A series of six derivatives of Bisquinones of type Q 1 -NH-Q 2 (Q 1 = naphthoquinone; Q 2 = substituted benzoquinone) was synthesized previously [1]. Their redox properties have been studied by cyclic voltammetry in CH 2 Cl 2 -Bu 4 NBF 4 on a glassy carbon electrode, with Ferrocene-Ag/AgCl as reference electrodes [2]. Figures 1 and 2 show cyclic voltammograms of two derivatives in which both consist of Q 1 = Q 2 = naphthoquinone. However, one of them (A) has “NMe” group as the spacer, and the second involves “NH” moiety (B) as such. Derivative A undergoes a total of 4e reduction steps (in the range of -0.5 to -1.3V) whereas B involves 5e reduction steps (within -0.3 to -1.3V). The mechanism of the cathodic reduction of these compounds, especially regarding the first step, has been controversial. Analysis of the two cyclic voltammograms and MO computations of the LUMO in both cases, could clarify this debatable issue [3]. References [1] S. Bittner, S. Gorohovsky, O. Paz-Tal (Levi), J.Y. Becker, Amino Acids , 2002 , 22 , 71-93. [2] G. Temtsin-Krayz, S. Bittner, A. Dhiman and J.Y. Becker, Chem. Rec., 2021 , 21 , 1-13. [3] Sebastian Kozuch and James Y. Becker, 2025 (unpublished results). Figure 1

It is well established that quinones play an important role in various biological systems. Studying electrochemical properties of quinones affords fundamental knowledge of semi-quinone radicals formation in vivo and in vitro in different media. Following our previous work on electrochemical properties of various quinonyl amines [1], Scheme 1 below describes seven diquinonyl amines. Noteworthy that six of them ( 1 - 6 ) contain an internal proton donor (‘NH’) except for the seventh one ( 7 ), in which both quinone moieties are attached to ‘NMe’ group. Their redox potentials were measured by cyclic voltammetry in dichloromethane [2]. The results show a strong dependence of the nature of substituent on the first reduction potentials, and that protonation of diquinonyl amines is feasible by internal proton source even in a non-polar medium. References [1] S. Bittner, S. Gorohovsky, O. Paz-Tal (Levi), J.Y. Becker, Amino Acids , 2002 , 22 , 71-93 [2] G. Temtsin-Krayz, S. Bittner, A. Dhiman and J.Y. Becker, "Electrochemistry of Quinones with Respect to their Role in Biomedical Chemistry", Chem. Rec., 2021 , 21 . Figure 1

Abstract The current comprehensive review covers four main parts, of which some are presented in the form of a personal account. 1. Anodic oxidation of a) N‐alkyl and N,N‐diallyl carbonyl moieties, b) Azacycloalkyl amides and the effect of ring‐size on the outcome, c) Lactams, d) Sulfonamides, and e) The effect of a substituent R attached to carbonyl (N−CO−R) or sulfonamides (N−SO2R) on their oxidation potentials. 2. Anodic oxidation of aromatic amides, in particular of type Ph2CHCONHAr, lacking hydrogen(s) at the α‐position to nitrogen. They undergo three types of bond‐cleavage, yielding a variety of fragmentation products. 3. a) Anodic oxidation of symmetrical bisamides of type ZCONH(CH2)nNHCOZ (Z=Me, Ph, Ar; n=2–4) under constant current electrolysis, in methanol. For n=3, 4 they afford mostly mono‐ and dimethoxylation products. For n=2 they undergo ′CH2−CH2′ bond cleavage to yield fragmentation products. b) Anodic oxidation of symmetrical bisamides of type ArCONH(CH2)2NHCOAr under controlled potential electrolysis, in acetonitrile, leads to gem‐unsymmetrical bisamides of type ArCONHCH2NHCOMe as the major product, in fair yields. 4. Utilization of the anodic process in organic synthesis to form C−C bonds by both intra‐ and inetrmolecular processes; as well as C−O and C−N bonds for generating heterocycles.

Previously we investigated electrochemical properties [1] of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran. Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives. Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products although their cyclic voltammograms are similar. References [1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 569, 15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 573, 139-146. [2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122. [3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem , 2019, 6, 1–6; J.Y. Becker, unpublished results (2021). Figure 1

