The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Ryosuke O. Suzuki - One of the best experts on this subject based on the ideXlab platform.
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fabrication of anodic porous alumina by Squaric Acid anodizing
Electrochimica Acta, 2014Co-Authors: Tatsuya Kikuchi, Shungo Natsui, Tsuyoshi Yamamoto, Ryosuke O. SuzukiAbstract:Abstract The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, Squaric Acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M Squaric Acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200–400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in Squaric Acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by Squaric Acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte.
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Fabrication of anodic porous alumina by Squaric Acid anodizing
Electrochimica Acta, 2014Co-Authors: Tatsuya Kikuchi, Shungo Natsui, Tsuyoshi Yamamoto, Ryosuke O. SuzukiAbstract:The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, Squaric Acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M Squaric Acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in Squaric Acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by Squaric Acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte. © 2014 Elsevier Ltd.
Tatsuya Kikuchi - One of the best experts on this subject based on the ideXlab platform.
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fabrication of anodic porous alumina by Squaric Acid anodizing
Electrochimica Acta, 2014Co-Authors: Tatsuya Kikuchi, Shungo Natsui, Tsuyoshi Yamamoto, Ryosuke O. SuzukiAbstract:Abstract The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, Squaric Acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M Squaric Acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200–400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in Squaric Acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by Squaric Acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte.
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Fabrication of anodic porous alumina by Squaric Acid anodizing
Electrochimica Acta, 2014Co-Authors: Tatsuya Kikuchi, Shungo Natsui, Tsuyoshi Yamamoto, Ryosuke O. SuzukiAbstract:The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, Squaric Acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M Squaric Acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in Squaric Acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by Squaric Acid anodizing consists of amorphous Al 2 O 3 containing 5-6 at% carbon from the electrolyte. © 2014 Elsevier Ltd.
Ferenc Sztaricskai - One of the best experts on this subject based on the ideXlab platform.
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a new class of semisynthetic anthracycline glycoside antibiotics incorporating a Squaric Acid moiety
The Journal of Antibiotics, 2005Co-Authors: Ferenc Sztaricskai, Gyula Batta, Pal Herczegh, Erzsebet Roth, Istvan F Pelyvas, Szabolcs Sandor, Judit Remenyi, Zsanett Miklan, Ferenc HudeczAbstract:A New Class of Semisynthetic Anthracycline Glycoside Antibiotics Incorporating a Squaric Acid Moiety
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A New Class of Semisynthetic Anthracycline Glycoside Antibiotics Incorporating a Squaric Acid Moiety
The Journal of Antibiotics, 2005Co-Authors: Ferenc Sztaricskai, Gyula Batta, Pal Herczegh, Erzsebet Roth, Istvan F Pelyvas, Szabolcs Sandor, Judit Remenyi, Zsanett Miklan, Ferenc HudeczAbstract:Treatment of the Squaric Acid amide esters ( 7 , 9 ) of anthracycline glycoside antibiotics with aliphatic and aromatic primary and secondary amines, amino Acids, peptides and aminodeoxy sugars furnished the new asymmetric diamides 16 ∼ 19 , 25 ∼ 30 , 32 , 34 and 38 ∼ 40 in stereoselective reactions which do not require protecting group-manipulations. The IC_50=0.12 µM value measured for daunorubicin ( 1 ) on human leukemia (HL-60) cells is comparable to those obtained for the daunomycin- L -leucyl Squaric Acid diamide ( 30 , IC_50=0.18 µM) and the corresponding D -galactosamine derivative ( 40 , IC_50=0.22 µM).
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formation of Squaric Acid amides of anthracycline antibiotics synthesis and cytotoxic properties
Bioorganic & Medicinal Chemistry Letters, 2004Co-Authors: Anna N Tevyashova, Ferenc Sztaricskai, Gyula Batta, Pal Herczegh, A JeneyAbstract:Abstract The reaction of the anthracycline glycoside antibiotics 1 – 3 with the Squaric Acid ester 4 gave the Squaric Acid amide esters 5 – 7 under neutral conditions, whereas over pH 7 the products are the symmetric diamides ( 8 , 9 , 11 , and 12 ). Of the prepared compounds 11 was the most active on MCF-7 human mammary adenocarcinoma cells.
Harmanton Klok - One of the best experts on this subject based on the ideXlab platform.
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Squaric Acid mediated bioconjugation expanded to polymers prepared by atrp
Polymer Chemistry, 2014Co-Authors: Tobias Steinbach, Frederik R Wurm, Harmanton KlokAbstract:The Squaric Acid mediated bioconjugation reaction is an attractive approach for the amine-selective protein modification with side-chain functional polymers. This manuscript presents 3 Squaric Acid based atom transfer radical polymerization (ATRP) initiators that significantly expand the scope of this bioconjugation reaction to a broad range of synthetic polymers that can be prepared by ATRP. Two proof-of-principle studies are discussed that demonstrate the feasibility of these novel initiators for the preparation of protein–synthetic polymer conjugates via both the grafting-onto as well as the grafting-from strategy. ATRP of polyethylene glycol methacrylate (PEGMA) with these initiators was used to generate a library of linear, mid-functional and 3-arm Squaric Acid functionalized PPEGMA derivatives. These PPEGMA polymers could subsequently be grafted onto bovine serum albumin (BSA), which was selected as a model protein. Alternatively, BSA could also be modified with these Squaric Acid based initiators to afford protein macroinitiators, which were successfully used to mediate ATRP of PEGMA and generate BSA–PPEGMA conjugates in a grafting-from process.
