Synthesis,characterization, aggregation and thermal properties of a novel polymeric metal-free phthalocyanine and its metal complexes

A novel polymeric metal-free phthalocyanine (M = 2H) and its metal complexes (M = Zn, Cu, Co and Ni) were prepared by the tetramerization reaction of 3,6,9-Tris(p-tolylsulfonyl)-1,11-bis(3,4-dicyanophenoxy)-3,6,9-triazaundecane 5 with the appropriate materials. The electrical conductivities of the metal-free phthalocyanine and the metal complexes, measured in air, were found to be ∼10⁻⁶–10⁻⁵ S m⁻¹. The aggregation property of the zinc complex 7 was investigated with Ni²⁺, Cu²⁺, Co²⁺, Pb²⁺, Cd²⁺ and Ag⁺ cations. Thermal analysis of the polymers were done by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) at a heating rate of 10 °C min⁻¹ under a nitrogen atmosphere. All the novel compounds were characterized by using elemental analysis, UV–Vis, FT–IR, NMR and MS spectral data and DSC, DTA/TG techniques.     

New long-chain-substituted polymeric metal-free and metallophthalocyanines by microwave irradiation: Synthesis and characterization

A tetranitrile monomer N,N-bis{2-[2-(3,4-dicyanophenoxy)ethoxy]ethyl}-4-methylbenzenesulfonamide (3) was synthesized by nucleophilic aromatic substitution of N,N-bis[2-(2-hydroxyethoxy)ethyl]-4-methylbenzenesulfonamide (1) onto 4-nitrophthalonitrile (2). The metal-free phthalocyanine polymer (4) was prepared by the reaction of a tetranitrile monomer 3 in 2-(dimethylamino)ethanol. Ni(II), Co(II) and Cu(II) phthalocyanine polymers were prepared by the reaction of the tetranitrile compound with the chlorides of Ni(II), Co(II) and Cu(II) in 2-(dimethylamino)ethanol (DMAE). The Zn(II)-phthalocyanine polymer was prepared by the reaction of the tetranitrile compound with the acetate of Zn(II) in DMAE. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis and MS spectral data.     

Tuning the selectivity of polymeric ionic liquid sorbent coatings for the extraction of polycyclic aromatic hydrocarbons using solid-phase microextraction

A new generation polymeric ionic liquid (PIL), poly(1-4-vinylbenzyl)-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide (poly(VBHDIm⁺ NTf₂⁻)), was synthesized and is shown to exhibit impressive selectivity towards the extraction of 12 polycyclic aromatic hydrocarbons (PAHs) from aqueous samples when used as a sorbent coating in direct-immersion solid-phase microextraction (SPME) coupled to gas chromatography (GC). The PIL was imparted with aromatic character to enhance π–π interactions between the analytes and the sorbent coating. For comparison purposes, a PIL with similar structure but lacking the π–π interaction capability, poly(1-vinyl-3-hexadecylimidazolium bis[(trifluoromethyl)sulfonyl]imide) (poly(HDIm⁺ NTf₂⁻)), as well as a commercial polydimethylsiloxane (PDMS) sorbent coating were evaluated and exhibited much lower extraction efficiencies. Extraction parameters, including stir rate and extraction time, were studied and optimized. The detection limits of poly(VBHDIm⁺ NTf₂⁻), poly(HDIm⁺ NTf₂⁻), and PDMS coatings varied between 0.003–0.07 μg L⁻¹, 0.02–0.6 μg L⁻¹, and 0.1–6 μg L⁻¹, respectively. The partition coefficients (log K_fs) of eight PAHs to the three studied fiber coatings were estimated using a static SPME approach. This study represents the first report of analyte partition coefficients to any PIL-based material.     

