Benzophenone and zinc(II) phthalocyanine dichromophores-labeled poly (aryl ether) dendrimer: synthesis,characterization and photoinduced energy transfer

A series of benzophenone chromospheres and zinc(II) phthalocyanine dichromophores labeled poly (aryl benzyl ether) dendrimer (G_n-DZnPc(BP)_8n, n = 1?2) were synthesized. Their structures were characterized by elemental analysis, ¹H NMR, IR, UV–vis and matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOF MS). Their photophysical properties were examined by steady-state and time-resolved fluorescence methods. Both the poly (aryl benzyl ether) dendrimer and BP terminal chromophores had a significant effect on photophysical properties of the zinc(II) phthalocyanine core. Time-resolved spectroscopic measurements indicated that the lifetime of benzophenone (donor) chromophore was longer than that of the zinc(II) phthalocyanine (acceptor). The fluorescence of the peripheral benzophenone chromophores was quenched by the phthalocyanine group attached to the focal point. All of these observations suggest that an intramolecular singlet energy transfer occurs in G_n-DZnPc(BP)_8n molecules. The light-harvesting abilities of these molecules increased with generations due to an increase in the number of benzophenone chromophores. The energy transfer efficiencies were ca. 0.49 and 0.68 for generations 1 and 2, respectively, and the rate constants of the singlet-singlet energy transfer were ca. 10⁸ s^?1. The rate constants changed inconspicuously with increase of dendron generations. The intramolecular singlet-singlet energy transfer is proposed to proceed mainly via a Förster-type interaction mechanism involving the dendrimer backbone as a scaffold to hold the peripheral benzophenone chromophores and the phthalocyanine core together. This dendrimer was an effective new energy transmission complex with high efficiency and could be used as a potential light-harvesting system.     

A novel Hg2+ fluorescence sensor TPE-TSC based on aggregation-induced emission

Abstract

A fluorescent sensor TPE-TSC with aggregation induced emission (AIE) characteristic is synthesized for detecting Hg²⁺ by attaching thiosemicarbazide (TSC) unit into tetraphenylethylene (TPE) group. TPE-TSC exhibits intense green emission in DMSO/H₂O (V:V?=?1:9) solution with the formation of the aggregation. TPE-TSC shows outstanding fluorescence quenching toward Hg²⁺ over other metal ions due to the formation of complex TPE-TSC/Hg²⁺ with a 2:1 binding ratio. The detection limit of TPE-TSC for Hg²⁺ is 1?×?10^?5 mol·L^?1.     

Effect of Oxyethylete Units on Adsorption and Micellization Properties of Novel Benzene Sulfonate Surfactants

The surface tension and fluorescence spectra of sodium octyl-[ω-octyloxy-poly(oxyethylene)]-yl-benzene sulfonates (APE_nBS) aqueous solutions have been investigated by Wilhelmy plate method and intrinsic probe methods, respectively to study the effect of EO units on their properties. It was discovered that the surface performance of these surfactants was greatly outstanding: the values of critical micelle concentration (CMC) reached to be of the order of magnitude of 10^?5 mol/L, the values of surface tension at CMC, γ_CMC, were between 25.79 to 31.02 mN/m, and the effectiveness and efficiency of surface tension reduction were excellent. The introduction of oxyethylene units to the surfactant molecule evidently improved the solubility of APE_nBS. With the increase in EO units, the CMC slightly changed after the first decreased. On the other hand, the surface excess concentration at saturation, Γ _max, decreased after the first increased and γ_CMC increased after the first decreased accordingly. The CMC determined by fluorescence spectra of intrinsic probe method were accorded with the CMC measured by surface tension method. The aggregation number N, characterized by quenching the fluorescence spectra with methyl viologen (MV²⁺) as the extrinsic quencher, gradually decreased first (from 0 to1) and then slightly changed (from 1 to 4) with increasing EO chain length. So we concluded that the appropriate number of EO units was the key factor to get the best physicochemical properties of APE_nBS.     

