The comparison of triboelectric power generated by electron-donating polymers KAPTON and PDMS in contact with PET polymer

The Triboelectric nanogenerators (TENGs) are Fabricated by contact between two surfaces of different materials and convert of electric loads between them. In such structures, the two contacting layers should be radically different in terms of their electric property so that one of the layers could induce positive electrical charge while the other induces a negative charge. The application of force on and friction between the two layers induce positive and negative charges. Through the electrodes in external load, the electrical charges flow as electric current. In the present study, TEGN structures fabricated of polyethylene terephthalate polymers (PET) act as electron acceptor while Polyamide (KAPTON) and polydimethylsiloxane (PDMS) act as electron donator. The resulting outputs are compared consequently. Considering the fact that the two materials are relatively identical in terms of electron donation as they are in contact with PET, the generators fabricated of KAPTON could generate 400% more power under identical conditions. Therefore, one may conclude that KAPTON could be more suitable for development of self-power system as they are more available and more environmentally compatible.

Coordination Chemistry of Phosphinocarbonyls with Platinum

<p>This thesis reports the coordination chemistry of phosphinocarbonyl ligands with platinum and describes the influence of phosphine substituents on the mechanism of chelation and the coordination mode of the carbonyl moiety. The ligands synthesised were 2-diphenylphosphinobenzaldehyde (1), 2-diphenylphosphinoacetophenone (2), 2-bis(pentafluorophenyl)phosphinobenzaldehyde (3), and 2-di-tert-butylphosphinobenzaldehyde (4). Compounds 1, 3, and 4 were selected on the basis of their steric bulk and extent to which they donate electron density to the metal. Compound 2 contained the same phosphine substituents to 1, but is the methyl ketone analogue and therefore does not contain the CHO moiety. The cone angle and electronic parameter of compounds 1–4 were compared to the reported values of PPh3, PPh(C6F5)2, and PPhtBu2. Compounds 3 and 4 were similarly bulky, and had larger cone angles than 1. The electron donating capacity of compound 4 was greater than that of 1, and compound 3 was the least electron donating. A new synthetic method for the preparation of 4 is also reported. The coordination chemistry of ligands 1–4 was investigated with platinum(II) and platinum(0) starting materials to assess the influence of the steric and electronic parameters of the phosphine on the chelation of the ligand through the carbonyl to platinum. Coordination of the ligand went through the initial coordination of the phosphine and, depending on the identity of that phosphine, may be followed by chelation of the carbonyl moiety to form a P,C chelate. However, the site of the platinum–carbon bond in the P,C metallacycle depends on the ligand employed. Coordination of the phosphinoaldehyde ligands 1, 3, and 4 produced Pt-C bonds via the C-H activation of the aldehyde CHO group whereas for ketophosphine 2, C-H activation occurred at the α-methyl group. The rate at which C-H activation occurred increased with increasing electron donation from the phosphorus to platinum. Compound 4 chelates to platinum more rapidly than compound 1, while 3 did not undergo chelation at room temperature. Although chelation was only observed to occur via C-H activation, the final products of the coordination reactions of 1–4 with platinum starting materials differed depending on the identity of the ligand. The C-H activation of two molecules of 1 with platinum(II) or platinum(0) produced a platina-β-diketone, cis-[Pt(P,C-2-PPh2C6H4CO)2] (21), which is capable of coordinating to H+, Li+, BF2 +, and [Rh(1,5-cyclooctadiene)]+ between the mutually cis carbonyl groups. One carbonyl moiety of 21 can also undergo condensation with primary amines and ammonia to produce platina-β-ketoimine complexes. The ketone moiety of ligand 2 reacted with platinum(II) starting materials through C-H activation of the terminal methyl group to form the six-membered bis-chelate complex analogous to complex 21. The reaction of 2 with platinum(0) starting materials resulted in the formation of a platinum hydride intermediate which mediated chelation through the partial reduction of the ketone group of one ligand, to form the product, [Pt(P,C-2-PPh2C6H4COCH2)(P,C-2-PPh2C6H4C(OH)CH3)] (48) . The reaction of 3 with [PtMe2(1,5-hexadiene)] at elevated temperatures resulted in the formation of [Pt(P,C-2-PPh2C6H4)(P,C-2-PPh2C6H4CO)] (54) – a decarbonylated and ortho-metallated complex containing a four-membered metallacycle. The platinum-phosphorus bond in the four-membered ring of 54 has a bond distance of 2.385(2) Å – the longest Pt–P bond reported to date. Ligand 4 reacted rapidly with platinum(II) starting materials and produced numerous chelation products. Complexes of ligand 4 were only observed to contain mutually trans phosphines, likely due to the steric bulk of the tert-butyl substituents. Comparison of the coordination chemistry of ligands 1–4 suggests that the propensity toward C-H activation of the ligands is predominantly determined by the electronic character of the phosphine (although steric effects cannot be disregarded), and the more electron-rich the phosphine, the more rapidly chelation occurs.</p>

