scholarly journals Síntesis regioespecífica y estudio electroquímico de dos derivados carboxílicos C60 solubles en agua

2021 ◽  
Author(s):  
Juan D. Villada ◽  
Álvaro Duarte-Ruiz ◽  
Manuel N. Chaur
Keyword(s):  
Cyclic Voltammetry ◽  
Liquid Chromatography ◽  
Electronic Properties ◽  
Reaction Times ◽  
C60 Fullerene ◽  
Reduction Processes ◽  
Vis Spectroscopy ◽  
Highperformance Liquid Chromatography ◽  
Electron Transfers ◽  
Reversible Reduction

We report a new methodology for the synthesis of two highly symmetric equatorial malonate hexaadducts of C60 fullerene. The synthetic methodology is based on a series of protection and deprotection steps that allow the preparation of a fullerene [60] functionalized with six symmetrical positioned malonate addends without using complicated and expensive separation techniques (highperformance liquid chromatography, HPLC) or long reaction times. This methodology allowed us to prepare the carboxylic adducts 6 (equatorial octacarboxylic tetraadduct of C60) and 8 (equatorial dodecacarboxylic hexakisadduct of C60). As far as we  now, compound 6 has not yet been reported. We also studied the electronic properties of the main compounds by UV-Vis spectroscopy and cyclic voltammetry (CV). The reported fullerene adducts exhibited several reversible reduction processes whose electron transfers are controlled by diffusion. 

scholarly journals Design of Promising Heptacoordinated Organotin (IV) Complexes-PEDOT: PSS-Based Composite for New-Generation Optoelectronic Devices Applications

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1023
Author(s):  
María Elena Sánchez-Vergara ◽  
Leon Hamui ◽  
Elizabeth Gómez ◽  
Guillermo M. Chans ◽  
José Miguel Galván-Hidalgo
Keyword(s):  
Thin Films ◽  
Electronic Properties ◽  
Optoelectronic Devices ◽  
Density Variation ◽  
Structural Modifications ◽  
Mixed Ligands ◽  
Vis Spectroscopy ◽  
Group A ◽  
Poly Styrene Sulfonate ◽  
New Generation

The synthesis of four mononuclear heptacoordinated organotin (IV) complexes of mixed ligands derived from tridentated Schiff bases and pyrazinecarboxylic acid is reported. This organotin (IV) complexes were prepared by using a multicomponent reaction, the reaction proceeds in moderate to good yields (64% to 82%). The complexes were characterized by UV-vis spectroscopy, IR spectroscopy, mass spectrometry, 1H, 13C, and 119Sn nuclear magnetic resonance (NMR) and elemental analysis. The spectroscopic analysis revealed that the tin atom is seven-coordinate in solution and that the carboxyl group acts as monodentate ligand. To determine the effect of the substituent on the optoelectronic properties of the organotin (IV) complexes, thin films were deposited, and the optical bandgap was obtained. A bandgap between 1.88 and 1.98 eV for the pellets and between 1.23 and 1.40 eV for the thin films was obtained. Later, different types of optoelectronic devices with architecture “contacts up/base down” were manufactured and analyzed to compare their electrical behavior. The design was intended to generate a composite based on the synthetized heptacoordinated organotin (IV) complexes embedded on the poly(3,4-ethylenedyoxithiophene)-poly(styrene sulfonate) (PEDOT:PSS). A Schottky curve at low voltages (<1.5 mV) and a current density variation of as much as ~3 × 10−5 A/cm2 at ~1.1 mV was observed. A generated photocurrent was of approximately 10−7 A and a photoconductivity between 4 × 10−9 and 7 × 10−9 S/cm for all the manufactured structures. The structural modifications on organotin (IV) complexes were focused on the electronic nature of the substituents and their ability to contribute to the electronic delocalization via the π system. The presence of the methyl group, a modest electron donor, or the non-substitution on the aromatic ring, has a reduced effect on the electronic properties of the molecule. However, a strong effect in the electronic properties of the material can be inferred from the presence of electron-withdrawing substituents like chlorine, able to reduce the gap energies.

