Extended Study of Visible-Light-Induced Photocatalytic [4 + 2] Benzannulation: Synthesis of Polycyclic (Hetero)Aromatics

Chatterjee, Tanmay,Lee, Da Seul,Cho, Eun Jin American Chemical Society 2017 Journal of organic chemistry Vol.82 No.8

<P>Herein we report an extended study of [4 + 2] benzannulation reactions of 2-(hetero)aryl-substituted,anilines with alkynes by visible light photocatalysis. The method requires the use of BuONO as a diazotizing agent and 0.3 mol % of fac-Ir(ppy)(3) as a photocatalyst at room temperature. The reaction-proceeded in a chemo-and regioselective manner with high functional group tolerance under mild conditions alloWing the preparation of a wide variety of polycyclic (hetero)arornatic compounds, including phenanthrenes, in moderate to high yields. This procedure is amenable to gram-scale synthesis of 9-phenyliphenanthrene.</P>

Enhanced mechanical strength of chitosan hydrogel beads by impregnation with carbon nanotubes

Chatterjee, S.,Lee, M.W.,Woo, S.H. Pergamon Press ; Elsevier Science Ltd 2009 Carbon Vol.47 No.12

Chitosan (CS) hydrogel beads were impregnated with carbon nanotubes (CNTs), and their mechanical strength, acid stability and adsorption capacity to the anionic dye, Congo red (CR), were investigated by comparing with a conventional reinforcing method of cross-linking with epichlorohydrin (ECH). CS/CNT hydrogel beads were manufactured by dispersing CNTs (0.01wt.%) with cetyltrimethylammonium bromide (CTAB) (0.05wt.%) into CS solution (1wt.%). Maximum endurable force at complete breakdown of CS hydrogel beads increased from 1.87 to 7.62N with incorporation of CNTs and its adsorption capacity increased from 178.32 to 423.34mgg<SUP>-1</SUP> for adsorption of CR.

Highly efficient capture of naphthalene by nonionic surfactants in hydrogel capsules

Chatterjee, Sudipta,Lim, Seong-Rin,Lee, Min W.,Woo, Seung H. Elsevier 2017 JOURNAL- TAIWAN INSTITUTE OF CHEMICAL ENGINEERS Vol.78 No.-

<P><B>Abstract</B></P> <P>The impregnation of Triton X-100 (TX100) in chitosan capsules (TCC) via an anionic surfactant gelation method was investigated for the sorption of naphthalene (NAP) from aqueous solutions. Impregnation with TX100 enhanced NAP sorption at all tested concentrations of TX100, ranging from 0.1 to 10g/l. The highest NAP sorption capacity (68.7mg/g) was obtained at 2g/l of TX100, a capacity 5.1-fold higher than that of chitosan capsules without TX100 impregnation (CC) (13.4mg/g). The highest molar sorption ratio of capsule (<I>MSR<SUB>C</SUB> </I>) was 12.23mol NAP/mol TX100 at 0.1g/l, which was much higher than the <I>MSR<SUB>B</SUB> </I> for beads (0.70) and the <I>MSR<SUB>W</SUB> </I> for the aqueous phase (0.11). Thus, when a nonionic surfactant is present in a hydrogel capsule, the ability of the surfactant to solubilize organic chemicals can be significantly increased compared to the surfactant in water or in hydrogel beads.</P> <P> <UL> <LI> Highlights </LI> </UL> <ce:list id='celist0002'> <ce:list-item id='celistitem0002'> <ce:label>•</ce:label> <ce:para id='para0002' view='all'>Chitosan hydrogel capsules were formed by a surfactant gelation method.</ce:para> </ce:list-item> <ce:list-item id='celistitem0003'> <ce:label>•</ce:label> <ce:para id='para0003' view='all'>Impregnation of a nonionic surfactant in hydrogel capsules enhanced naphthalene sorption.</ce:para> </ce:list-item> <ce:list-item id='celistitem0004'> <ce:label>•</ce:label> <ce:para id='para0004' view='all'>The effect of a nonionic surfactant impregnation was much higher in capsules than in beads.</ce:para> </ce:list-item> <ce:list-item id='celistitem0005'> <ce:label>•</ce:label> <ce:para id='para0005' view='all'>Nonionic surfactants in hydrogel capsules can be used as separate-phase surfactants.</ce:para> </ce:list-item> </ce:list> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Searching for boosted dark matter at ProtoDUNE

Chatterjee, Animesh,De Roeck, Albert,Kim, Doojin,Moghaddam, Zahra Gh.,Park, Jong-Chul,Shin, Seodong,Whitehead, Leigh H.,Yu, Jaehoon American Physical Society 2018 Physical Review D Vol.98 No.7

Controlled Fluoroalkylation Reactions by Visible-Light Photoredox Catalysis

Chatterjee, Tanmay,Iqbal, Naeem,You, Youngmin,Cho, Eun Jin American Chemical Society 2016 Accounts of chemical research Vol. No.

