Synthesis Of Phosphole-Based Organic Small Molecules And Study On The Properties Of Fluorescence Sensing

Phosphole is a weakly aromatic five-membered phosphorus-containing heterocycle compound,which consisting of phosphorus-bridged 1,3-diene moiety π-conjugated system.Compared with other five-membered phosphorus-containing heterocycle compounds,the lone-pair electrons at the phosphorus center and π electrons in1,3-butadiene moiety can easily form σ*-π* conjugated system,which gives phosphole advantages of low LUMO gap,good thermal and chemical stability.In addition,the phosphorus atom with unique “pyramid configuration” is easy to be chemical modified,such as phosphine oxides,phosphine sulfides,formation of phosphonium salts,etc.Therefore,the charge properties of the phosphorus atom center can be adjusted by proper chemical modification.In this work,a series of benzo[b]phosphole derivatives and dithieno[3,2-b:2’,3’-d]phosphole derivatives with different substituents were synthesized.The UV-vis absorption spectra,fluorescence emission spectra and fluorescence sensing properties of these compounds were studied.The related study mainly includes the following three parts:Part 1: Synthesis of benzo[b]phosphole derivatives and detection of Cr(Ⅵ)In this work,three aggregation-induced emission molecule(AIE)phosphole-based small organic molecules with different substituents were synthesized.UV-vis absorption spectra showed that the absorption spectra of OMe-PIO with electron-donating substituent has a red-shift of about 100 nm compared to F-PIO and H-PIO,which with or without electron-withdrawing substituent,and significantly enhanced fluorescence intensity under the same test conditions.Next,we selected OMe-PIO to detect Cr(Ⅵ),which has a wide linear range(0.5-80 μM),low LODs(0.276 μM),and good recovery for Cr(Ⅵ)detection in actual samples such as Yellow River water and tap water.The system has the advantages of simple structure,friendly environment and small interference to analytes.This work not only systematically revealed the effect of substituent effect on the luminescence properties of AIE materials,but also enriched the further application of benzo[b]phosphole derivatives in the field of sensing.Part 2: Synthesis of D-π-A type benzo[b]phosphole and detection of curcumineIn this work,TPA-PIO with donor-π-acceptor(D-π-A)structrue was synthesized.Triphenylamine was electron donor,benzene ring was π-bridge and benzo[b]phosphole was electron acceptor in TPA-PIO.The fluorescence emission spectra showed that TPA-PIO has good luminescence property and solvent effect.With the increase of water content,the fluorescence intensity decreased firstly,and increased subsequently,indicating that the compound was an AIE molecule.The linear range(0.1-26 μM)and LODs(0.05 μM)of the compound showed good selectivity and sensitivity to the curcumine,and it was successfully applied to the detection of actual sample of curcuma powder,which broadened the idea of benzo[b]phosphole compounds in the application of fluorescence sensing.Part 3: Synthesis of dithieno[3,2-b:2’,3’-d]phosphole oxide and detection of TNPIn this work,a series of dithieno[3,2-b:2’,3’-d]phosphole derivatives with different substituents were synthesized.These compounds with more rigid planar structure have higher π conjugation,and essentially provide a smaller HOMO-LUMO gap and more red-shift emission than benzo[b]phosphole.In addition,these compounds have good selectivity for recognition of 2,4,6-trinitrophenol(TNP).In this work,we selected DTPP and F-DTP for the detection of TNP,the linear ranges were 0.17-30 μM and 0.33-60 μM,and LODs were 0.113 μM and 0.23 μM,respectively.This kind of material provides a promising candidate material for the detection of TNP in environmental water samples.