1931-44-8Relevant academic research and scientific papers
Chemistry of Heterocyclic Compounds. 61. Synthesis and Conformational Studies of Macrocycles Possessing 1,8- or 1,5-Naphthyridino Subunits Connected by Carbon-Oxygen Bridges
Newkome, George R.,Garbis, Sam J.,Majestic, Veronica K.,Fronczek, Frank R.,Chiari, Giacomo
, p. 833 - 839 (1981)
Polyethereal macrocycles were prepared from both 2,6-dichloro-1,5-naphthyridine (2) and 2,7-dichloro-1,8-naphthyridine (6).The "cross-the-face" structures of 1:1 macrocycles 7, derived from 2, were confirmed by NMR.The 2,7-(1,8-naphthyridino) macrocyclic structures 9 and 10 were also supported by NMR data which were indicative of diminished N-electron density, when compared to the parent 1,8-naphthyridine.Template reactions did not appreciably enhance product yields.The X-ray crystal structure of 1:1 macrocycle 9b was conducted and showed that the imidate moieties possess a nearly 0 deg dihedral angle and that the naphthyridine subunit exhibits marginal deviation from planarity.
Tuning the sensitivity towards mercury: Via cooperative binding to d-fructose: Dual fluorescent chemosensor based on 1,8-naphthyridine-boronic acid derivative
Rajadurai, Marina,Reddy, E. Ramanjaneya
, p. 14862 - 14870 (2021)
A novel fluorescent chemosensor naphthyridine-boronic acid derivative (1.1) was synthesized and its ability to act as a selective chemosensor was examined for various metal ions. Compound 1.1 displayed highly selective fluorescence quenching upon interaction with Hg2+, possibly by means of photo induced electron transfer (PET) mechanism. The binding stoichiometry of the naphthyridine-boronic acid-Hg2+ complex and the association constant was determined. It was found that in the presence of d-fructose at physiological concentration, the sensitivity of chemosensor 1.1 towards Hg2+ improved by at least 7 times, perhaps as a result of the cooperative binding of both d-fructose and mercury ion to the sensor. Till now, the presented dual d-fructose-mercury chemosensor is the first example of utilizing boronic acid-diol complexation for enhancement of the sensor's sensitivity towards a toxic metal ion. The utility of compound 1.1 lays in applications in the food industry, e.g. for detection of mercury contamination of high fructose corn syrup, or in estimation of mercury in polluted biological samples and underground water. This journal is
Dynamic Cross-Linking of Polyethylene via Sextuple Hydrogen Bonding Array
Tellers, Jonathan,Canossa, Stefano,Pinalli, Roberta,Soliman, Maria,Vachon, Jér?me,Dalcanale, Enrico
, p. 7680 - 7691 (2018)
Multiple hydrogen bonding motifs are promising tools for polymer functionalization to obtain adaptable networks combining advantages of permanently cross-linked systems with processability of thermoplastics. Here we describe the use of a new multiple hydrogen bonding motif to impart increased tensile strength, stiffness, barrier properties, and a plateau modulus after melting to functional polyolefins, while retaining adaptability of the polymer network. The cross-linked nature of these polymers was elucidated by thermal and mechanical analysis, revealing a raised glass transition and rheology similar to permanently cross-linked polymer matrices. The apolar polymer matrix was found to stabilize the new hydrogen bonding motif at elevated temperatures. The resulting polymer showed thermal resistance superior to ureidopyrimidone (UPy) motif functionalized materials, the most commonly employed synthetic multiple hydrogen bonding motif to date.
A real time colorimetric 'two in one' kit for tracking ppb levels of uric acid and Hg2+ in live HeLa S3 cells and Hg2+ induced keto-enol tautomerism
Kumari, Chanda,Sain, Dibyendu,Kumar, Ashish,Debnath, Sushanta,Saha, Partha,Dey, Swapan
, p. 62990 - 62998 (2016)
A TBET based 'turn-on' fluorescent reagent with high Stokes shifts, exhibits selective and colorimetric detection of biologically important uric acid as well as toxic Hg2+. A new Hg2+ induced keto-enol tautomerism phenomenon associated with a solvatochromic effect was reported. The sensor has proved its real time application as an accurate 'two in one' kit for tracking uric acid and Hg2+ in live HeLa cells via a fluorescence bio-imaging technique.
