Study On Quantum Dots And Fluorescent Probes Of Cyclophanes For Pesticide Detection

As agricultural production demand is developing rapidly,pesticides are widely applied in the crop planting,preservation,inventory and conveyance of crops.However,they will cause serious pollution to air,water,soil and agricultural products,which may become the direct way of human contact and ultimately affect human health.As a result,it is necessary to set up a convenient,facilitate and visual pesticide detection method,so as to wise up the safety and environmental protection of agricultural production and life.So far,the methods of pesticide detection at home and abroad mainly include microchemical test,chromatography,enzyme inhibition,capillary electrophoresis and so on.However,the above methods have many certain limitations in the sensitivity,simplicity and feasibility of detecting trace pesticides as before.Fluorescence analysis techniques with simple process,strong pertinence and high sensitivity stand out,in which the fluorescence material determines the detection performance.In this study,we devised and synthesized two kinds of fluorescent probes,Cd S quantum dots and organic alkanes based on cyclophanes structure,to explore their functions in identifying and determining pesticides,and further discuss their sensitivity and selectivity.The key experimental content of this study is shown below:1.In this study,we presented one-pot prepared Cd S fluorescent quantum dots（QDs）and explored their sensing application for organic pesticides.The Cd S QDs can sensitively and selectively detect three different pesticides,dichlorvos（DDVP）,paraquat,and glufosinate-ammonium,through different fluorescence responses.Paraquat can effectively quench the fluorescence of the QDs,and DDVP can cause remarkable fluorescent enhancement.Glufosinate-ammonium can induce both 150nm fluorescent blueshift and 30-fold fluorescent enhancement.The probe exhibited low detection limits for the three pesticides:1.44μM for paraquat,0.23 m M for DDVP,and 49.8μM for glufosinate-ammonium.On this basis,we use the powerful function of smart phone,through RGB value and gray value to establish the concentration-gray value standard curve,to achieve the qualitative detection and quantitative analysis of DDVP.It is believed that this work presents a new platform for the simultaneous detection of multiple pesticides using a single QDs probe.The present on-site method using a smartphone is of great potential for water monitoring in rural areas.2.We report herein a simple,yet effective,strategy based on well-established chemistry to design a new class of fluorescent probes for detection of triadimefons.A composite scheme,which takes advantage of donor-acceptor interactions,is used to compose a semi-rigid cycloalkane(Py Box⁴⁺)that has a box geometry and has been synthesized by connecting twoπ-electron-poor 1,4-phenylene-bridged bipyridinium units in an end-to-end fashion with two 1,1-bis（p-tolyl）-2-biphenyleneethylene linkers.This synthetic method greatly shortens the reaction time and has a very high yield.Owing to its large accommodative cavity and the ability in organic or aqueous media to born powerful non-covalent interactions withπ-electron rich triadimefons,therefore Py Box⁴⁺functions can be used as a scavenger of triadimefons.Using this excellent synthesis strategy,we designed and synthesized Py Box⁴⁺analogs,namely CSY-12 and CSY-13.Compared with the three semi-rigid cycloalkane,it is found that Py Box⁴⁺has the largest cavity and box-like geometry,and has the most excellent test effect.A great breakthrough in synthesis and application of cassette cycloalkane has been achieved.