Prevalence of Aspergillus species on selected Colombian animal feedstuffs and ability of Aspergillus section Flavi to produce aflatoxins

2009 ◽  
Vol 2 (1) ◽  
pp. 31-34 ◽  
Author(s):  
G. Diaz ◽  
M. Lozano ◽  
A. Acuña
Keyword(s):  
Liquid Chromatography ◽  
Cottonseed Meal ◽  
Sunflower Seed ◽  
Seed Meal ◽  
Aspergillus Section Flavi ◽  
Wheat Middlings ◽  
Highperformance Liquid Chromatography ◽  
Animal Feedstuffs ◽  
Aflatoxin B ◽  
Aspergillus Section

A total of 57 samples of feedstuffs commonly used for animal nutrition in Colombia (maize, soybean, sorghum, cottonseed meal, sunflower seed meal, wheat middlings and rice) were analysed for Aspergillus contamination. Aspergillus fungi were identified at species level and their ability to produce aflatoxins was determined by highperformance liquid chromatography. A total of 31 of the feedstuffs analysed (54.4%) were found to contain Aspergillus spp. The most contaminated substrate was maize (100%) followed by cottonseed meal (80%), sorghum (60%) and wheat middlings (60%). Soybean showed lower levels of contamination (10%). No Aspergillus spp. could be isolated from rice or sunflower seed meal. Total Aspergillus strains isolated were 50, with 28 belonging to section Flavi (56%), 17 to section Nigri (34%), 4 to section Circumdati (8%) and 1 to section Fumigati (2%). Among section Flavi, 17 isolates were identified as A. flavus, seven as A. parasiticus, two as A. oryzae and two as A. tamarii. Production of aflatoxins by Aspergillus section Flavi was screened by liquid chromatography. About three quarters of the A. flavus strains (76.5%) produced aflatoxin B1 (0.2 to 240.4 µg/g) and aflatoxin B2 (0.2 to 1.6 µg/g), while all A. parasiticus strains produced the four naturally occurring aflatoxins (aflatoxin B1 from 0.6 to 83.5 µg/g, aflatoxin B2 from 0.3 to 4.8 µg/g, aflatoxin G1 from 0.4 to 19.3 µg/g and aflatoxin G2 from 0.1 to 1.0 µg/g). This is the first study demonstrating the presence of highly toxigenic Aspergillus fungi in Colombian animal feedstuffs.

A study of the decomposition behaviour of 12-tungstophosphate heteropolyacid in solution

2003 ◽  
Vol 81 (10) ◽  
pp. 1044-1050 ◽  
Author(s):  
Zhirong Zhu ◽  
Ruan Tain ◽  
Colin Rhodes
Keyword(s):  
Aqueous Solution ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Potentiometric Titration ◽  
Inductively Coupled Plasma ◽  
High Performance ◽  
Atomic Emission ◽  
Inductively Coupled ◽  
Vis Spectroscopy ◽  
Decomposition Behaviour

In this paper, the decomposition of H3PW12O40 in aqueous solution or in mixed solutions of water–ethanol or water–acetone is investigated by potentiometric titration and 31P NMR. Identification of the products from H3PW12O40 decomposition over a pH range of 1–12 was achieved using preparation high performance liquid chromatography (Pre-HPLC) combined with IR, UV–vis spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP). It is found that H3PW12O40 in aqueous solution decomposes in a stepwise fashion with increasing pH, with the following solution compositions: [PW12O40]3– (at pH ~ 1) [Formula: see text] [PW12O40]3– + [P2W21O71]6– + [PW11O39]7– (at pH 2.2) [Formula: see text] [PW12O40]3– + [P2W21O71]6– + [PW11O39]7– + [P2W18O62]6– + [P2W19O67]10– (at pH 3.5) [Formula: see text] [P2W21O71]6– + [PW11O39]7– + [P2W18O62]6– (at pH 5.4) [Formula: see text] [PW9O34]9– (at pH 7.3) [Formula: see text] PO43– + WO42– (pH > 8.3). In the first stages at pH < 8, H3PW12O40 decomposes partially with removal of W=O units. In the second stage at pH > 8, tungstophosphoric completely decomposes to PO43–. In contrast, the decomposition of H3PW12O40 is reduced, or the stability of the [PW12O40]3– anion is enhanced, in ethanol–water or acetone solution at pH < 8. Key words: 12-tungstophosphate heteropolyacid, decomposition behaviour, potentiometric titration, 31P NMR, preparation high performance liquid chromatography.