Preparation of stir cake sorptive extraction based on polymeric ionic liquid for the enrichment of benzimidazole anthelmintics in water,honey and milk samples

In this work, a new stir cake sorptive extraction (SCSE) using polymeric ionic liquid monolith as sorbent was prepared. The sorbent was obtained by in situ copolymerization of an ionic liquid, 1-allyl-3-methylimidazolium bis[(trifluoro methyl)sulfonyl]imide (AMII) and divinylbenzene (DB) in the presence of N,N-dimethylformamide. The influence of the content of ionic liquid and the porogen in the polymerization mixture on extraction performance was studied thoroughly. The physicochemical properties of the polymeric ionic liquid were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The usefulness of SCSE–AMIIDB was demonstrated by the enrichment of trace benzimidazole anthelmintics. Several parameters affecting the extraction efficiency were investigated, and under the optimized conditions, a simple and effective method for the determination of trace benzimidazoles residues in water, milk and honey samples was established by coupling SCSE–AMIIDB with high performance liquid chromatography/diode array detection (SCSE–AMIIDB–HPLC/DAD). Results indicated that the limits of detection (S/N = 3) for target compounds were 0.020–0.072 μg L⁻¹, 0.035–0.10 μg L⁻¹ and 0.026–0.076 μg L⁻¹ in water, milk and honey samples, respectively. In addition, an acceptable reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations (RSD) of less than 9% and 11%, respectively. Finally, the established AMII–SCSE–HPLC/DAD method was successfully applied for the determination of benzimidazoles residues in milk, honey and environmental water samples. Recoveries obtained for the determination of benzimidazole anthelmintics in spiking samples ranged from 70.2% to 117.6%, with RSD below 12% in all cases.     

Evaluation of low-cost disposable polymeric materials for sorptive extraction of organic pollutants in water samples

The capabilities of four commercially available and low cost polymeric materials for the extraction of polar and non-polar contaminants (log K_ow = −0.07–6.88, from caffeine to octocrylene, respectively) from water samples was compared. Tested sorbents were polyethersulphone, polypropylene and Kevlar, compared to polydimethylsiloxane as reference material. Parameters that affect the extraction process such as pH and ionic strength of the sample, extraction time and desorption conditions were thoroughly investigated. A set of experimental partition coefficients (K_pw), at two different experimental conditions, was estimated for the best suited materials and compared with the theoretical octanol–water (K_ow) partition coefficients of the analytes. Polyethersulphone displayed the largest extraction yields for both polar and non-polar analytes, with higher K_pw and lower matrix effects than polydimethylsiloxane and polypropylene. Thus, a sorptive microextraction method, followed by large volume injection (LVI) gas chromatography–tandem mass spectrometry (GC–MS/MS), was proposed using the former sorbent (2 mg) for the simultaneous determination of model compounds in water samples. Good linearity (>0.99) was obtained for most of the analytes, except in the case of 4-nonylphenol (0.9466). Precision (n = 4) at 50 and 500 ng L⁻¹ levels was in the 2–24% and limits of detection (LODs) were in the 0.6–25 ng L⁻¹ range for all the analytes studied.     

A new anionic exchange stir bar sorptive extraction coating based on monolithic material for the extraction of inorganic anion

A novel anionic exchange stir bar sorptive extraction (SBSE) coating based on poly(2-(methacryloyloxy)ethyltrimethylammonium chloride-co-divinylbenzene) monolithic material for the extraction of inorganic anion was prepared. The effect of preparation conditions such as ratio of functional monomer to cross-linker, content of porogenic solvent on the extraction efficiencies were investigated in detailed. The monolithic material was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to investigate the extraction capacity of the new coating for inorganic anion, the new SBSE was combined with ionic chromatography with conductivity detection, Br⁻, NO₃⁻, PO₄³⁻ and SO₄²⁻ were selected as detected solutes. Several extractive parameters, including pH value and ionic strength in sample matrix, desorption solvent, extraction and desorption time were optimized. The results showed that strongly ionic strength did not favor the extraction of anlaytes. Under the optimum experimental conditions, low detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target anions were achieved within the range of 0.92–2.62 and 3.03–9.25 μg/L, respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction inorganic anions. Finally, the proposed method was successfully used to detect the two different trademarks of commercial purified water with satisfactory recovery in the range of 70.0–92.6%. To the best of our knowledge, this is the first to use SBSE to enrich inorganic anions.     