Adsorption and Surface Properties of Vladipor Cellulose Acetate and Polysulfonamide Membranes

Surface and adsorption characteristics of porous cellulose acetate (UAM) and polysulfonamide (UPM) membranes with pore diameters from 0.015 to 0.1 μm are compared. The specific surface areas of UPM membranes are 130 and 150 cm²/cm², whereas those of UAM membranes vary from 80 to 360 cm²/cm² of the membrane area. The density of negative charges on the pore surface is 5 × 10^{− 8} and about 20 × 10⁻⁸ C/cm² for UAM and UPM membranes, respectively. The adsorption of basic and acidic substances, proteins (cytochrome C and ovalbumin) and dyes (rhodamine 6G and Acid Orange), from aqueous solutions is studied. Far stronger hydrophobic interactions are observed for the UPM than for UAM membranes. The adsorption of basic substances is markedly higher than that of acidic substances because of acidic properties of the membrane surface. The distribution constants for the adsorption of Acid Orange and cytochrome C on the UPM membrane with a pore diameter of 0.1 μm are 50- and 100-fold higher than for the UAM membrane of the same pore diameter and specific surface area. __________ Translated from Kolloidnyi Zhurnal, Vol. 67, No. 6, 2005, pp. 835–838. Original Russian Text Copyright ? 2005 by Khokhlova, Dzyubenko, Berezkin, Bon, Pervov, Shishova, Dubyaga, Mchedlishvili.     

Surface and Solution Properties of Cationic Gemini Surfactants with Primary Linear Alkanols

Using surface tension and fluorescence methods, the surface and solution properties of two cationic gemini surfactants {pentanediyl-1,5-bis(dimethylcetylammonium bromide) and hexanediyl-1,6-bis(dimethylcetylammonium bromide)} (referred to as 16-5-16 and 16-6-16) have been studied in the presence and absence of primary linear alkanols. Parameters studied include the critical micelle concentration (CMC), C ₂₀ (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m^?1), Г _max (maximum surface excess), and A _min (minimum surface area per molecule). These parameters indicate mixed micelle formation and, therefore, surfactant-additive interaction parameters in mixed micelles and mixed monolayers, as well as activity coefficients, were calculated. A synergistic effect was observed in all instances and was found to be correlated with the chain length of the alkanols. The CMC values of 16-s-16 (s = 5, 6) decrease with increasing alkanol concentration and the extent of this effect follows the sequence: 1-octanol (C₈OH) > 1-heptanol (C₇OH) > hexan-1-ol (C₆OH) > 1-pentanol (C₅OH) > butanol (C₄OH). The micelle aggregation number (N _agg) of mixed micelles has been obtained using the steady state fluorescence quenching method. The micropolarity of gemini/alkanol systems has been evaluated from the ratio of intensity of peaks (I ₁/I ₃) of the pyrene fluorescence emission spectra. Results are interpreted on the basis of the structure of mixed micelles and monolayers.     

Turn-on fluorometric immunosensor for diethylstilbestrol based on the use of air-stable polydopamine-functionalized black phosphorus and upconversion nanoparticles

The preparation of air-stable black phosphorus (BP) is challenging because atomic layers of BP degrade rapidly on exposure to oxygen. A strategy is presented for the synthesis of BP functionalized with polydopamine (PDA/BP). Dopamine was self-polymerized to yield polydopamine (PDA) which then was used to coat the surface of BP. PDA can be easily reduced and this prevents BP degradation. PDA/BP also is a viable matrix for the adsorption of proteins due to the presence of functional groups. Without any chemical activation, diethylstilbestrol (DES)-specific monoclonal antibody was adsorbed on the PDA/BP surface. PDA/BP quenches the fluorescence antigen-modified NaYF₄:Yb,Ho,Nd upconversion nanoparticles (UCNPs; photoexcited at 808 nm) via specific immuno recognition. Exposure to DES causes the dissociation of UCNP from the PDA/BP surface and fluorescence at 475, 525, 545 and 660 nm to recover. This is due to the DES competition with antigen for binding to the antibody. Based on this competitive immuno mechanism, a turn-on fluorometric immunoassay was constructed. It has a response that covers the 0.1 to 1000 ng mL^?1 DES concentration range with a detection limit of 83 pg mL^?1. This method was successfully applied to the determination of DES in spiked food and human urine samples.

