Highly Strained Phenylene Bicyclophanes

Abstract

Bending the rules: Strained bicyclophanes (see structure) with highly bent biphenylene units and a central aromatic moiety (yellow) forced into a perpendicular position were accessible in high yields by cyclization of the appropriate bromides by Yamamoto condensation. They were able to bind to graphite cutouts in solution and were adsorbed at the liquid/highly oriented pyrolytic graphite (HOPG) interface to form extended 2D structures.

Comprehensive Benchmark of Association (Free) Energies of Realistic Host–Guest Complexes

“…However, achieving "chemical accuracy" on an 1 kcal mol −1 level for ∆G a seems to be extremely difficult and likely requires improvement of gas phase interaction energies, inclusion of anharmonic and dynamic effects as well as a much more accurate solvation treatment. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60…”

“…DFT-D3 17 ) together with a relatively large basis set in a non-dynamic single-structure approach without any system-specific adjustments. [18][19][20][21] For the so-called S12L set of complexes, 18 which was the first benchmark set for NCI in large systems, the DFT-D3 gas phase interaction energies were confirmed by independent DFT-SAPT calculations 22 and high level electronic Quantum Monte-Carlo simulations. 23 For the related L7 benchmark set for NCI in large model complexes see…”

On the Way to Carbon Nanotubes: The First Synthesis of an Aromatic Nanobelt

“…Pushing chemistry to its extremes by synthesizing molecules that should not exist according to textbooks,t his is what advances the field not in as tep-by-step fashion but in great leaps.T he synthesis of a" carbon nanobelt" by Itami and coworkers certainly falls into this category. [1] This first synthesis of an isomer of a [12]cyclophenacene can be regarded as the cornerstone for rational carbon nanotube preparation.…”

“…Whydid it take nearly 50 years to prepare an aromatic nanobelt?T he key reaction is the nickel-mediated cyclization. This reaction has only recently been shown to be highly effective in building up strain in aromatic systems,f or example,i nt he highly strained cyclophane prepared by Hçger and co-workers [12] or the nanotube end cap synthesized by Stępień et al [13] There have been reports on carbon nanobelts before.F or example,G leiter and co-workers prepared ar igid carbon (Figure 2; 15). [14] In this case,t he phenyl rings are also conjugated via ethenyl bridges.H owever,the whole system with its 24 p-electrons is not aromatic.…”

Kovalent gebundene, ineinander verkettete Cyclohexa‐m‐phenylene und ihre Selbstorganisation: Auf dem Weg zu supramolekularen 3D‐Kohlenstoffnanostrukturen

“…Ausgehend von einem funktionalisierten Benzolring als einfachste aromatische Einheit, wurde 2 durch oxidative Homokupplung in Biphenyl 3 überführt. Als nächstes wurden 3 und (m-Chlorphenyl)boronsäure einer vierfachen Suzuki-Miyaura-Kupplung unterzogen, indem unser kürzlich publiziertes Protokoll verwendet wurde, [7] [8] erzeugt:Hierbei wurden zwei ¾quivalente des entsprechenden Acetophenons und ein ¾quivalent des jeweiligen Benzaldehyds mit Bortrifluorid-Etherkomplex als Lewis-Säure umgesetzt. Kondensation der zwei Schlüsselbausteine 7 und 8a-c ergab dann die gewünschten Octachlorvorläuferstrukturen 9a-c in mäßigen Ausbeuten, die dann wiederum durch intramolekulare Yamamoto-Kupplung der vororganisierten m-Chlorphenylen-Einheiten in die schaufelradfçrmigen Strukturen 10 a-c umgewandelt wurden.…”