Hydrogen-bond-driven dimers of naphthyridine derivatives for selective identification of DNA G-quadruplexes
Gao, Lianxun,Hao, Xueyu,Jin, Rizhe,Kang, Chuanqing,Li, Chunjie,Ma, Xiaoye,Wang, Liangpeng,Wang, Yu
supporting information, p. 4768 - 4774 (2021/06/11)
G-quadruplex (GQ) ligands as potential anti-cancer drugs have received extensive attention. Large aromatic systems are usually considered in the design of the ligands to improve the binding with GQs, which are typically constructed by the combination of small modules with covalent bonds. In this study, we presented a non-covalent bond approach to construct GQ ligands with an extended planar structure. The ligands were stable dimers assembled through quadruplex intermolecular hydrogen bonds between two molecules of naphthyridine derivatives. Spectroscopic analyses showed that dimeric ligands could stabilize GQs with an increase of the melting temperature up to 12 °C and induced conformational conversion of hybrid GQs. Confocal fluorescence microscopy confirmed the enrichment of naphthyridine ligands in the nucleus. The ligands showed moderate cytotoxicity against HeLa cells with an IC50 value of 7.5 μg mL-1 and effectively induced growth inhibition and apoptosis in HeLa cells. These results confirmed the feasibility of the quick building of GQ ligands through intermolecular interactions of simple molecules that are easily obtained during synthesis, which is helpful for GQ ligand design and quick establishment of a ligand library through the self-assembly of easily available molecular components.
A naphthyridine-indole ligand for selective stabilization of G-quadruplexes and conformational conversion of hybrid topology
Gao, Lianxun,Hao, Xueyu,Jin, Rizhe,Kang, Chuanqing,Li, Chunjie,Ma, Xiaoye,Wang, Liangpeng,Wang, Yu
supporting information, (2021/09/22)
The development of ligands to stabilize G-quadruplexes (G4s) or induce G4s to transition from metastable topology to stable topology is a potential strategy for inhibiting cancer cell proliferation. In this study, a novel G-quadruplex (G4) ligand based on a naphthyridine scaffold with two indole pendants, L5-DA, is reported to convert hybrid to the parallel topology. Circular dichroism (CD) and fluorescence spectroscopies were used to investigate the interactions between L5-DA and G4s. The CD spectra revealed that the L5-DA induced the conformational conversion from hybrid topologies to parallel topologies with a melting temperature increase of more than 30 °C. According to F?rster resonance energy transfer assays, the presence of excess duplex competitor had no effect on the ligand-induced stabilization of the hybrid topology, confirming the L5-DA's selectivity for G4s over ds26. With IC50 values of 4.3 μM, the ligand showed significant cytotoxicity against HeLa cells and effectively induced growth inhibition and apoptosis in HeLa cells. Immunofluorescence microscopy revealed an increase in BG4 foci in the presence of the L5-DA, confirming ligand-induced G4s stabilization in HeLa cells. According to these results, the combination of naphthyridine and indole scaffold was an effective design strategy for G4s stabilization and conformational conversion of metastable G4 topology for inhibiting cancer cell growth.
Muscle-Mimetic Synergistic Covalent and Supramolecular Polymers: Phototriggered Formation Leads to Mechanical Performance Boost
Zhang, Zhaoming,Cheng, Lin,Zhao, Jun,Zhang, Hao,Zhao, Xinyang,Liu, Yuhang,Bai, Ruixue,Pan, Hui,Yu, Wei,Yan, Xuzhou
supporting information, p. 902 - 911 (2020/12/22)
A thin filament stimulated by Ca2+ to combine with myosin is the structural basis to achieve filament sliding and muscle contraction. Though a large variety of artificial materials has been developed by mimicking muscle, the on-demand combination of the actin filament and myosin has never been precisely reproduced in polymeric systems. Herein, we show that both the combination process and the combined structure of actin filament and myosin have been mimicked to construct synergistic covalent and supramolecular polymers (CSPs). Specifically, photoirradiation as a stimulus induces the independently formed covalent polymers (CPs) and supramolecular polymers (SPs) to interact with each other through activated quadruple H-bonding. The resultant CSPs possess a unique network structure which not only facilitates the synergistic effect of CPs and SPs to afford stiff, strong, yet tough materials but also provides efficient pathways to dissipate energy with the damping capacity of the representative material being higher than 95%. Furthermore, muscle functions, for example, by becoming stiff during contraction and self-growth by training, are imitated well in our system via in situ phototriggered formation of CSP in the solid state. We hope that the fundamental understanding gained from this work will promote the development of synergistic CSP systems with emergent functions and applications by mimicking the principle of muscle movements.