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Graphical abstract Air-stable polydopamine-functionalized black phosphorus was obtained by modification of black phosphorus with polydopamine and then was coupled with specific monoclonal antibody. Combined with antigen-modified upconversion nanoparticles, a turn-on fluorometric immunoassay was constructed to detect diethylstilbestrol.

     

Surface Thermodynamic Properties of Micas and Related Layer Silicate Minerals

The surface tension values for a series of 2:1 phyllosilicate minerals with different structural characteristics and layer charges ranging from 0 to 2 per O₁₀ group have been examined. The average Lifshitz-van der Waals component (Γ^LW)value is 40.3 ± 1.9 mJ/m², and the average Lewis acid (®) parameter is 1.2 ± 0.6 mJ/² for those minerals with a layer charge greater than zero. In contrast, the Lewis base parameter (γ^e) varied greatly from a maximum of 59.7 mJ/m to a minimum of 23.7 mJ/m². Those minerals with a layer charge of zero (three samples) had smaller γ^LW values of 32.0 ± 1.6 mJ/m², slightly larger γ® values of 2.0 ± 0.4 mj/m² and significantly smaller values of γ® of 4.5 ± 1.6 mJ/m². The hydrophobic versus hydrophilic character of these materials is largely governed by the value of γ° which is strongly related to the value of the layer charge.

Thus, the hydrophilicity of a smectite is determined by the charge unbalancing ionic substitutions which attract hydrophilic interlayer cations and render adjacent oxygen atoms of the panicle surface hydrophilic.     

Synthesis and Surface Properties of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants, p-[C _n H_2n+1N⁺(CH₃)₂CH₂CH(OH)CH₂O]₂C₆H₄·2Cl^? [A(n = 12), B(n = 14) and C(n = 16)], containing a spacer group with two flexible and hydrophilic groups (2-hydroxy-1,3-propylene) on both sides of a rigid and hydrophobic group (1,4-dioxyphenylene) has been synthesized by the reaction of hydroquinone diglycidyl ether with N,N-dimethylalkylamine and N,N-dimethylalkylamine hydrochloride. Their surface-active properties have been investigated by surface tension measurement. The critical micelle concentration (cmc) values of the synthesized cationic gemini surfactants are one order of magnitude lower than those of their corresponding monomeric surfactants (C _n H_2n + 1N⁺(CH₃)₃·Cl^?). Both the cmc and surface tension at the cmc (γ_cmc) of A are lower than those of p-[C₁₂H₂₅N⁺(CH₃)₂CH₂]₂C₆H₄·2Cl^? (D). The novel cationic gemini surfactants A and B also show good foaming properties.     

A new lawsone azo-dye for optical sensing of Fe3+ and Cu2+ and their DFT study

A new lawsone-based azo-dye 2-hydroxy-3-((pyridin-2-ylmethyl)diazenyl)naphthalene-1,4-dione (1) was synthesized and applied for sensing of metal ions. Receptor 1 showed selective fluorescent and colorimetric response for the detection of Cu²⁺ and Fe³⁺ over other tested metal ions. The fluorescence intensity of 1 was significantly quenched allowing detection of Fe³⁺ and Cu²⁺ down to 0.61 and 6.06 μM, respectively. The binding has been established by fluorescence spectroscopic method. Receptor 1 provided a 1?:?1 binding scaffold for recognition of Fe³⁺ and Cu²⁺ ions with the association constant of 3.33 × 10⁶ and 3.33 × 10⁵ M^?1, respectively. The B3LYP/6-31G/LANL2DZ method was employed for the optimization of 1 and 1·Fe³⁺ and 1·Cu²⁺.     

Coagulation of poly(p-phenylene benzobisoxazole) in polyphosphoric acid using aqueous and nonaqueous solutions

Diffusion of aqueous and nonaqueous coagulants into lyotropic/nematic solutions of poly(phenylene benzobisoxazole) in polyphosphoric acid using fluorescence microscopy is reported. The fluorescence microscopy technique offers advantages in that the experiment is independent of the coagulant and the experiments can be performed in a front surface mode so that optically thin samples are not required. The diffusion process is modeled as Case II diffusion as described by Crank and Park. The apparent diffusion coefficients are found to range from ～ 2 × 10^?6 cm²/s to ～ 2 × 10^?7 cm²/s for aqueous and nonaqueous coagulants. The apparent diffusion coefficients can be varied by several orders of magnitude (e.g., down to ～ 3 × 10^?10 cm²/s) by varying the concentration of polyphosphoric acid in the coagulant. © 1995 John Wiley & Sons, Inc.     