<P>Owing to their unique biological, iihysical, and chemical properties, fluoroalkylated organic substances have attracted significant attention from researchers in a variety of disciplines. Fluoroalkylated compounds are considered particularly important in pharmaceutical chemistry because of their superior lipophilicity, binding selectivity, metabolic stability, and bioavailability to those of their nonfluoroalkylated analogues. We have developed various methods for the synthesis of fluoroalkylated substances that rely on the use of visible-light photoredox catalysis, a powerful preparative tool owing to, its environmental benignity and mechanistic versatility in promoting a large number of synthetically important reactions with high levels of selectivity. In this Account, we describe the results of our efforts, which have led to the development of visible-light photocatalytic methods for the introduction of a variety of fluoroalkyl groups (such as, CF3, CF2R, CH2CF3, C3F7, and C4F9) and arylthiofluoroalkyl groups (such as, CF2SPh, C2F4SAr, and C4F8SAr) to organic substances. In these studies, electron deficient carbon-centered fluoroalkyl radicals were successfully generated by the appropriate choice of fluoroalkyl source, photocatalyst, additives, and solvent. The redox potentials of the photocatalysts and the fluoroalkyl sources and the choice of sacrificial electron donor or acceptor as the additive affected the photocatalytic pathway, determining whether an oxidative or reductive quenching pathway was operative for the generation of key fluoroalkyl radicals. Notably, we have observed that additives significantly affect the efficiencies and selectivities of these reactions and can even change the outcome of the reaction by playing additional roles during its course. For instance, a tertiary amine as an additive in the reaction medium can act not only as a sacrificial electron donor in.photoredox catalysis but also as a hydrogen atom source, an elimination base for dehydrohalogenation of the intermediate, and also a Bronsted base for deprotonation. In the same context, the selection of solvent is also critical since it affects the rate and selectivity of reactions depending upon its polarity and reagent solubilizing ability and plays additional roles in the process, for example, as a hydrogen atom source. By clearly understanding the roles of additives and solvent, we designed several controlled fluoroalkylation reactions where different products were formed selectively from the same starting substrates. In addition, we could exploit one of the most important advantages of radical reactions, that is, the use of unactivated Jr-systems such as alkenes, alkynes, arenes, and heteroarenes as radical acceptors without prefunctionalization. Furthermore, fluoroalkylation processes under mild room temperature reaction conditions tolerate various functional groups and are therefore easily applicable to late-stage modifications of highly functionalized advanced intermediates.</P>

LUNAR ECLIPSE COMPUTATION IN INDIAN ASTRONOMY WITH SPECIAL REFERENCE TO SIDDHNTIC TEXTS

CHATTERJEE, SOMENATH The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

Indian astronomical texts have records of lunar astronomy since the Puranic age. In the Vednga Jyotia (1350 B CE), the algorithm for computing eclipses is not found. This phenomenon was interpreted in the Siddhntic texts as the occurrence of Vyatipati Yoga. This paper attempts to explain the computing and observational method found in astronomical texts of Siddhntic period.

Selective Fluorogenic and Chromogenic Probe for Detection of Silver Ions and Silver Nanoparticles in Aqueous Media

Chatterjee, Amrita,Santra, Mithun,Won, Nayoun,Kim, Sungjee,Kim, Jae Kyung,Kim, Seung Bin,Ahn, Kyo Han American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.6

<P>A novel rhodamine-based fluorogenic and chromogenic probe for Ag(+) ions in aqueous media is developed, which can be also used for the detection of AgNPs. The sensing mechanism is based on irreversible tandem ring-opening and -forming processes promoted by Ag(+)-coordination to the iodide of the probe, which is accompanied by both color and turn-on type fluorescence changes. The probe shows remarkably high selectivity over other metal ions and detects silver ions up to 14 ppb.</P>

A systems toxicology approach reveals the Wnt-MAPK crosstalk pathway mediated reproductive failure in <i>Caenorhabditis elegans</i> exposed to graphene oxide (GO) but not to reduced graphene oxide (rGO)

