The kinetics for the coil-to-globule transition of linear poly(N-isopropylmethacrylamide) (PiPMA) chains has been studied by use of the fluorescence and Rayleigh scattering with a fast laser pulse infrared heating. We have observed the two-stage kinetics in the collapse transition with the chara...
In this work, poly(N-isopropylmethacrylamide-co-acrylic acid) [p(NIPMAM-co-AAc)] microgels were synthesized by using precipitation polymerization method. Silver nanoparticles (AgNPs) were uniformly dispersed inside the sieves of the engineered microgels by in situ reduction method. Both microgel...
Poly(N-isopropylmethacrylamide-acrylic acid) [pniM-Ac] microgel particles were synthesized by surfactant free radical precipitation polymerization method. Microgel particles were used as adsorbent for the removal of toxic dyes such as Congo red (CR) (anionic), methylene blue (MB) (cationic) and ...
Here we studied the homologation of leucic and phenyl lactic acid via Wolff-rearrangement of their diazoketones to the corresponding β-hydroxy acids. This reaction requires distinct conditions to that of their amino acid analogues. The choice of the Oα-substituent can selectively direct the re...
α-Hydroxy acids are commonly encountered in natural bioactive molecules. For convenient determination of the absolute configurations of α-hydroxy acids, a simple method, named the “O-Marfey method” was developed using a chiral derivatization strategy with (1-fluoro-2,4-dinitrophenyl-5)-l-ala...
Biodegradable polydepsipeptides having the sequences of l-alanyl-l-amino acyl-γ-ethyl l-glutamyl-l-hydroxy acyl [Ala-AA-Glu(OEt)-HA] were synthesized to evaluate the hydrolysis of the specimens by the action of enzymes. The enzymatic degradation and its degradation pattern were strongly depende...
DL-alfa-hydroxy-isocaproic acid (HICA), also known as leucic acid or DL-2-hydroxy-4-methylvaleric acid, is an alfa-hydroxyl acid metabolite of leucine. According to clinical and experimental studies, HICA can be considered as an anticatabolic substance that may also increase muscle protein synth...
Two BINOL based boronate esters, namely (S)-2 and (S)-3, were designed and synthesized. Fluorescent recognition studies of (S)-2 towards enantiomers of mandelic acid revealed that sensor (S)-2 exhibited high fluorescent enantioselective response towards mandelic acid. The other boronate ester (S...
The oxidation system comprised of TEMPO and (diacetoxyiodo)benzene (stoichiometric) is enhanced during the conversion of primary alcohols to aldehydes by adding a catalytic amount of acids, p-TsOH and PPTS. 2-Alkylidene-1,3-propanediols, available from 1,3-dihydroxyacetone, are oxidized under th...
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), a key enzyme in the folate biosynthetic pathway, catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin. The enzyme is essential for microorganisms, is absent from humans, and is not the target for any exist...
The crystal structure of the title compound was determined by X-ray crystallography and solved by direct methods; the molecule has C2h symmetry. The carbon atoms are arranged in a diamondoid lattice, but not of the rectangular type that might have been expected. The dipole moment for the conform...
(±)-Tryptoquivaline G was formally synthesized through shortened steps from tryptophan, in which oxidation with thallium(III) trinitrate(TTN) was effected at the crucial stage. The present work also constitutes the first synthesis of oxindole lactones carrying 2-alkyl quinazolinones.
An unusual oxidative cyclization of chalcones by thallium (III) trinitrate (TTN) to 4-methoxyaurones has been studied. A key feature of this reaction is the introduction of a methoxyl group into the aurone skeleton. Several reactions have been performed to understand the mechanism and regiochemi...
An efficient four step protocol for the construction of functionalized indans was developed. 1-Tetralones were transformed into unsaturated esters by Reformatsky reaction with bromo-esters (ethyl 2-bromopropionate, ethyl bromoacetate or ethyl 2-bromobutyrate), followed by dehydration of the β-h...
The reaction of 3- and 4-alkylcyclohexanones with thallium trinitrate (TTN) leads to the alkylcyclopentanecarboxylic acids in good yields and with high degree of stereoselectivity. The ring contraction of 2-methylcyclohexanone gives poor yields and 2,6-dimethylcyclohexanone does not undergo cont...
Oxidation of 1,2-dihydronaphthalenes with thallium trinitrate was studied. 1,2-dihydronaphthalene, 1-methyl-1,2-dihydronaphthalene, 6- and 8-methoxy-1,2-dihydronaphthalenes gave rise to the respective ring contraction products in good yields, whereas the rearrangement was not observed using 4-me...
Influence of the water content to chemical status of trivalent rare earth ions in calcium nitrate hydrate melt was studied by spectroscopic techniques. Fluorescence spectrometry for Eu(III) in Ca(NO3)2·RH2O and electronic absorption spectrometry for Nd(III) in Ca(NO3)2·RH2O were performed for ...
The nitrate conversion with liquefied NO2 and the nitrate extraction with SC-CO2 were demonstrated for copper powder and neodymium nitrate instead of actinide compounds. Copper contacted with NO2 in an autoclave at 353 K changed to water-soluble compounds. By XRD analysis of the product in the a...
A series of dinuclear complexes having general formula, [M1(NO3)(valpn)M2(NO3)2(H2O)2]·H2O where M1 = Cu(1–6) and M2 = La(1), Nd(2), Sm(3), Gd(4), Tb(5) and Er(6), have been synthesized from the bifunctional ligand (H2valpn = 2,2'-{propane-1,3-diylbis[nitrilo(E)methylylidene]}bis(6-methox...
Compounds with composition Ln(pic)3·2pyzNO·7H2O (Ln=Nd, Eu; pic=picrate; pyzNO=pyrazine-N-oxide) were obtained by reaction of the hydrated lanthanide picrate with pyrazine-N-oxide in ethanol (molar ratio 1:4). The adducts were characterized by elemental analyses and IR spectra. X-ray single cr...
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