Thermolysis of Biphenylene toward Cyclo-ortho-phenylenes

The solvent and catalyst free thermolysis of biphenylenes at 350 °C furnishes [n]cyclo-ortho-phenylenes ([n]COPs, n=4-10) in one step and in high yields. At 400 °C biphenylene dimerizes into tetraphenylene, but lower reaction temperatures produce cyclooligomers. If suitably substituted, the oligomers are soluble and can be isolated and characterized. The products are exclusively cyclic. In the crystalline state, [6]COP displays an alternating crown-shaped conformation.

The role of multiple observations in small-molecule single-crystal service X-ray structure determination

In order to gain a better understanding of how to improve the quality of small-molecule single-crystal X-ray diffraction data achievable in a finite time, a study was carried out to investigate the effect of varying the multiplicity, acquisition time, detector binning, maximum resolution and completeness. The results suggest that, unless there are strong arguments for a different strategy, a good routine procedure might be to optimize the conditions necessary to get the best data from single scans, and then choose a multiplicity of observations (MoO) to utilize the available time fully. Different strategies may be required if the crystal is highly absorbing, is larger than the incident beam, is enclosed in a capillary tube or is unusual in some other way. The signal-to-noise ratio should be used with care, as collecting data for longer or at higher multiplicity appears to give a systematic underestimate of the intensity uncertainties. Further, the results demonstrate that including poor-quality data in a refinement may degrade the result and, in the general case, the accidental omission of reflections has a very small impact on the refinement as long as they are omitted at random. Systematic omission of reflections needs a convincing procedural justification.

Synthesis of tetraphenylene derivatives and their recent advances

The synthetic strategies towards tetraphenylene derivatives are comprehensively summarized in this review. Recent advances in the functionalized tetraphenylene skeleton for research into their structurally unique properties are described together with their potential applications.

Non-planar oligoarylene macrocycles from biphenyl

Saddle- and propeller-shaped, partially condensed conjugated macrocycles are synthesized by fourfold Perkin condensation plus fourfold photocyclizations. Their macrocyclic loops are pronouncedly non-planar.

Synthesis and studies of 1,4,5,8,9,12,13,16-octamethoxytetraphenylene

[structure: see text] The synthesis of 1,4,5,8,9,12,13,16-octamethoxytetraphenylene (6) is accomplished in five steps from 3,6-dimethoxy-2-nitroaniline (8). Its inclusion property and the electrochemical data of the corresponding tetraquinone 7 are presented.