A novel organic-inorganic hybrid nanomaterial-based fluorescent chemosensor was synthesized by functionalizing rice husk-derived nanosilica with 3-(aminopropyl)triethoxysilane (APTES) and then grafting it with para-aminobenzoic acid, benzaldehyde, and indole organic moieties, respectively, to detect Ag+ ions in the aqueous medium. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), fluorescence spectroscopic techniques, and thermogravimetric analysis (TGA) were used to characterize the synthesized material. The synthesized ligand showed highly selective and sensitive fluorescence-enhanced, "Turn-ON" chemosensor activity towards Ag+ ions at an excitation wavelength of 355 nm, with observable variations in fluorescence intensity compared to other metal ions. The detection limit for Ag+ was 1.94 × 10–4 M, and the limit of quantification was calculated as 6.49 × 10–4 M. These findings suggest that the silica-supported indole derivative (Indole-APTES@nanosilica) can be utilized as a sensitive and selective, Turn-ON fluorometric chemosensor for detecting Ag+ ions.

The development of chemosensors has been driven by concurrently advanced research in fluorescence and colorimetric chemosensing. Over the last few decades, the development of copper ion-selective fluorogenic and chromogenic chemosensors has been extensively studied due to their high sensitivity, low cost, and simplicity. They can interact with the metal ion in a unique manner and create measurable color, fluorescence, or redox potential changes. Copper (Cu2+) ion is deemed the third most prevalent transition metal in human beings owing to its various biological and physiological processes. It has drawn a great deal of attention from many researchers in various disciplines such as biology, medicine, and environmental studies. However, an excessive buildup of copper in the body has been linked to several diseases. Thus, more recent research is being focused on developing fluorometric and colorimetric chemosensors for the selective detection of copper ions. Recently, there have been a lot of studies reported in this field of study that describe highly sensitive and sophisticated indole-based chemosensors for various metal ions of interest. In addition, indole derivatives possess inherent fluorescence properties due to their electron-rich nature caused by the π-excessive system of indole, and therefore they can be employed in chemosensors for metal ion detection. Both cations and anions employ it as a molecular recognition system. This review summarizes selective and sensitive Cu2+ ion detection accomplished byvarious indole-based chemosensors between the years 2011 to 2021. Furthermore, sensor design, sensing methods, ligand-metal binding stoichiometry, association constant, and the detection limit by the chemosensors are all summarized and explored. Keywords: Indole, Fluorescent chemosensors, Colorimetric chemosensors, Cu2+, Turn-on, Turn-off

Chitosan is a well-studied biomaterial which has been widely used for environmental applications as an efficient natural polymer for the adsorption and removal of metal ions. Owing to its unique properties, chitosan shows good metal-binding behavior toward several different metal ions such as Cu2+, Zn2+, Cd2+, Ni2+, Co2+, and Ca2+. Chemical modifications with the introduction of functional groups have been carried out extensively and thereby producing various chitosan derivatives to increase the selectivity and adsorption capacity toward metal ions. The present work focuses on two such monofunctional derivatives, namely, carboxymethyl chitosan (CMC) and ethylenediaminetetraacetic acid chitosan (EDTA-CS) which have been recognized as excellent adsorbents for metal removal. The main objective of this study was to synthesize a new bifunctional chitosan derivative, namely, ethylenediaminetetraacetic acid–carboxymethyl chitosan (EDTA-CMC) by attaching both carboxymethyl and EDTA functional groups on the polymer backbone and thereby enhancing its metal-binding properties. The bifunctional derivative synthesis was conducted by combining the procedures of synthesis of CMC and EDTA-CS. Newly synthesized EDTA-CMC derivative was characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscope analysis, and thermogravimetric analysis. Adsorption properties of EDTA-CMC were investigated with Cu2+ ions which produced an adsorption capacity of 111.90 mg g−1 for 1000.0 mg/L and 12.20 mg g−1 for 10.00 mg/L Cu2+ solutions. The preliminary results revealed that EDTA-CMC is an effective adsorbent than CMC to remove Cu2+ in aqueous samples. The effects of pH, initial concentration, and mass of the adsorbent in the adsorption process were studied. Under the optimized parameters of an adsorbent dosage of 10.00 mg and pH 5.5, a comparable maximum adsorption capacity up to 112.44 mg g−1 was achieved with a 150.00 mg/L of Cu2+ solution. Furthermore, EDTA-CMC showed good adsorption performance even after five cycles of regeneration.