Ultra-sensitive determination of cyanide in surface water by gas chromatography–tandem mass spectrometry after derivatization with 2-(dimethylamino)ethanethiol

A gas chromatography–tandem mass spectrometric (GC–MS/MS) method has been established for the determination of cyanide in surface water. This method is based on the derivatization of cyanide with 2-(dimethylamino)ethanethiol in surface water. The following optimum reaction conditions were established: reagent dosage, 0.7 g L⁻¹ of 2-(dimethylamino)ethanethiol; pH 6; reaction carried out for 20 min at 60 °C. The organic derivative was extracted with 3 mL of ethyl acetate, and then measured by using GC–MS/MS. Under the established conditions, the detection and quantification limits were 0.02 μg L⁻¹ and 0.07 μg L⁻¹ in 10-mL of surface water, respectively. The calibration curve had a linear relationship relationship with y = 0.7140x + 0.1997 and r² = 0.9963 (for a working range of 0.07–10 μg L⁻¹) and the accuracy was in a range of 98–102%; the precision of the assay was less than 7% in surface water. The common ions Cl⁻, F⁻, Br⁻, NO₃⁻, SO₄²⁻, PO₄³⁻, K⁺, Na⁺, NH₄⁺, Ca²⁺, Mg²⁺, Ba²⁺, Mn⁴⁺, Mn²⁺, Fe³⁺, Fe²⁺ and sea water did not interfere in cyanide detection, even when present in 1000-fold excess over the species. Cyanide was detected in a concentration range of 0.07–0.11 μg L⁻¹ in 6 of 10 surface water samples.     

Sensitive and robotic determination of bromate in sea water and drinking deep-sea water by headspace solid-phase micro extraction and gas chromatography–mass spectrometry

A robotic method has been established for the determination of bromate in sea water and drinking deep-sea water. Bromate in water was converted into volatile derivative, which was measured with headspace solid-phase micro extraction and gas chromatography–mass spectrometry (HS-SPME GC–MS). Derivatization reagent and the HS-SPME parameters (selection of fibre, extraction/derivatization temperature, heating time and; the morality of HCl) were optimized and selected. Under the established conditions, the detection and the quantification limits were 0.016 μg L⁻¹ and 0.051 μg L⁻¹, respectively, and the intra- and inter-day relative standard deviation was less than 7% at concentrations of 1.0 and 10.0 μg L⁻¹. The calibration curve showed good linearity with r² = 0.9998. The common ions Cl⁻, NO₃⁻, SO₄²⁻, HPO₄²⁻, H₂PO₄⁻, K⁺, Na⁺, NH₄⁺, Ca²⁺, Mg²⁺, Ba²⁺, Mn⁴⁺, Mn²⁺, Fe³⁺ and Fe²⁺ did not interfere even when present in 1000-fold excess over the active species. The method was successfully applied to the determination of bromate in sea water and drinking deep-sea water.     

A new water-soluble metal-free phthalocyanine substituted with naphthoxy-4-sulfonic acid sodium salt. Synthesis,aggregation, electrochemistry and in situ spectroelectrochemistry

A new water-soluble metal-free phthalocyanine, 2,9,16,23-tetrakis(4-(1-naphthoxy-4-sulfonic acid sodium salt))phthalocyanine NhtH₂Pc, where Nht indicates naphthoxy-4-sulfonic acid sodium salt, was synthesized and its aggregation, electrochemical and spectroelectrochemical properties were investigated in non-aqueous solutions. The aggregation study of NhtH₂Pc showed that NhtH₂Pc had both aggregated and non-aggregated mono phthalocyanine forms in the case of the 1:1 ratio of methanol and water, while it exhibited only the characteristic UV–Vis absorption of monomeric phthalocyanine in methanol and DMSO. NhtH₂Pc displayed three reversible one-electron reductions waves, assigned to Pc³⁻/Pc²⁻, Pc⁴⁻/Pc³⁻ and Pc⁵⁻/Pc⁴⁻ couples, respectively. The electrochemical half-wave potentials of the reduction processes were located at E_1/2 = −0.510, −0.924 and −1.24 V, respectively while the anodic potential of the oxidation process was displayed at E_1/2 = 0.590 V versus pseudo Ag/AgCl. The half-wave potentials of the first and second reductions were positively shifted by 0.150 and 0.136 V compared with those of the unsubstituted metal-free phthalocyanine (H₂Pc). These shift values are almost the same as those observed for [(SO₃)₄H₂Pc]. The electrochemical studies showed that the electron-withdrawing sulfonated-naphthoxy groups on the macrocycle core made the reduction processes of NhtH₂Pc easier in DMSO solution. The well-defined UV–Vis spectra of the electro-reduced species [NhtH₂Pc]⁻ were obtained with an applied potential (E_app = −0.70 V) in a thin-layer cell. The spectroelectrochemical results showed that the first reduction product exhibited characteristic spectral changes corresponding to mono-anionic species of metal-free phthalocyanines, having long-term stability during the reduction process.     