BICYCLIC ETHER O-GLYCOPROTEIN-2-ACETAMIDO-2-DEOXY-3-D-GLUCOPYRANOSIDASE INHIBITORS
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Paragraph 00334, (2020/08/22)
Described herein are compounds represented by formula (I) or a pharmaceutically acceptable salt thereof, pharmaceutical compositions comprising the same and methods of preparing and using the same. The variables Ar, X, R1, R3, R 4, Y1, Y2, n and p are as defined herein.
A proton-responsive annulated mesoionic carbene (MIC) scaffold on IR complex for proton/hydride shuttle: An experimental and computational investigation on reductive amination of aldehyde
Bera, Jitendra K.,Daw, Prosenjit,Din Reshi, Noor U.,Ehmann, Kira R.,H?lscher, Markus,Leitner, Walter,Pandey, Pragati
supporting information, p. 3849 - 3863 (2020/11/23)
A Cp*Ir(III) complex (1) bearing a proton-responsive hydroxy unit on an annulated imidazo[1,2-a][1,8]naphthyridine based mesoionic carbene scaffold was synthesized by two different synthetic routes. The molecular structure of 1 revealed an anionic lactam form of the ligand. The acid?base equilibrium between the lactam-lactim tautomers on the ligand scaffold was examined by 1H NMR and UV?vis spectra. The pKa of the appendage ?OH group in the lactim form of 1 was estimated to assess the proton transfer property of the catalyst. The catalytic efficacy of 1 for reductive amination of aldehyde was evaluated by utilizing three different hydrogen sources: molecular H2iPrOH/KOtBu combination, and HCOOH/Et3N (5:2) azeotropic mixture. The HCOOH/Et3N (5:2) azeotropic mixture rotocol was found to be the best amon the three different h dro enation methods. Catalyst 1 hydrogenates imines chemoselectively over carbonyls under the reaction conditions. A range of aldehydes was reductively aminated to the corresponding secondary amines using the HCOOH/Et3N (5:2) azeotropic mixture. Further, catalyst 1 showed high efficiency for the reduction of a wide variety of N-heterocyclic imine derivatives. The lactam-lactim tautomerization of the ligand system is proposed for direct hydrogenation, whereas only the lactam form operates in the strongly basic medium (iPrOH/KOtBu). Under HCOOH/Et3N (5:2) conditions, the lactam scaffold is not protonated; rather, an outer-sphere hydride transfer from formate to the Ir is proposed, which is supported by 1H NMR and DFT calculations. Finally, ligand-promoted hydride transfer from metal-hydride to the protonated imine affords the corresponding amine. A close agreement between the experimentally estimated and computed thermodynamic/kinetic parameters gives credence to the metal-ligand cooperative mechanism for the imine hydrogenation reaction using the HCOOH/Et3N (5:2) azeotropic mixture.
Supramolecular Self-Sorting Networks using Hydrogen-Bonding Motifs
Coubrough, Heather M.,van der Lubbe, Stephanie C. C.,Hetherington, Kristina,Minard, Aisling,Pask, Christopher,Howard, Mark J.,Fonseca Guerra, Célia,Wilson, Andrew J.
supporting information, p. 785 - 795 (2019/01/04)
A current objective in supramolecular chemistry is to mimic the transitions between complex self-sorted systems that represent a hallmark of regulatory function in nature. In this work, a self-sorting network, comprising linear hydrogen motifs, was created. Selecting six hydrogen-bonding motifs capable of both high-fidelity and promiscuous molecular recognition gave rise to a complex self-sorting system, which included motifs capable of both narcissistic and social self-sorting. Examination of the interactions between individual components, experimentally and computationally, provided a rationale for the product distribution during each phase of a cascade. This reasoning holds through up to five sequential additions of six building blocks, resulting in the construction of a biomimetic network in which the presence or absence of different components provides multiple unique pathways to distinct self-sorted configurations.
