Thermally induced oxidative trimerization of benzimidazole by copper(II) chloride in the solid state

Abstract

Benzimidazolium trichlorocuprate(II) undergoes a redox reaction in the solid state at elevated temperature (¹ 240 ± C) to produce the cyclic trimer of benzimidazole and cuprous chloride. The trimer has been characterized by IR, NMR, and Mass spectroscopy. It has also been synthesized in lower yield by heating the mixtures of CuCl 2 and benzimidazole in di¬erent ratios or heating other compounds of CuCl 2 and benzimidazole. The absorption, emission, and excitation spectra of the trimer in two di¬erent solvents (TFA and DMSO) and a comparison of these results with those of benzimidazole are presented here.

Facile Synthesis and Structures of Cyclic Triimidazole and Its Boric Acid Adduct

“…5 In addition, C-substituted derivatives of 1 have also been prepared from C-substituted 2-fluoro-and 2-aryloxy-imidazoles. 6,7 Notably, C-substituted derivatives of triimidazole, including tribenzimidazole, were prepared by oxidation of the parent monomer with copper(II) chloride. 6 Although formation of 1 in up to 56% yield is reported from 2-azoimidazole, this precursor is inconvenient to prepare, and specialized photolysis equipment is required.…”

“…5 Herein we describe an alternative method for the facile preparation of multigram quantities of 1 involving thermolysis of the easily prepared copper imidazolate framework solid, Cu(C 3 H 3 N 2 ) 2 (2). 7 This method provides a simple and inexpensive route to 1, making it more readily available for further studies.…”

Formation of Active Catalysts in the System: Chlorocuprates−CCl4−n-C10H22

“…Tris-tributylbenzylammonium cation was used as a counterion. Amines and ammonium cations are known to reduce Cu(II) easily − and could participate in step 1.…”

Cyclic Triimidazole Derivatives: Intriguing Examples of Multiple Emissions and Ultralong Phosphorescence at Room Temperature

“…These results may explain the presence of dual fluorescence in the solid state: a stronger S 2 →S 0 emission (at 335 nm) and a weaker S 1 →S 0 one (at 407 nm) selectively activated by populating the S 1 state. Unfortunately, all attempts to prepare single crystals of 1 suitable for X‐ray diffraction analysis failed, as also previously reported, so that the origin of the RTUP can only be guessed on the basis of the similarity of the photophysical behavior of 1 with that of the parent compound TT . For the latter compound, the solid‐state RTUP was attributed to the presence of H‐aggregates, whose formation is expected also in 1 , resulting in a stabilized level.…”

“…The nature of the emissions was confirmed and interpreted through complete steady‐state and time‐resolved photophysical characterization of the compounds in solution and as crystalline powders in air (see Table ), as well as by structure determination and theoretical calculations. Compound 1 was synthesized as reported in the literature while the new compounds 2 and 3 were prepared by bromination of TT with N ‐bromosuccinimide (see the Supporting Information for experimental details).…”