Syntheses and Characterisation of Diurea Molecular Tweesors for the Recognition of Anion

Abstract

Two novel urea anion receptors (11) and (12) were synthesized from building block 3,3' methylene diamine and was characterized via the techniques of 1 H NMR, 13 C NMR, DEPT-135 1 H-1 H COSY, HMQC and HMBC spectroscopy. The 1 H NMR profile of both compounds reveals diagnostic peaks. For compound (11), the urea NH protons resonate as two singlets downfield at 8.706 ppm and 8.635 ppm, whereas for compound (12) these two urea -NHCONH protons resonate together at 8.614 ppm. There seem to be no rotation of the structure on the NMR time scale as the bridged CH 2 protons resonate as a singlet. The integration pattern for the aromatic hydrogens for both compounds is: 2: 4: 2: 4: 4, consistent with the structure.13 CNMR spectrums reveal fourteen signals for both structures in accordance with fourteen different types of carbon. Dept-135 indicates eight different CH protons. Preliminary anion binding studies via 1 HNMR spectroscopy revealed complexation with dicarboxylate anions in the highly competitive solvent, d 6 -DMSO.