Showing papers in "Journal of Chemical Sciences in 2012"
TL;DR: Microwave assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved as discussed by the authors.
Abstract: Microwave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed moderate to good activity.
64 citations
TL;DR: In this paper, a novel and practically useful protocol has been designed wherein, polyvinyl pyrrolidone (PVP) stabilized nickel nanoparticles have been used as a catalyst for promoting the synthesis of 2,2′-aryl-methylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one), also known as tetraketones, and biscoumarins via Knoevenagel condensation followed by rapid Michael addition.
Abstract: A novel and practically useful protocol has been designed wherein, polyvinyl pyrrolidone (PVP) stabilized nickel nanoparticles have been used as a catalyst for promoting the synthesis of 2,2′-aryl-methylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one), 2,2′-aryl-methylene bis(3-hydroxy-2-cyclohexene-1-one), also known as tetraketones, and biscoumarins via Knoevenagel condensation followed by rapid Michael addition.
55 citations
TL;DR: In this article, a simple, green and efficient protocol for synthesis of dihydropyrano[2,3-c]pyrazole derivatives is developed by a four component reaction of various benzaldehydes, ethyl acetoacetate, hydrazine hydrate and malononitrile in the presence of 3-methyl-1-(4-sulphonic acid)butylimidazolium hydrogen sulphate [(CH2)4SO3HMIM][HSO4], an acidic ionic liquid and as a catalyst, under solvent-
Abstract: A simple, green and efficient protocol for synthesis of dihydropyrano[2,3-c]pyrazole derivatives is developed by a four component reaction of various benzaldehydes, ethyl acetoacetate, hydrazine hydrate and malononitrile in the presence of 3-methyl-1-(4-sulphonic acid)butylimidazolium hydrogen sulphate [(CH2)4SO3HMIM][HSO4], an acidic ionic liquid and as a catalyst, under solvent-free conditions. The key advantages of this process are high yields, shorter reaction times, easy work-up, purification of products by non-chromatographic method and the reusability of the catalyst.
42 citations
TL;DR: In this paper, a series of Mn(II)bipy complexes with different loading of Mn2+ ions supported on HMS was prepared for the oxidation of benzyl alcohol in the liquid phase using tert-butylhydroperoxide (TBHP) as an oxidant.
Abstract: A series of Mn(II)bipy complexes with different loading of Mn2 + supported on HMS was prepared. These samples were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Thermogravimetric and Differential Scanning Calorimetry (TG-DSC), Ultraviolet and Visible spectra (UV-Vis) and Fourier transforms Infrared (FT-IR). The catalytic activity of the supported Mn(II)bipy complexes, [Mn(bipy)2]2 + /HMS was evaluated in the oxidation of benzyl alcohol in the liquid phase using tert-butylhydroperoxide (TBHP) as an oxidant. The effects of Mn2 + loading and various solvents on the conversion and selectivity were studied. A second order function for the variation in catalytic activity with respect to the loading of Mn2 + ions in different catalyst samples was observed. The activity of the [Mn(bipy)2]2 + /HMS catalyst differs with the type of the solvent and in this case, acetonitrile gives the best conversion results. The kinetic of benzyl alcohol oxidation was investigated at temperatures of 27, 46, 60, 75 and 90°C using [Mn(bipy)2]2 + /HMS and excess TBHP. The order of reaction with respect to benzyl alcohol was determined to be pseudo-first order. The value of the apparent activation energy was also determined.
42 citations
TL;DR: In this article, an efficient green chemistry method was developed for the synthesis of 1-amidoalkyl-2-naphthol derivatives via a one-pot three-component condensation of 2 naphthols, aldehydes and amide in the presence of boric acid as a mild catalyst.
Abstract: An efficient green chemistry method has been developed for the synthesis of 1-amidoalkyl-2-naphthol derivatives via a one-pot three-component condensation of 2-naphthol, aldehydes and amide in the presence of boric acid as a mild catalyst.
39 citations
TL;DR: Anatase Ag-TiO2 microwires with high sensitivity and photocatalytic activity were synthesized via polyol synthesis route followed by a simple surface modification and chemical reduction approach for attachment of silver as discussed by the authors.
