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Macrocyclic Anion Receptors
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
A novel ferrocene bis(triazole) macrocycle receptor was synthesized by intramolecular Eglinton coupling of an acyclic 1,1'-bis(triazolylalkyne) ferrocene precursor followed by alkylation (White and Beer 2012). The receptor was investigated for its anion binding properties by means of NMR titration in CD3CN. WinEQNMR2 analysis showed that the cyclic receptor, 28, binds strongly with benzoate (Ka = 4.6(2) × 103 M −1) and chloride benzoate (Ka = 2.5(2) × 103 M −1), while it binds weakly with iodide (Ka = 2(2) × 102 M −1); [NOTE: Estimated standard errors in Ka is given in parentheses] which was interpreted due to charge assisted C–H· · ·anion interactions. Cyclic voltammetry analysis revealed that the redox-active macrocycle can sense chloride anion, causing a cathodic shift of the Epa wave of the ferrocene/ferrocenium redox couple.
Electrochemistry of Porous Polymers and Hybrid Materials
Published in Antonio Doménech-Carbó, Electrochemistry of Porous Materials, 2021
Electrochromism is a property widely studied in conducting polymers [37]. First, it is pertinent to note that for many practical purposes, HOMO and LUMO energies (EHOMO, ELUMO, respectively) and energy gap, Egap, can be approximated by the onset potentials (Eonset) measured in CVs. These are defined as the potential values obtained from the intersection of two tangents drawn at the rising current and the baseline charging current of the CV curves. In voltammetric experiments in organic solvents, the energies can be calculated as EHOMO (ELUMO) = – [–(Eonset – 0.45) – 4.75] eV [38]. In this equation, Eonset represents the onset potential vs. Ag+/Ag, 4.75 eV represents the energy level of ferrocene below the vacuum, and 0.45 V is the value of the ferrocenium/ferrocene couple vs. Ag+/Ag. Notice that it is assumed that the potential of the ferrocenium/ferrocene couple is solvent-independent.
Biomedical Applications of Organic Conducting Polymers
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Alexander R. Harris, Paul J. Molino, Caiyun Wang, Gordon G. Wallace, Zhilian Yue
To further enhance the electron transfer, enzymes as well as mediators can be co-entrapped within conducting polymer matrices, where mediators ease the electron transfer distance while conducting polymer enhances the rate of electron transfer. They can be simultaneously deposited into a conducting polymer matrix during the polymer growth via an electrochemical route, which is generally preferred to produce a clean polymer with a controlled thickness [148]. Ammam et al. demonstrated the application of such an enzyme-mediator co-doped polypyrrole composite in biofuel cells: laccase and mediator of bis-(bipyridine)-(5-amino-phenanthroline) ruthenium bis (hexafluorophosphate) or 4,4-sulfonyldiphenol as cathode; glucose and mediator of ferrocenium hexafluorophosphate or pyrroloquinoline quinone as anode [149]. The electro-deposition was performed from ultrapure water at a high potential of 4 V vs. Ag/AgCl, allowing the growth of a thick film for high power output. In equilibrium with air at 37˚C, the maximum power density reached 3.1 µW mm−2 at a cell voltage of 0.28 V in phosphate buffered saline (PBS), and it decreased to 1.6 µW mm−2 at 0.21 V in human serum. Inamuddin et al. reported a porous matrix of PANI incorporated with a redox mediator ferritin and an enzyme glucose oxidase [150]. A normalised saturation current density of 22.3 ± 2 mA cm−2 was obtained for the oxidation of 50 mM glucose at a scan rate of 100 mV s−1.
