Design,synthesis and biological evaluation of novel N1,N8-bis(((4-((5-aryl-1,3,4-oxadiazol-2-yl)methoxy)phenyl)amino)oxy)-1-naphthamide derivatives

A new series of 1,8-bis(4-((5-phenyl-1,3,4-oxadiazol-2-yl) methoxy)-substituted aryl) naphthalene-1,8-dicarboxamide derivatives (6a–j) were synthesized in the presence of POCl₃ and obtained good yields. All the synthesized novel compounds were characterized by IR, ¹H NMR, ¹³C NMR, HRMS spectroscopic data and elemental analysis. All the synthesized compounds evaluated for their antibacterial and antifungal activities. The antibacterial activity screened against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli and used standard reference drug ciprofloxacin. The antifungal activity screened against two pathogenic fungal strains Aspergillus niger and Candida albicans used a reference standard drug Voriconazole. All these compounds (6a–j) demonstrate good antibacterial and antifungal activity. Among them, compounds 6h and 6c show highest antibacterial and antifungal activity.     

Fluorescence properties of amido-substituted 2,3-naphthalimides: Excited-state intramolecular proton transfer (ESIPT) fluorescence and responses to Ca2+ ions

2,3-Naphthalimide derivatives incorporating trifluoroacetamido (3a) and methansulfonamido (3b) functionalities at the 1-position were prepared and their intramolecular excited state proton transfer (ESIPT) fluorescence and responses to metal ions were investigated. Compound 3a displayed normal fluorescence in the amide form in toluene and MeCN and no response to metal cations in the corresponding amidate ion form. In contrast, compound 3b gave off dual emission assignable to normal and ESIPT fluorescence. Additionally, the amidate form of compound 3b displayed off-on fluorescence response to Ca²⁺.     

The AIEE properties and solid state fluorescence of 3-indolyl-4-indazolyl maleimide compounds: Synthesis and fluorescence characteristics

A range of 3-indolyl-4-indazolyl maleimide fluorescent compounds, including 2a, 2b, 2c, 3a and 3b, were synthesized efficiently. In different organic dissolvents, the photo-physical performance was checked, either in the aggregated state or in the solid state. When being in solid and in solution state, these fluorescent compounds showed high fluorescent intensity, indicating a highest fluorescence quantum efficiency of 45% accompanying a large Stokes Shift longer than 100 nm in toluene. Also, they can carry out a phenomenon of aggregation-induced emission enhancement (AIEE). TDDFT and DFT calculations were used to confirm the experimental findings.     

Synthesis, fluorescence study and biological evaluation of three Zn(II) complexes with Paeonol Schiff base

The synthesis of three Paeonol Schiff base ligand and their Zn(II) complexes are reported. The complexes were fully characterized by IR, ¹H NMR, elemental analysis and molar conductivity. The experiment results show the three Zn(II) complexes can emit bright fluorescence at room temperature in DMF solution and solid state. The fluorescence quantum yields (Φ) of three Schiff base ligands and their Zn(II) complexes were calculated using quinine sulfate as the reference with a known Φ_R of 0.546 in 1.0N sulfuric acid. Furthermore, in order to develop these Zn(II) complexes’ biological value, the antioxidant activities against hydroxyl radicals (OH) were evaluated. The results show the three complexes possess excellent ability to scavenge hydroxyl radicals.     

Thiazonaphthalimide derivatives: Synthesis and interaction with DNA

The synthesis of several thiazonaphthalimide derivatives is described. The exclusive formation of angular rather than linear isomers was unequivocally demonstrated by NMR and single crystal X-ray diffraction. Their photophysical properties and ability to bind calf-Thymus DNA with affinities in the range of 10⁴ makes them interesting candidates to probe DNA by fluorescence.     

水溶性CdTe量子点的合成及其用于荧光猝灭法测定肌红蛋白

以3-巯基丙酸为稳定剂,合成了具有特殊光学性质的水溶性CdTe量子点,其最大发射波长位于544 nm.利用荧光光谱、紫外可见光谱及圆二色光谱法系统的研究了CdTe量子点与肌红蛋白(Mb)二者结合前后体系光谱的变化,从而证实了CdTe量子点与Mb之间静电结合反应的特征.在pH 7.0的PBS缓冲液中,用CdTe量子点作为荧光探针研究了肌红蛋白与量子点的相互作用,并基于肌红蛋白对CdTe量子点有显著的荧光猝灭作用,建立了肌红蛋白的快速检测方法.在最佳实验条件下,该体系荧光强度的猝灭程度(△F)与肌红蛋白质量浓度呈良好的线性关系,线性范围为0.3～24 μg/mL,检出限为0.13 μg/mL.该方法已对合成样品中肌红蛋白进行检测,并用于人体尿样中肌红蛋白的测定.     

