Showing papers on "Derivative (chemistry) published in 2017"
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15 Dec 2017
TL;DR: DFO algorithms have principally fallen into one of two categories: direct search methods and modelbased methods, and researchers began mixing direct search and model-based methods to create hybrid methods with improved performance.
Abstract: Derivative-free optimization (DFO) is the mathematical study of the optimization algorithms that do not use derivatives. While a DFO algorithm was used to test one of the worlds first computers (the MANIAC in 1952), it was not until the 1990s that DFO algorithms were studied mathematically. Blackbox optimization (BBO) is the study of optimization problems where the objective function is a blackbox. That is, no analytic description of the function is available, but given an arbitrary input the blackbox returns a function value. As BBO naturally arises whenever a computer simulation is involved in an optimization problem, BBO is one of the most rapidly expanding areas of applied optimization. BBO can naturally be approached by DFO. DFO algorithms have principally fallen into one of two categories: direct search methods and modelbased methods. Direct search methods work from an incumbent solution and examine a collection of trial points; if improvement is found, then the incumbent solution is updated, otherwise a search radius parameter is decreased and a new collection of trial points is examined. Model-based methods approximate the objective function with a model function, and use the gradients or even second derivatives of the model function to help guide optimization. (Note that while DFO studies algorithms that do not use derivatives, this does not mean that the objective function is nondifferentiable – for example the objective could be a computer simulation using numerical integration.) It was not until very recently that researchers began mixing direct search and model-based methods to create hybrid methods with improved performance.
374 citations
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TL;DR: Inherently and artificially layered materials are commonly investigated both for fundamental scientific purposes and for technological application as mentioned in this paper, when a layered material is thinned or delaminated, and when a layer is deformed.
Abstract: Inherently and artificially layered materials are commonly investigated both for fundamental scientific purposes and for technological application. When a layered material is thinned or delaminated ...
208 citations
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TL;DR: The pivotal aim of this paper was to analyze a new fractional model of chemical kinetics system related to a newly discovered Atangana-Baleanu derivative with fractional order having non-singular and non-local kernel.
Abstract: The pivotal aim of this paper was to analyze a new fractional model of chemical kinetics system related to a newly discovered Atangana-Baleanu derivative with fractional order having non-singular and non-local kernel. The numerical solution is derived by making use of the iterative scheme. The existence of the solution of chemical kinetics system of arbitrary order is examined by implementing the fixed-point theorem. The uniqueness of the special solution of the studied model is shown. The effect of different variables and order of arbitrary ordered derivative on concentrations is demonstrated in tabular and graphical forms. The numerical results for chemical kinetics system pertaining to the newly derivative with fractional order are compared with the chemical kinetics system involving classical derivative.
96 citations
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TL;DR: In this article, five new organotin(IV) complexes were synthesized and characterized using 1H NMR, 13C NMR, 119Sn NMR and infrared spectroscopic techniques, and the results demonstrate that the compounds containing Sn-Ph ligands are more effective than those with Sn-Bz ligands.
Abstract: Five new organotin(IV) complexes of composition [Bz2SnL1]n (), [Bz3SnL1H⋅H2O] (), [Me2SnL2⋅H2O] (), [Me2SnL3] () and [Bz3SnL3H]n () (where L1 = (2S)-2-{[(E)-(4-hydroxypentan-2-ylidene)]amino}-4-methylpentanoate, L2 = (rac)-2-{[(E)-1-(2-hydroxyphenyl)methylidene]amino}-4-methylpentanoate and L3 = (2S)- or (rac)-2-{[(E)-1-(2-hydroxyphenyl)ethylidene]amino}-4-methylpentanoate) were synthesized and characterized using 1H NMR, 13C NMR, 119Sn NMR and infrared spectroscopic techniques. The crystal structure of reveals a distorted trigonal-bipyramidal geometry around the tin atom where the oxygen atoms of the carboxylate ligand and a water ligand occupy the axial positions, while the three benzyl ligands are located at the equatorial positions. On the other hand, the analogous derivative of enantiopure L3H () consists of polymeric chains, in which the ligand-bridged tin atoms adopt the same trans-Bz3SnO2 trigonal-bipyramidal configuration and are now coordinated to a phenolic oxygen atom instead of H2O. In , the OH hydrogen of the ketoimine substituent has moved to the nearby nitrogen atom while in the salicylidene derivative , the OH is located almost midway between the phenolic oxygen atom and the nitrogen atom of the C[DOUBLE BOND]N group. For the dibenzyltin derivative , a polymeric chain structure is observed as a result of a long intermolecular Sn⋅⋅⋅O bond involving the exocyclic carbonyl oxygen atom from the tridentate ligand of a neighbouring tin-complex unit. The tin atom in this complex has distorted octahedral coordination geometry. In contrast, the racemic dimethyltin(IV) complexes and display discrete monomeric structures with a distorted octahedral- and trigonal-bipyramidal geometry, respectively. The structures show that the coordination mode of the Schiff base ligand depends primarily on the number of bulky benzyl ligands (R) at the tin atom, as indeed found in the structures of related complexes where R = phenyl. With three bulky R groups, the tridentate chelating O,N,O coordination mode is preferred, whereas with fewer or less bulky R ligands, only the carboxylate and hydroxy groups are involved, which leads to polymers. Larvicidal efficacies of two of the new tribenzyltin(IV) complexes ( and ) were assessed on the second larval instar of Anopheles stephensi mosquito larvae and compared with two triphenyltin(IV) analogues, [Ph3SnL1H]n and [Ph3SnL3H]n. The results demonstrate that the compounds containing Sn–Ph ligands are more effective than those with Sn–Bz ligands. Copyright © 2016 John Wiley & Sons, Ltd.
