Controlled Zn²⁺-Triggered Drug Release by Preferred Coordination of Open Active Sites within Functionalization Indium Metal Organic Frameworks

Drug delivery in target regions could make extraordinary progress in chemoselective therapies. A novel preferred coordination (PC) strategy referring to proactive interacting with open active sites to replace previous occupation by ion-exchange for controlling release of drug molecules is well-constructed. Two topological types of MOF - In1 (Schläfli symbol: (4,8)-connected of (4 10 ·6 15 ·8 3 )(4 5 ·6) 2 ) and MOF - In2 (Schläfli symbol: (4,4)-connected of (6 6 )) show the specific way. Increasing node connectivity as well as the trapping of guest OH – anions, 5-fluorouracil (5-FU) is preferentially captured into the MOF - In1, which exhibits an outstanding loading capacity around 34.32 wt %. 19 F NMR spectroscopy was further employed to investigate host–guest interaction and reveal the binding constant ( K a = 3.84 × 10 2 M –1 ). Meanwhile, the controlled release of 5-FU in a simulated human body with liquid phosphate-buffered saline solution by biofriendly Zn 2+ -triggered is realized. With an elevated Zn 2+ concentration, the drug release will be enhanced. This efficient strategy for MOFs as multifunctional drug carrier opens a new avenue for biological and medical applications.