A dual-function [Ru(bpy)3]2+ encapsulated metal organic framework for ratiometric Al3+ detection and anticounterfeiting application

In this work, a novel composite material (HPU-24@Ru) has been prepared by combining a blue-emission Cd-based metal-organic framework (MOF, [Cd-2(TCPE)(DMF)(H2O)(3)](n), HPU-24) with a red-emission tris (2,2 & PRIME;-bipyridine) dichlororuthenium(ii) hexahydrate ([Ru(bpy)(3)](2+)) molecule for ratiometric fluorescence sensing of Al3+ ions in aqueous medium and high-level dynamic anticounterfeiting application. The luminescence measurement results indicated that the fluorescence intensity of HPU-24 at 446 nm showed a red shift in the presence of Al3+ ions, and the new peak appeared at 480 nm and continued to increase with an increase in Al3+ ion concentration. Meanwhile, the fluorescence intensity of [Ru(bpy)(3)](2+) almost showed no change. The detection limit was calculated as 11.63 mu M, which was better than that for the MOF-based Al3+ ions in some reported examples in aqueous media and achieved through strong electrostatic interactions between HPU-24@Ru and Al3+ ions. Moreover, owing to the particularity of the tetrastyryl structure in HPU-24, HPU-24@Ru showed intriguing temperature-dependent emission behavior. This unique structure provides the composite material HPU-24@Ru with attributes for high-level information encryption that make it difficult for counterfeiters to identify all of the right decryption measures.