Chemistry

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Shiv Nadar University

Development of drugs to tackle the ever-increasing cases of cancer and many other diseases including any pandemic is itself challenging. Repurposing existing drugs is an upcoming drug development strategy established for the reuse of existing licensed drugs to ensure accessible, sustainable, and affordable care against cancer. Herein, we presented a nanochemotherapeutic approach based on PEGylated graphene oxide (GO-PEG) loaded with superparamagnetic iron oxide nanoparticles (NPs) and a sustainable natural origin drug, artesunate (ART) to kill cancerous cells. GO-PEG provided a larger surface area to load the dual cargo, iron oxide NPs (∼40%) and ART (∼13%), at a high loading efficiency and simultaneously affected nanotization and crystallinity of the iron oxide NPs. The morphology and internalization of NPs were determined qualitatively and quantitatively by atomic force microscopy (AFM)–Raman imaging and atomic absorption spectroscopy (AAS) analysis, respectively. Furthermore, the loading and unloading of iron reserves were characterized by high-resolution transmission electron microscopy (TEM) images. The loaded iron oxide NPs underwent a pH-triggered release of iron ions, which is higher in acidic pH than in neutral pH. A ∼sevenfold reduction in the IC50 value of ART upon treatment with the designed nanoconjugate is observed. ART is repositioned as a therapeutic drug against cancer cells, and its efficacy is amplified by the Fenton reaction due to iron oxide NPs, as confirmed by a high oxidative stress generated within the cells. The current work suggests that ART and iron oxide NPs loaded on GO-PEG, a biocompatible carrier, are a promising drug–nanoparticle conjugate for cancer treatment.

(SoNS) School of Natural Sciences

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Amplified Activity of Artesunate Mediated by Iron Oxide Nanoparticles Loaded on a Graphene Oxide Carrier for Cancer Therapeutics

The development of new photoluminescent (PL) materials with simultaneous room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) features is highly desirable for bio-imaging, security applications and sensors due to the involvement of both singlet and longerlived triplet states. Here, we report two carbazolyl-phenoxy-phthalonitrile conjugates (CPPN, CPPNF). Spectroscopic studies combining two daughter compounds (PPN, PPNF) in polar and nonpolar hosts confirmed efficient blue-RTP from the higher-energy triplet state (TPPN) due to the phenoxyphthalonitrile (PPN) part, and blue-TADF via reverse intersystem crossing from the low-lying triplet state (TCzPN) of the carbazolyl-phthalonitrile (CzPN) part to the singlet (S1) state of the same CzPN part, utilizing the TPPN state that acts as an intermediate for spin–vibronic coupling. Such PL characteristics are observed due to the energetic proximity of 3LEPPN, 1CTCzPN and 3CTCzPN. In the hydrogen-bonded matrix and crystals, we found faint persistent green-RTP characteristics of the PPNF due to supramolecular interactions and aggregation of the molecule. This study could pave the way to understanding the involvement of different excited states associated with TADF and RTP processes of asymmetric-donor– acceptor systems

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Materials Advances

Asymmetric-donor (D2D2' )–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF

While temporal considerations are of prime importance for chemical reactions, as well as for molecular stability, most chemical concepts (outside of the field of chemical kinetics) are not explicitly formulated on a diachronic basis (Earley in Found Chem 14:235, 2012). It will be argued here that a formulation explicitly incorporating temporal and epistemological considerations enables us to treat chemical reactions and chemical substances on ontologically equivalent terms, instead of assigning a more fundamental status to the latter. After all, in collision theory, a chemical substance is just a collision complex (a “resonance”) that takes too long. How long qualifies as “too long”, and “too long” in relation to what, are crucial questions that distinguish chemical substances from chemical reactions, and reversible reactions from irreversible ones, thereby introducing anthropocentric considerations into these distinctions. Too long for a lab chemist is very different from too long for an astrochemist studying chemical reactions between chemical substances in inter-stellar space on cosmological timescales. Examining several physical and chemical properties on the basis of which chemical substances are distinguished from one another, the role of temporal and anthropocentric considerations in defining molecular properties is emphasized. I conclude with some observations on the much-debated reduction of chemistry to other disciplines, arguing that such reduction depends on our aesthetic choices as to what kinds of observations demand explanation, and what kinds of explanation are acceptable.