Abstract: Anatase Ag–TiO2 microwires with high sensitivity and photocatalytic activity were synthesized via polyol synthesis route followed by a simple surface modification and chemical reduction approach for attachment of silver. The superior performance of the Ag–TiO2 composite microwires is attributed to improved surface reactivity, mass transport and catalytic property as a result of wiring the TiO2 surface with Ag nanoparticles. Compared to the TiO2 microwires, Ag–TiO2 microwires exhibited three times higher sensitivity in the detection of cationic dye such as methylene blue. Photocatalytic degradation efficiency was also found to be significantly enhanced at constant illumination protocols and observation times. The improved performance is attributed to the formation of a Schottky barrier between TiO2 and Ag nanoparticles leading to a fast transport of photogenerated electrons to the Ag nanoparticles.
36 citations
TL;DR: Carboxy functionalized ionic liquid [cmmim][BF4] has been demonstrated to be an efficient and green catalyst for the one pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones heterocycles under microwave irradiation as discussed by the authors.
Abstract: Carboxy functionalized ionic liquid [cmmim][BF4] has been demonstrated to be an efficient and green catalyst for the one pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones heterocycles under microwave irradiation. The ionic liquid-microwave strategy represents an easy access to Biginelli compounds with high yields and purity. The protocol was found to be compatible with different structurally diverse aldehydes. The ionic liquid was recycled and reused in at least six subsequent reactions with consistent activity.
36 citations
TL;DR: The metal organic frameworks (MOFs) have evolved to be an important family and a corner stone for research in the area of inorganic chemistry and have attracted researchers from other disciplines to actively engage themselves in this area as discussed by the authors.
Abstract: The metal organic frameworks (MOFs) have evolved to be an important family and a corner stone for research in the area of inorganic chemistry. The progress made since 2000 has attracted researchers from other disciplines to actively engage themselves in this area. This cooperative synergy of different scientific believes have provided important edge and spread to the chemistry of metal-organic frameworks. The ease of synthesis coupled with the observation of properties in the areas of catalysis, sorption, separation, luminescence, bioactivity, magnetism, etc., are a proof of this synergism. In this article, we present the recent developments in this area.
35 citations
TL;DR: In this article, various 2-amino-N′-{3-(2′,5′-disubstituted-1H-indol-3′-yl)methylene}-4,5-dimethylthieno-3- carbohydrazides (3) synthesized by condensation of 2.
Abstract: Various 2-amino-N′-{3-(2′,5′-disubstituted-1H-indol-3′-yl)methylene}-4,5-dimethylthieno-3- carbohydrazides (3) synthesized by condensation of 2-amino-4,5-dimethyl thiophene-3-carbohydrazide (2) with 2,5- disubstituded indole-3-carboxaldehyde (1). The Schiff’s base (3) on cyclocondensation with acetic anhydride and triethyl orthoformate afforded thienopyrimidine analogues (4) and (7), respectively. Compounds 4 or 7 on cyclization with thioglycolic acid and chloroacetyl chloride gave thiazolidin-4-ones (5) or (8) and azitidin-2-ones (6) or (9) respectively. The structures of these newly synthesized compounds have been established on the basis of their spectral data and elemental analysis. Some of the compounds exhibited promising antioxidant and antimicrobial activities.
33 citations
TL;DR: In this paper, a brief account on designing of calixarene-based molecular sensor for recognition of various metal ions and anions and also different analytical techniques to monitor the recognition event is presented.