Synthesis of novel copoly(styrene-maleic anhydride) materials and their luminescent properties

Two series of new high fluorescent polymeric materials based on copoly(styrene-maleic anhydride) (SMA) were prepared by the condensation of SMA with fluorescent groups. One series consists of 1,8-naphthalimides derivatives that are linked with SMA. The other series were prepared by the condensation of SMA with 3,4,9,10-perylene tetracarboxylic mono-anhydride mono-imide. These simple routes to copolymer of styrene and maleic anhydride containing pendent luminescent moiety are promising in increasing fluorescent quantum yield in solid state and processing, in which styrene is employed as “diluents”. The luminescent and the preliminary photovoltaic properties of these copolymers have been investigated.     

Synthesis and fluorescence properties of 2-aryl-3-hydroxyquinolones, a new class of dyes displaying dual fluorescence

A series of 2-aryl-3-hydroxyquinolones (3HQs) with different electron donating aryl substituents at the position 2 were synthesized. Their absorption and fluorescence properties were studied in solvents of medium and high polarity. Almost all the synthesized 3HQs display dual fluorescence in the tested solvents, in line with an excited state intramolecular proton transfer reaction. For N-methyl substituted compounds, the intensity ratio of the two emission bands was found to be exquisitely sensitive to solvent polarity, with a two orders of magnitude change from toluene to dimethylsulfoxide. Consequently, these compounds appear as prospective polarity fluorescent labels for proteins and nucleic acids.     

Anomalous fluorescence spectra of benz[a]azulene derivatives

The electronic and fluorescence spectra of banz[a]azulene derivatives have been measured. the fluorescence from the second excited singlet state have been observed for these compounds. The fluorescence quantum yields (φ_f) is sensitive to the energy difference between the first excited singlet (S₁) and the second excited singlet state (S₂).     

衍生荧光法测定盐酸西布曲明

通过衍生反应，建立了用荧光光度法测定盐酸西布曲明的新方法。并对衍生体系、反应条件、产物稳定性等进行了研究。实验确定丙二酸和乙酸酐混合试剂与盐酸西布曲明在75℃的水浴中加热15min，所得产物发射强荧光，最大激发波长λcx=456nm，最大发射波长λem=496nm。在上述波长下，荧光强度与盐酸西布曲明的质量浓度在0．11～9．5μg／mL范围内呈良好的线性关系，检出限为13．4ng／mL，标准加入回收率在95．4％～104．2％。用于曲美胶囊中盐酸西布曲明的测定。     

CdSe/CdS量子点荧光猝灭法测定芹黄素的研究

以巯基乙酸为稳定剂,在水溶液中合成了具有特殊光学性质的水溶性CdSe/CdS量子点。以该量子点为荧光探针,基于荧光猝灭法对芹黄素进行了定量检测。考察了缓冲体系、反应时间、量子点浓度等多种因素的影响。实验结果表明,在0.001 mol/L、pH为6.80的KH2PO4-Na2HPO4缓冲液中,当量子点浓度为1.2×10^-4mol/L、反应时间为20 min时,该方法的线性范围为0.16-27.02μg/mL,其线性回归方程为F0/F=0.99665＋0.11067ρ（μg/mL）,相关系数r=0.998,检出限为0.13μg/mL,并用于合成样品的分析。     

Synthesis and characterization of novel fluorescent BOPIM dyes with large Stokes shift

A novel BOPIM (boron 2-(2-pyridyl)imidazole complex) dye 1 was facilely synthesized by treatment of previously reported 2-(2′-pyridyl)imidazole with BF₃·Et₂O under basic condition. The bromination of BOPIM dye 1 by NBS gives an unexpected product 2-(2′-pyridyl)-4,5-dibromoimidazole (L2) with no BF₂ group. The desired brominated boron complex 2 was obtained by treating L2 with BF₃·Et₂O. The photophysical properties of these two compounds are thoroughly studied in various solvents. Compound 1 formed aggregates in non-polar solvents, inducing abnormal emission in long-wavelength region. Both 1 and 2 show moderate fluorescent intensity and comparatively large Stokes shift, especially for compound 2 (fluorescent quantum yield is more than 0.30, and Stokes shift is over 70 nm in all adopted solvents) due to its p, π-conjugated effect, which makes BOPIM a valuable building block for synthesis of multi-functional materials.     

CdTe量子点荧光猝灭法测定奥沙利铂中微量银

以谷胱甘肽作为稳定剂,100℃恒温回流,直接合成水溶性CdTe量子点。基于Ag+对合成的CdTe量子点的荧光猝灭效应,建立了测定抗癌药物奥沙利铂中微量银的方法。考察了量子点浓度、缓冲液种类、缓冲液浓度、缓冲液pH和反应时间对银离子测定的影响。当量子点浓度为0.004 g/L时,在0.10 mmol/LpH7.4的磷酸缓冲溶液中,反应时间为5 min,体系的相对荧光强度与Ag+的质量浓度呈良好的线性关系,其线性范围为16.42～98.50μg/L,线性相关系数为0.9975,检出限为0.12μg/L。     

Quantum dot-based immunosensor for the detection of prostate-specific antigen using fluorescence microscopy

A sensitive optical method based on quantum dot (QD) technology is demonstrated for the detection of an important cancer marker, total prostate-specific antigen (TPSA) on a disposable carbon substrate surface. Immuno-recognition was carried out on a carbon substrate using a sandwich assay approach, where the primary antibody (Ab)-protein A complex covalently bound to the substrate surface, was allowed to capture TPSA. After the recognition event, the substrate was exposed to the biotinylated secondary Abs. After incubation with the QD streptavidin conjugates, QDs were captured on the substrate surface by the strong biotin-streptavidin affinity. Fluorescence imaging of the substrate surface illuminated the QDs, and provided a very sensitive tool for the detection of TPSA in undiluted human serum samples with a detection limit of 0.25 ng/mL. The potential of this method for application as a simple and efficient diagnostic strategy for immunoassays is discussed.     