92 citations
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TL;DR: The first examples for the rhenium-catalysed hydroboration of aldehydes, ketones and aldimines, including heteroaromatic quinoline, are reported herein, and reactions are remarkably chemoselective and tolerant of several functional groups.
Abstract: The first examples for the rhenium-catalysed hydroboration of aldehydes, ketones and aldimines, including heteroaromatic quinoline, are reported herein Reactions are remarkably chemoselective and tolerant of several functional groups A wide array of rhenium complexes were efficient pre-catalysts for these hydroborations, including new low-valent complexes of the formula [Re(N–N)(CO)3(L)]X (N–N = bipy derivative, L = labile ligand/solvent, and X = [BArF4]− and [B(3,5-di-tBu-cat)2]−), which have been characterized fully including an X-ray diffraction study for [Re(bipy)(CO)3(quin)][BArF4] (2) A new silver spiroboronate ester Ag[B(3,5-di-tBu-cat)2](NCCH3)3 (3) was prepared and characterized fully, including an X-ray diffraction study, and used to make one of the new rhenium complexes
57 citations
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TL;DR: A new bidentate Lewis acid consisting of two stiborane units connected by a 1,8-triptycenediyl backbone is described, which captures fluoride with an unprecedented affinity for a neutral, water-compatible Lewis acid.
Abstract: Fluoride anion complexation impacts a number of areas ranging from sensing to nucleophilic fluorination chemistry. Described here is a new bidentate Lewis acid consisting of two stiborane units connected by a 1,8-triptycenediyl backbone. This neutral derivative captures fluoride with an unprecedented affinity for a neutral, water-compatible Lewis acid. Structural, spectroscopic and computational studies demonstrate that fluoride anion binding is assisted by the formation of a C-H⋅⋅⋅F hydrogen bond which involves a methine group of the 1,8-triptycenediyl backbone.
53 citations
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TL;DR: A europium-containing isopolyoxoniobate with the formula (CN3H6)7K3H17{Eu3(H2O)9Nb48O138(H 2O)6}·40 H2O is synthesized under the protection of citric acid and displays a red emission with the long lifetime of 258 μs.
53 citations
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TL;DR: Theoretical study of thiol-thione tautomeric forms of 1,2,4-triazole derivative with Schiff base was performed by the density functional theory (DFT) method with 6-311++G(d,p) basis set as mentioned in this paper.
48 citations
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TL;DR: Two fluorescent coordination polymers have been designed and synthesized from a tetraphenylethene (TPE) derivative that exhibit reversible mechanochromic luminescence with color changes visible to the naked-eye from blue to green-yellow by grinding or soaking in N,N-dimethylformamide (DMF) under UV irradiation.
48 citations
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TL;DR: In this paper, the global existence result for the derivative NLS equation was extended to the case when the initial data set includes a finite number of solitons, by an application of the B\"{a}cklund transformation.
Abstract: We extend the global existence result for the derivative NLS equation to the case when the initial datum includes a finite number of solitons. This is achieved by an application of the B\"{a}cklund transformation that removes a finite number of zeros of the scattering coefficient. By means of this transformation, the Riemann--Hilbert problem for meromorphic functions can be formulated as the one for analytic functions, the solvability of which was obtained recently.
43 citations
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TL;DR: N -[2-(2-bromophenyl)-1,3-benzoxazol-5-yl]-2-phenylacetamide (NBBPA) was synthesized in this paper as an original compound in order to evaluate its antibacterial activity against representative Gram-negative and Gram-positive bacteria, with their drug-resistant clinical isolate.
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TL;DR: The synthesis of a BODIPY dye substituted with a Lewis acidic antimony(v) moiety shows a high affinity for small anions including fluoride and cyanide, the complexation of which elicits a fluorescence turn-on response.