Previously we investigated electrochemical properties [1] of various 2,3,4,5-tetraphenylsiloles (I) with different substituents attached to the Si atom. Major products include 1,2-dibenzoyl, 1,2-diphenylethene, tetraphenylfuran and tetraphenyldihydrofuran. Later [2] we explored the redox properties of four silafluorenes of type (II). Major products after CPE involve both aromatic hydrocarbons and siloxane derivatives. Recently [3] we studied the electrochemical redox properties of four spiro-derivatives (III) in which the central atom is C, Si, Ge or Sn, both by cyclic voltammetry and controlled potential electrolysis. The outcome from these measurements will be presented in this talk. It is noteworthy to indicate that each spiro derivative afford different products although their cyclic voltammograms are similar. References [1] A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 569, 15-22; A. Dhiman, Z.-R. Zhang, R. West, J. Y. Becker, J. Electroanal. Chem., 2004, 573, 139-146. [2] A. C. Herath, R. West, J.Y. Becker, J. Electroanal. Chem., 2014, 728, 118-122. [3] T. Golub-Sedinkin, A. C. Herath, R. West, and J. Y. Becker, ChemElectroChem , 2019, 6, 1–6; J.Y. Becker, unpublished results (2021). Figure 1

AbstractThe present article is fully confined to cyclic voltammetric measurements of a series of bridged and non‐bridged annulenediones (quinones of large conjugated rings of aromatic character). The evaluation of their electrochemical redox properties shed light on remarkable and interesting conclusions such as aromaticity, electrostatic repulsion, disproportionation constants, and stability of their reduced charged intermediates. The results reveal that in the case of the non‐bridged quinones 1–4, as the number of fused rings increases the reduction becomes gradually more difficult because the aromatic stabilization of the ‘quinone’ on conversion to aromatic ‘hydroquinone’ system decreases. However, since all studied annulenediones 5–11 possess a ‘C2’ bridge that keeps the macrocycles flat, causing better aromaticity, they are relatively easily reduced at both E1 and E2 potentials and therefore, they could be considered as quinones of aromatic systems. On the other hand, when the bridge is longer (as in 12 and 13) the macrocycles tend to bend, causing a decrease in the degree of aromaticity and as a consequence, their reduction becomes more difficult.

Previously [1] we studied the anodic oxidation of symmetrical bisamides of type RCONH(CH 2 ) n NHCOR (n = 2-4) under constant current electrolysis (CCE), in methanol. Those with 3 and 4 methylene groups as spacers undergo mostly mono- and dimethoxylation at the alpha-position to 'N' atom. However, when the spacer contains two methylene groups only, the anodic process favors fragmentation products due to CH 2 -CH 2 bond cleavage, as shown in Eq. 1. Following the above results, for better selectivity, the anodic oxidation of symmetrical aromatic bisamides with ‘CH 2 CH 2 ’ as a spacer (ArCONHCH 2 CH 2 NHCOAr), was investigated [2] in acetonitrile, and under controlled potential electrolysis (CPE). The outcome indicates that the major products involve unsymmetrical geminal bisamides (Eq. 2) that are difficult to synthesize by other methods. References [1] T. Golub and J.Y. Becker, Beilstein J. Org. Chem. 2018, 14, 861–868. [2] T. Golub, G.-Y. Dou, C.-C. Zeng and J. Y. Becker, Org. Lett. , 2019 , 21, 7961-7964; J.Y. Becker, unpublished results ( 2022 ). Figure 1

The electronic structure of donor and acceptor components is more or less predictable and the general relationship between, for example, structure and donor strength or structure and stability of ion radicals, is quite familiar to organic chemists. The design of new “electronic structures” is not only quite possible but represents the main trend of current research activities in the field. Ionradical species, formed by oxidation of a donor, reduction of an acceptor, or electron transfer from a donor to an acceptor, might undergo further transformations, such as dimerization, fragmentation, and reactions with solvent, moisture, or oxygen from air. Heterocycles such as furane, thiophene, and pyrrole have rather moderate donor ability. An extensive body of information on oxidation potentials of organic compounds, usually determined by cyclic voltammetry, is available. The determination of electron affinity of neutral acceptors is not so straightforward as the determination of the ionization potential of neutral donors.

Quinones are ubiquitous in nature and form one of the largest class of antitumor agents approved for clinical use. They are known to be efficient in inhibiting cancer cells growth. Under physiological conditions they can undergo non-enzymatic one-electron reduction to give the moderately toxic species of semiquinone radical-anion. Thus, electrochemical study of quinones might provide a basic knowledge on semi-quinone radicals formation in both in vivo and in vitro under different media. Several processes are outlined briefly and discussed in the present article. Previously we investigated the electrochemical and spectral properties of ω-N-quinonyl amino acids. Such quinone-bearing peptides are known to be cytotoxic and of potential clinical significance. We were able to prove that the ω-amino quinonyl compounds are very effective in producing stable semiquinone radicals. Moreover, a direct relation was found between the first reduction potentials of the quinonyl moiety and their reactivity towards the ω-amino acids. In order to increase our knowledge of such amino quinonyl compounds and enlarge the arsenal of such cytotoxic compounds, a series of N,N-diquinonyl amines (1-6) bearing an internal proton (stems from the NH moiety) were synthesized. Their electron-transfer capabilities were probed by cyclic voltammetry measurements, in dichloromethane. It was found that the acidic NH group linking the two quinonyl moieties undergoes an initial electrochemical reduction step and generates a nitride anion. This step is followed by further reductions to yield quasi-stable semiquinone radicals and polyanions, Since these acidic diquinones (1-6) serve also as a source of internal proton donors even in non-polar medium, they might cause protonation of basic radical-anions and polyanion intermediates during the various electrochemical stages. The processes are demonstrated and discussed by analyzing different mechanistic schemes. The successful generation of relatively stable semiquinone radicals is a prerequisite for the manifestation of site directed antitumor activity by these bis-quinonyl amino derivatives. Based on the values of their redox potentials some of them could be promising candidates for clinical development.