Abstract: This article presents a brief account on designing of calixarene-based molecular sensor for recognition of various metal ions and anions and also different analytical techniques to monitor the recognition event. This review focuses only on calix[4]arene derivatives, in which mainly the lower rim is modified incorporating either crown moiety to make calix–crown hybrid ionophore to encapsulate metal ions or some fluoregenic inorganic and organic moieties to use it as signalling unit. In order to investigate effect of conformation of the calixarene unit and steric crowding on ion selectivity, designing of these molecules have been made using both the cone and 1,3-alternate conformations of the calixarene unit and also incorporating bulky ter-butyl group in few cases to impose controlled steric crowding. Among various ions, here focuses are mainly on biologically and commercially important alkali metal ion such as K + , toxic metal ions such as Hg2 + , Pb2 + , Cd2 + , important transition metal ion such as Cu2 + and toxic anion like F − . The techniques used to monitor the recognition event and also to determine binding constants with strongly interacting ions are fluorescence, UV-vis and 1H NMR spectroscopy. Most of the ionophores reported in this review have been characterized crystallographically, however no structural information (except one case) are incorporated in this article, as it will occupy space without significant enhancement of chemistry part. Different factors such as size of the ionophore cavity, size of metal ion, coordination sites/donor atoms, steric crowding and solvents, which determine selectivity have been discussed. Response of ion recognition process to different analytical techniques is another interesting factor discussed in this article.
33 citations
TL;DR: In this article, different substituted diesters of thiazolopyrimidine were prepared by the treatment of 3,4 dihydropyrimidine2-thione with α-haloesters using ethanol under reflux condition affording 71-85% yield.
Abstract: Different substituted diesters of thiazolopyrimidine were prepared by the treatment of 3,4 dihydropyrimidine2-thione with α-haloesters using ethanol under reflux condition affording 71–85% yield. IR, 1HNMR, 13CNMR and elemental analyses were used for the characterization of these compounds. The crystal and molecular structure of one of the product, 5-phenyl-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarboxylic acid diethyl ester (3e) was verified by single crystal X-ray diffraction method. The antimicrobial activity was evaluated against four bacterial strains and one fungal species. Few of the derivatives exhibited antibacterial and antifungal activities.
TL;DR: In this paper, Bhageerath et al. present a critique on the current status of prediction of protein tertiary structures and present a hybrid model which exploits local similarities together with ab initio models to arrive at reasonable predictions.
Abstract: Protein folding, considered to be the holy grail of molecular biology, remains intractable even after six decades since the report of the first crystal structure. Over 70,000 X-ray and NMR structures are now available in protein structural repositories and no physico-chemical solution is in sight. Molecular simulation methodologies have evolved to a stage to provide a computational solution to the tertiary structures of small proteins. Knowledge base driven methodologies are maturing in predicting the tertiary structures of query sequences which share high similarities with sequences of known structures in the databases. The void region thus seems to be medium (>100 amino acid residues) to large proteins with no sequence homologs in the databases and hence which has become a fertile ground for the genesis of hybrid models which exploit local similarities together with ab initio models to arrive at reasonable predictions. We describe here the development of Bhageerath an ab initio model and Bhageerath-H a hybrid model and present a critique on the current status of prediction of protein tertiary structures.
TL;DR: One pot synthesis of 1,4-dihydropyridine derivatives was achieved via condensation of various β-ketoesters with aromatic/aliphatic aldehydes and ammonium acetate as discussed by the authors.
Abstract: One pot synthesis of 1,4-dihydropyridine derivatives was achieved via condensation of various β-ketoesters with aromatic/aliphatic aldehydes and ammonium acetate. The reaction was catalysed by a stable and reusable Bronsted acidic ionic liquid (IL), 1-methyl-imidazolium trifluoroacetate ([Hmim]Tfa), under microwave (MW) irradiation. The synergistic combination of MW with IL can potentially go a long way to meet the increasing demand for chemical processes. This homogeneous catalytic procedure is simple and efficient. The catalyst can be reused at least four times with almost complete retention in its activity.
TL;DR: In this article, a series of dihydrobenzo[h]quinazoline derivatives were synthesized using arylmethylene 2, thiopyrimidine 3 and 2-(4-(thiophen-2-yl)-5,6-dihydrobenzos[h]-quinazolin 2-ylthio) acetic acid (4) as starting materials.