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TL;DR: Four Cd(ii)-based compounds were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-d Liamine (L), Cd (NO3)2·4H2O and aldehyde and showed excellent luminescent sensitivity for Fe3+ detection.
Abstract: Four Cd(II)-based compounds (1–4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.
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TL;DR: In this paper, a new method for free radical methylation of pyrimidinones and pyridinone with dicumyl peroxide (DCP) under metal-free conditions is introduced.
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TL;DR: In this article, a combination of X-ray structural analysis and quantum chemistry calculations was used for comparative analysis of molecular packing in the crystals of the synthesized compounds, and it was shown that the fluorinated derivative contained a shortened F···F halogen bond of the first type, and in the bromo derivative, bromine atoms formed a relatively strong Br···O=C halogen link of the second type, while the chlorine atom in the structure of chloro derivative interacted with a nitro group oxygen atom, also forming a weak Cl−·O2
Abstract: We report the synthesis, as well as the molecular and crystal structures of N-(2-halo-2,2-dinitroethyl)pyrrolidine-2,5-diones (Hal = F, Cl, Br). A combination of X-ray structural analysis and quantum chemistry calculations was used for comparative analysis of molecular packing in the crystals of the synthesized compounds. It was shown that the fluorinated derivative contained a shortened F···F halogen bond of the first type, and in the bromo derivative the bromine atoms formed a relatively strong Br···O=C halogen bond of the second type, while the chlorine atom in the structure of chloro derivative interacted with a nitro group oxygen atom, also forming a weak Cl···O2N halogen bond of the second type. These variations in the “preferences” of different halogen atoms resulted in observable differences in the crystal structures of the studied compounds.
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TL;DR: The preclinical evaluation of 99mTc-dioxime in solid tumor-bearing mice showed high accumulation inSolid tumor cells with a high Target/Non-Target ratio of 5.14 at 30 min post-injection.
Abstract: A novel dioxime derivative (2E,2′E,3E,3′E)-3,3′-(pyrimidine-4,5-diylbis(azanylylidene))bis(butan-2-one)dioxime was synthesized with a yield of 65%. IR, elemental analysis, mass spectroscopy and 1H-NMR were used to characterize the structure of the synthesized compound. 99mTc-dioxime was radio-synthesized with a high radiochemical yield of 97.8 ± 0.5% and in vitro stability of 6 h under the optimum conditions. The preclinical evaluation of 99mTc-dioxime in solid tumor-bearing mice showed high accumulation in solid tumor cells with a high Target/Non-Target ratio of 5.14 at 30 min post-injection. This study suggests that 99mTc-dioxime derivative is a promising candidate as a new 99mTc-based tumor-imaging agent after further preclinical studies.
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TL;DR: In this article, a self-assembling coumarin-bridged bifunctional UPy derivative was used to construct a 3D polymer network upon UV light irradiation via photo-cross-linking.
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TL;DR: It was demonstrated that the defluorination caused by TEMPO occurred in a radical mechanism, thus leading to formations of new spin centers on graphene nanosheets as well as C[double bond, length as m-dash]C bonds.
Abstract: Fluorinated graphene (FG) can be regarded as the representative two-dimensional (2D) material to study the characteristics of “2D chemistry”, whereas its derivative reaction mechanism is still required to be revealed for the destination of deciduous fluorine atoms after defluorination of FG. Herein, we proposed a particular derivative reaction of FG by employing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as the attacking reagent, and the products were characterized via Electron Paramagnetic Resonance Spectroscopy (EPR), Mass Spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). It was demonstrated that the defluorination caused by TEMPO occurred in a radical mechanism, thus leading to formations of new spin centers on graphene nanosheets as well as CC bonds. More importantly, the deciduous fluorine atoms after defluorination, which existed in TEMPO fluoride molecules, have been detected for the first time. Meanwhile, some TEMPO molecules were covalently grafted on the nanosheet, which resulted from the coupled reaction between TEMPO radical and the spin center on the FG nanosheet. These findings deepen the research of derivative reactions of FG, meanwhile providing a particular view to investigate the chemistry characteristics of 2D materials from a radical mechanism.
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TL;DR: In this article, the synthesis of 4-phenyl-4H-arsolo[2,3-d:5,4-d′]bis(thiazole) is reported, and its properties are compared to those of the previously prepared phosphole analogue.
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TL;DR: One new 2-aryl benzofuran derivative, artocarstilbene B, and one new benzaldehyde derivative, (E )-3,5-dihydroxy-4-(3-methylbut-1-enyl)benzaldehyde, as well as 18 known compounds ( 3,20 ) were obtained from the leaves of Artocarpus heterophyllus as mentioned in this paper.
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01 Feb 2017••
TL;DR: Exposure to MMT-containing gasoline may result in increasing reactive oxygen stress among filling station attendants and plasma Hsp70 levels could be used as a sensitive responsive biomarker for exposed workers.