Synthesis and electronic structure of a series of first-row transition-metal pyrazine(diimine) complexes in two oxidation states
Published in Journal of Coordination Chemistry, 2022
Daniela Sanchez Arana, Jaylan R. Billups, Bruno Donnadieu, Sidney E. Creutz
Cyclic voltammetry of 1 in THF (0.3 M tetrabutylammonium hexafluorophosphate electrolyte) shows an essentially irreversible reduction at −1.26 V versus the ferrocene/ferrocenium couple (Fc/Fc+) (vide infra). In order to probe the locus of reduction on this complex, we sought to chemically access and crystallographically characterize the reduction product. One-electron reduction of (DiPPPZDI)FeBr2 (1) with cobaltocene in toluene followed by filtration leads to a dark green solution containing (DiPPPZDI)FeBr, 2. Other reducing agents such as KC8 and sodium amalgam give the same species, albeit with more extensive decomposition and impurities. Unfortunately, even with the mild reductant cobaltocene, reduction inevitably led to a significant degree of decomposition resulting in the presence of free ligand in the solution as detected by NMR spectroscopy. Because of the similar solubility properties of the reduction product and the free ligand, we have been unable to obtain analytically and spectroscopically pure bulk samples of 2. Nevertheless, NMR spectra of the filtered reaction mixture from cobaltocene reduction shows complete consumption of 1 and one new paramagnetic product (six major new peaks in the range between −80 to 140 ppm) in addition to free ligand and residual cobaltocene.
Recovery of Palladium by Extraction-electrodeposition Using N, N, N’, N’, N”, N”- Hexaoctyl-nitrilotriacetamide
Published in Solvent Extraction and Ion Exchange, 2022
Ryoma Kinoshita, Masahiko Matsumiya, Yuji Sasaki
The extracted Pd(II) complexes dissolved in the NTAamide(C8)/AP, NTAamide(C8)/DCE, and NTAamide(C8)/OC systems were prepared and analyzed by cyclic voltammetry (CV) using a three-electrode system. A Pt disk electrode with an inner diameter of 1.6 mm (No. 002422, BAS Inc.) was used as the working electrode. The electrode surface on the working electrode was carefully polished with alumina and diamond paste to prevent IR drop. IR drop is the electrical potential difference between the two ends of a conducting phase, and this voltage drop across any resistance is the product of the current value (I) passing through the resistance value (R). Pt wires with an inner diameter of 0.5 mm (No. 002233, BAS Inc.) were used as the counter electrode and quasi-reference electrode (QRE) because the electrode potential was stable and exhibited good reproducibility. The potential was compensated against a ferrocene/ferrocenium (Fc/Fc+) redox couple. The cylindrical cell was sealed with a silicone sealant after setting the electrolyte and all the electrodes to prevent the volatility of the organic phase. The cylindrical cell was placed in a glovebox (DBO-1KP-YUM01, MIWA Inc.) under an Ar atmosphere (H2O, O2 < 1 ppm). CV measurements were carried out using an electrochemical apparatus (ALS-760E, BAS Inc.), and semi-integral (SI) analysis was applied to the obtained voltammogram.
Structural modifications on nickel dithiolene complexes lead to increased metal participation in the electrocatalytic hydrogen evolution mechanism
Published in Journal of Coordination Chemistry, 2021
Maria Drosou, Athanasios Zarkadoulas, Kostas Bethanis, Christiana A. Mitsopoulou
Reagents and solvents were purchased from Aldrich, Alfa Aesar, Merck, and Fisher and used as received unless otherwise noted. IR spectra were recorded in KBr pellets with a 2.0 cm−1 resolution using a Shimadzu IR Affinity-1 spectrophotometer. EA was conducted with a Carlo Erba 1106 analyzer. NMR spectra were recorded using a Varian Unity Plus instrument (300 MHz), and spectra were corrected with the residual solvent peak as an internal standard. Cyclic voltammetry was carried out with a Bipotentiostat AFCBP1 from Pine Instrument Company and controlled with the AfterMath software. Experiments were performed using a glassy carbon (50 mm diameter) disk and an Ag/AgCl/KCl (sat.) as a working and reference electrode, respectively. A Pt wire was employed as counter electrode. The working electrode was polished using successively 6, 3 and 1 μm alumina paste on a DP-Nap polishing cloth (Struers, Westlake, OH), washed with water, acetone and air-dried. The potential sweep rate was 100 mV/s unless otherwise noted. All potentials are reported versus the ferrocenium/ferrocene (Fc+/0) couple.