Surface activities and thermodynamic properties of novel cationic surfactants with hydroxymethyl group

A new series of cationic surfactants, N–alkyl–N,N–dimethyl–N–(p–(hydroxymethyl) benzyl) ammonium chlorides (p-DHBA-m), were synthesized and the structures were characterized by ¹HNMR, ¹³CNMR, FT–IR and ESI–MS. The surface activities, thermodynamic properties and aggregation behaviors of p-DHBA-m in aqueous solutions were respectively studied by means of surface tension, isothermal titration calorimetry and steady-state fluorescence methods. Thermodynamic parameters show that the micellization is an entropy-driven process. According to the fluorescence quenching method, the micelle aggregation numbers (N_agg) of p-DHBA-m were calculated and found that the increase of temperature or the elongation of alkyl chain length could lead to the reduction of the N_agg, respectively.     

Aggregation of Alkyl Substituted Salchxn Complexes Studied by 1H-N.M.R

Abstract

A difference in the ¹H-n.m.r. peak shift due to aggregation was observed between chloroform-d₁ solutions of optically active and racemic forms of chiral (4′,4′'-dihexyl-N, N'-disalicylidene)-1,2-diaminocyclohexanenickel(II) (1). The difference is caused by the formation of racemic dimer in the racemic form of 1, which is not formed in the optically active form. The equilibrium constants of dimer formations and the aggregation structures were estimated from the concentration dependence of ¹H-n.m.r.     

Synthesis and aggregational behavior of acidic proteinoid

Polypeptide-based acidic proteinoid containing L -glutamic acid and L -aspartic acid in excess and five other neutral and basic amino acids in minor proportions have been synthesized and found that it forms organized aggregates in an aqueous solution. The proteinoid aggregate has been characterized using ¹³C-NMR, IR, and fluorescence spectroscopic techniques. The c.m.c. of the proteinoid has been determined by conductometric and pH metric methods. The aggregation studies were carried out at different temperatures and varying ionic strengths of the medium. The phase transition of the proteinoid aggregate has been determined using the fluorescence absorbance method. The aggregation behavior is shown to be dependent on the pH of the solution. This was also supported by conductivity measurements. Using methylene blue as a model drug, the drug delivery property of the proteinoid micelles were studied in acidic (pH 4.5) and neutral (pH 7.4) mediums. Using biphasic model thermochemical parameters, ΔG, ΔH, ΔS, and ΔC_p have been evaluated. © 1996 John Wiley & Sons, Inc.     

Physicochemical properties of α, ω-type bolaform surfactant in aqueous solution. Eicosane-1,20-bis(triethylammonium bromide)

The physicochemical properties of the, - type (bolaform) surfactant, eicosane-1, 20-bis(triethylammonium bromide) (C₂₀Et₆), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization, and time-resolved fluorescence quenching (determination of average micelle aggregation number). Using electrical conductivity, the critical micelle concentration of C₂₀Et₆ was found to be 6.0×10^–3 mol dm^–3 and the ionization degree of C²⁰Et₆ micelle was found to be 0.42. From surface tension measurments, the molecular area of C₂₀Et₆ at the air-water interface was about twice that of normal type surfactants such as dodecyltrimethylammonium bromide (DTAB). The solubilizing power of micellar solution of C₂₀Et₆ toward Orange OT was 1.0×10^–2 mole of dye per mole of surfactant, i. e., slightly smaller than that of DTAB. The micelle aggregation number,N, was found to be 17±2 by time-resolved fluorescence quenching. C₂₀Et₆ showed a very small temperature dependence ofN, much less than for normal surfactants.     

