Directional Supramolecular Assembly of π-Amphiphiles with Tunable Surface Functionality and Impact on the Antimicrobial Activity

This article elucidates H-bonding-regulated directional supramolecular assembly of naphthalene diimide (NDI)-derived unsymmetric cationic bola-shaped π-amphiphiles and systematic investigations on the thermodynamics of their interaction with bacteria mimic lipid vesicles and antimicrobial activity with mechanistic insights. Four NDI-amphiphiles (NDI-1, NDI-2, NDI-3, and NDI-2a) have been studied, all of which contain a central NDI chromophore, a nonionic wedge, an amine containing a head group, and a hydrazide group. In NDI-2 and NDI-2a, the hydrophilic wedge and the head group (pyridine) are the same but the location of the hydrazide group is different. On the basis of this difference, the pyridyl groups are displayed at the outer and inner walls of the vesicle, respectively. Isothermal titration calorimetry (ITC) studies revealed the spontaneous interaction of NDI-2 assembly with bacteria membrane mimic DPPE liposome (ΔG = −6.35 kcal/mol), whereas the NDI-2a assembly did not interact at all, confirming ...