A dual-function [Ru(bpy) 3 ] 2+ encapsulated metal organic framework for ratiometric Al 3+ 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(TCPE)(DMF)(HO)], HPU-24) with a red-emission tris (2,2'-bipyridine) dichlororuthenium(II) hexahydrate ([Ru(bpy)]) molecule for ratiometric fluorescence sensing of Al 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 Al ions, and the new peak appeared at 480 nm and continued to increase with an increase in Al ion concentration. Meanwhile, the fluorescence intensity of [Ru(bpy)] almost showed no change. The detection limit was calculated as 11.63 μM, which was better than that for the MOF-based Al ions in some reported examples in aqueous media and achieved through strong electrostatic interactions between HPU-24@Ru and Al 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.