Abstract: Objectives:Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) and is used as an antiknock agent and octane enhancer in gasoline. In this article, we teste...
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TL;DR: N-methylation and cyclopropylation of the bioactive l-methionine sulfoximine derivative was demonstrated under standard reaction conditions and the reactions provide excellent yields in a short span of time under mild conditions.
Abstract: The copper meditated N-methylation of sulfoximines using methylboronic acid is reported. The reactions provide excellent yields in a short span of time under mild conditions. The optimized conditions were also found to be suitable for the N-alkylation of sulfoximine with different alkylboronic acids. In addition, N-methylation and cyclopropylation of the bioactive l-methionine sulfoximine derivative was demonstrated under standard reaction conditions.
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TL;DR: A batch of a promising candidate for optimization studies turned out to be a mixture containing two unknown species with a better biological activity than the pure compound, and this serendipitous discovery led to investigate the chemical nature of the unknown components of the mixture.
Abstract: In the last two decades, the repertoire of clinically effective antibacterials is shrinking due to the rapidly increasing of multi-drug-resistant pathogenic bacteria. New chemical classes with innovative mode of action are required to prevent a return to the pre-antibiotic era. We have recently reported the identification of a series of linear guanidine derivatives and their antibacterial properties. A batch of a promising candidate for optimization studies (compound 1) turned out to be a mixture containing two unknown species with a better biological activity than the pure compound. This serendipitous discovery led us to investigate the chemical nature of the unknown components of the mixture. Through MS analysis coupled with design and synthesis we found that the components were spontaneously generated oligomers of the original compound. Preliminary biological evaluations eventually confirmed the broad-spectrum antibacterial activity of this new family of molecules. Interestingly the symmetric dimeric derivative (2) exhibited the best profile and it was selected as lead compound for further studies.
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TL;DR: The preparation and characterization of a functional polymer bearing a pendant indole group via a reversible-addition fragmentation and chain transfer process followed by its modification via an Alder-ene 'click' reaction using a 1,2,4-triazoline-3,5-dione (TAD) derivative showed thermo-reversible as well as healing characteristics.
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TL;DR: Significantly, the rodamine-coumarin derivative exhibited highly selective and sensitive recognition toward Zn2+ with a limit of detection (LOD) down to 10−9 M.
Abstract: A coumarin-appended rhodamine derivative was prepared by reacting rhodamine hydrazide and coumarin-3-carboxylic acid, which fluorescence sensing behavior toward Zn2+ against other metal ions was investigated in CH3CN. Significantly, the rodamine-coumarin derivative exhibited highly selective and sensitive recognition toward Zn2+ with a limit of detection (LOD) down to 10−9 M. Upon addition of Zn2+, remarkable fluorescent intensities enhanced and also clear color changed from colorless to pink. The Job’s plot indicated the formation of 1:1 complex between the rhodamine-coumarin derivative and Zn2+. The presence of common coexisting alkali, alkaline earth, and transition metal ions showed small or no interference with the detection of Zn2+. The conjugate dye could be used for “naked-eye” detection of Zn2+.
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TL;DR: In this paper, a solid acid derivative of β-cyclodextrin was synthesized as an adsorbent for CO2 capture, and the adsorption characteristics, such as adsorship capacity, selectivity, and uptake rate, under different temperatures and gas pressures were analyzed.
Abstract: A solid acid derivative of β-cyclodextrin was synthesized as an adsorbent for CO2 capture. The adsorption characteristics, such as adsorption capacity, selectivity, and uptake rate, under different temperatures and gas pressures were analyzed. The results from scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller (BET) sorption, Fourier transform infrared spectroscopy, andthermogravimetric analysis indicated that the dehydration and grafting of sulfonic groups changed the structure of β-cyclodextrin aggregates into a relatively homogeneous porous structure with a concave–convex surface. Meanwhile, the specific BET surface area and pore volume of the solid acid derivative were increased by 40 and 37 times compared to β-cyclodextrin aggregates. Thereby, the performance of the solid acid derivative of β-cyclodextrin toward CO2 sorption was significantly enhanced, in which CO2 adsorption capacity at 3.5 bar was increased to 1.78 mmol/g and the selectivity of CO2 over N2, O...
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TL;DR: This work reports the first Bronsted acidic ionic liquid (IL) promoted reaction of 5-pyrazolones with aryltriazenes to prepare arylazopyrazolone and obtained the desired products in good to excellent yields.
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TL;DR: One new chromone derivative, (2ʹS*)-2-(2-hydroxypropyl)-5-methyl-7, 8-dihydroxy-chromone, together with three known compounds, bacillisporin A, bacsporin B and 5-carboxyphthalide were obtained from the mangrove-derived fungus Penicillium aculeatum by the detailed analysis of comprehensive spectroscopic data.