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Asymmetric <i>N</i>-heterocyclic carbene benzimidazolium salts and their silver(I) complexes: potential as ionic liquid crystals Choon Wan Yeap (4787880) Rosenani A. Haque (532124) Wan Sinn Yam (4787883) Mohd. R. Razali (17602480) Biophysics Biochemistry Physical Sciences not elsewhere classified Medicine Microbiology Chemical Sciences not elsewhere classified Benzimidazolium salts silver(I)–NHC thermotropic liquid crystal polarised optical microscope differential scanning calorimetry smectic A <p>The synthesis and characterisation of a homologous series of monodentate benzimidazolium salts, <b>1</b>–<b>4</b> and their mononuclear silver(I)–NHC (where NHC = <i>N</i>-heterocyclic carbene) complexes, <b>5</b>–<b>8,</b> are reported. The benzimidazolium salts were prepared from the <i>N</i>-alkylation of 1-methyl-benzimidazole with alkyl halides of varying carbon chain lengths. The mono silver(I)-NHC complexes, <b>5</b>–<b>8,</b> were prepared by the reaction of the benzimidazolium salts with Ag₂O. All the synthesised compounds were fully characterised by ¹H-nuclear magnetic resonance (¹H-NMR), ¹³C-NMR and fourier-transform infrared (FTIR) spectroscopy. The molecular structures of compounds <b>3</b>·PF₆, <b>4</b>·PF₆, <b>7</b> and <b>8</b> were elucidated through single-crystal X-ray diffraction analyses. We postulate that the attachment of long alkyl chains to the heterocyclic core of 1-methyl benzimidazole could induce mesophase formation. The liquid crystalline behaviour of the benzimidazolium salts was investigated by polarised optical microscope and differential scanning calorimetry. Salts <b>3</b> and <b>4</b> were found to be thermotropic liquid crystals which exhibited a smectic A phase. However, upon complexation with silver(I) ions, all the Ag(I)–NHC complexes are found to be non-mesogenic.</p> 2018-05-31T11:55:39Z Dataset Dataset 10.6084/m9.figshare.5812758.v2 https://figshare.com/articles/dataset/Asymmetric_i_N_i_-heterocyclic_carbene_benzimidazolium_salts_and_their_silver_I_complexes_potential_as_ionic_liquid_crystals/5812758 CC BY 4.0