Coordination Chemistry of Phosphinocarbonyls with Platinum

<p>This thesis reports the coordination chemistry of phosphinocarbonyl ligands with platinum and describes the influence of phosphine substituents on the mechanism of chelation and the coordination mode of the carbonyl moiety. The ligands synthesised were 2-diphenylphosphinobenzaldehyde (1), 2-diphenylphosphinoacetophenone (2), 2-bis(pentafluorophenyl)phosphinobenzaldehyde (3), and 2-di-tert-butylphosphinobenzaldehyde (4). Compounds 1, 3, and 4 were selected on the basis of their steric bulk and extent to which they donate electron density to the metal. Compound 2 contained the same phosphine substituents to 1, but is the methyl ketone analogue and therefore does not contain the CHO moiety. The cone angle and electronic parameter of compounds 1–4 were compared to the reported values of PPh3, PPh(C6F5)2, and PPhtBu2. Compounds 3 and 4 were similarly bulky, and had larger cone angles than 1. The electron donating capacity of compound 4 was greater than that of 1, and compound 3 was the least electron donating. A new synthetic method for the preparation of 4 is also reported. The coordination chemistry of ligands 1–4 was investigated with platinum(II) and platinum(0) starting materials to assess the influence of the steric and electronic parameters of the phosphine on the chelation of the ligand through the carbonyl to platinum. Coordination of the ligand went through the initial coordination of the phosphine and, depending on the identity of that phosphine, may be followed by chelation of the carbonyl moiety to form a P,C chelate. However, the site of the platinum–carbon bond in the P,C metallacycle depends on the ligand employed. Coordination of the phosphinoaldehyde ligands 1, 3, and 4 produced Pt-C bonds via the C-H activation of the aldehyde CHO group whereas for ketophosphine 2, C-H activation occurred at the α-methyl group. The rate at which C-H activation occurred increased with increasing electron donation from the phosphorus to platinum. Compound 4 chelates to platinum more rapidly than compound 1, while 3 did not undergo chelation at room temperature. Although chelation was only observed to occur via C-H activation, the final products of the coordination reactions of 1–4 with platinum starting materials differed depending on the identity of the ligand. The C-H activation of two molecules of 1 with platinum(II) or platinum(0) produced a platina-β-diketone, cis-[Pt(P,C-2-PPh2C6H4CO)2] (21), which is capable of coordinating to H+, Li+, BF2 +, and [Rh(1,5-cyclooctadiene)]+ between the mutually cis carbonyl groups. One carbonyl moiety of 21 can also undergo condensation with primary amines and ammonia to produce platina-β-ketoimine complexes. The ketone moiety of ligand 2 reacted with platinum(II) starting materials through C-H activation of the terminal methyl group to form the six-membered bis-chelate complex analogous to complex 21. The reaction of 2 with platinum(0) starting materials resulted in the formation of a platinum hydride intermediate which mediated chelation through the partial reduction of the ketone group of one ligand, to form the product, [Pt(P,C-2-PPh2C6H4COCH2)(P,C-2-PPh2C6H4C(OH)CH3)] (48) . The reaction of 3 with [PtMe2(1,5-hexadiene)] at elevated temperatures resulted in the formation of [Pt(P,C-2-PPh2C6H4)(P,C-2-PPh2C6H4CO)] (54) – a decarbonylated and ortho-metallated complex containing a four-membered metallacycle. The platinum-phosphorus bond in the four-membered ring of 54 has a bond distance of 2.385(2) Å – the longest Pt–P bond reported to date. Ligand 4 reacted rapidly with platinum(II) starting materials and produced numerous chelation products. Complexes of ligand 4 were only observed to contain mutually trans phosphines, likely due to the steric bulk of the tert-butyl substituents. Comparison of the coordination chemistry of ligands 1–4 suggests that the propensity toward C-H activation of the ligands is predominantly determined by the electronic character of the phosphine (although steric effects cannot be disregarded), and the more electron-rich the phosphine, the more rapidly chelation occurs.</p>

