(E)-(4-Hydroxyphenyl)(4-nitrophenyl)diazene, (E)-(4-methoxyphenyl)(4-nitrophenyl)diazene and (E)-[4-(6-bromohexyloxy)phenyl](4-cyanophenyl)diazene

• Published in: Acta crystallographica. Section C, Crystal structure communications Crystal structure communications, 2002-10, Vol.58 (10), p.o624-o628
• Main Authors: Huang, Xinjiang, Kuhn, Genevieve H., Nesterov, Vladimir N., Averkiev, Boris B., Penn, Benjamin, Antipin, Mikhail Yu, Timofeeva, Tatiana V.
• Format: Article
• Language: English
• ISSN: 0108-2701; 1600-5759
• DOI: 10.1107/S010827010201627X

Syntheses and X‐ray structural investigations have been carried out for (E)‐(4‐hydroxy­phenyl)(4‐nitro­phenyl)­diazene, C12H9N3O3, (Ia), (E)‐(4‐methoxy­phenyl)(4‐nitro­phenyl)­diazene, C13H11N3O3, (IIIa), and (E)‐[4‐(6‐bromo­hexyl­oxy)­phenyl](4‐cyano­phenyl)­diazene, C19H20BrN3O, (IIIc). In all of these compounds, the mol­ecules are almost planar and the azo­benzene core has a trans geometry. Compound (Ia) contains four and compound (IIIc) contains two independent mol­ecules in the asymmetric unit, both in space group P (No. 2). In compound (Ia), the independent mol­ecules are almost identical, whereas in crystal (IIIc), the two independent mol­ecules differ significantly due to different conformations of the alkyl tails. In the crystals of (Ia) and (IIIa), the mol­ecules are arranged in almost planar sheets. In the crystal of (IIIc), the mol­ecules are packed with a marked separation of the azo­benzene cores and alkyl tails, which is common for the solid crystalline precursors of mesogens.