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be squared expanding the horizon of Squaric Acid mediated conjugations
ChemInform, 2014Co-Authors: Frederik R Wurm, Harmanton KlokAbstract:Review: overview of the well-established Squaric Acid diester mediated coupling reactions for glycoconjugates and recent advances to expand this very versatile reaction protocol to the modification of peptides and proteins; 101 refs.
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Be Squared: Expanding the Horizon of Squaric Acid‐Mediated Conjugations
ChemInform, 2013Co-Authors: Frederik R Wurm, Harmanton KlokAbstract:Review: overview of the well-established Squaric Acid diester mediated coupling reactions for glycoconjugates and recent advances to expand this very versatile reaction protocol to the modification of peptides and proteins; 101 refs.
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be squared expanding the horizon of Squaric Acid mediated conjugations
Chemical Society Reviews, 2013Co-Authors: Frederik R Wurm, Harmanton KlokAbstract:Squaric Acid diesters can be applied as reagents to couple two amino-functional compounds. Consecutive coupling of two amines allows the synthesis of asymmetric Squaric Acid bisamides with either low molecular weight compounds but also biomolecules or polymers. The key feature of the Squaric Acid diester mediated coupling is the reduced reactivity of the resulting ester-amide after the first amidation step of the diester. This allows the sequential amidation and generation of asymmetric squaramides with high selectivity and in high yields. This article gives an overview of the well-established Squaric Acid diester mediated coupling reactions for glycoconjugates and presents recent advances that aim to expand this very versatile reaction protocol to the modification of peptides and proteins.
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one pot Squaric Acid diester mediated aqueous protein conjugation
Chemical Communications, 2013Co-Authors: Frederik R Wurm, Tobias Steinbach, Harmanton KlokAbstract:A water-soluble Squaric Acid dialkyl diester derivative is presented, which enables one-pot, two-step amine-selective protein conjugation reactions with (functional) amines in water. This reagent not only allows all-aqueous protein modifications, but also tolerates e.g. hydroxyl groups and can also be used for the modification of proteins with water-insoluble amines.
Tsonko Kolev - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic elucidation of hydrogensquarate and ester amide of Squaric Acid of 2-cloro-3-amino-pyridine
Bulgarian Chemical Communications, 2020Co-Authors: Ts. D. Tsanev, Tsonko KolevAbstract:Novel derivatives of Squaric Acid with 2-chloro-3-amino-pyridine, i.e. hydrogensquarate and ester amide of Squaric Acid are synthesized, isolated and spectroscopically characterized in solution and in solid-state. Methods as conventional and linear polarized IR-spectroscopy of oriented colloid suspensions, UV-spectroscopy, 1 H- and 13 C-NMR, mass spectrometry (positive and negative ESI, FAB, HPLC tandem MS/MS), TGV and DSC methods are used. Quantum chemical ab initio and DFT calculations are performed, supporting the obtained optical experimental data.
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crystal structures and spectroscopic properties of ester amide and diamide of Squaric Acid with prolinamide
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2009Co-Authors: Tsonko Kolev, Rudiger W Seidel, Heike Mayerfigge, Michael Spiteller, William S Sheldrick, Bojidarka B KolevaAbstract:Abstract We report the synthesis, spectroscopic and structural elucidation of two prolinamide derivatives of Squaric Acid, i.e. prolinamide ester amide of Squaric Acid ethyl ester (1) and prolinamide diamide of Squaric Acid dihydrate (2). Both compounds crystallize in non-centrosymmetric space groups, monoclinic P21 (1) and orthorhombic P212121 (2), respectively. For first time in the literature the crystal structure of homodiamide of amino Acid amide of Squaric Acid is reported. The data for heterodiamides is also absent. Supramolecular zig-zag chains by hydrogen bonds of H2N–C O⋯HNH (3.020 A) and HNH⋯O C(Sq) (2.972 A) types with the participation of amide and Squaric Acid (Sq) fragments, –C O–NH2 and O C(Sq) are refined in (1). A helix supramolecular structure is formed in (2) by moderate intermolecular HNH⋯O C(NH2) hydrogen bond with length of 2.947 A. The two crystallographical non-equivalent water molecules stabilized the helix by interactions of types HOH⋯O C(Sq) (2.917 A), HOH⋯O C(NH2) (2.899 A), H2O⋯NH2(C O) (2.972 A), respectively. Optical and magnetic properties are investigated with a view to explain the correlation structure-properties of the newly synthesized molecules.
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synthesis and spectral and structural elucidation of some pyridinium betaines of Squaric Acid potential materials for nonlinear optical applications
Advanced Functional Materials, 2004Co-Authors: Tsonko Kolev, Denitsa Yancheva, S I StoyanovAbstract:A series of substituted pyridinium betaines of Squaric Acid have been prepared by quaternization reaction of 3- and 4-substituted pyridines with Squaric Acid. The products were characterized by means of elemental analysis, melting points, and their UV-vis and IR spectra. The UV-vis spectra of all investigated compounds in five different solvents were studied in detail. The UV-vis spectral elucidation has given evidence of the clearly distinct negative solvatochromism of the pyridinium betaines of Squaric Acid, characteristic for compounds with a dipolar electronic ground state structure. The two absorption bands observed in the visible region show a charge-transfer character, which determines their strong dependence on the polarity of the medium and the nature of the substituent. The investigation of the spectral behavior of pyridinium betaines of Squaric Acid has revealed their potential nonlinear optical and electro-optical properties. Furthermore, these compounds exhibit remarkable thermal stability, required for such applications. The eventual technical application of these colored single crystals is discussed.