Steroidogenic electron-transfer factors and their diseases

Most steroidogenesis disorders are caused by mutations in genes encoding the steroidogenic enzymes, but work in the past 20 years has identified related disorders caused by mutations in the genes encoding the cofactors that transport electrons from NADPH to P450 enzymes. Most P450s are microsomal and require electron donation by P450 oxidoreductase (POR); by contrast, mitochondrial P450s require electron donation via ferredoxin reductase (FdxR) and ferredoxin (Fdx). POR deficiency is the most common and best-described of these new forms of congenital adrenal hyperplasia. Severe POR deficiency is characterized by the Antley-Bixler skeletal malformation syndrome and genital ambiguity in both sexes, and hence is easily recognized, but mild forms may present only with infertility and subtle disorders of steroidogenesis. The common POR polymorphism A503V reduces catalysis by P450c17 (17-hydroxylase/17,20-lyase) and the principal drugmetabolizing P450 enzymes. The 17,20-lyase activity of P450c17 requires the allosteric action of cytochrome b5, which promotes interaction of P450c17 with POR, with consequent electron transfer. Rare b5 mutations are one of several causes of 17,20-lyase deficiency. In addition to their roles with steroidogenic mitochondrial P450s, Fdx and FdxR participate in the synthesis of iron-sulfur clusters used by many enzymes. Disruptions in the assembly of Fe-S clusters is associated with Friedreich ataxia and Parkinson disease. Recent work has identified mutations in FdxR in patients with neuropathic hearing loss and visual impairment, somewhat resembling the global neurologic disorders seen with mitochondrial diseases. Impaired steroidogenesis is to be expected in such individuals, but this has not yet been studied.

Comment on Weber et al. Mayenite-Based Electride C12A7e−: A Reactivity and Stability Study. Catalysts 2021, 11, 334

In 2012, we reported that C12A7 electride (C12A7: e−) significantly promotes the catalytic activity of Ru nanoparticles for ammonia synthesis through the electron donation from the C12A7: e− with a low work function (2.4 eV) to Ru [...]

In Silico Studies on Selected Neutral Molecules, CGa2Ge2, CAlGaGe2, and CSiGa2Ge Containing Planar Tetracoordinate Carbon

Density functional theory (DFT) was used to study the structure, stability, and bonding in some selected neutral pentaatomic systems, viz., CGa2Ge2, CAlGaGe2, and CSiGa2Ge containing planar tetracoordinate carbon. The systems are kinetically stable, as predicted from the ab initio molecular dynamics simulations. The natural bond orbital (NBO) analysis showed that strong electron donation occurs to the central planar carbon atom by the peripheral atoms in all the studied systems. From the nucleus independent chemical shift (NICS) analysis, it is shown that the systems possess both σ- and π- aromaticity. The presence of 18 valence electrons in these systems, in their neutral form, appears to be important for their stability with planar geometries rather than tetrahedral structures. The nature of bonding is understood through the adaptive natural density partitioning analysis (AdNDP), quantum theory of atoms in molecules (QTAIM) analysis, and also via Wiberg bond index (WBI) and electron localization function (ELF).

