2,2′-[1,5-Bis(4-aminophenyl)-1,5-dihydrobenzo[1,2-d;4,5-d′]diimidazole-2,6-diyl]diphenol

The title molecule, C32H24N6O2, has a crystallographic inversion centre in the middle of the benzodiimidazole core. It exists as the enol–imine tautomeric form and exhibits a strong intramolecular O—H⋯N hydrogen bond. The dihedral angles between the planes of the 2-hydroxyphenyl and 4-aminophenyl substituents and the plane of the benzodiimidazole unit [12.69 (8) and 84.71 (8)°, respectively] differ significantly due to steric reasons. In the crystal, molecules are linked by C—H⋯π interactions, forming a two-dimensional network.

The title molecule, C 32 H 24 N 6 O 2 , has a crystallographic inversion centre in the middle of the benzodiimidazole core. It exists as the enol-imine tautomeric form and exhibits a strong intramolecular O-HÁ Á ÁN hydrogen bond. The dihedral angles between the planes of the 2-hydroxyphenyl and 4aminophenyl substituents and the plane of the benzodiimidazole unit [12.69 (8) and 84.71 (8) , respectively] differ significantly due to steric reasons. In the crystal, molecules are linked by C-HÁ Á Á interactions, forming a two-dimensional network.
Financial support by the Ministry of Science, Education and Sport of the Republic of Croatia is gratefully acknowledged (grant No. 119-1193079-3069

Comment
Benzodiimidazole and its derivatives are capable of adopting various coordination modes as well as forming multiple hydrogen bonds, which may provide a tool in crystal-engineering design for assembling building blocks into multi-dimensional structures (Aakeröy et al., 2001;Holman et al., 2001;Lin et al., 2004;Boydston et al., 2006;Boydston et al., 2007;Jiang et al., 2008). These compounds as potential complexing agents have been extensively investigated in recent years and were found to have a broad scope for spin crossover and biological activity. Benzodiimidazole and its derivatives are potential antitumor agents as inhibitors (Schulz & Skibo, 2000;Ansari & Lal, 2009;Demirayak, et al., 2011) and some of their metal complexes have the property of metal-to-ligand charge-transfer excited states (Ohno et al.,1992;Wang et al., 2011).
In this paper we report the synthesis and solid state structure of a novel heterocyclic system, the compound (I) containing benzodiimidazole core as a central moiety. The imidazole rings of later are substituted with 2-OH-and 4-aminobenzyl.

Experimental
The title compound has been prepared as a part of an investigation of the synthesis and characterisation of Schiff base ligands and their metal complexes. The compound (I) was derived from 1,5-dihydrobenzo [1,2 -d;4,5-d']diimidazole in an attempt of template synthesis of copper(II) complexes with Schiff base ligand prepared from p-phenylenediamine and salycylaldehyde. It is known that metal Shiff base complexes have very low solubility and that it is hard to prepare appropriate single crystals for the X-ray structure analysis. For these reasons we examined the possibility of getting crystal suitable for X-ray analysis by slow synthesis reaction through liquid diffusion method. The expected compound was prepared in U-tube in such a way that one arm contained ethanolic metal-aldehydate solution (1 mmol of copper(II) chloride dihydrate and 2 mmol of salycilaldehyde) and the other one ethanolic diamine solution (2 mmol of p-phenylenediamine). Chloroform was in between two solutions. The resulting precipitate was orange plated crystals.

Refinement
The position of hydrogen atoms bounded to N3 and O1 were located in the difference Fourier map and refined. Hydrogen atoms bounded to carbon were treated as riding atoms with C-H = 0.93 Å. Isotropic thermal parameters were set up as U iso (H) = 1.2 U eq. Fig. 1. An ORTEPIII presentation of the molecule in a general orientation showing crystallographic numbering scheme. Anisotropic thermal ellipsoids are pictured with 30% of probability level. Fig. 2. Two symmetry related molecules of (I), one in x, y, z and the another one in -x + 1, -y -1, -z (i) position, showing spatial relationship between primary amino group N3 with C12to-C17 aromatic ring.  (000) and (001)   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.