Removal of trihalomethane from chlorinated seawater using gamma radiation.

Chlorine addition as a biocide in seawater results in the formation of chlorination by-products such as trihalomethanes (THMs). Removal of THMs is of importance as they are potential mutagenic and carcinogenic agents. In this context, a study was conducted that used ionizing radiation to remove THMs from chlorinated (1, 3, and 5 mg/L) seawater by applying various dosages (0.4-5.0 kGy) of gamma radiation. Bromoform (BF) showed a faster rate of degradation as compared to other halocarbons such as bromodichloromethane (BDCM) and dibromochloromethane (DBCM). In chlorine-dosed seawater, total irradiation dose of 0.4 to 5 kGy caused percentage reduction in the range of 6.9 to 76.7%, 2.3 to 99.6%, and 45.7 to 98.3% for BDCM, DBCM, and BF, respectively. During the irradiation process, pH of the chlorinated seawater decreased with increase in the absorbed dose; however, no change in total organic carbon (TOC) was observed. The results show that gamma dose of 2.5 kGy was adequate for maximum degradation of THM; but for complete mineralization, higher dose would be required.

Spectral investigation and characterization of host-guest inclusion complex of 4,4'-methylene-bis(2-chloroaniline) with beta-cyclodextrin.

The host-guest inclusion complex of 4,4'-methylene-bis(2-chloroaniline) (MBCA) with beta-cyclodextrin (ß-CD) was prepared by co-precipitation method and characterized using absorption, fluorescence, fourier transform infrared, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy and X-ray diffraction. The spectral shifts revealed that the aniline ring of 4,4'-methylene-bis(2-chloroaniline) was entrapped in the beta-cyclodextrin cavity. Nano second time resolved fluorescence studies revealed that 4,4'-methylene-bis(2-chloroaniline) exhibits single exponential decay in aqueous medium and bi-exponential in beta-cyclodextrin medium confirmed the formation of 1:1 inclusion complex. The Gibbs free energy change of the complexation process was determined and the complexation process was spontaneous. The differential scanning calorimetry analysis showed that the thermal stability of 4,4'-methylene-bis(2-chloroaniline) was altered in the presence of beta-cyclodextrin. The implementation of molecular docking test confirmed that the complexation could reduce the energy of the system. A mechanism was proposed to explain the mode of inclusion in the inclusion process.

Discovery of novel 1,4-dihydropyridine-based PDE4 inhibitors.

Substituted 1,4-dihydropyridines were discovered as a novel and potent series of phosphodiesterase 4 (PDE4) inhibitors. Structure-activity relationships within this series have been carried out and studies revealed that the dihydropyridine core, with indole moiety and 3,4-dimethoxybenzyl group, is a potent analogue for PDE4 inhibition. These novel series of compounds were prepared via a 3-component reaction in a single pot. In vitro biological activity, modeling studies and crystallography data are also reported.

An integrated laser Raman optical sensor for fast detection of nitrogen and oxygen in a cryogenic mixture.

An integrated fiber optic Raman sensor was designed for real-time, nonintrusive detection of liquid nitrogen (LN(2)) in liquid oxygen (LO(2)) at high pressures and high flow rates. This was intended to monitor the quality of LO(2) in oxidizer feed lines during the ground testing of rocket engines. Various issues related to optical diagnosis of cryogenic fluids (LN(2)/LO(2)) in supercritical environment of rocket engine test facility, such as fluorescence from impurity in optical window of feed line, signal-noise ratio, and fast data acquisition time, etc., are well addressed. The integrated sensor employed a frequency doubled 532-nm continuous wave Nd:YAG laser as an excitation light source. The other optical components included were InPhotonics Raman probes, spectrometers, and photomultiplier tubes (PMTs). The spectrometer was used to collect the Raman spectrum of LN(2) and LO(2). The PMT detection unit was integrated with home-built LABVIEW software for fast monitoring of concentration ratios LN(2) and LO(2). Prior to designing an integrated sensor system, its optical components were also tested with gaseous nitrogen (GN(2)) and oxygen (GO(2)).

Sequential coupling/desilylation-coupling/cyclization in a single pot under Pd/C-Cu catalysis: synthesis of 2-(hetero)aryl indoles.

A new one-pot synthesis of 2-(hetero)aryl indoles via sequential C-C coupling followed by C-Si bond cleavage and a subsequent tandem C-C/C-N bond forming reaction is described. A variety of functionalized indole derivatives were prepared by conducting this four step reaction under Pd/C-Cu catalysis. The methodology involved coupling of (trimethylsilyl)acetylene with iodoarenes in the presence of 10% Pd/C-CuI-PPh(3) and triethylamine in MeOH, followed by treating the reaction mixture with K(2)CO(3) in aqueous MeOH, and finally coupling with o-iodoanilides. The single crystal X-ray data of a synthesized indole derivative is presented. Application of the methodology, in vitro pharmacological properties of the synthesized compound, along with a docking study is described.

Discovery of indoline-based, natural-product-like compounds as probes of focal adhesion kinase signaling pathways.

