QAQ dichloride is a photoswitchable compound that blocks voltage-gated Na v and K v channels. Its channel-blocking activity is observed in the trans form of the azobenzene photoswitch, while the cis form does not exhibit this effect. This compound is membrane-impermeant and selectively enters pain-sensing neurons expressing endogenous import channels. QAQ dichloride functions as a light-sensitive analgesic and provides a valuable tool for investigating signaling mechanisms involved in acute and chronic pain [1] [2].

QAQ dichloride (100 μM) does not cross the membrane and can be injected into cells through a micropipette to photosensitize a single cell and afford subcellular control of action potential propagation. It blocks Shaker-IR current in the trans configuration and unblocks it in the cis configuration [1]. QAQ dichloride can be used to develop red-shifted derivatives of QAQ wihch are powerful doubly charged photochromic blockers.These derivatives allow for remote control of K v and Na v channel conductance with light and offer the opportunity to silence neuronal activity reversibly [2].