Synthesis and Phase Structures of Novel π-Acceptor Discotic Liquid Crystalline Compounds Having a Pyrenedione Core

In Situ Molecular Reconfiguration of Pyrene Redox-Active Molecules for High-Performance Aqueous Organic Flow Batteries

Aqueous organic flow batteries (AOFBs) hold great potential for large-scale energy storage, however, scalable, green, and economical synthetic methods for stable organic redox-active molecules (ORAMs) are still required for their practical applications. Herein, pyrene-based ORAMs are obtained via an in situ organic electrolysis strategy in a flow cell. It is revealed that the water attacking pyrenes restructured molecules to produce a variety of isomers and dimers during the electrolysis, which can be modulated by regulating the local electron cloud density and steric hindrance of pyrene precursors. As a result, the molecularly reconfigured pyrene-based catholytes, even without any further purification, achieved a high electrolyte utilization of ≈96% and volumetric capacity above 50 Ah L-1. Inspiringly, remarkable cell stability with almost no capacity decay for ≈70 days is achieved, benefiting from the robust aromatic structure of the pyrene cores. The insights into the in situ electrosynthesis of pyrene-based ORAMs provided in the work will provide guidance for designing ultra-stable ORAMs for AOFB applications.

Pyrene-Fused Poly-Aromatic Regioisomers: Synthesis, Columnar Mesomorphism, and Optical Properties

π-Extended pyrene compounds possess remarkable luminescent and semiconducting properties and are being intensively investigated as electroluminescent materials for potential uses in organic light-emitting diodes, transistors, and solar cells. Here, the synthesis of two sets of pyrene-containing π-conjugated polyaromatic regioisomers, namely 2,3,10,11,14,15,20,21-octaalkyloxypentabenzo[a,c,m,o,rst]pentaphene (BBPn) and 2,3,6,7,13,14,17,18-octaalkyloxydibenzo[j,tuv]phenanthro [9,10-b]picene (DBPn), is reported. They were obtained using the Suzuki-Miyaura cross-coupling in tandem with Scholl oxidative cyclodehydrogenation reactions from the easily accessible precursors 1,8- and 1,6-dibromopyrene, respectively. Both sets of compounds, equipped with eight peripheral aliphatic chains, self-assemble into a single hexagonal columnar mesophase, with one short-chain BBPn homolog also exhibiting another columnar mesophase at a lower temperature, with a rectangular symmetry; BBPn isomers also possess wider mesophase ranges and higher mesophases' stability than their DBPn homologs. These polycyclic aromatic hydrocarbons all show a strong tendency of face-on orientation on the substrate and could be controlled to edge-on alignment through mechanical shearing of interest for their implementation in photoelectronic devices. In addition, both series BBPn and DBPn display green-yellow luminescence, with high fluorescence quantum yields, around 30%. In particular, BBPn exhibit a blue shift phenomenon in both absorption and emission with respect to their DBPn isomers. DFT results were in good agreement with the optical properties and with the stability ranges of the mesophases by confirming the higher divergence from the flatness of DBPn compared with BBPn. Based on these interesting properties, these isomers could be potentially applied not only in the field of fluorescent dyes but also in the field of organic photoelectric semiconductor materials as electron transport materials.

Aerobic C–H Functionalization Using Pyrenedione as the Photocatalyst

We disclose a visible-light-promoted aerobic alkylation of activated C(sp3)–H bonds using pyrenedione (PYD) as the photocatalyst. Direct C–H bond alkylation of tetrahydrofuran with alkylidenemalononitriles is accomplished in over 90% yield in the presence of 5 mol% of PYD and 18 W blue LED light under ambient conditions. The substrate scope is extended to ethers, thioethers, and allylic C–H bonds in reactions with various electrophilic Michael acceptors. The catalytic turnover process is facilitated by oxygen. Our work represents the first example of using PYD as a photocatalyst to promote C(sp3)–H alkylation, revealing the unique character of PYD as a novel organophotocatalyst.

A comparison of optical, electrochemical and self-assembling properties of two structural isomers based on 1,6- and 1,8-pyrenedione chromophores

Near-IR absorbing, self-assembling pyrene donor–acceptor chromophore with low reduction potentials.

Synthesis and characterization of new H-shaped triphenylene discotic room-temperature liquid crystal tetramers by a copper-free click reaction

A series of new H-shaped triphenylene discotic liquid crystal tetramers has been designed and synthesized using a copper-free [3+2] cycloaddition reaction.

Photo-induced C–H bond activation of N,N′-dialkylethylenediamine upon aza-Michael addition to 1,8-pyrenedione: facile synthesis of fluorescent pyrene derivatives

We discovered a reaction between 1,8-pyrenedione and N,N′-dialkylethylenediamine to form highly fluorescent products, via aza-Michael addition followed by double C–H activation facilitated by visible light.