Dr Paulson Mathewhttp://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/342026-04-20T13:52:01Z2026-04-20T13:52:01ZSynthesis of silver and copper oxide nanoparticles using Myristica fragrans fruit extract: Antimicrobial and catalytic applicationsSasidharan, DrishyaNamitha, T.R.Johnson, Smera PJose, VimalaMathew, Paulsonhttp://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/3722025-01-15T09:43:30Z2020-06-01T00:00:00ZSynthesis of silver and copper oxide nanoparticles using Myristica fragrans fruit extract: Antimicrobial and catalytic applications
Sasidharan, Drishya; Namitha, T.R.; Johnson, Smera P; Jose, Vimala; Mathew, Paulson
The pericarp of Myristica fragrans fruit extract was utilized for a low cost, eco-friendly synthesis of silver (AgNPs) and copper oxide (CuONPs) nanoparticles. The aqueous fruit extract of the plant was used as reducing and stabilizing agents for this preparation. Characterization of the biosynthesized nanoparticles was carried out using UV–Vis spectroscopy, FTIR spectroscopy and X-Ray Diffraction studies. Morphology and size of the particles was observed using Field-Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopy (HRTEM). The copper and silver nanoparticles show Surface Plasmon Resonance (SPR) band at 360 and 478 nm respectively in the UV–Vis spectrum. It was observed that size of the synthesized copper oxide and silver nanoparticles are in the range 10–50 nm. The presence of copper and silver elements was confirmed from their respective EDS spectrum. Involvement of phytochemicals in the stabilization and reduction of the nanoparticles was confirmed by FTIR spectroscopy. CuONPs exhibited catalytic activity in 1,3-dipolar cycloaddition reaction between azides and terminal alkynes to form 1,2,3-triazoles. Silver nanoparticle possesses good antibacterial activity against multidrug human pathogens Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis. The present study focuses on the utilization of the less economic part of Myristica fragrans fruit's pericarp for the preparation of copper oxide and silver nanoparticles which have good catalytic and antibacterial activities.
2020-06-01T00:00:00ZSynthesis, Z-Scan and Degenerate Four Wave Mixing characterization of certain novel thiocoumarin derivatives for third order nonlinear optical applicationsJayakrishnan, KJoseph, AntonyMathew, PaulsonSiji, TBChandrasekharan, KNarendran, N K SijiJaseela, MAMuraleedharan, Khttp://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/1882022-03-03T11:06:53Z2016-08-01T00:00:00ZSynthesis, Z-Scan and Degenerate Four Wave Mixing characterization of certain novel thiocoumarin derivatives for third order nonlinear optical applications
Jayakrishnan, K; Joseph, Antony; Mathew, Paulson; Siji, TB; Chandrasekharan, K; Narendran, N K Siji; Jaseela, MA; Muraleedharan, K
The third order nonlinear optical features of certain novel thiocoumarin derivatives have been studied. Single beam Z-scan study on these compounds reveals that the compounds exhibit self defocusing effect upon irradiation with 532 nm, 7 ns pulses of Nd:YAG laser. Nonlinear absorption coefficient, nonlinear refractive index and second order molecular hyperpolarizability values were estimated. The optical power limiting properties of the compounds are found to be attributable to both two-photon and excited state absorption. Some of the samples show nonlinear absorption coefficient (βeff) as high as 24.5 cm/GW. UV–Visible and photoluminescence outputs of these compounds reveal remarkable absorptive and emissive properties. This article also reports extraordinary growth of third order optical nonlinearity in pure coumarin upon certain donor substitutions in lieu of hydrogen. Degenerate Four Wave Mixing (DFWM) signals of the compounds were analyzed to verify the Z-scan results. Electrostatic Surface Potential (ESP) mapping and structure optimization techniques have been employed to interpret the structure-property relationship of each molecule.
2016-08-01T00:00:00ZAn efficient synthesis of highly substituted pyrroles from β-oxodithiocarboxylatesMathew, PaulsonAsokan, CVhttp://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/1652022-03-02T06:08:43Z2006-02-20T00:00:00ZAn efficient synthesis of highly substituted pyrroles from β-oxodithiocarboxylates
Mathew, Paulson; Asokan, CV
α-Oxoketene-N,S-acetals, prepared by the reaction of alkyl glycinate hydrochlorides with β-oxodithiocarboxylates followed by alkylation, underwent cyclization in presence of chloromethyleneiminium salt derived from POCl3/DMF to afford alkyl-3-aryl-4-formyl-5 (alkylsulfanyl)-1H-pyrrole-2-carboxylates in excellent yields. Alkyl-3-aryl 5(alkylsulfanyl)-1H-pyrrole-2-carboxylates were formed in moderate yields when the same N,S-acetals were treated with DBU.
2006-02-20T00:00:00ZCyclization of functionalized ketene-N,S-acetals to substituted pyrroles: applications in the synthesis of marine pyrrole alkaloidsMathew, PaulsonAsokan, CVhttp://starc.stthomas.ac.in:8080/xmlui/xmlui/handle/123456789/1622022-03-02T05:23:00Z2005-01-17T00:00:00ZCyclization of functionalized ketene-N,S-acetals to substituted pyrroles: applications in the synthesis of marine pyrrole alkaloids
Mathew, Paulson; Asokan, CV
α-Oxoketene-N,S-acetals, prepared by the reaction of alkyl glycinates with β oxodithiocarboxylates followed by alkylation, underwent cyclization in the presence of the Vilsmeier reagent to afford alkyl 3-aryl-4-formyl-5-(alkylsulfanyl)-1H-pyrrole-2 carboxylates in excellent yields. When the reaction was extended to β oxodithiocarboxylates derived from deoxyanisoin, 3,4-diarylpyrrole-2-carboxylates, the key intermediates in the synthesis of lukianol A and lamellarin Q were formed.
2005-01-17T00:00:00Z