Novel Organic Small Molecular Fluorescent Probes:Design,Syntheses And Properties

Fluorescent probes are widely used for the specific detection of some heavy metal ions and biologically active species due to their unique advantages such as high selectivity,high sensitivity,and suitability for in vivo imaging studies.Metal ions have an important impact on social production activities,such as mercury ions,copper ions and aluminum ions.The abnormal content of these ions is closely related to a series of physiological activities and diseases in life.Therefore,the research on fluorescent probes that specifically recognize heavy metal ions has become a hot spot.A lot of fluorescent probes are designed and synthesized based on the excellent optical properties and easily modified chemical structures of 1,8-naphthimide and rhodamine B fluorophiles.There are two types of fluorescence quenching probes L and BNP1 based on naphthalimide derivatives,probe Rh F is designed based on fluorescence resonance energy transfer and the unique structure of rhodamine B derivatives,and a multi-functional near-infrared probe NB is designed based on the expanded rhodamine B fluorophore.The structures of related compounds have been characterized by MS,¹H NMR and ¹³C NMR.The specific contents are as follows:1.Two highly sensitive and selective fluorescent probes L and BNP1 based on 1,8-naphthimide derivatives are designed and synthesized to detect copper ion in domestic water samples and living cells.Probe L has good selectivity for Cu²⁺in CH₃CN/PBS（10 m M,9:1,v/v）.After the addition of Cu²⁺,the fluorescence of probe L is almost completely quenched.The2:1stoichiometric ratio of L-Cu²⁺complex is confirmed by Job’s diagram and ESI-MS.Further evidence of the interaction between the probe and Cu²⁺is provided by ¹H NMR titration data and density functional theory（DFT）studies.Probe L with good permeability has been successfully applied to the imaging of Cu²⁺in A549 cells.Similarly,the identification behavior of probe BNP1and copper/mercury ion is also studied in detail.Probe BNP1 has been successfully applied to the detection of Cu²⁺in water and A549 cells with high sensitivity,high selectivity,low detection limit,strong anti-interference ability and low cytotoxicity.And it has also been successfully made into strips that can quickly detect copper ions.2.A novel fluorescent probe Rh F based on rhodamine B derivative is designed and synthesized.Based on FRET mechanism,the probe shows a ratiometric fluorescence response to Cu²⁺and a large stokes displacement（237 nm）.And the recognition process is not disturbed by other co-existing metal ions.The potential application of the probe to Cu²⁺can be accomplished by strip paper.In addition,the probe can be used to detect Cu²⁺in water samples.3.The response behavior,recognition mechanism and cell imaging of near-infrared fluorescent probe NB based on rhodamine lactam platform in DMF and H₂O mixture are studied.The probe specifically identify Cu²⁺（UV response）,Hg²⁺（UV and fluorescence response）and Al³⁺（fluorescence response）.The probe NB has strong anti-ion interference ability,wide application range of p H value and low detection limit,as low as nanomole level.At the same time,the probe with low cytotoxicity has been successfully used in the imaging of Hg²⁺and Al³⁺ions in A549 cells.