Aggregation-induced emission enhancement properties of phosphaphenanthrene-containing styrene derivant and its application of detection to transition metal ions

Fluorescence of the organic light-emitting compounds are often quenched when the luminophors are fabricated into solid thin films, which have greatly limited their scope of practical applications. So, it is important to design and synthesize the novel organic luminophors with excellent light emission property in solid state. Phosphaphenanthrene-containing styrene derivant (MED) was synthesized by means of two-step esterification from 2-(6-oxide-6H-dibenz (c,e) < 1,2 > oxaphos-phorin-6-yl) dihydroxyphenylenes (ODOPB), 4-(pentyloxy) benzoic acid and 4-ethylenebenzoic acid, respectively. And then the compound was characte-rized by ¹H NMR, FTIR, mass spectra, UV-Vis and PL. When MED aggregates to a certain degree in mixture of water and acetonitrile, the fluorescence strength of MED proportionably increases, which shows obvious aggregation-induced emission enhancement (AIEE) property because the aggregation state of MED restricts the intramlecular rotation of phosphaphenanthrene group based on π-π stacking and polarity interaction between the molecules. Pt²⁺, Ru³⁺, Fe²⁺ and Fe³⁺ ions (1 × 10^-4 mol/L) can efficiently quench the emission intensity of MED (1 × 10^-5 mol/L) and higher than those by Pb²⁺, Zn²⁺, Cd²⁺, In²⁺, Co²⁺, Cu²⁺, Ni²⁺ and Ag⁺ ions. The quenching efficiency of Pt²⁺ and Ru³⁺ are the same when they are added into the mixture of water-acetonitrile (90/10, volume ratio) during or after the aggregation state formation of MED. Fe³⁺ shows the highest quenching efficiency to the PL of MAD during aggregation. If being added into the aggregated systems, Fe³⁺ has the same quenching ability to MED. Fe²⁺ only shows its quenching effect on MED during aggregation. This novel phenomenon may enable the molecule to find applications to discriminating chemosensors to detect the transition metal ions.