Ring-strain release in neutral and dicationic 7,8,17,18-tetrabromo-5,10,15,20-tetraphenylporphyrin: crystal structures of C<sub>44</sub>H<sub>26</sub>Br<sub>4</sub>N<sub>4</sub>and C<sub>44</sub>H<sub>28</sub>Br<sub>4</sub>N<sub>4</sub><sup>2+</sup>·2ClO<sub>4</sub><sup>−</sup>·3CH<sub>2</sub>Cl<sub>2</sub>
Acta crystallographica. Section E, Crystallographic communications