Janus base nanotubes are novel, self-assembled nanomaterials. Their original designs were inspired by DNA base pairs, and today a variety of chemistries has developed, distinguishing them as a new family of materials separate from DNA origami, carbon nanotubes, polymers, and lipids. This review article covers the principal examples of self-assembled Janus base nanotubes, which are driven by hydrogen-bond and π-π stacking interactions in aqueous environments. Specifically, self-complementary hydrogen bonds organize molecules into ordered arrays, forming macrocycles, while π-π interactions stack these structures to create tubular forms. This review elucidates the molecular interactions that govern the assembly of nanotubes and advances our understanding of nanoscale self-assembly in water.
more »
« less
Columnar Organization of Nonalternant Fluorinated Dehydrobenzannulenes
Abstract Two new partially fluorinated dehydrobenzannulenes have been prepared by inter‐ and intramolecular oxidative homocoupling of diyne precursors. These systems contain fluorinated and nonfluorinated arene rings in a desymmetrized non‐alternant arrangement. Both macrocycles are roughly planar and organize into extended columns in the solid state. The assembly of these columns is mediated by the combination of dispersion interactions, slipped [π⋅⋅⋅π] stacking interactions of the perfluorinated rings with each other, and their association with the nonfluorinated rings in the molecules of the neighboring macrocycles. These results suggest that partial fluorination of dehydrobenzannulenes can serve as a versatile motif for their assembly into columnar superstructures.
more »
« less
- PAR ID:
- 10582468
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 30
- Issue:
- 68
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
After a brief introduction highlighting the challenges of fluorine chemistry and the latest developments in the field, this Perspective will discuss how a combination of fluorine and fluorous chemistry together with fluorinated reagents helped to bridge between organic, molecular, macromolecular, supramolecular and biological sciences to create functions in the laboratory of the corresponding author. The reactivity of fluoride as a leaving group is best illustrated by SNAr reactions when it helped to demonstrate single electron transfer-mediated side reactions and through molecular design replaced activated aryl fluorides with aryl chlorides in the synthesis of poly(etherketone)s. Subsequently it was demonstrated how Ni(II) sigma complexes provided an orthogonal approach to the Suzuki-type cross-coupling of arylfluorides, other halides and all aryl C–O based electrophiles. Fluorinated reagents facilitated cylotrimetrization vs cyclotetramerization of bis(methoxy)benzyl chloride and alcohol and the synthesis of the simplest molecular liquid crystals. Triflic acid, methyl triflate facilitated the most tolerant living polymerizations including of cyclic siloxanes, functional vinyl ethers and oxazolines to generate self-organizable dendronized polymers while fluorine, trifluoromethyl and trifluoromethoxy groups facilitated disassembly and reassembly of liquid crystal polyethers and poly(p-phenylenes). Fluorinated stereocenters accessed the first heterochiral recognition in side-chain liquid crystal poly(vinyl ether)s and their model compounds. Alkali metal triflates mediated self-organization of supramolecular nonfluorinated and fluorinated self-assembling minidendrons, dendrons, dendrimers and self-organizable dendronized polymers. The role of fluorinated alkyl groups and of alkali metal triflates in the self-assembly, disassembly and isomorphic replacement analysis, of supramolecular helical columns, of the assembly of helical cogwheel coat and of spherical supramolecular dendrimers forming Frank-Kasper periodic and quasiperiodic arrays was highlighted. A brief discussion of fluorinated amino acids, peptides and peptoids and their potential role in the self-assembly and functions resulted from dendritic dipeptides followed by a discussion of semifluorinated amphiphilic Janus dendrimers as models of biological membranes, including for cell fusion and fission, concludes this Perspective.more » « less
-
Self-assembly of brominated triphenylamine bis-urea macrocycles affords robust porous materials. Urea hydrogen bonds organize these building blocks into 1-dimensional columns, which pack via halogen–aryl interactions. The crystals are stable when emptied, present two distinct absorption sites for Xe with restricted Xe diffusion, and exhibit single-crystal-to-single-crystal guest exchange.more » « less
-
The asymmetric unit of the title salt, C 21 H 18 N 4 2+ ·2Br − , comprises half of the molecule and a bromide ion. The chevron-shaped cations stack as columns in the [001] direction with suitable intermolecular distance for π–π interactions. These cationic columns are further stabilized by intercolumnar C—H...N hydrogen bonding with the bromide ions distributed between them.more » « less
-
Lithium metal batteries promise higher energy densities than current lithium-ion batteries but require novel electrolytes to extend their cycle life. Fluorinated solvents help stabilize the solid electrolyte interphase (SEI) with lithium metal, but are believed to have weaker solvation ability compared to their nonfluorinated counterparts and are deemed ‘poorer electrolytes’. In this work, we synthesize tris(2-fluoroethyl) borate (TFEB) as a new fluorinated borate ester solvent and show that TFEB unexpectedly has higher lithium salt solubility than its nonfluorinated counterpart (triethyl borate). Through experiments and simulations, we show that the partially fluorinated –CH2F group acts as the primary coordination site that promotes lithium salt dissolution. TFEB electrolyte has a higher lithium transference number and better rate capability compared to methoxy polyethyleneglycol borate esters reported in the literature. In addition, TFEB supports compact lithium deposition morphology, high lithium metal Coulombic efficiency, and stable cycling of lithium metal/LiFePO4 cells. This work ushers in a new electrolyte design paradigm where partially fluorinated moieties enable salt dissolution and can serve as primary ion coordination sites for next-generation electrolytes.more » « less
An official website of the United States government