Abstract: A series of dihydrobenzo[h]quinazoline derivatives 5–19 were synthesized using arylmethylene 2, thiopyrimidine 3 and 2-(4-(thiophen-2-yl)-5,6-dihydrobenzo[h]quinazolin-2-ylthio) acetic acid (4) as a starting materials. The biological screening showed that many of these compounds have good anticancer and antiviral activities. The structure assignments of the new compounds based on chemical and spectroscopic evidence. The detailed synthesis, spectroscopic data, and pharmacological properties are reported.
TL;DR: Attempts have been made in this perspective article to review and highlight the photocytotoxic behaviour of various lanthanide complexes for their potential photochemotherapeutic applications.
Abstract: Lanthanide complexes have recently received considerable attention in the field of therapeutic and diagnostic medicines. Among many applications of lanthanides, gadolinium complexes are used as magnetic resonance imaging (MRI) contrast agents in clinical radiology and luminescent lanthanides for bioanalysis, imaging and sensing. The chemistry of photoactive lanthanide complexes showing biological applications is of recent origin. Photodynamic therapy (PDT) is a non-invasive treatment modality of cancer using a photosensitizer drug and light. This review primarily focuses on different aspects of the chemistry of lanthanide complexes showing photoactivated DNA cleavage activity and cytotoxicity in cancer cells. Macrocyclic texaphyrin-lanthanide complexes are known to show photocytotoxicity with the PDT effect in near-IR light. Very recently, non-macrocyclic lanthanide complexes are reported to show photocytotoxicity in cancer cells. Attempts have been made in this perspective article to review and highlight the photocytotoxic behaviour of various lanthanide complexes for their potential photochemotherapeutic applications.
TL;DR: Alkyl/benzyl azides can be readily synthesized in excellent yields from their corresponding alcohols by stirring a solution of sodium azide in DMSO with a thoroughly ground equimolecular mixture of triphenylphosphine, iodine and imidazole.
Abstract: Alkyl/benzyl azides can be readily synthesized in excellent yields from their corresponding alcohols by stirring a solution of sodium azide in DMSO with a thoroughly ground equimolecular mixture of triphenylphosphine, iodine and imidazole.
TL;DR: A cheap and recyclable silica supported Fe (III) was prepared as heterogeneous catalyst for the synthesis of various substituted 1,4-dihydropyridines via condensation of aldehydes with ethyl acetoacetate and ammonium acetate in ethanol.
Abstract: A cheap and recyclable silica (NPs) supported Fe (III) was prepared as heterogeneous catalyst for the synthesis of various substituted 1,4-dihydropyridines via condensation of aldehydes with ethyl acetoacetate and ammonium acetate in ethanol. The products were separated from the catalyst simply by filtration and the catalyst could be recycled and reused for several times without noticeable decrease in the catalytic activity.
TL;DR: In this paper, a density functional analysis of LiN3 and KN3 is performed with the inclusion of van der Waals interactions at semi empirical level, as these materials are typical molecular solids.
Abstract: Metal azides are well-known for their explosive properties such as detonation or deflagration. As chemically pure sources of nitrogen, alkali metal azides under high pressure have the ability to form polymeric nitrogen, an ultimate green high energy density material with energy density three times greater than that of known high energetic materials. With this motive, in this present work, we try to address the high-pressure behaviour of LiN3 and KN3 by means of density functional calculations. All the calculations are performed with the inclusion of van der Waals interactions at semi empirical level, as these materials are typical molecular solids. We found that both LiN3 and KN3 are structurally stable up to the studied pressure range of 60 GPa and 16 GPa, respectively. At ambient conditions both the materials are insulators with a gap of 3.48 eV (LiN3) and 4.08 eV (KN3) and as pressure increases the band gap decreases and show semiconducting nature at high pressures. We also found that the compressibility of both the crystals is anisotropic which is in good agreement with experiment. Our theoretical study proved that the materials under study may have the ability to form polymeric nitrogen because of the decrease in interazide ion distance and possible overlapping of N atomic orbitals.
TL;DR: In this paper, the synthesis and antibacterial activity of some novel biologically active sulfonamide derivatives at C-8 alkyl chain of anacardic acid (7a−7l) were tested for Gram positive and Gram negative bacterial cultures.
