ORT Braude College, Israel
Title: In silico study of the self-assembly and gelation of sugar derivatives
Biography: Dafna Knani
Low molecular weight gelators are molecules capable of forming gels in which they are self-assembled into a physical 3D network of fibers, held together by non-covalent interactions like hydrogen bonds, Van der Waals forces and π−π-interactions. The organic gelator 1,3 (R):2,4(S)-dibenzylidene-D-sorbitol (DBS) self-organizes to form a 3-D network at relatively low concentrations in a variety of nonpolar organic solvents and polymer melt. DBS could be transformed into a hydrogelator by introduction of hydrophilic groups, which facilitate its self-assembly in aqueous medium. In this work, the self-assembly of DBS and its derivatives was investigated by molecular modeling. A dynamic molecular simulation was carried out using atomistic and quantum tools included in the Material Studio 8.0 (by Biovia) software. Various properties (cohesive energy density, mixing energy, radial distribution function) were calculated to illustrate the interactions that govern the self-assembly of the examined compounds. The results of the simulation indicate that the interaction between DBS-COOH molecules is stronger than DBS-CONHNH2 and DBS and its water compatibility is highest. Therefore, DBS-COOH seems to be a better hydrogelator than DBS-CONHNH2 and DBS. Intermolecular H-bonding interactions are formed between the three molecules as pure substances and they dramatically decrease in the presence of water. In contrast, the intra-molecular interactions increase in water. This result indicates that in aqueous environment the molecular structure tends to be more rigid and fixed in the preferred conformation. Due to H-bonds, DBS and its derivatives form a rigid structure which might explain their tendency to create nanofibrils. In order to obtain effective hydrogelators, fine-tuning of the balance between the hydrophilic (soluble) and hydrophobic (insoluble) parts is essential.