Synthesis,Crystal Structure and Fluorescence Property of N-n-butyl-4-[di(bromoethyl)]amino-1,8-naphthalimide

The halogen as a kind of alkylating reagent is used to introduce new group to realize the fluorescence sensors efficient of metal ion detection. The substituent at C-4 position was double bromine, which defined that the halogen as an alkylating reagent should be further researched and detected for Hg2＋. Therefore, the N-n-butyl-4-[di（bromoethyl）]amino-1,8-naphthalimide has been synthesized to detect some metal ions. The title compound has been prepared via substitute reaction and was characterized by IR, 1H NMR, 13 C NMR, and MS. It crystallizes in triclinic, space group P1 with a = 9.0071（18）, b = 9.804（2）, c = 13.073（3）A, α = 73.17（3）, β = 71.73（3）, γ = 62.95（3）°, Z = 2, V = 961.5（3） A3, Dc = 1.666 g/cm3, F（000） = 484, μ（Mo Kα） = 4.232 mm-1, R = 0.0429 and w R = 0.1004. The presence of intermolecular hydrogen bonds as well as π-π stacking interaction led to the stability of the compound. The fluorescence intensity was obviously lower than that of other ions when Hg2＋ was added with the concentration of 1 × 10^-5 mol·L-1.

The remarkable effect of amino hydrogen on membrane permeability and organelle staining of 1,8-naphthalimide dyes

Membrane permeability and intracellular diffusion of fluorescent probes determine staining selectivity of intracellular substructures.However,the relationship between the molecular structure of fluorescent probes and their membrane permeability and intracellular distribution is poorly understood.In this paper,we reported a series of 1,8-naphthalimide dyes and carried out cell imaging experiments,and found that the presence of amino hydrogen in these dyes played a crucial role in their cell membrane permeability and intracellular distribution.The secondary amino group containing compounds 1-4 show excellent membrane permeability and strong fluorescence in living cells.While the tertiary amine containing dyes 5 and 6 can hardly permeate the cell membrane though they show extremely similar structure with compounds 2-4.Compound 1 can selectively image lipid droplets by selecting the wavelength of excitation light.With the specificity for lysosomes,2 and 4 have been used in long-term time-lapses imaging of lysosomal dynamics and tracking the process of lysosome-lysosome interaction,fusion and movement.The effect of hydrogen-containing amino substituent on the cell membrane permeability of fluorescent molecules is promising for the development of better biocompatible probes.

New trends of molecular probes based on the fluorophore4-amino-1,8-naphthalimide

4-Amino-1,8-naphthalimide(ANI) represents a valuable fluorophore from which a large number of probes have been derived in order to meet the requirements from the fields of biological sensing and imaging. In this review, the major progresses of ANI-based fluorescent probes in the past decade have been highlighted and categorized into three trends. The future development of ANI probes is also expected. This review provides a great deal of references and illuminating comments which will be helpful for the researchers designing and using fluorescent probes.

Selective and Sensitive Fluorescent Chemosensors for Cu2＋ Ion Based upon Bis-1,8-naphthalimide Dyads

A series of new fluorescent chemosensors 5a--5e, composed of two aminonaphthalimide fluorophores and 2,6-bis（（N-aminoalkyl）aminocarboxy）pyridines, were prepared, characterized, and their fluorescent properties to- wards heavy and transition metal （HTM） ions were investigated. Chemosensors 5e--Se exhibited high selectivity and sensitivity for Cu2＋ ion over other HTM ions with fluorescent quenching （green to colourless）. It clearly demonstrated that the length of the linkers （diamines） between the aminonaphthalimides and 2,6-dicarboxypyridine of 5a--Se was very important for their sensitivity and selectivity for Cu2~ ion over other HTM ions.

A New Fluorescent Chemosensor for Metal Ions Based upon 1,8-Naphthalimide and 8-Hydroxyquinoline

A new fluorescent chemosensor based upon 1,8-naphthalimide and 8-hydroxyquinoline was synthesized, and its fluorescent properties in the presence of different metal cations （Hg^2＋, Ag^＋, Zn^2＋, Fe^2＋, Cd^2＋, Pb^2＋, Ca^2＋, Cu^2＋, Mg^2＋, and Ba^2＋） were investigated. It displayed fluorescence quenching with some heavy and transition metal （HTM） ions, and the quenching strongly depended on the nature of HTM ions.