A Study on the Location and Aggregation of Tetrahydrophenylporphyrin with a Single Hexadecyl Chain in Triton X-100 Micelle

The location and aggregation of 5,10,15-tris(4-hydroxyphenyl)-20-(hexadecyloxyphenyl)porphyrin (P) in nonionic polyoxyethylene (9.5) octylphenol (Triton X-100) micelle solutions were studied by means of UV–Vis and fluorescence spectra. P forms premicelle surfactant–porphyrin aggregates when the surfactant concentration is below and approaching the CMC. In Triton X-100 micelle solutions, different types of H-aggregates of P were formed when the concentration of P is higher than 3.9×10^-6?mol?dm^-3. As the bulk pH is changed, a transfer process for the porphyrin moiety in Triton X-100 micelle occurs. In neutral Triton X-100 micelle solutions, P may be located at the inner layer of the micelle; in basic conditions, the porphyrin moiety may transfer to the outer surface of the micelle. The kinetic study of porphyrin complexed with Cu(II) in Triton X-100 micelle solutions shows that the metalation rate could be controlled by changing the pH.     

Synthesis,crystal structure,and fluorescence properties of two 1-D chain polymers extended by a semi-rigid bis(triazole) ligand

Two 1-D luminescent metal-organic frameworks with identical structures, {[Mn(BBPTZ)₂(MeCN)₂]·(ClO₄)₂}_n (1) and {[Zn(BBPTZ)₂(MeCN)₂]·(MeCN)₂·(ClO₄)₂}_n (2), have been synthesized under solvent diffusion evaporation and characterized by elemental analyses, thermal analyses and single-crystal X-ray diffraction. Both complexes crystallize in the monoclinic system, space group C2/c with six-coordinate M(II). Thermal decompositions of the complexes have been studied using thermogravimetric analyses (TGA). The complexes exhibit a significant fluorescence quenching effect to Fe³⁺ in acetonitrile solution. The LoDs (Limit of Detection) of the complexes to Fe³⁺ are 2.59 × 10^?8 M and 1.57 × 10^?8 M for 1 and 2, respectively. The complexes could be applied to efficient chemosensor for Fe³⁺ detection.     

Hetero‐oligophenylene‐Based AIEE Material as a Multiple Probe for Biomolecules and Metal Ions to Construct Logic Circuits: Application in Bioelectronics and Chemionics

New hetero‐oligophenylene derivative ( 2 ) was synthesized which exhibits aggregation‐induced emission enhancement (AIEE) in H₂O/THF (80:20). The aggregates serve as a biological probe for three different proteins, that is bovine serum albumin (BSA), cytochrome c, and lysozyme, and DNA in contrasting modes. Further, among 29 metal ions tested, the contrasting fluorescence behavior of aggregates of 2 is observed with only Pb²⁺ and Pd²⁺ ions. Multiple output logic circuits based upon the fluorescence behavior between BSA and cytochrome c and between Pb²⁺ and Pd²⁺ ions are constructed.     