With the goal of identifying small molecule modulators of protein-protein interactions, we developed a solid-phase synthesis method, which was then successfully utilized in a library generation of 164 aminoindoline-derived, natural-product-like compounds. This library and several other related intermediates synthesized during this project were then subjected to different biological assays in search of small molecule modulators of focal adhesion kinase (FAK)-mediated signaling pathways. This study included (i) an in vitro, full length FAK inhibition assay, (ii) a cell proliferation assay, and (iii) a wound healing assay. In FAK inhibition assay, eight library members (5-12) and three aminoindoline derivatives (13, 14, and 2) were identified as promising candidates. Compounds 13 and 2 inhibited the FAK activity by 25-45% at 10 microM. These two lead compounds also showed activity in a wound healing assay. To our knowledge, these aminoindoline-derived small molecules belong to a new family of FAK inhibitors.

Building skeletally diverse architectures on the Indoline Scaffold: the discovery of a chemical probe of focal adhesion kinase signaling networks.

Inspired by bioactive indoline alkaloid natural products, here, we report a divergent synthesis approach that led to skeletally diverse indoline alkaloid-inspired compounds. The natural product-inspired compounds obtained were then subjected to a series of in vitro and cellular assays to examine their properties as modulators of focal adhesion kinase (FAK) activity. This study resulted in the identification of a promising lead inhibitor of FAK (42), which also showed activity in a wound healing and cell invasion assay. The in silico study of the lead compound (42) was also undertaken.

Host-guest interaction of L-tyrosine with beta-cyclodextrin.

The inclusion complexes of beta-cyclodextrin (beta-CD) with L-tyrosine (L-TYN) were investigated by using spectrophotometers. The absorption and fluorescence enhancement occurs with beta-CD and L-TYN forms 1:1 inclusion complex. The unusual blue shift of hydroxyl ion in the beta-CD medium confirms OH groups present in the interior part of the beta-CD cavity and -COOH group present in the upper part of the beta-CD cavity. A mechanism is proposed to explain inclusion process. The inclusion interaction was examined and the thermodynamic parameters of inclusion process DeltaG, DeltaH and DeltaS were determined. The results indicated that the inclusion process was an exergonic and spontaneous process. Stable solid inclusion complexes were established and characterized by FT-IR, scanning electron microscope (SEM) methods.

Inclusion complexation and photoprototropic behaviour of 3-amino-5-nitrobenzisothiazole with beta-cyclodextrin.

The inclusion complexation and photoprototropic behaviour of 3-amino-5-nitrobenzisothiazole (ANBT) in aqueous beta-cyclodextrin (beta-CDx) solution have been investigated. Absorption and fluorescence intensities of the neutral form of ANBT are enhanced due to the formation of 1:1 complex with beta-CDx. The complex formation has been confirmed by IR spectral and SEM studies. In the presence of beta-CDx, no change was observed in the ground and excited state acidity constant values when compared with aqueous medium. Based on its inclusion complexation and photoprototropic characteristics of ANBT in beta-CDx, the structure of the 1:1 complex is proposed.

Fiber optic Raman sensor to monitor the concentration ratio of nitrogen and oxygen in a cryogenic mixture.

A spontaneous Raman scattering optical fiber sensor was developed for a specific need of the National Aeronautics and Space Administration (NASA) for long-term detection and monitoring of the purity of liquid oxygen (LO(2)) in the oxidizer feed line during ground testing of rocket engines. The Raman peak intensity ratios for liquid nitrogen (LN(2)) and LO(2) with varied weight ratios (LN(2)/LO(2)) were analyzed for their applicability to impurity sensing. The study of the sensor performance with different excitation light sources has helped to design a miniaturized, cost-effective system for this application. The optimal system response time of this miniaturized sensor for LN(2)/LO(2) measurement was found to be in the range of a few seconds. It will need to be further reduced to the millisecond range for real-time, quantitative monitoring of the quality of cryogenic fluids in a harsh environment.

Microwave-assisted sequential amide bond formation and intramolecular amidation: a rapid entry to functionalized oxindoles.

A general method has been developed for the synthesis of N-substituted oxindoles. The two-step process involves initial microwave-assisted amide bond formation between 2-halo-arylacetic acids and various alkylamines and anilines, followed by a palladium-catalyzed intramolecular amidation under aqueous conditions. In the case of alkylamines, the procedure can be carried out as a one-pot process without isolation of the intermediate amide. [structure: see text]

Efficient palladium-catalyzed cross-coupling of beta-chloroalkylidene/arylidene malonates using microwave chemistry.

A general method for the synthesis of beta-aryl/alkylarylidene malonates is reported. The key step involves the coupling of an arylboronic acid to a beta-chloroalkyl/arylidene malonate, in the presence of K2CO3 and 1 mol % of the air-stable palladium catalyst (POPd) under microwave irradiation, to afford beta-aryl/alkylarylidene malonates in good yields. The combination of mild reaction conditions, air stable catalyst, microwave-enhanced chemistry, and high levels of functional group compatibility make this an attractive synthetic approach to this class of compounds.