Foundations of Chemistry

Ontological Status of Time in Chemistry

Development of drugs to tackle the ever-increasing cases of cancer and many other diseases including any pandemic is itself challenging. Repurposing existing drugs is an upcoming drug development strategy established for the reuse of existing licensed drugs to ensure accessible, sustainable, and affordable care against cancer. Herein, we presented a nanochemotherapeutic approach based on PEGylated graphene oxide (GO-PEG) loaded with superparamagnetic iron oxide nanoparticles (NPs) and a sustainable natural origin drug, artesunate (ART) to kill cancerous cells. GO-PEG provided a larger surface area to load the dual cargo, iron oxide NPs (∼40\%) and ART (∼13\%), at a high loading efficiency and simultaneously affected nanotization and crystallinity of the iron oxide NPs. The morphology and internalization of NPs were determined qualitatively and quantitatively by atomic force microscopy (AFM)-Raman imaging and atomic absorption spectroscopy (AAS) analysis, respectively. Furthermore, the loading and unloading of iron reserves were characterized by high-resolution transmission electron microscopy (TEM) images. The loaded iron oxide NPs underwent a pH-triggered release of iron ions, which is higher in acidic pH than in neutral pH. A sevenfold reduction in the IC50 value of ART upon treatment with the designed nanoconjugate is observed. ART is repositioned as a therapeutic drug against cancer cells, and its efficacy is amplified by the Fenton reaction due to iron oxide NPs, as confirmed by a high oxidative stress generated within the cells. The current work suggests that ART and iron oxide NPs loaded on GO-PEG, a biocompatible carrier, are a promising drug-nanoparticle conjugate for cancer treatment. © 2020 American Chemical Society.

ACS Applied Bio Materials

Amplified Activity of Artesunate Mediated by Iron Oxide Nanoparticles Loaded on a Graphene Oxide Carrier for Cancer Therapeutics

The authors regret that an affiliation was incorrect in the original manuscript. The correct affiliations are as shown in this Correction article. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

New Journal of Chemistry

Erratum: Understanding alloy structure and composition in sinter-resistant AgPd@SiO2 encapsulated catalysts and their effect on catalytic properties (New Journal of Chemistry (2017) 41 (14652-14658) DOI: 10.1039/C7NJ03652C)

A new library of pyrido-pyrrolidine hybrid compounds were designed, developed and screened for their antidiabetic property with α-glucosidase. The design is based on preliminary screening of key fragments identified from literature reported α-glucosidase inhibitors and antidiabetic compounds. The most active fragments were stitched to provide a pyrido-pyrrolidine hybrid molecule as a new motif. A library of these compounds were synthesized and screened against a series of α-glycosidases. Subsequently, compound 3k was the most efficacious analog with IC50 of 0.56 μM. Photoluminescence study and circular dichroism experiments indicated that compound 3k modulates the primary and secondary structure of the enzyme. It successfully brings down the fasting blood glucose level for streptozotocin (STZ, 70 mg/kg, Intraperitoneal) induced type I diabetic male Sprague-Dawley rats (250–320 g). At lower concentration, compound 3k slightly stimulates proliferation of BRIN-BD11 (α-glucose responsive beta cells from rat pancreas islets that secretes insulin) cells. © 2020 Elsevier Masson SAS

European Journal of Medicinal Chemistry

Discovery of novel pyrido-pyrrolidine hybrid compounds as alpha-glucosidase inhibitors and alternative agent for control of type 1 diabetes

Water is the most prominent solvent. The unique properties of water are rooted in the dynamical hydrogen-bonded network. While TeraHertz (THz) radiation can probe directly the collective molecular network, several open issues remain about the interpretation of these highly anharmonic, coupled bands. In order to address this problem, we need intense THz radiation able to drive the liquid into the nonlinear response regime. Firstly, in this study, we summarize the available brilliant THz sources and compare their emission properties. Secondly, we characterize the THz emission by Gallium Phosphide (GaP), 2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile (OH1), and 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) crystals pumped by an amplified near-infrared (NIR) laser with tunable wavelength. We found that both OH1 as well as DSTMS could convert NIR laser radiation between 1200 and 2500 nm into THz radiation with high efficiency (&gt; 2 x 10-4), resulting in THz peak fields exceeding 0.1 MV/cm for modest pump excitation (~ mJ/cm2). DSTMS emits the broadest spectrum, covering the entire bandwidth of our detector from ca. 0.5 to ~7 THz, also at a laser wavelength of 2100 nm. Future improvements will require handling the photothermal damage of these delicate organic crystals, and increasing the THz frequency. © 2020 by the authors.