Multifunctional photo acid generator for fluorescence imaging based on self-contained photoreaction

We present N-(p-anilinesulfonyloxy)-1,8-naphthalimide (ASNI) as fluorescence imaging material based on a novel fluorescence imaging mechanism. ASNI is composed of two functional moieties in one molecule: an acid-reactive fluorescence probe and a photoacid generator (PAG). When ASNI is photoirradiated, a bond in the PAG moiety breaks and an acid is generated. The fluorescence probe moiety then detects the acid and fluoresces. We call this novel mechanism a self-contained photoreaction (SCP). The photophysical properties and photoreactivity of ASNI were measured and compared with those of a prototype PAG, N-(phenylsulfonyloxy)-1,8-naphthalimide. These were well represented by density functional theory calculations. SCP permits one-step fluorescence imaging without any wet or dry developing process.     

Study of maleated ethylene-propylene copolymers by fluorescence: Evidence for succinimide induced polar associations in an apolar solvent

A maleated ethylene-propylene copolymer (EP-MAH) was labelled with 1-naphthalene- and/or 1-pyrenemethylamine to yield an EP copolymer bearing succinimide pendants all labelled with a chromophore. The labelled EPs were reacted with LiAlH₄ so that the polar succinimide linker group between the EP backbone and the chromophore was converted into apolar pyrrolidine units. The resulting products were purified through a gel permeation chromatography column to remove the cleaved off chromophores. FT-IR spectroscopy revealed that after reduction, the peak assigned to the succinimide carbonyls was strongly diminished. UV-vis absorption and steady-state and time-resolved fluorescence measurements were performed in hexane and THF. The reduction of the succinimide carbonyls was found to have a significant effect on the luminescence properties of the labelled EPs. The polar associations taking place between the succinimide moieties in hexane were found to be dramatically decreased after reduction as shown by UV-vis absorption, steady-state excitation and emission fluorescence, time-resolved fluorescence, and fluorescence resonance energy transfer. These results demonstrate that the presence of pyrene aggregates for EP-MAH labelled with 1-pyrenemethylamine is due primarily to the polar succinimide moieties rather than the aromatic pyrene.     

量子点标记链霉亲和素荧光免疫分析测定雌三醇

以生物素化羊抗兔免疫球蛋白和量子点标记链霉亲和素为荧光探针,采用竞争免疫分析模式,建立了一种灵敏度高、选择性好的检测雌三醇的荧光免疫分析方法.对几种测量参数如温育时间和温度、缓冲溶液pH、试剂浓度等进行了优化;方法的线性范围为0.01～1000ng/mL,检出限0.0029 ng/mL,血清样品加标回收率在91%～117%之间.     

Identification of catecholamine neurotransmitters using fluorescence sensor array

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual catecholamine (i.e., dopamine, norepinephrine, and l-DOPA) and their mixtures in the concentration range of 0.25–30 μmol L⁻¹. Finally, we found that the sensor had capability to identify the various catecholamines in urine sample.     

Synthesis and Absorption Properties of Some 4-Thioaryl-1,8-naphthalimides and 4-Thioaryl-7H-benzimidazo-[2,1-a]-benz-[d,c]-isoquinolin-7-one Derivatives

A series of novel 4-thioaryl-1,8-naphthalimide derivatives were synthesized using 4-chloro-1,8-naphthalic anhydrid and arylthioles as starting materials. 4-thioaryl-1,8-naphthalic anhydride was treated with different primary amines and o-phenylene diamine or 1,2-diaminoethene to produce 4-thioaryl-1,8-naphthalimides and 4-thioaryl-7 H-benzimidazo-[2,1-a]-benz-[d,c]-isoquinolin-7-one derivatives, respectively. The UV/VIS absorption properties are discussed.     

Size and branching effects on the fluorescence of benzylic dendrimers possessing one apigenin fluorophore at the core

Different generations of dendrimers incorporating one fluorescent core of apigenin and three Fréchet benzylic dendrons have been prepared. The chief geometric features of these dendrimers have been obtained by Molecular Dynamics simulations. These computational data suggest that the asphericities of dendrimers belonging to the third and fourth generations are considerably larger than those associated with lower radii of gyration. Fluorescence spectra of high generation dendrimers evolve along time and quantum yields show an appreciable lowering for the fourth generation dendrimer. All these data suggest aggregation phenomena and lower quantum yields for nonspheric dendrimers in solution.