A ferrocene-based organogel with multi-stimuli properties and applications in naked-eye recognition of F? and Al3+

摘要

A novel organogelator (F-6) with multiple hydroxyl groups and a ferrocene group was designed and synthesized. F-6/chloroform gel exhibited smart thixotropic property and displayed stimuli responsiveness to temperature, mechanical stress, redox, anions and cations. Further, a gel–sol phase transition was observed when halogen anions (F?, Cl?, Br?) were added. In particular, only the addition of F? converted the color of the gel from orange to red and was therefore unique for F?. More interestingly, Al3+ could also be recognized by the naked eye through the color change and gel–sol transition. The conclusive stoichiometric ratio between F-6 and Al3+ was determined to be 2?:?1. The detection limit of Al3+ by using F-6 for the analysis was calculated to be 6.84 × 10?7 M in CH₃OH/H₂O (8?:?2, v/v) at room temperature, which is far below the World Health Organization's (WHO) acceptable limit (1.85 μM of Al3+). Thus, the recognition of F? and Al3+ was achieved through the F-6/chloroform gel system, which was uncommon among organogels. It was shown that the ferrocene group played an important role in the response to ions.