Nitrocellulose with silver nanoparticle (AgNP/NC) composite was prepared in situ using Ag(CH3CO2) and nitrocellulose without any reducing agent. The composite materials synthesized were spray coated onto glass substrates to obtain thin films. The AgNPs/NC composites were characterized by ultraviolet-visible, Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The antimicrobial activity of AgNPs/NC composite was investigated by tube method and time-kill kinetic studies against three microbial species, including Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 10231). The antibiofilm activities were qualitatively determined against all three organisms. Prepared AgNPs/NC films exhibited good antimicrobial activity and significant inhibition of biofilm development against all three microbial species. The effective dispersion of AgNPs/NC in biofilm was responsible for the significant antibiofilm activity of the prepared material. The reported AgNPs/NC composite can be used as coating additive in bacteriocidal paint which can be applied onto surfaces such as in healthcare environments.

Cobalt (Co2+) is an essential constituent in the human body while excessive exposure leads to severe systemic toxic reactions which highlight the importance of developing effective methods to detect Co2+ ions. A simple and highly efficient fluorescence enhanced turn OFF-ON chemosensor was synthesized to detect the paramagnetic Co2+. The ligand, N-((1H-indol-3-yl)(phenyl)methyl)aniline (L), was synthesized in 92% yield by means of hydrated ferric chloride catalyzed one -pot multicomponent microwave irradiation in the presence of Indole, benzaldehyde, and aniline as reactants. The major green principles of waste prevention, high atom economy (94.3%), green solvent, higher energy efficiency, and catalysis were the highlights of the ligand synthesis. The ligand exhibited remarkable fluorescence enhancement with Co2+ and a turn ON ratio of over 160-fold in MeOH/H2O (at pH 3.5) solution at an excitation wavelength of 369 nm in the Ultra-Violet range. The detection limit of L- Co2+ was 2.2 μM. The excitation and the emission spectra indicated stoke’s shift of 93 nm which supports the fluorescence enhancement observed in L- Co2+ with respect to the free ligand. The Job’s plot indicated fluorometric sensing of Co2+ ascribed to the complex formation with a stoichiometric ratio of 2:1 (L- Co2+). Furthermore, the high linearity (r2 =0.992) observed in the Benesi Hildebrand plot in a wide concentration range of 0.5−80 μM confirmed the above stoichiometric ratio. The association constant (Ka) for the L-Co2+ was determined to be 8.382 ×1 04 M−1 ± 5.8 ×103M−1.The prepared Co2+ fluorometric probe indicated long-term stability in −18 ℃ up to 45 days. Furthermore, the presence of Fe2+ and Fe3+ in the medium with Co2+ exhibited an interference effect in the fluorescence intensities. Upon further concentration studies, it was evident that the interference of Fe2+ and Fe3+ starts around 10.00 μM and rises exponentially. Keywords: MCR, Green synthesis, Fluorescent Chemo-sensor, Turn OFF-ON, Cobalt (II), indole derivatives

Recently, there is an upsurging interest in textile industry towards production of antimicrobial fabrics due to their potential for reducing the transmission of infections. These products are of greater interest in sportswear industry and medical/healthcare industry due to the high moisture content that aggravate the microbial growth in sportswear and high exposure to pathogenicmicroorganisms in hospital settings. Fabric provides a hospitable growth surface to microorganisms resulting in irritation of the skin, development of body odor and finally deterioration of the fabric. The main objective of this study was to develop an antimicrobial fabric using a natural origin in a sustainable manner. Natural antimicrobial agents are important in terms of their bio-compatibility, eco-friendliness and low or zero toxicity to human body. Garcinia zeylanica which is an endemic plant to Sri Lanka and tea dust are two natural resources that can be easily found in the country. Aqueous and ethanolic crude extracts of these were characterised using UV-Vis spectra and, FTIR spectroscopic techniquesa and Total Phenolic content studies. Aqueous and ethanolic extracts of G. zeylanica showed inhibition of 120.5 mm and 140.5 mm against Escherichia coli respectively andinhibitions of 140.5 mm and 170.5 mm against Staphylococcus aureus respectively. Aqueous and ethanolic extracts of tea dust showed inhibition of 100.5 mm and 130.5 mm against S. aureus respectively. Optimisation of the dyeing pH and temperature were carried out and on cotton, nylon and polyester fabric in order to compare the effect of dyeing on natural fibers vs synthetic fibers.Using aqueous and ethanolic solutions of concentration of 5% by weight of the solvent the premordanted fabric (by ferrous sulphate) were dyed, under the optimised conditions. The antimicrobial activity of aqueous and ethanolic extracts of G. zeylanica and tea dust were investigated using well-diffusion assay whereas the antimicrobial activity of dyed fabric were investigated via disc-diffusion assay. Aqueous and ethanolic extracts of G. zeylanica and tea dust showed pronounced inhibition against S. aureus and E. coli while no antifungal activity was observed against Candida albicans. Polyester fabric dyed from ethanolic extract of G. zeylanica and tea dust showed inhibition of 90.5 mm and 120.5 mm against S. aureus respectively, when a discs of 6 mm were used. Hence, it can be concluded G. zeylanica and tea dust can be used to give fabric an antimicrobial finish naturally.Keywords: Green approach, Garcinia zeylanica, Tea waste, Antimicrobial, Fabric, Ferrous sulphate, Staphylococcus aureus, Escherichia coli