Studies on the Transition Metal Ion Induced Fluorescence Enhancement of 1,8-Naphthalimide Derivatives

Two fluorosensor systems have been designed and synthesized with their photophysical properties and fluorescence responses toward the transition metal ions studied. The fluorosensor was composed of 1,8-naphthalimide and 4-chloro-1,8-naphthalimide as fluorophore respectively, an amino moiety as the receptor and a hydrocarbon chain as the spacer to link the fluorophore and receptor. Fluorescence intensity of these systems is very weak due to the process of the efficient intramolecular photoinduced electron transfer （PET） in the absence of metal ions. Titration of the transition metal ions can switch on the fluorescence immediately. The intensity of released fluorescence is even higher than the expected from the consideration of the PET in these systems. It may be rationalized that the receptor bound to transition metal ions and the solvation of the fluorophore by the water molecules from the hydrated transition metal salts, may significantly cause fluorescence enhancement.

Design of a 1,8-naphthalimide-based OFF-ON type bioorthogonal reagent for fluorescent imaging in live cells

A novel 1,8-naphthalimide-based OFF-ON type fluorogenic sydnone(Naph-Syd) is designed as bioorthogonal probe for imaging.Sydnone moiety efficiently quenches the native fluorescence of 1,8-naphthalimide,which can be restored with the enhancement of about 300-fold,after reacting with strained cyclooctynes to form pyrazole products(Naph-Pyr).The second-order rate constant of this bioorthogonal cycloaddition can be up to 2.5 L mol^-1s^-1,which benefits imaging of biomolecules at low concentrations in cellular environment.

Syntheses,Crystal Structures and Property Studies on Cu(Ⅱ) and Co(Ⅱ) Complexes with 1,8-Naphthalimid Schiff Base

The ligand of N-（2-hydroxybenzylideneamino）-1,8-naphthalimide （HL） and its metal complexes of CuL2 （1） and CoL2 （2） have been synthesized. Elemental analysis, IR and X-ray single-crystal diffraction characterizations for 1 and 2 have been carried out. In the complexes of 1 and 2, the central metallic ions of Cu^2＋ and Co^2＋ coordinate with two deprotonated ligands of L-, respectively and adopt distorted square planar geometries. The thermal analysis result shows that the two complexes undergo two similar decomposition processes because of their similar geometric configurations. For the two complexes, fluorescence spectra measurements indicate that complex CoL2 emits stronger blue fluorescence than HL and the complex CuL2 does not emit fluorescence at all.

An ultra-sensitive and easy-to-use assay for sensing human UGT1A1 activities in biological systems

The human UDP-glucuronosyltransferase 1A1(UGT1A1),one of the most essential conjugative enzymes,is responsible for the metabolism and detoxification of bilirubin and other endogenous substances,as well as many different xenobiotic compounds.Deciphering UGT1A1 relevance to human diseases and characterizing the effects of small molecules on the activities of UGT1A1 requires reliable tools for probing the function of this key enzyme in complex biological matrices.Herein,an easy-to-use assay for highly-selective and sensitive monitoring of UGT1A1 activities in various biological matrices,using liquid chromatography with fluorescence detection(LC-FD),has been developed and validated.The newly developed LC-FD based assay has been confirmed in terms of sensitivity,specificity,precision,quantitative linear range and stability.One of its main advantages is lowering the limits of detection and quantification by about 100-fold in comparison to the previous assay that used the same probe substrate,enabling reliable quantification of lower amounts of active enzyme than any other method.The precision test demonstrated that both intra-and inter-day variations for this assay were less than 5.5%.Furthermore,the newly developed assay has also been successfully used to screen and characterize the regulatory effects of small molecules on the expression level of UGT1A1 in living cells.Ove rall,an easy-to-use LC-FD based assay has been developed for ultra-sensitive UGT1A1 activities measurements in various biological systems,providing an inexpensive and practical approach for exploring the role of UGT1A1 in human diseases,interactions with xenobiotics,and characterization modulatory effects of small molecules on this conjugative enzyme.