Ultra-sensitive quantification of lysozyme based on element chelate labeling and capillary electrophoresis–inductively coupled plasma mass spectrometry

In this study, an ultra-sensitive method for the quantification of lysozyme based on the Gd³⁺ diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid labeling and capillary electrophoresis–inductively coupled plasma mass spectrometry (CE–ICP–MS) was described. The Gd³⁺-tagged lysozyme was effectively separated by capillary electrophoresis (CE) and sensitively determined by inductively coupled plasma mass spectrometry (ICP–MS). Based on the gadolinium-tagging and CE–ICP–MS, the lysozyme was determined within 12 min with an extremely low detection limit of 3.89 attomole (3.89 × 10⁻¹¹ mol L⁻¹ for 100 nL of sample injection) and a RSD < 6% (n = 5). The proposed method has been successfully used to detect lysozyme in saliva samples with a recovery of 91–106%, suggesting that our method is sensitive and reliable. The success of the present method provides a new potential for the biological assays and sensitive detection of low-abundant proteins.     

Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100–200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography–mass spectrometry (GC–MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2–10 ng L⁻¹. The relative standard deviations (RSD) (n = 3) at the concentration level of 1.7–6.7 ng mL⁻¹ were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27–1330 ng L⁻¹ for phenol and monochlorophenols and 7–1000 ng L⁻¹ for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.     

Determination of mercury species by the diffusive gradient in thin film technique and liquid chromatography – atomic fluorescence spectrometry after microwave extraction

A diffusive gradient in thin films technique (DGT) was combined with liquid chromatography (LC) and cold vapor atomic fluorescence spectrometry (CV-AFS) for the simultaneous quantification of four mercury species (Hg²⁺, CH₃Hg⁺, C₂H₅Hg⁺, and C₆H₅Hg⁺). After diffusion through an agarose diffusive layer, the mercury species were accumulated in resin gels containing thiol-functionalized ion-exchange resins (Duolite GT73, and Ambersep GT74). A microwave-assisted extraction (MAE) in the presence of 6 M HCl and 5 M HCl (55 °C, 15 min) was used for isolation of mercury species from Ambersep and Duolite resin gels, respectively. The extraction efficiency was higher than 95.0% (RSD 3.5%). The mercury species were separated with a mobile phase containing 6.2% methanol + 0.05% 2-mercaptoethanol + 0.02 M ammonium acetate with a stepwise increase of methanol content up to 80% in the 16th min on a Zorbax C18 reverse phase column. The LODs of DGT–MAE–LC–CV-AFS method were 38 ng L⁻¹ for CH₃Hg⁺, 13 ng L⁻¹ for Hg²⁺, 34 ng L⁻¹ for C₂H₅Hg⁺ and 30 ng L⁻¹ for C₆H₅Hg⁺ for 24 h DGT accumulation at 25 °C.     

Spectroscopic and structural characterization of Na2[(VO)2(ttha)]·8H2O (ttha = triethylenetetraamine-N,N,N′,N″,N′″,N′″-hexaacetate): Interpreting the results with density functional theory

Na₂[(V^IVO)₂(ttha)]·8 H₂O (ttha = triethylenetetraamine–N,N,N′,N″,N′″,N′″–hexaacetate ion), prepared by treating [VO(H₂O)₅][(VO)₂(ttha)]·4 H₂O with Na₆(ttha), has been characterized by single crystal X-ray diffraction, infrared spectroscopy, UV–Vis absorption spectroscopy, electron spin resonance spectroscopy, and modeled by density functional theory (DFT). The X-ray structure revealed a distorted octahedral geometry around each vanadium center. The electronic absorption spectrum of [(VO)₂(ttha)]²⁻ (aq) features absorptions at ca. 200 nm (ε > 13900 L mol⁻¹ cm⁻¹), 255 nm (ε = 3480 L mol⁻¹ cm⁻¹), 586 nm (ε = 33 L mol⁻¹ cm⁻¹), and 770 nm (ε = 38 L mol⁻¹ cm⁻¹). The time-dependent density functional theory (TDDFT) calculated electronic absorption spectrum was remarkably similar to the actual spectrum, and TDDFT predicts absorption peaks at 297, 330, 458, 656, and 798 nm. TDDFT assigned the peak at 798 nm to be the α spin HOMO → LUMO transition. Hence, the peak at 770 nm in the actual spectrum is most likely the α spin HOMO → LUMO transition. Moreover, the TDDFT calculations revealed that the α spin HOMO and LUMO are partly comprised of d orbitals on both vanadium centers, and the first derivative electron spin resonance spectrum also suggests that the two unpaired electrons in [(VO)₂(ttha)]²⁻ are localized near the vanadium centers.     