Previously we studied the anodic oxidation of different types of amides, including cyclic ones [1-3]. Recently we investigated [4] the anodic oxidation of bisamides (from diaminoalkanes) involving 2-4 methylene groups as spacers between the two amide functionalities. Those with 3 and 4 methylene groups behave similar to monoamides. They both undergo mostly mono- and dimethoxylations at the alpha-position to 'N' atom. However, when the spacer contains two methylene groups only, the anodic process affords mostly fragmentation products due to CH2-CH2 bond cleavage: RCONHCH2OCH3 exclusively, or along with RCONHCHO, depending on the supporting electrolyte used. The scheme below describes the outcome in both cases: References [1] Golub T.; Becker J. Y., Org. Biomol. Chem. 2012, 10, 3906-3912. [2] Golub T.; Becker J. Y., J . Electrochem. Soc. 2013, 160, G3123-G3127. [3] Golub T.; Becker J. Y., Electrochim. Acta 2015, 173, 408–415. [4] Golub T.; Becker J. Y., Beilstein J. Org. Chem. 2018, 14, 861–868. Figure 1

Microsupercapacitors are touted as one of the promising "next frontiers" in energy-storage research and applications. Despite their potential, significant challenges still exist in terms of physical properties and electrochemical performance, particularly attaining high energy density, stability, ease of synthesis, and feasibility of large-scale production. We present new freestanding microporous electrodes comprising self-assembled scaffold of gold and reduced graphene oxide (rGO) nanowires coated with MnO2 . The electrodes exhibited excellent electrochemical characteristics, particularly superior high areal capacitance. Moreover, the freestanding Au/rGO scaffold also served as the current collector, obviating the need for an additional electrode support required in most reported supercapacitors, thus enabling low volume and weight devices with a high overall device specific energy. Stacked symmetrical solid-state supercapacitors were fabricated using the Au/rGO/MnO2 electrodes in parallel configurations showing the advantage of using freestanding electrodes in the fabrication of low-volume devices.

The electrode active surface area is a crucial determinant in many electrochemical applications and devices. Porous metal substrates have been employed in electrode design, however construction of such materials generally involves multistep processes, generating in many instances electrodes exhibiting incomplete access to internal pore surfaces. Here we describe fabrication of electrodes comprising hierarchical, nano-to-microscale porous gold matrix, synthesized through spontaneous crystallization of gold thiocyanate in water. Cyclic voltammetry analysis revealed that the specific surface area of the conductive nanoporous Au microwires was very high and depended only upon the amount of gold used, not electrode areas or geometries. Application of the electrode in a pseudo-capacitor device is presented.

Anodic oxidation of N-alkylamides in the presence of nucleophiles such as water, alcohol or carboxylic acid, affords the respective alpha- hydroxy, -alkoxy or -carboxy derivatives as final products (Eq. 1). The electrochemical properties of three cyclic amides of the type N-acylazacycloalkanes (I - III) (Scheme 1) have been investigated in acetonitrile by cyclic voltammetry. Each one of them exhibits one irreversible anodic wave (at ~2 V) and one irreversible cathodic wave (at around -1.3 V). Preparative anodic oxidation of I - III in methanol at C anodes under various electrochemical conditions (current density, electricity consumption and supporting electrolytes) led to four major products by all three substrates: alpha-methoxy- and alpha,alpha'-dimethoxy cyclic amides, and two cyclic eneamide derivatives. Their relative ratio was found to be highly dependent on the nature of the electrolyte and current density. References [1] E. Steckhan in Organic Electrochemistry (H. Lund, M.M. Baizer, Eds.), 3rd Ed., Chap. 15, pp. 601-607, Marcel Dekker, New York, 1990. [2] T. Golub and J. Y. Becker, J. Electrochem. Soc., 2013, 160 (7), G1-G5. Figure 1