Abstract: Synthesis and antibacterial activity of some novel biologically active sulfonamide derivatives at C-8 alkyl chain of anacardic acid (7a–7l), prepared from commercially available anacardic acid mixture (1a–d). These compounds were tested for Gram positive and Gram negative bacterial cultures; most of the compounds showed higher antibacterial activity compared with standard drug ampicillin.
TL;DR: 3-Alkylidene-1,3-dihydroisobenzofurans exhibited moderate antidepressant activity as evaluated by forced swim and tail suspension test methods and virtual screening was carried out by docking the designed compounds into the serotonin binding sites of arabinase protein to predict the analogue binding mode of the compounds to the SSRIs.
Abstract: 3-Alkylidene-1,3-dihydroisobenzofurans exhibited moderate antidepressant activity as evaluated by forced swim and tail suspension test methods. Virtual screening was carried out by docking the designed compounds into the serotonin binding sites of arabinase protein to predict the analogue binding mode of the compounds to the SSRIs.
TL;DR: The simple connection between the Slater orbitals and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics as mentioned in this paper.
Abstract: The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.
TL;DR: In this paper, the electrostatic interaction energy distribution (EIED) of individual water molecules (hydrogen bonded to SCO) with side chain oxygen atoms shows a surprising two peak character with the lower energy peak almost coincident with the energy distribution of water hydrogen bonded to backbone oxygen atoms (BBO).
Abstract: Dielectric dispersion and NMRD experiments have revealed that a significant fraction of water molecules in the hydration shell of various proteins do not exhibit any slowing down of dynamics. This is usually attributed to the presence of the hydrophobic residues (HBR) on the surface, although HBRs alone cannot account for the large amplitude of the fast component. Solvation dynamics experiments and also computer simulation studies, on the other hand, repeatedly observed the presence of a non-negligible slow component. Here we show, by considering three well-known proteins (lysozyme, myoglobin and adelynate kinase), that the fast component arises partly from the response of those water molecules that are hydrogen bonded with the backbone oxygen (BBO) atoms. These are structurally and energetically less stable than those with the side chain oxygen (SCO) atoms. In addition, the electrostatic interaction energy distribution (EIED) of individual water molecules (hydrogen bonded to SCO) with side chain oxygen atoms shows a surprising two peak character with the lower energy peak almost coincident with the energy distribution of water hydrogen bonded to backbone oxygen atoms (BBO). This two peak contribution appears to be quite general as we find it for lysozyme, myoglobin and adenylate kinase (ADK). The sharp peak of EIED at small energy (at less than 2 k(B)T) for the BBO atoms, together with the first peak of EIED of SCO and the HBRs on the protein surface, explain why a large fraction (similar to 80%) of water in the protein hydration layer remains almost as mobile as bulk water Significant slowness arises only from the hydrogen bonds that populate the second peak of EIED at larger energy (at about 4 k(B)T). Thus, if we consider hydrogen bond interaction alone, only 15-20% of water molecules in the protein hydration layer can exhibit slow dynamics, resulting in an average relaxation time of about 5-10 ps. The latter estimate assumes a time constant of 20-100 ps for the slow component. Interestingly, relaxation of water molecules hydrogen bonded to back bone oxygen exhibit an initial component faster than the bulk, suggesting that hydrogen bonding of these water molecules remains frustrated. This explanation of the heterogeneous and non-exponential dynamics of water in the hydration layer is quantitatively consistent with all the available experimental results, and provides unification among diverse features.
TL;DR: In this paper, the fabrication of thin films of porphyrin and metallophthalocyanine derivatives on different substrates for the optochemical detection of HCl gas and electrochemical determination of L-cysteine (CySH) was described.
