Supramolecular hydrogen bonding interactions of self-assembled mixed-hydrophobic/hydrophilic benzene-1,3,5-tricarboxamides for sensing nitrobenzene

Abstract

Supramolecular self-assembly of weak non-covalent hydrogen, metal-metal, and interactions have been developed for molecular recognition due to its easy to control and tune precisely. Moreover, nitrobenzene (NB) have been reported to penetrate skins rapidly, cause formation of methemoglobin on acute exposure, and used as explosive compounds in the bomb for terrorist activities. In recent years, benzene-1,3,5-tricarboxamides (BTAs) self-assembled to form nanofiber; however, there is no report on the use of its hydrogen bondings for sensing this hazardous NB. Herein we report, self-assemblies via hydrogen bonding interactions as a chemosensor of NB by using mixed-hydrophobic/hydrophilic version of BTAs. Hydrophobic BTA as a white powder solid showed self-assembly with a tape-like morphology, while hydrophilic BTA as an oily liquid formed less order characteristic of self-assemblies, thus suggesting the competitive intramolecular hydrogen bonding with amphiphilic prope - Both chemosensors BTAs, showed disappearances of N H vibrational peaks at 3233 and 1540 cm-1 and appearance of a new peak at 1478 cm-1 for nitroso (N N=O) upon addition of NB. These sensing capabilities was found to strongly depend on the anisotropic behavior of the self-assembled BTAs where highly ordered hydrophobic BTA with more rigid side chain has better N N=O formation compared to hydrophilic BTA. Interestingly, mixing of both BTAs at equal molar ratio give a stable suspension indicating the formation of organogel with tape-like morphology due to -so-hydrophobic/hydrophilic BTAs organogel turned to liquid upon addition of NB, suggesting improvement of sensing capability and breaking of hydrogen bonding or disassembly. The optimization of sensing capability parameters will be discussed in details later.