Materials

Towards intense THz spectroscopy on water: Characterization of optical rectification by GaP, OH1, and DSTMS at OPA wavelengths

An environmentally compatible organic solar cell (OSC) has potential to build a global clean energy infrastructure for the world. However, much less attention has been focused on the structures sourced from greener origins to enhance the sustainability aspect of these devices. Herein, we report a rational design, synthesis, and characterization of donor (D)-acceptor (A)-based green organic small molecules, consisting of difluoro-2,1,3-benzothiadiazole (BTF2) as the acceptor, with thiophene (T) and renewable resource materials, cardanol (C) and guaiacol (G) as the donor materials. The reference molecule, abbreviated as T4BTF2, is fully petro-sourced, while C2T2BTF2 and G2T2BTF2 are partly renewable origin molecules. Broad and strong absorption characteristics ranging from 300 to 600 nm along with high thermal stability are supportive for utility of the green origin small molecules in solar cells. Density functional theory (DFT) calculations revealed that G2T2BTF2 is more highly planar than C2T2BTF2 due to the difference in the positioning of the alkyl/alkoxy chain. With bulk heterojunction OSCs with PC71BM as the acceptor, G2T2BTF2 exhibited a high Voc of 0.83 V among all the analyzed small molecules. When compared with the reference molecule T4BTF2, G2T2BTF2 showed a high PCE of 5.56\% with a high Jsc of 10.98 mA/cm2 and FF of 0.61, whereas the PCEs of T4BTF2 and C2T2BTF2 are 3.98\% and 3.23\%, respectively. Our work demonstrates a rational approach to synthesize and develop green organic semiconductors using the biofeedstock derived starting materials for realizing efficient and environment compatible OSCs. Copyright © 2020 American Chemical Society.

Physics

ACS Sustainable Chemistry and Engineering

Cardanol- And Guaiacol-Sourced Solution-Processable Green Small Molecule-Based Organic Solar Cells

Reactive carbonyl species (RCSs) including one carbon formaldehyde (FA) and dicarbonyl compounds such as methylglyoxal (MGO) and glyoxal (GO) are produced during demethylase reactions and various glucose metabolic pathways respectively. Elevation of the RCSs concentrations in cells is due to abnormal DNA damage, glycation adducts with macromolecules that lead to various neurotoxic diseases. Hence, regular monitoring of these RCSs with an easy tool is of utmost interest. However, conventional methods such as chromatography and mass spectrometry for the detection of these species are not so economically viable. These issues were well addressed by the non-invasive reactivity-based fluorescence techniques. However, tedious synthesis, only specific to either mono aldehyde is limited to detect multiple RCSs in physiologies by synthesized fluorophores. An alternative, simple small molecules are widely applied as commercial biomarkers such as terephthalate and 2,3-diaminonaphthalene (NAP) for hydroxy radical (OH·) and nitric oxide (NO) respectively. Herein, we report an analogue of NAP, 1,8-diamino naphthalene (DAN) is an efficient chemosensor for highly sensitive detection of FA, MGO and GO with minimum detection limits of 0.95–3.97 μM. Surprisingly, DAN shows a “turn on” response towards RCSs but remaining silent towards NO which are exactly opposite to commercial probe NAP. Exogenous RCSs imaging in vitro cancerous cells shows the efficacy of the probe and its potential application for RCSs monitoring in cancer cells, generation of toxic byproducts. © 2020 Elsevier B.V.

Journal of Photochemistry and Photobiology B: Biology

Highly selective chemosensor for reactive carbonyl species based on simple 1,8-diaminonaphthalene

We report a novel blue LED mediated intramolecular C-H functionalization of tryptamine derivatives to generate azepino[4, 5-b]indoles (4) in moderate to good yields. By altering the substitution at the tryptamine nitrogen, intramolecular cyclopropanation is achieved in high yields under the same reactions condition to provide natural product inspired polycyclic indoles (6), which are further transformed to spiropiperidino (5 and 8) indoles in decent yields. The mechanism of formation of the compounds was investigated through DFT studies. © 2020 American Chemical Society.

Organic Letters

Blue LED Mediated Intramolecular C-H Functionalization and Cyclopropanation of Tryptamines: Synthesis of Azepino[4, 5-b]indoles and Natural Product Inspired Polycyclic Indoles