N-acyl (-CHO, -COMe, -COOMe, -COPh, -COCF3) and N-sulfonyl (-SO2Me, -SO2Ph, -SO2 (p-tolyl) piperidines were synthesized and studied by cyclic voltammetry. Their anodic methoxylation was performed at various anodes (carbon rod, carbon felt, glassy carbon, Pt and PbO2), in the presence of different electrolytes (But(4)NClO(4), Et4NBF4 and Et4NOTs), applying a current density of 20 mA cm(-2). Methoxylation on graphite with Et4NOTs favored the formation of a-monomethoxy products whereas in the presence of Et4NBF4, the alpha,alpha'-dimethoxy derivatives become predominant in selected cases. (C) 2015 Elsevier Ltd. All rights reserved.

Amide bonds are considered to be stable and therefore, difficult to break. So far, electrochemical oxidation of amides and lactams has afforded almost exclusively products stemming from alkoxylation (in alcohols) and acyloxylation (in acetic and formic acids) products at the α-position to nitrogen [1]. Anodic oxidation of ArNCOCH2Ph in acetonitrile affords low currents and not effective. The minor products obtained do not stem from a cleavage of the benzylic (PhCH2-CO) bond. However, the anodic oxidation of amides with more activated benzylic group such as ArNCOCHPh2undergo three types of bond-cleavage [2], of which routes A (between the benzylic carbon and the carbonyl group) and C (between the ‘N’ atom and aryl group) prevail, as illustrated below. The selectivity of the cleavage and nature of emerged products is highly dependent on the nature of substituent attached to the aryl group. The type of products obtained and the mechanism involved will be discussed. References [1] S. D. Ross, M. Finkelstein and R. C. Petersen, J. Am. Chem. Soc., 1964, 86, 2745; Ibid., 1966, 88, 4657; M. Finkeistein, K. Nyberg, S. D. Ross and Servin, Acta Chem. Scand., Ser. B, 1978, 32b, 182; M. Lennartz, M. Sadakane and E. Steckhan, Tetrahedron, 1999, 55, 14407. [2] T. Golub and J.Y. Becker, Org. Biomol. Chem. (OBC), 2012, 10, 3906.

ABSTRACTThe tetrasilyl‐substituted digermene (tBu2MeSi)2GeGe(SiMetBu2)2 1 was prepared by the reduction of the readily available 1,1‐dichlorogermane (tBu2MeSi)2GeCl2 with potassium graphite. Compound 1 is a rather unusual example of a digermene featuring planar geometry at the doubly bonded germanium atoms, on the one hand, and an extraordinarily twisted GeGe bond, on the other hand, caused by the electronic and steric factors of the bulky σ‐donating silyl substituents. Although it maintains the structural integrity of its double bond in solution, 1 revealed reactivity that is not characteristic of the >GeGe< bond but is typical for germylenes >Ge: upon reaction with nucleophilic reagents (isocyanide, orthoquinone). Unlike common alkenes, 1 affords stable cation and anion radicals generated by cyclic voltammetry.

New lanthanide-containing ionic liquids (ILs) based on thiocyanate complexes of the type [BMIM]x-3[Ln(NCS)x(H2O)8-x] (BMIM = 1-butyl-3-methylimidazolium; x = 6,7,8) have been reported in recent studies. These complexes are highly efficient for dissolving lanthanide complexes within ILs. Until now, only partial characterization of their properties has been reported. The present work describes the characterization of this type of complexes in both their pure liquid phase and in solution with EuIII and SmIII as the lanthanide ions. The number of water molecules as ligands was determined by luminescence measurements in the UV/Vis region. The composition of the complexes in solution was found to be similar to those in the solid state. The electrochemical behavior of the EuIII/EuII redox couple for [BMIM]5[Eu(NCS)8] at a glassy carbon electrode has been investigated in acetonitrile and in the [BMIM][SCN] IL. This couple is electrochemically quasireversible with E1/2 = -0.23 V [vs. normal hydrogen electrode (NHE)]. The diffusion coefficients of the complexes in solution were determined by cyclic voltammetry and chronopotentiometry and were found to be DEuIII = 1.1 +/- 0.1x10-5 and 2.5 +/- 0.3x10-8 cm2/s in acetonitrile and [BMIM][SCN], respectively. The diffusion coefficients of the reduced species were found to be DEuII = 8.2 +/- 0.4x10-6 and 2.1 +/- 0.4x10-8 cm2/s in the two solvents, respectively. The standard rate constants of the single electron reduction were determined by cyclic voltammetry and found to be k0 = 1.2 +/- 0.1x10-3 and 5.4 +/- 0.8x10-5 cm/s in the two solvents, respectively.