Identification of a pathway for electron uptake in Shewanella oneidensis

Extracellular electron transfer (EET) could enable electron uptake into microbial metabolism for the synthesis of complex, energy dense organic molecules from CO2 and renewable electricity1–6. Theoretically EET could do this with an efficiency comparable to H2-oxidation7,8 but without the need for a volatile intermediate and the problems it causes for scale up9. However, significant gaps remain in understanding the mechanism and genetics of electron uptake. For example, studies of electron uptake in electroactive microbes have shown a role for the Mtr EET complex in the electroactive microbe Shewanella oneidensis MR-110–14, though there is substantial variation in the magnitude of effect deletion of these genes has depending on the terminal electron acceptor used. This speaks to the potential for previously uncharacterized and/or differentially utilized genes involved in electron uptake. To address this, we screened gene disruption mutants for 3667 genes, representing ≈99% of all nonessential genes, from the S. oneidensis whole genome knockout collection using a redox dye oxidation assay. Confirmation of electron uptake using electrochemical testing allowed us to identify five genes from S. oneidensis that are indispensable for electron uptake from a cathode. Knockout of each gene eliminates extracellular electron uptake, yet in four of the five cases produces no significant defect in electron donation to an anode. This result highlights both distinct electron uptake components and an electronic connection between aerobic and anaerobic electron transport chains that allow electrons from the reversible EET machinery to be coupled to different respiratory processes in S. oneidensis. Homologs to these genes across many different genera suggesting that electron uptake by EET coupled to respiration could be widespread. These gene discoveries provide a foundation for: studying this phenotype in exotic metal-oxidizing microbes, genetic optimization of electron uptake in S. oneidensis; and genetically engineering electron uptake into a highly tractable host like E. coli to complement recent advances in synthetic CO2 fixation15.

Recent advances in the structural diversity of reaction centers

Photosynthetic reaction centers (RC) catalyze the conversion of light to chemical energy that supports life on Earth, but they exhibit substantial diversity among different phyla. This is exemplified in a recent structure of the RC from an anoxygenic green sulfur bacterium (GsbRC) which has characteristics that may challenge the canonical view of RC classification. The GsbRC structure is analyzed and compared with other RCs, and the observations reveal important but unstudied research directions that are vital for disentangling RC evolution and diversity. Namely, (1) common themes of electron donation implicate a Ca2+ site whose role is unknown; (2) a previously unidentified lipid molecule with unclear functional significance is involved in the axial ligation of a cofactor in the electron transfer chain; (3) the GsbRC features surprising structural similarities with the distantly-related photosystem II; and (4) a structural basis for energy quenching in the GsbRC can be gleaned that exemplifies the importance of how exposure to oxygen has shaped the evolution of RCs. The analysis highlights these novel avenues of research that are critical for revealing evolutionary relationships that underpin the great diversity observed in extant RCs.

Phase Transition and Anisotropic Transport of MoS 2 /Chlorophyll Van der waal Heterostructure Formed via Biomimetic Photo-electron Donation

In atomically-thin two-dimensional Vander-Waal-heterostructure [VDWHs], phase transition due to biomimetic photoelectron donationwith molecular ad-layer has never been explored. In this pursuit, systematic quantification of biomimetic-optical-creation of stable easy-solution-processed 1T MoS2 chlorophyll (CHL-a) VDWHs has been examined. The 1T phase transformation dynamics and stabilization phenomenon have been quantified by optical anisotropy and Time-correlated-single-photon-counting. The material shows Luttinger transport phenomenon in the two-port device and supports MoS2 interfaces can be fine-tuned with the molecular ad-layer as a result of strong anisotropic finite range correlation. This is validated by Density-Function-Theory. The negative differential resistance in Luttinger transport arises from conformational heterogeneity of CHL-a related to the scaling of Van der waal distances, which regulates coupling strength with temperature as supported by Molecular-Dynamics simulation. The photo-induced evolution of novel “anisotropic heterojunction” can stimulate a plethora of function-designable 2D VDWHs creation.