Synthesis, Chemical Characterisation, and DNA Binding Studies of Ferrocene-Incorporated Selenoureas

2013 ◽  
Vol 66 (6) ◽  
pp. 626 ◽  
Author(s):  
Raja Azadar Hussain ◽  
Amin Badshah ◽  
Muhammad Nawaz Tahir ◽  
Bhajan Lal ◽  
Inayat Ali Khan
Keyword(s):  
Cyclic Voltammetry ◽  
Dna Binding ◽  
Atomic Absorption Spectrophotometry ◽  
Free Drug ◽  
X Ray Diffraction ◽  
Peak Potential ◽  
Binding Studies ◽  
Vis Spectroscopy ◽  
Dna Binding Studies ◽  
And Diffusion

In this article we have presented the synthesis, chemical characterisation (by NMR and FTIR spectroscopy, atomic absorption spectrophotometry, elemental analysis, and single crystal X-ray diffraction), electrochemistry, and DNA binding studies (with cyclic voltammetry, viscometry, and UV-vis spectroscopy) of six new ferrocene incorporated selenoureas. All the six compounds interact electrostatically with DNA which was evident by a negative shift in the cyclic voltammetry peak potential of the drug–DNA adduct relative to the free drug. The drug–DNA binding constant was calculated by a decrease in peak current after the addition of DNA to the free drug. We have also reported binding site sizes and diffusion coefficients of the synthesised compounds.

scholarly journals Synthesis and Optoelectronic Properties of Iptycene–Naphthazarin Dyes

Synlett ◽  
2018 ◽  
Vol 30 (01) ◽  
pp. 54-58 ◽  
Author(s):  
Timothy Swager ◽  
Cagatay Dengiz ◽  
You-Chi Wu
Keyword(s):  
Single Crystal ◽  
Electronic Properties ◽  
Diels Alder ◽  
Optoelectronic Properties ◽  
Synthesis And Characterization ◽  
Nmr Analysis ◽  
X Ray ◽  
Vis Spectroscopy

We report the synthesis and characterization of iptycene–naphthazarin dyes by using a sequential Diels–Alder approach. The tautomerization of naphthazarin was used as the key step in the synthesis, with structures confirmed by single-crystal X-ray and NMR analysis. The systematic trends in electronic properties were investigated by UV/Vis spectroscopy. BF2 complexes of the dyes were prepared by reaction with BF3·OEt2 in CH2Cl2.

scholarly journals Effect of the coordination of π-acceptor 4-cyanopyridine ligand on the structural and electronic properties of meso-tetra(para-methoxy) and meso-tetra(para-chlorophenyl) porphyrin cobalt(ii) coordination compounds. Application in the catalytic degradation of methylene blue dye

RSC Advances ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 6900-6918 ◽  
Author(s):  
Mouhieddinne Guergueb ◽  
Soumaya Nasri ◽  
Jihed Brahmi ◽  
Frédérique Loiseau ◽  
Florian Molton ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Cyclic Voltammetry ◽  
Electronic Properties ◽  
Catalytic Oxidation ◽  
Coordination Compounds ◽  
Molecular Structures ◽  
Blue Dye ◽  
Methylene Blue Dye ◽  
H Nmr ◽  
Structural And Electronic Properties

Preparation and UV/vis, IR, MS, 1H NMR, cyclic voltammetry and molecular structures of two new Co(ii) complexes with para-methoxy-phenyl and para-chloro meso-porphyrins and 4-cyanopyridine ligand (1–2). Catalytic oxidation data of MB dye using 1–2.

GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART II. THE DEHYDRATION PRODUCTS OF α-TERPINEOL

1961 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
E. Von Rudloff
Keyword(s):  
Liquid Chromatography ◽  
Oxalic Acid ◽  
Complex Mixture ◽  
Reaction Times ◽  
Gas Liquid Chromatography ◽  
Minor Components ◽  
Reaction Products ◽  
The Third ◽  
Major Reaction ◽  
Trace Constituents

The complex mixture of terpenes obtained on dehydrating α-terpineol with aqueous oxalic acid was almost completely separated by gas–liquid chromatography (GLC), using rapeseed oil as a new liquid phase. Terpinolene, dipentene, α- and γ-terpinene, Δ2,4(8)-p-menthadiene, and 1,8-cineole were identified as the major reaction products; three minor and seven trace constituents were also detected. One of the minor components was p-cymene, one an oxide, and the third an unidentified hydrocarbon. The yield of these components after different reaction times was determined by GLC. The initial dehydration gives terpinolene and dipentene in the ratio of approximately 2:1. Terpinolene is isomerized to α- and γ-terpinene, Δ2,4,(8)-p-menthadiene, and the unidentified hydrocarbon, but not to dipentene. 1,8-Cineole and the other oxide are formed in a reversible reaction. Dehydration of α-terpineol with several other acidic reagents yielded mixtures of products similar to that obtained with aqueous oxalic acid. With acetic acid or acetic anhydride, however, dipentene was formed preferentially and this reaction appears to proceed via the derived acetate.

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