Designing new synthetic schemes for synthesis of biomedical significant compounds in environmentally benign manner is an emerging challenge. Microwave assisted solvent-free synthetic methodology for drug synthesis address our future challenges by maximising atom economy and minimising by-product formation. Oxindole nucleus is a ubiquitous pharmacopore found in variety of pharmaceutical active compounds having extensive range of biological applications. There are different types of methodologies for synthesis of 3-benzylidene-indolin-2-ones by modifying oxindole nucleus with different functional groups. Major disadvantage associated with the above methods is usage of environmentally hazardous solvents. The present study introduce a novel green approach to synthesise 3-benzylidene-indolin-2-ones from naturally occurring aldehydes in solvent free conditions under microwave irradiation. (3-Aminopropyl) triethoxysilane (APTES) modified silica was used as the catalyst for the above reaction. Silica was extracted from rice husk waste collected from Polonnaruwa, Sri Lanka. Further it was activated using concentrated hydrochloric acid. APTES was immobilised on activated rice husk silica to attached amino functionality on the silica surface. Surface amino functionality of the APTES-Silica facilitate the reaction between oxindole and aldehydes. The reaction afforded targeted compounds in high yield within 12 minutes under the microwave irradiation. Percentage yield of the compounds A, B and C was 91%, 87%, 88% respectively. The silica supported catalyst was characterised by thermogravimetric analysis (TGA) and showed a similar weight loss as reported in the literature. Synthesised compounds were characterised by Fourier-Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance Spectroscopy (1H NMR) and melting point analysis. Melting points of the compounds A, B and C were 174o C, 178o C and 205o C respectively. FTIR spectra showed that the characteristic peaks for the main functional groups present in the compounds. 1H NMR spectra of the resulting compounds confirmed that the expected products were successfully synthesised. Microwave assisted synthesis is a rapid efficient and environmentally safe green method in the synthesis of 3-benzylidene-indolin-2-ones derivatives. Further silica obtained from rice husk waste can be effectively modified to use as a solid catalyst in the synthesis of biologically important compounds of medicinal interest. Keywords: Microwave assisted, Solvent free, APTES-Silica, Oxindole, 3-Benzylidene-Indolin-2-Ones

Ilmenite mineral sand was used to synthesize titanium bismonohydrogen orthophosphate monohydrate, Ti(HPO4)2·H2O, and titanium phosphate, TiP2O7, two white pigments suitable in cosmetic applications. Ti(HPO4)2·H2O was obtained after digesting ilmenite in 85% phosphoric acid at 150 °C for 5 hours. On standing, unreacted ilmenite and white Ti(HPO4)2·H2O solid separated into two layers and Ti(HPO4)2·H2O was calcined at 900 °C to obtain the crystalline TiP2O7. Chemical and morphological characteristics were investigated using X-ray diffraction, transmission electron microscopy, scanning electron microscopy coupled with energy dispersive X-ray analysis, Fourier-transform infrared, and X-ray photoelectron spectroscopic techniques. The water retention (WR) capacities were measured at a relative humidity of 57% and indicate that Ti(HPO4)2·H2O and TiP2O7 have increased WR ability when compared with the pigment grade (PG) TiO2. The optical properties of Ti(HPO4)2·H2O, TiP2O7, and PG-TiO2 were compared using Ultraviolet-visible diffuse reflectance spectroscopy. The relative photoactivity of Ti(HPO4)2·H2O and TiP2O7 was determined using a chemical method based on the photobleaching behavior of a stable radical, 1,1-diphenyl 2-picrylhydrazyl. The photoactivities of Ti(HPO4)2·H2O and TiP2O7 are lower than that of PG-TiO2.

