Geminal Bis-ureas As Gelators For Organic Solvent: Gelation Properties And Structural Studies In Solution And In The Gel State

Several geminal bis-urea compound were synthesised by means of an acid-catalysed condensation of various benzaldehydes with different monoalkylureas. Many of these compound form thermoreversable gels with a number of organic solvants at very low concentrations (<mM) and wich are stable to temperatures higher than 100°C. Electron Microscopy revealed a three-dimensional (3D) network of intertwined fibres, which are several tens of micrometers long and have a wide ranging from approximately 30-300 nm. The possible aggregate forms and aggregate symmetries were evaluated by means of molecular mechanics calculations. 1H NMR, 2D NMR, 13C NMR and 13C-CP/MAS NMR techniques were used to obtain information about the aggregation and possible aggregate symmetry of geminal bis-ureas in solution, in gel state, and in solid state.