Abstract: This paper describes the fabrication of thin films of porphyrin and metallophthalocyanine derivatives on different substrates for the optochemical detection of HCl gas and electrochemical determination of L-cysteine (CySH). Solid state gas sensor for HCl gas was fabricated by coating meso-substituted porphyrin derivatives on glass slide and examined optochemical sensing of HCl gas. The concentration of gaseous HCl was monitored from the changes in the absorbance of Soret band. Among the different porphyrin derivatives, meso- tetramesitylporphyrin (MTMP) coated film showed excellent sensitivity towards HCl and achieved a detection limit of 0.03ppm HCl. Further, we have studied the self-assembly of 1,8,15,22-tetraaminometallophthalocyanine (4α-MTAPc; M = Co and Ni) from DMF on GC electrode. The CVs for the self-assembled monolayers (SAMs) of 4α-CoIITAPc and 4α-NiIITAPc show two pairs of well-defined redox couple corresponding to metal and ring. Using the 4α-CoIITAPc SAM modified electrode, sensitive and selective detection of L-cysteine was demonstrated. Further, the SAM modified electrode also successfully separates the oxidation potentials of AA and CySH with a peak separation of 320mV.
TL;DR: In this paper, a stable dialkylsilylene, 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl (1), is summarized and their mechanisms are discussed.
Abstract: Various reactions for a stable dialkylsilylene, 2,2,5,5-tetrakis(trimethylsilyl)silacyclopentane-1,1-diyl (1), are summarized and their mechanisms are discussed. Silylene 1 isomerizes to the corresponding silaethene via the 1,2-trimethylsilyl migration. Reduction of 1 with alkali metals affords the corresponding radical anion 1
. − with a relatively small 29Si hfs constant (2.99 mT) and a large g-factor (g = 2.0077) compared with those for trivalent silyl radicals. Photo-excitation of 1 generates the corresponding singlet excited state (1
1 ∗ ) with the lifetime of 80.5 ns. The excited state reacts with C=C double bond compounds including benzene, naphthalene, and (E)- and (Z)-2-butenes. Although the thermal reactions of 1 with haloalkanes occur via radical mechanisms, the insertion into O–H, Si–H and Si–Cl bonds proceeds concertedly via the three-membered cyclic transition states. The reaction of 1 with H2SiCl2 gives the Si–Cl insertion product exclusively, while the quantitative insertion to Si–H bond occurs when Me2SiHCl is used as a substrate. The origin of the rather unusual Si–H/Si–Cl selectivity is elucidated using DFT calculations. Silylene 1 adds to C=C, C≡C, and C=O π bonds to afford the corresponding silacycles as stable compounds. The importance of the carbonyl silaylides during the reactions of silylenes with aldehydes and ketones is emphasized.
TL;DR: In this article, transition metal oxide (TiO2, Fe2O3, CoO) loaded MCM-41 and MCM 48 were synthesized by a two-step surfactant based process.
Abstract: Transition metal oxide (TiO2, Fe2O3, CoO) loaded MCM-41 and MCM-48 were synthesized by a two-step surfactant based process. Nanoporous, high surface area compounds were obtained after calcination of the compounds. The catalysts were characterized by SEM, XRD, XPS, UV-vis and BET surface area analysis. The catalysts showed high activity for the photocatalytic degradation of both anionic and cationic dyes. The degradation of the dyes was described using Langmuir–Hinshelwood kinetics and the associated rate parameters were determined.
TL;DR: Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of β, γ-unsaturated ketones and allylation to acid chlorides is presented as discussed by the authors.
Abstract: Copper ferrite nano material as reusable heterogeneous initiator in the synthesis of β, γ-unsaturated ketones and allylation to acid chlorides are presented The reaction of allylichalides with various acid chlorides is achieved in the presence of copper ferrite nano powders at room temperature in tetrahydrofuran (THF) The present method is first of its kind in the synthesis of title compounds without any additive/ co-catalyst The nano catalyst is easily recovered and its reusability is recorded
TL;DR: In this paper, a method for the voltammetric determination of dopamine (DA) and norepinphrine (NE) based on poly(L-aspartic acid) modified glassy carbon electrode (GCE) is reported.