Chatterjee, Nivedita,Kim, Youngho,Yang, Jisu,Roca, Carlos P.,Joo, Sang-Woo,Choi, Jinhee Informa UK (TaylorFrancis) 2017 Nanotoxicology Vol.11 No.1

<P>The potential hazards of graphene nanomaterials were investigated by exposing the nematode Caenorhabditis elegans to graphene oxide (GO) and reduced graphene oxide (rGO). The underlying mechanisms of the nano-bio interaction were addressed with an integrated systems toxicology approach using global transcriptomics, network-based pathway analysis, and experimental validation of the in-silico-derived hypotheses. Graphene oxide was found to reduce the worms' reproductive health to a greater degree than rGO, but it did not affect survival (24h endpoint). Comparative analysis of GO vs. rGO effects found that the wingless-type MMTV integration site family (Wnt) pathway and the mitogen-activated protein kinase (MAPK) pathway were evoked in GO- but not in rGO-exposed worms. We therefore hypothesized that crosstalk between the Wnt and MAPK pathways is responsible for C. elegans' reproductive sensitivity to GO exposure. By targeting the individual components of the Wnt-MAPK crosstalk pathway (with qPCR gene expression and mutant reproduction analysis), we found a signaling cascade of MOM-2 -> MOM-5 -> MOM-4 -> LIT-1 -> POP-1 -> EGL-5. Specifically, the activation of POP-1 (the TCF protein homolog) and subsequent repression of the Wnt/beta-catenin target gene (EGL-5), analyzed with target-gene-specific RNAi in POP-1 mutant [pop-1(q645)] worms, were the central mechanisms of reduced reproductive potential in the worms exposed to GO. Our results highlight the distinct biological and molecular mechanisms of GO and rGO exposure and the role of Wnt-MAPK pathway crosstalk in regulating GO-induced reproductive failure in in vivo systems, and they will contribute to the development of efficient and innocuous graphene applications as well to improvements in mechanism-based risk assessment.</P>

III-nitride nanowires for solar light harvesting: A review

Chatterjee, U.,Park, Ji-Hyeon,Um, Dae-Young,Lee, Cheul-Ro PERGAMON 2017 RENEWABLE AND SUSTAINABLE ENERGY REVIEWS Vol.79 No.-

<P><B>Abstract</B></P> <P>The world needs economical and sustainable alternate energy sources to combat the irreversible phenomenon like global warming. Solar photovoltaic technology, which converts sunlight directly to electricity, is the most potential candidate for alternate energy source. On the other hand, increasing global pollution due to energy emission compels the worldwide researcher community to deliberate over various green fuels. Recently due to numerous advancements hydrogen fuel cells are thought to be the green power source of 21st century and may develop the hydrogen economy. However, despite of many promising breakthroughs energy production harvesting solar light does not find wide spread applications due to their low efficiency associated with unsuccessful utilization of entire solar spectrum which leads researchers to consider materials with multi energy band gap. Due to their unique property of band gap tuning (~6.2eV for AlN to ~0.65eV for InN) III-nitride nanowire structures have been extensively investigated in the past decade in pursuit of multi band gap materials. Intensive research efforts have been paid into studying GaN, InN, InGaN, AlN and their different compositions. It is clear that this material family has enormous potential in harvesting solar energy to light the new dawn of clean and sustainable energy sources. In this article, we present an overview on recent advancements in III-nitride solar energy devices. We have made a review for more than 200 articles in this regard. All the recent developments in realizing III-nitride nanostructures and novel yet recent advances in III-nitride solar devices are reviewed in and its subsequent subsections. The III-nitride nanowire photovoltaic devices are discussed in whereas deals with the current progresses in artificial photosynthesis involving III-nitride nanowires. Finally in the present challenges in realizing high efficiency III-nitride nanowire solar energy devices are summarized along with paths for future work.</P>

Synthesis of Substituted Oxazoles by Visible-Light Photocatalysis

Chatterjee, Tanmay,Cho, Ji Young,Cho, Eun Jin American Chemical Society etc. 2016 Journal of organic chemistry Vol.81 No.16

<P>A simple and practical method for the synthesis of substituted oxazoles has been developed using readily available alpha-bromoketones and benzylamines by visible-light photocatalysis at room temperature. The process, which requires 1 mol % of [Ru(bpy)(3)]Cl-2 photocatalyst with K3PO4 and CCl3Br, is effective for accessing a variety of valuable oxazole compounds. The synthetic utility of our protocol was also demonstrated by preparing a natural prochict, texaline.</P>