103 kPa, a tensile fracture strength of 0.81 MPa, a tensile stretch of 25.3 and a compressive stress of 62.5 MPa when the compressive strain increased up to 99%. The DN gel could withstand ten compression tests under 90% compressive strain without observable damage. The DN gel demonstrated 84% stiffness recovery and 97% toughness recovery after the deformed samples were relaxed and stored at 95 °C for 4 h. The stiffness and fracture stress of the DN gel were enhanced after sterilization treatment at 120 °C. Furthermore, the gels exhibited 52% self-healing of fracture stretch after the samples were cut and brought into contact at 95 °C for 4 h. The self-recovery and self-healing properties of the DN gel both originated from the first curdlan network via the reformation of hydrophobic interactions and the second HPAAm network via reformation of the broken hydrophobic associations.