A chloride-responsive molecular switch: driving ion transport and empowering antibacterial properties.

A molecular switch was developed to recognize and transport Cl across lipid bilayers. The XRD-crystal structure and NOESY NMR spectra of a potent 4-aminoquinazoline analogue confirmed Cl-induced conformation changes. Systematic biophysical studies revealed that the quinazoline moiety forms cooperative interactions of H and Cl ions with the thiourea moiety, resulting in the transport of H/Cl across the membranes. A pH-dependent analysis revealed that the transport of Cl by the potent compound increased in an acidic environment. The potent compound could also transport H/Cl across Gram-positive bacteria, leading to antibacterial activities.