Abstract: A convenient and useful method for the voltammetric determination of dopamine (DA) and norepinphrine (NE) based on poly(L-aspartic acid) modified glassy carbon electrode (GCE) is reported in this paper. The modified electrode exhibits excellent electro-catalytic activities for the oxidation–reduction of DA and NE, as well as eliminating the interference of ascorbic acid (AA) and uric acid (UA). Factors influencing the detection processes are optimized and the kinetic parameters are calculated. Under the optimal conditions, the anodic peak currents of DA and NE are linear with their concentration and the detection limits (S/N = 3) are 1.0 × 10 − 9 mol L − 1 for DA and 4.31 × 10 − 9 mol L − 1 for NE, respectively. The practical application of this method is demonstrated by determining the concentration of NE and DA in injection which is commercially available with satisfactory results. Compared with other electrochemical methods, this method is simple, highly selective and sensitive.
TL;DR: In this article, an ab initio molecular dynamics study of vibrational spectral diffusion and hydrogen bond dynamics in aqueous solution of acetone at room temperature is presented, which reveals three time scales: a short-time relaxation (~80fs), a slower relaxation (~1.3ps), and another longer time constant (12ps) corresponding to the escape dynamics of water from the solute hydration shell.
Abstract: We present an ab initio molecular dynamics study of vibrational spectral diffusion and hydrogen bond dynamics in aqueous solution of acetone at room temperature. It is found that the frequencies of OD bonds in the acetone hydration shell have a higher stretch frequency than those in the bulk water. Also, on average, the frequencies of hydration shell OD modes are found to increase with increase in the acetone–water hydrogen bond distance. The vibrational spectral diffusion of the hydration shell water molecules reveals three time scales: A short-time relaxation (~80fs) corresponding to the dynamics of intact acetone–water hydrogen bonds, a slower relaxation (~1.3ps) corresponding to the lifetime of acetone–water hydrogen bonds and another longer time constant (~12ps) corresponding to the escape dynamics of water from the solute hydration shell. The present first principles results are compared with those of available experiments and classical simulations.
TL;DR: In this paper, a single crystal tetramethylpiperazinium picrate (TMPP) was grown by slow evaporation solution growth method at room temperature.
Abstract: Good quality single crystals of 4-hydroxy tetramethylpiperazinium picrate (TMPP) were grown by slow evaporation solution growth method at room temperature. The average dimensions of the grown crystals were 0.6 × 0.2 × 0.2 cm3. The solubility of the compound was estimated using methanol and acetone. The elemental analysis confirms the formation of the compound in the stoichiometric proportion. The UV-visible transmittance study indicates that the crystal possesses minimum transmittance at 370 nm and no absorption at 470–900 nm. The Bragg peaks obtained in the powder X-ray diffraction pattern confirm its crystallinity. The thermal behaviour of the crystal was investigated using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The structure of the compound was determined by using single crystal X-ray diffraction method. The compound was found to be crystallize in the monoclinic space group P2(1)/c (a = 6.9513(8)A, b = 11.8016(14)A, c = 22.018(2)A, α = 90.00°, β = 92.575(2)°, γ = 90.00°). The thermal anomalies observed in the differential scanning calorimetry (DSC) heating and cooling cycles indicate the occurrence of first order phase transition. Fourier transform infrared (FTIR) and polarized Raman spectral analyses were used to confirm the presence of various functional groups in the compound. The nonlinear optical property (NLO) of the crystal was analysed by Kurtz-Perry powder technique and found that the compound has SHG efficiency 1.5 times greater that of potassium dihydrogen phosphate (KDP).
TL;DR: A clean and environmentally friendly protocol for the synthesis of amides by using different benzylic or tertiary alcohols and different nitriles in the presence of silica-bonded N- propyl sulphamic acid (SBNPSA) as catalyst under solvent-free conditions in high yields was developed in this article.
Abstract: A number of methods have been proposed for the modification of the Ritter reaction. However, many of these methods involve the use of strongly acidic conditions, stoichiometric amounts of reagents, harsh reaction conditions and extended reaction times. Therefore, the development of mild, efficient, convenient and benign reagents for the Ritter reaction is desirable. In this research, we have developed a clean and environmentally friendly protocol for the synthesis of amides by using different benzylic or tertiary alcohols and different nitriles in the presence of silica-bonded N- propyl sulphamic acid (SBNPSA) as catalyst under solvent-free conditions in high yields.