Rapid, Sensitive, and Selective "ON-OFF" Detection of Fe3+ Ions Using Novel Acetalophanes and Their Applications in Real Samples.

Three novel acetalophanes 1a-c have been designed, synthesized and characterized. The receptors 1b-c, featuring bulky anthracene groups, displayed significant selectivity for Fe3+ ions, resulting in a turn-off fluorescence mode in a DMF-buffer solution. Conversely, the non-steric probe 1a could serve as a versatile sensor for the simultaneous detection of Fe3+ and Cu2+ ions in MeOH-buffer solution. The sensing mechanism for the capability of 1a was demonstrated to be different, as evidenced by the addition of cyanide ions. The probes with Fe3+ exhibited a sensing mechanism that resulted in the deprotection of acetals to the corresponding starting materials, as confirmed by 1H NMR, IR spectra and TLC analysis. The attractive features of these practical and efficient sensors are selectivity, sensitivity (limit of detection = 0.15 µM by 1a, 0.16 µM by 1b and 0.14 µM by 1c), rapid response (less than 5 s). The on-site monitoring of various real samples, including well water, apricot, and green tea, proved to be successful for the quantitative and cost-effective detection of Fe3+. The method demonstrated good precision, even in the presence of other interfering materials.

Fast, Selective and Sensitive Fluorescence Detection of Levofloxacin, Fe3+ and Cu2+ Ions in 100% Aqueous Solution Via Their Reciprocal Recognition.

The fluorescence detection of ions and pharmaceutical effluents by using organic chemosensors is a valuable surrogate to the currently existing expensive analytical methods. In this regard, the design of multi-functional chemosensors to recognize desirable guests is of utmost importance. In this study, we first show that levofloxacin (LVO) is able to use as a fluorescent chemosensor for the detection of biologically important Cu2+ (turn-off) and Fe3+ (turn-on) ions via independent signal outputs in 100% aqueous buffer solutions. Next, using the reciprocal recognition of LVO and Fe3+ provides a unique emission pattern for the detection of LVO. This approach exhibited a high specificity to LVO among various pharmaceutical samples, namely acetaminophen (AC), azithromycin (AZ), gemifloxacin (GEM) and ciprofloxacin (CIP) and also showed great anti-interference property in urine. The attractive features of this sensing system are availability, easy-to-use, high sensitivity (limit of detection = 18 nM for Cu2+, 22 nM for Fe3+ and 0.12 nM for LVO), rapid response (5 s) with an excellent selectivity. Levofloxacin (LVO) is able to use as a fluorescent chemosensor for the detection of Cu2+ (turn-off) and Fe3+ (turn-on) ions via independent signal outputs. Moreover, using the reciprocal recognition of LVO and Fe3+ a unique emission pattern for the detection of LVO was achieved which is applicable for biological samples. The attractive features of this sensing system are availability, easy-to-use, high sensitivity, rapid response (5 s) with an excellent selectivity.

Highly Selective and Sensitive Colorimetric and Fluorescent Chemosensors for Rapid Detection of Cyanide Anions in Aqueous Medium: Investigation on Supramolecular Recognition of Tweezer­shaped Salophenes.

Three tweezer­shaped salophenes having catechols (1), phenols (2) and anisoles (3) units in conjunction to the dipodal Schiff bases have been applied for the optical sensing of cyanide (CN¯) ions in CH3CN-H2O (7:3) as solvent of choice. Among them, compounds 1 and 2 recognized CN¯, relying on distinct color and spectral changes. They are easy-to-use probes that exhibit extremely high sensitivity (limit of detection = 1-10 nM), rapid response (5 s) and excellent selectivity. Moreover, the visual detection and concentration determination of CN¯ by solution test kits of both sensors are the advantages for the practical applications. Based on the fluorescence and NMR spectroscopy, as well as the OH¯ and reversibility experiments, the explicit effect of hydroxyl groups on sensing and as well the different recognition of 1 and 2 toward CN¯ ions was proved. While probe 1 senses CN¯ via deprotonation, probe 2 recognizes it through an intramolecular aldimine condensation cyclization, leading to formation of anions of dihydroxyquinoxaline 4. This chemodosimetry is being reported for the first time in a Schiff's base. Furthermore, the similarity of fluorescence and NMR responses of 2 and 4 toward CN¯ supports the proposed process.

A highly sensitive "ON-OFF" optical sensor for the selective detection of cyanide ions in 100% aqueous solutions based on hydrogen bonding and water assisted aggregation induced emission.

Nanoparticles N,N'-(pyridine-2,6-diyl)bis(2-(2,4-dichlorophenoxy)acetamide) (1) exhibited an "on-off" emission response toward cyanide (CN-) ions in 100% aqueous solutions based on AIE features. AIEgen 1 is an easy-to-use probe that exhibits rapid response (5 s), extremely high sensitivity (limit of detection = 8.2 nM) and excellent selectivity. The sensing performance of CN- through a test kit and bitter seed solutions was good. The experimental results show that compound 1 is planar and can self-assemble into a supramolecular system and show blue emission. Then, CN- destroys both hydrogen bonds and the aggregates of 1 and quenches the emission. This process is reversible upon the addition of HCl solution.

A new chromogenic and fluorescent chemosensor based on a naphthol-bisthiazolopyridine hybrid: a fast response and selective detection of multiple targets, silver, cyanide, sulfide, and hydrogen sulfide ions and gaseous H2S.

