2,2′‐Diaryl‐1,1′‐biazulenes were synthesized and electronic communication between the azulene subunits was suggested based on redox measurements. The linkage of azulene at the 1‐position also appeared to increase the HOMO levels. In addition, cyclic voltammetry measurements of 2‐arylazulenes showed a return peak associated with the oxidation, which was not observed for azulene. The stabilization of the single‐electron oxidant may be due to the SOMO‐HOMO energy inversion phenomenon. X‐ray crystallography of the azulene dimers revealed that this species possessed a syn‐type structure in which both aryl groups in the 2‐positions formed π‐stacks. The twisted structure was indicated to be in the (R)‐ or (S)‐configuration for all molecules in the unit cell. Spontaneous resolution was also shown. Furthermore, from the solid circular dichroism (CD) spectral measurements, the relationship between the absolute configuration of the molecules and the CD spectra was determined. A racemization rotational barrier of ca. 27 kcal mol−1 was calculated. Moreover, the pyridylazulene dimer cyclized upon reaction with PdCl2 to form a 3 : 3 complex, in which the biazulene units cyclized to give ratios between the (R)‐ and (S)‐forms of either 2 : 1 or 1 : 2.

Invited for this month's cover are Takahiro Tsuchiya and Yasuhiro Mazaki, and their colleague Yuka Katsuoka, from Kitasato University, Japan, along with collaborators from Bruker Japan (Kenji Yoza) and Rigaku Corporation (Hiroyasu Sato). The cover picture shows the twisted structure of 2,2′‐di(pyridin‐4‐yl)‐1,1′‐biazulenes, which form a 3:3 cyclic complex with PdCl2. The rotation of the bonds at the 1,1′‐positions of the azulene subunits was padlocked by the complexation. Read the full text of the article at 10.1002/cplu.201900262.

The front cover shows the twisted structure of 2,2′‐di(pyridin‐4‐yl)‐1,1′‐biazulenes, which form a 3:3 cyclic complex with PdCl2. The uncomplexed azulenes racemize in solution (unlocked conformation), whereas the three biazulene units in the complex were found to cyclize in the (R)‐ and (S)‐forms in a ratio of either 2:1 or 1:2, with an overall C2 symmetry (locked conformation). The intramolecular electronic communication among the azulene units was also demonstrated by redox measurements. Details are given in the Full Paper by T. Tsuchiya, Y. Mazaki, and co‐workers on page 1659 in Issue 11, 2019 (DOI: 10.1002/cplu.201900262).