Resistivity–viscosity relationship in liquid–liquid critical mixtures with added ions

Precise resistivity ρ (Ω cm) and viscosity η (10⁻² P) measurements for isobutyric acid–water (IBAW) critical mixtures with added K⁺ and Cl⁻ ions have been performed in the Arrhenius temperature domain of the electrolyte. From the activation energy, the resistivity–viscosity relation reveals a fraction power character over the whole range of parameters investigated. To analyze our data we have used an exponential formula derived from the equivalent Arrhenius law: ρ/T is proportional to (η/T)^R, where R = E_ρ/E_η is the ratio between the resistivity and viscosity activation energies. In the case of the pure system (IBAW), the value of R is in vicinity of 1, but when the salt is added, the ratio R shows dependence on the (K⁺, Cl⁻) concentrations: 0.6 < R < 1. The domain of the validity of R is in conformity with the theoretical prediction. The Coulombic interaction is the origin of the deviation.     

A novel sorptive extraction method based on polydimethylsiloxane frit for determination of lung cancer biomarkers in human serum

In this study, a porous polypropylene frit was coated with polydimethylsiloxane (PDMS) as extraction medium, based on the home-made PDMS-frit, a rapid, simple and sensitive sorptive extraction method was established for analysis of potential biomarkers of lung cancer (hexanal and heptanal) in human serum samples. In the method, derivatization and extraction occurred simultaneously on the PDMS-frit, then the loaded frit was ultrasonically desorbed in acetonitrile. Polymerization, derivatization–extraction and desorption conditions were optimized. Under the optimal conditions, satisfactory results were gained, a wide linear application range was obtained in the range of 0.002–5.0 μmol L⁻¹ (R > 0.997) for two aldehydes, the detection limits (S N⁻¹ = 3) were 0.5 nmol L⁻¹ for hexanal and 0.4 nmol L⁻¹ for heptanal. The relative standard deviations (RSDs, n = 5) of the method were below 7.9% and the recoveries were above 72.7% for the spiked serum. All these results hint that the proposed method is potential for disease markers analysis in complex biological samples.     

Thermal properties of N-alkyl-N-methylpyrrolidinium and N-butylpyridinium fluorometallates and physicochemical properties of their melts

A series of N-alkyl-N-methylpyrrolidinium (RMPyr⁺, where R = E: ethyl, B: butyl, and H: hexyl) and N-butylpyridinium (BPy⁺) salts based on the fluorocomplex anions, BF₄⁻, PF₆⁻, SbF₆⁻, NbF₆⁻, TaF₆⁻, and WF₇⁻, have been synthesized and their thermal behavior has been investigated. The melting points of the RMPyr⁺ salts are above room temperature with the trend; BMPyrAF₆ < HMPyrAF₆ < EMPyrAF₆ for the hexafluorocomplex salts. Some of the salts containing BMPyr⁺ and HMPyr⁺ exhibit phase transitions in the solid states. Similar melting points of BPy⁺ salts of PF₆⁻, SbF₆⁻, NbF₆⁻, TaF₆⁻, and WF₇⁻ are observed at around 350 K. Ionic conductivity and viscosity for BMPyrNbF₆ (3.0 mS cm⁻¹ and 164 cP at 328 K) are similar to those for BMPyrTaF₆ (3.0 mS cm⁻¹ and 165 cP at 328 K), resulting from the similarity of the anions in size. The activation energies of ionic conductivity for the NbF₆⁻ and TaF₆⁻ salts are 18 and 20 kJ mol⁻¹, and those for viscosity are 23 and 25 kJ mol⁻¹, respectively calculated by Arrhenius equation in the temperature range between 328 and 348 K. Electrochemical windows of BMPyrNbF₆, BMPyrTaF₆, and BMPyrWF₇ are about 4.0, 5.0 and 3.1 V, respectively.     