A novel chemosensor 1 based on a naphthol-bisthiazolopyridine hybrid was synthesized and characterized. Among the various screened cations and anions, chemosensor 1 selectively recognized Ag+ and CN- ions by relying on the color change and distinct absorption and emission changes. Moreover, the probe 1·Ag+ was well operable for the selective monitoring of S2-, HS- and H2S as evidenced by the different color and optical changes. The selective detection of all the anions was simply based on the breakage of the intramolecular hydrogen bonding of 1, followed by the protonation or deprotonation mechanism. In general, chemosensor 1 is a promising indicator in terms of its ease-of-use, selectivity, sensitivity, and rapid response (<1 s). Moreover, the visual detection and concentration determination of these analytes by solution or solid kits are the advantages for the practical applications of this sensor.

N-Functionalized L-proline anchored MCM-41: a novel organic-inorganic hybrid material for solvent-free aminolysis of styrene oxide under microwave irradiation.

A novel organic-inorganic hybrid material, namely L-prol-N-pMCM-41, was synthesized via two steps by covalently anchoring N-functionalized proline derivative (L-prol-N-pTMS) into the pore channels of MCM-41 silica. The prepared material was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), nitrogen adsorption-desorption isotherm, Brunauer-Emmett-Teller (BET) surface area analysis, and Fourier Transform Infrared spectroscopy (FTIR). The immobilized catalyst demonstrated moderate to high catalytic activity and excellent regioselectivity for the ring opening of styrene oxide with aniline derivatives under microwave irradiation and solvent-free conditions. The catalyst could be rapidly separated from the reaction mixture and reused up to five runs with good conversion and high regioselectivity.

Piperazine and its carboxylic acid derivatives-functionalized mesoporous silica as nanocarriers for gemcitabine: adsorption and release study.

Piperazine-functionalized SBA-15 nanorods were synthesized by post grafting method with methyldimethoxysilylpropylpiperazine (MDSP). The carboxylic acid derivatives of piperazine-functionalized SBA-15 nanorods were obtained using two different kinds of precursors (bromoacetic acid and succinic anhydride). The prepared materials were used as nanocarriers for the anticancer drug (gemcitabine). The obtained samples were characterized by SAXS, N2 adsorption-desorption, SEM, TEM, DLS, thermogravimetric analysis, FTIR, Raman and UV spectroscopies. The adsorption and release properties of all samples were investigated. In vitro study included cell toxicity. It was found that the surface functionalization increases the interaction between the carrier and gemcitabine and results in the loading enhancement of the drug. In addition, the adsorption of gemcitabine on the modified mesoporous matrix depends on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 36wt.% that it is related to PC2-SBA-15 sample which obtained using succinic anhydride. The obtained results reveal that the surface functionalization leads toward a significant decrease of the drug release rate without any appreciable cytotoxicity. No significant differences are observed among the drug release rate from the modified samples.

A bioactive foamed emulsion reactor for the treatment of benzene-contaminated air stream.

An adapted bioactive foamed emulsion bioreactor for the treatment of benzene vapor has been developed. In this reactor, bed clogging was resolved by bioactive foam as a substitute of packing bed for interfacial contact of liquid to gaseous phase. The pollutant solubility has been increased using biocompatible organic phase in liquid phase and this reactor can be applied for higher inlet benzene concentration. Experimental results showed a benzene elimination capacity (EC) of 220 g m(-3) h(-1) with removal efficiency (RE) of 85% for benzene inlet concentration of 1-1.2 g m(-3) at 15 s gas residence time in bioreactor. Assessment of benzene concentration in liquid phase showed that a significant amount of transferred benzene mass has been biodegraded. By optimizing the operational parameters of bioreactor, continuous operation of bioreactor with high EC and RE was demonstrated. With respect to the results, this reactor has the potential to be applied instead of biofilter and biotrickling filters.

A facile synthesis of novel pyrrolizidines under classical and ultrasonic conditions.

Novel pyrrolizidines (1) were synthesized from 1,3-dipolar cycloaddition of azomethine ylides and dipolarophiles (4). The reactions were highly diastereoselective and regioselective and were carried out under reflux and ultrasonic condition at room temperature. In general, milder conditions and moderate improvements in rates and reaction times were observed when ultrasonic condition was used. The products were obtained in high yields, and their structures were determined by (1)H and (13)C NMR spectral data and X-ray diffraction.

A structure-activity relationship study on a natural germination inhibitor, 2-methoxy-4-vinylphenol (MVP), in wheat seeds to evaluate its mode of action.

The first aim of the present study was to evaluate which structural elements of the 2-methoxy-4-vinylphenol (MVP) molecule (1) are responsible for its observed activity as germination inhibitor in wheat seeds. To find its mode of action, a series of compounds with varying functional moieties and substitution patterns were prepared and evaluated for their inhibitory activity. This systematic competitive inhibition study characterized two criteria for the effective increase of the inhibiting ability: (i) ortho substitution to each of the hydroxy and methoxy groups; (ii) alkene moiety on the ring. Understanding how the structure of natural compounds relates to their inhibition function is fundamentally important and may help to facilitate their application as novel inhibitors to restrain preharvest sprouting (PHS) in wheat fields. In this regard, in MVP and its natural analogues 8 and 9 as the most active inhibitors, the ortho substitution of hydroxy and methoxy groups plays a key role in their activity and, as well, the alkene moiety influences the activity significantly.