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.

Lubricants are the substances used to lubricate machinery parts to reduce friction and increase their lifetimes. Producing environment-friendly lubricants from renewable feed stocks as alternatives to depleting petroleum based resources has attracted considerable attention in recent years. The lubricants prepared from renewable feed stocks exhibited excellent lubricating properties and nontoxicity. The present study was carried out to synthesise biolubricant base stock from palm oil biodiesel using a green approach. Synthesis of biodiesel and biolubricants using green approaches have attracted much attention in last decade. Synthesis is mainly based on three steps: firstly, the synthesis of palm oil biodiesel, then epoxidation of biodiesel and finally ring-opening of epoxide to yield the potential biolubricant. The trans-esterification reaction was performed to yield biodiesel from palm oil using methanol and NaOH as a catalyst. The modification of biodiesel in to epoxidised form was carried out using glacial acetic acid, H2O2 and amberlite IR-120H resin as a catalyst. The ring opening of epoxidised biodiesel was performed using 1-naphthol in the presence of magnesium silicate catalyst, which was synthesise using rice hull ash. However, the expected ring opening product was not observed. Then, epoxidised biodiesel was reacted with lauric acid in the absence of magnesium silicate and the expected product was formed. The prepared magnesium silicate catalyst was characterised by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Fourier Transform Infra-Red (FTIR) spectroscopy and GC-MS analysis were used to characterise the products. Both GC-MS and FTIR results indicates the formation of fatty acid methyl esters and their conversion to epoxidised form. Disappearance of epoxy characteristic band which appeared at 845 cm-1 in FTIR spectrum confirms the formation of potential biolubricant. Density and viscosity of potential biolubricant were measured in contrast to the biodiesel. The measured density values of biodiesel and biolubricant are 0.830 g/cm3, 0.937 g/cm3 respectively. The measured kinematic viscosity values of biodiesel and biolubricant at 40° C are 4.0932 cSt, 14.9087 cSt and at 100° C are 1.6009 cSt, 3.5539 cSt respectively. These results illustrate that synthesised biolubricant consist of better lubricant properties compared to the biodiesel.Keywords: Biolubricants, Green approach, Biodiesel

The water soluble fraction (WSF) of diesel particulate matter (DPM), an environmental pollutant was used to synthesize silver nanoparticles (AgNPs). FTIR, fluorescence and UV-Vis data suggest that water soluble oxygenated PAHs in the WSF of DPM are capped to the surface of AgNPs providing the stability. The particle size, the size distribution, and the crystalline nature were confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The particles are spherical in shape having an average size of 7.7±1.5 nm. The antimicrobial activity of synthesized AgNPs was investigated using Agar well diffusion method and an enhanced activity was shown against the pathogens of Candida albicans, Escherichia coli and Staphylococcus auerus. A high level of photocatalytic activity for the degradation of rhodamine B and 2,4-dichlorophenoxyacetic acid (2,4-D), a common dye and a pesticide was exhibited by the AgNPs. KeywordsAg nanoparticles, Diesel particulate matter, Antimicrobial activity, Photocatalyst

Bis-corannulenoanthracene (C50H22, 5) was prepared by the Diels-Alder double cycloaddition of isocorannulenofuran with "bis-benzyne", followed by deoxygenation of the adducts. Despite the presence of a pentacene core, 5 is stable enough to be isolated and stored. A cycloaddition reaction of 5 with maleic anhydride produces 10 which exhibits strong affinity toward C60, as evidenced by (1)H NMR titration experiment. Synthesis of 10 demonstrates the synthetic utility of hydrocarbon 5 in the preparation of the barrelene-based molecular clips with two benzocorannulene pincers adorned with polar substituents on their tethers, which will allow for immobilization of the receptors on solid supports.

AbstractThe formation of a C—N bond between the C—3 carbon of α‐lactams and the nitrogen atom of indoles in only 25 minutes is reported.

We report herein a method that allows for the formation of a C-N bond between the C-3 carbon of alactams and the nitrogen atom of indoles. A general procedure for the coupling of indoles and alpha-lactams in only 25 mm with high yield is reported. The scope of the reaction was extended by the development of a method for the in situ generation of less stable phenyl-substituted a-lactams. The developed method provides an atom-economical method for the formation of substituted a-amino amides that are found in a variety of biologically-active compounds. (C) 2014 Elsevier Ltd. All rights reserved.