Supramolecular solvent-based hollow fiber liquid phase microextraction of benzodiazepines

A new, efficient, and environmental friendly hollow fiber liquid phase microextraction (HF-LPME) method based on supramolecular solvents was developed for extraction of five benzodiazepine drugs. The supramolecular solvent was produced from coacervation of decanoic acid aqueous vesicles in the presence of tetrabutylammonium (Bu₄N⁺). In this work, benzodiazepines were extracted from aqueous samples into a supramolecular solvent impregnated in the wall pores and also filled inside the porous polypropylene hollow fiber membrane. The driving forces for the extraction were hydrophobic, hydrogen bonding, and π-cation interactions between the analytes and the vesicular aggregates. High-performance liquid chromatography with photodiode array detection (HPLC-DAD) was applied for separation and determination of the drugs. Several parameters affecting the extraction efficiency including pH, hollow fiber length, ionic strength, stirring rate, and extraction time were investigated and optimized. Under the optimal conditions, the preconcentration factors were obtained in the range of 112–198. Linearity of the method was determined to be in the range of 1.0–200.0 μg L⁻¹ for diazepam and 2.0–200.0 μg L⁻¹ for other analytes with coefficient of determination (R²) ranging from 0.9954 to 0.9993. The limits of detection for the target benzodiazepines were in the range of 0.5–0.7 μg L⁻¹. The method was successfully applied for extraction and determination of the drugs in water, fruit juice, plasma and urine samples and relative recoveries of the compounds studied were in the range of 90.0–98.8%.     

An acyclic,dansyl based colorimetric and fluorescent chemosensor for Hg(II) via twisted intramolecular charge transfer (TICT)

An efficient fluorescent chemosensor for Hg²⁺ ion, based on 5-(dimethylamino)-N-(2-mercaptophenyl)naphthalene-1-sulfonamide, has been developed. It exhibits Hg²⁺-selective on–off fluorescence quenching behavior via twisted intramolecular charge transfer (TICT) mechanism, which is rationalized by time dependent density functional theory (TD-DFT) calculations. The system exhibits visible color change from colorless to gray upon Hg²⁺ binding with very high selectivity and sensitivity (as low as 5.0 × 10⁻¹⁰ mol L⁻¹) over other metal ions such as K⁺, Na⁺, Ag⁺, Mn²⁺, Ca²⁺, Ba²⁺, Fe²⁺, Zn²⁺, Pb²⁺, Cu²⁺, Sn²⁺, Cd²⁺, Ni²⁺ and Co²⁺. The present sensing system is also successfully applied for the detection of Hg²⁺ ion in real samples.     

A method for rapid screening of interactions of pharmacologically active compounds with albumin

We determine the association constants for ligand–protein complex formation using the flow injection method. We carry out the measurements at high flow rates (F = 1 mL min⁻¹) of a carrier phase. Therefore, determination of the association constant takes only a few minutes. Injection of 1 nM of the ligand (10 μL of 1 μM concentration of the ligand solution) is sufficient for a single measurement. This method is tested and verified for a number of complexes of selected drugs (cefaclor, etodolac, sulindac) with albumin (BSA). We obtain K = 4.45 × 10³ M⁻¹ for cefaclor, K = 1.00 × 10⁵ M⁻¹ for etodolac and K = 1.03 × 10⁵ M⁻¹ for sulindac in agreement with the literature data. We also determine the association constants of 20 newly synthesized 3β- and 3α-aminotropane derivatives with potential antipsychotic activity – ligands of 5-HT_1A, 5-HT_2A and D₂ receptors with the albumin. Results of the studies reported here indicate that potential antipsychotic drugs bind weakly to the transporter protein (BSA) with K ≈ 10²–10³ M⁻¹. Our method allows measuring K in a wide range of values (10²–10⁹ M⁻¹). This range depends only on the solubility of the ligand and sensitivity of the detector.