Herein, we report the design, synthesis and trypanocidal activity of some novel trisubstituted imidazole derivatives. These heterocyclic derivatives were structurally planned by exploring the concept of molecular hybridisation between two arylhydrazones derived from megazol, which has potent trypanocidal activity. The trypanocidal activity of these triarylimidazole derivatives was evaluated against infective trypomastigote forms of OPEN ACCESSMolecules 2013, 18 3446T. cruzi and the derivative 2'-(4-bromophenyl)-1-methyl-5'-phenyl-1H,3'H-2,4'-biimidazol-3'-ol showed moderate biological activity (IC 50 = 23.9 µM) when compared to benznidazole, a standard trypanocidal drug. These compounds did not present cytotoxic effects at concentrations near the trypanocidal IC 50 , being considered a good starting point for the development of new anti-Chagas drug candidates.

The N-oxide or 1-hydroxy forms of four solid 1-hydroxy-5-(4-methyl-2-nitroimidazol-2-yl)-4-phenyl-2-(Xphenyl)-imidazole derivatives, 6, have been studied by X-ray crystallography. Compounds, (6: X = 4-Br) and (6: X = 2-O 2 N), both recrystallized from EtOH, and (6: X = 4-F), recrystallized from EtOCH 2 CH 2 OH, were isolated in the 1-hydroxyimidazole form. In contrast, (6: X = H), recrystallized from EtOCH-2 CH 2 OH, was obtained in the imidazole N-oxide form. Two independent molecules, Mol A and Mol B, rotamers, are present in the asymmetric unit of the imidazole N-oxide compound, (6: X = H) and are linked into chains of alternating compounds, mainly by N-H···O hydrogen bonds, but also by N-H···N and C-H···O hydrogen bonds and π···π interactions. These chains are linked by other C-H···O and C-H···N hydrogen bonds and π···π interactions into a 3-D arrangement. In the 1-hydroxyimidazole compound, (6: X = 2-O 2 N), classical hydrogen bonds, O1-H1···N3, are the major interactions linking molecules into C(5) chains: weak π···π stacking interactions also link the molecules within the chains. These chains are linked by C-H···O and hydrogen bonds and by N-O···π interactions into a three-dimensional array. The other 1-hydroxyimidazole compounds, (6: X = 4-Br) and(6: X = 4-F), have similar structures, which differ from that of (6: X = 2-O 2 N). In (6: X = 4-Br) and (6: X = 4-F), pairs of classical O-H···N hydrogen bonds link molecules into symmetric dimers: these dimers are further stabilized by π···π interactions. Other intermolecular interactions found in both (6: X = 4-Br) and (6: X = 4-F) are C-H···O hydrogen bond and N-O···π interactions, which link the O-H···N hydrogen bonded dimers into a 3-dimensional array.

The intrinsic relationship between helicenes and circulenes is of fundamental interest and importance in molecular engineering. Herein, electrophilic borylation of phenanthroline-derived aza [5]helicenes is presented, resulting in the incorporation of a boryl unit into two termini of helicenes to afford quasi-[7]circulenes. Their bowl-shaped structures were determined by X-ray diffraction. UV−vis absorption and fluorescence spectroscopy, as well as electrochemical measurements and DFT calculations, gave insight into their electronic properties. Variable-temperature NMR studies and DFT calculations revealed bowl-to-bowl inversion at room temperature and bowl-to-helix equilibria at elevated temperature, highlighting the important role of B ← N bond strength in tuning their dynamic properties.

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