C60吡咯烷羧酸衍生物的合成及其在水溶液中的聚集行为

C60与亚氨基二乙酸甲酯[NH(CH₂COOMe)₂]的光化学反应制得2,5-双(甲氧羰基)富勒烯吡咯烷(1), 产率为52% (基于已反应的C60). C60吡咯烷衍生物1与氯乙酸甲酯(ClCH₂COOCH₃)的N-烃基化反应, 在微波辐射、无溶剂及相转移条件下, 得到2,5-双(甲氧羰基)-N-(甲氧羰基)甲基富勒烯吡咯烷(2), 产率47%(基于C60吡咯烷衍生物1). C60吡咯烷衍生物1和2用NaH, CH₃OH水解后, 经盐酸酸化得相应的二羧酸衍生物3和三羧酸衍生物4, 产率分别为65%和53% (基于C60吡咯烷衍生物1和2). C60吡咯烷衍生物1～4的结构由¹H NMR, ¹³C NMR, IR, FAB-MS和元素分析证实. 用电导法测定了C60吡咯烷二羧酸3和三羧酸4钠盐的临界聚集浓度(CAC), 分别为3.58×10^－4 mol/L (3)和3.33×10^－4 mol/L (4). 这一结果被C60吡咯烷衍生物3和4, 在临界聚集浓度(CAC)附近的UV-Vis光谱的特征变化所支持. 透射电子显微镜(TEM)和静态光散射(SLS)等方法也被用于检测C60吡咯烷衍生物3和4在临界聚集浓度(CAC)时的聚集行为, 结果显示, C60吡咯烷衍生物3在缓冲溶液中(0.001 mol/L NaCO₃-NaHCO₃), 其聚集体粒径的大小(R_g≈21 nm)不同于C60吡咯烷衍生物4 (R_g≈23 nm). C60吡咯烷二羧酸3钠盐的临界聚集浓度(CAC)比C60吡咯烷三羧酸4钠盐的临界聚集浓度(CAC)大, 聚集体粒径大小的不同, 表明C60单加成衍生物加成基团中羧基(COOH)数目的多少对其聚集行为的影响. 用化学发光法分别检测了C60吡咯烷二羧酸3和C60吡咯烷三羧酸4在缓冲溶液(0.05 mol/L NaCO₃-NaHCO₃)中对邻苯三酚自氧化产生的超氧阴离子(O₂^－·)的清除活性. C60衍生物3和4对 O₂^－· 的清除呈现有明显的剂量效应, 但当超过一定浓度时(3: ～3.50×10^－4 mol/L, 4: ～3.25×10^－4 mol/L), 清除效率出现转折, 并下降. 这一现象与电导率测定时出现的CAC现象相一致, 进一步证实了C60吡咯烷二羧酸3和C60吡咯烷三羧酸4在较高浓度的水溶液中有聚集的倾向, 也说明了C60吡咯烷二羧酸3和C60吡咯烷三羧酸4的聚集会影响其清除超氧阴离子(O₂^－·)的活性.     

Exploring the interactions between gold nanoparticles and analytes through surface‐assisted laser desorption/ionization mass spectrometry

Surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) is applied to provide strong evidence for the chemical reactions of functionalized gold nanoparticles (Au NPs) with analytes – Hg²⁺ ions induced MPA?Au NPs aggregation in the presence of 2,6‐pyridinedicarboxylic acid (PDCA) and H₂O₂ induced fluorescence quenching of 11‐MUA?Au NDs. PDCA‐Hg²⁺‐MPA coordination is responsible for Au NPs aggregation, while the formation of 11‐MUA disulfide compounds that release into the bulk solution is responsible for H₂O₂‐induced fluorescence quenching. In addition to providing information about the chemical structures, SALDI‐MS is also selective and sensitive for the detection of Hg²⁺ ions and H₂O₂. The limits of detection (LODs) for Hg²⁺ ions and H₂O₂ by SALDI‐MS were 300 nM and 250 µM, respectively. The spot‐to‐spot variations in the two studies were both less than 18% (50 sample spots). Our results reveal that SALDI‐MS can be used to study analyte‐induced changes in the surface properties of nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd.     

Iron(II) complexes containing the 2,6-bis-iminopyridyl moiety. Synthesis,characterization, reactivity,and DNA binding

Two iron(II) complexes, [Fe^II(py^tBuN₃)₂](FeCl₄) (1) and [Fe^II(py^tBuMe₂N₃)Cl₂] (2), with sterically constrained py^tBuN₃ and py^tBuMe₂N₃ chelate ligands (py^tBuN₃ = 2,6-bis-(aldiimino)pyridyl; py^tBuMe₂N₃ = 2,6-bis-(ketimino)pyridyl), have been synthesized and characterized by elemental analysis, IR, UV–vis spectra, and preliminary X-ray single-crystal diffraction. The latter revealed that Fe(II) in 1 is six-coordinate by six nitrogen donors from two bisiminopyridines in a distorted octahedron. Complex 2 reacts with thiourea with a second-order rate constant k₂ = (2.50 ± 0.05) × 10^?3 M^?1 s^?1 at 296 K, and the reaction seemed to be slow. In a similar way, the interaction of 2 and DNA was studied by fluorescence and absorption spectroscopy. The results revealed that 2 caused fluorescence quenching of DNA through a dynamic quenching procedure. The binding constants K_A, K_app, and K_SV as well as the number of binding sites between 2 and DNA were determined.