Systematic structure-property optimization of an achiral gelator (aryl-triazolyl homo dipeptide, 1.0) through a fragment replacement approach led to the identification of a new chiral system (aryl-triazolyl dipeptide 1.4 having leucine as the C-terminal residue) which exhibits consistent and perfectly reversible chiro-optical responses on sol-gel transition that can work like an ON-OFF switch. The gelator 1.4 could also direct the assembly of 1.0 in a sergeant-soldier mode to give similar CD responses. In addition, its gels are mouldable, self-healing and highly thixotropic, making it important from an application standpoint. © 2018 The Royal Society of Chemistry.