Peptides-assisted charge transfers in proteins: relay mechanism and its controllability

This feature article addresses several novel aspects regarding the peptide-mediated charge migrations, including: i) radical exchanges with tunable radical types (σ-radical versus π-radical) and electron-transfer (ET)-channel-tunable cooperative proton-coupled ET (PCET) mechanism, including hydrogen-atom transfer (HAT), single ET-channel PCET, double ET channel PCET, and channel-type-tunable (σ-channel versus π-channel) PCET; ii) hole hopping migration between the active groups in the side-chains and its controllability; iii) hole hopping through stepping-stones via a solvated “hole” form; and iv) electron hopping through positively charged groups as stepping-stones via a solvated electron state. In particular, the controllability of the ET channels (pathways and types) and solvated-“hole”/“electron”-based relay mechanisms are mainly mentioned. Clearly, this is an important addition to the well-documented mechanisms for charge migration in proteins. In view of the complexity of protein charge migration, further exploration on details of the stepping-stone-based relay mechanisms, by considering the properties and structures of the redox active centers, their intercalators, and the real surroundings, is still needed.     

Syntheses, structures and magnetic properties of three Co(II) coordination architectures based on a flexible multidentate carboxylate ligand and different N-donor ligands

Three new cobalt complexes, {[Co₅(tci)₂(bimb)₃(µ₃-O)₂(H₂O)₂]·3DMF·4H₂O} _n (1), {[Co₃(tci)₂(bib)]·2DMF·2H₂O} _n (2) and {[Co(Htci)(bpea)_0.5]·H₂O} _n (3) (H₃tci = tris(2-carboxyethyl)isocyanurate, bimb = 4,4′-bis(imidazol-1-yl)biphenyl, bib = 1,4-bis(imidazol-1-yl)benzene, bpea = 1,2-bis(4-pyridyl)ethane, DMF = N,N′-dimethylformamide), have been successfully synthesized through the assembly of Co(II) ions, H₃tci and different N-donor ligands, respectively. All complexes were structurally characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, thermogravimetric (TG) analyses and X-ray powder diffraction (XRPD). Complex 1 exhibits a 3D three-fold parallel interpenetrated 3D → 3D structure with (6⁵·8) CdSO₄ topology. Complex 2 is built from [Co₃(µ₂-O_carboxyl)₂(CO₂)₄] clusters and linear bib ligands, displaying a two-fold parallel interpenetrated (3,8)-connected (4³)₂(4⁶·6¹⁸·8⁴) topology, while complex 3 is a 3D pillar-layered structure involving an infinite -Co-(µ₂-Ocarboxyl)(CO₂)-Co-chain. The diverse structures of the three complexes indicate that the skeletons of different N-donor ligands play an important role in the assembly of such different frameworks. In addition, magnetic investigation indicates that besides spin-orbit coupling of Co(II) ions, there exist antiferromagnetic exchange interactions in Co₅ and Co₃ clusters of 1 and 2, respectively.     

Influence of feedstock source on biocatalyst stability and behavior,and on reactor performance,in continuous intensified ethanol fermentation

An ethanol process based on a gas-lift tower fermenter arrangement was used as a model system to show the strong dependence of reactor behavior on the developing chemical environment within the reactor. The reactor performance limits for realistic substrates—starch and molasses—are characterized and compared with those attainable on an ideal substrate, glucose.

     

ADSORPTION OF SULFOXIDES ON SOLID FROM AQUEOUS SOLUTIONS Ⅲ.THE ADSORPTION ON CARBON BLACK

The adsorption of decylmethylsulfoxide (DEMS) onto carbon black and the effects of temperature, salt (NaCl) and acid (HCl) have been measured.Typical two plateaux type adsorption isotherms were obtained. Applying the two step model of surfactant adsorption on solid/liquld interface and the general adsorption isotherm equation[9]the experimental results were interpreted qualitatively and quantitatively.     

Magnetism‐Tunable Oligoacene Dioxide Diradicals: Promising Magnetic Oligoacene‐Like Molecules

Graphene oxide has attracted intense research interest recently because the graphene oxide synthesis route, as a promising alternative for cost‐effective mass production of graphene, has been explored. To further study the oxidation process and possible mechanism and to explore applicability of the oxidized products, we have performed a computational study on three series of oligoacene dioxides, focusing on their structures and electronic properties. Taking 1,5‐dioxidized naphthalene as a starting point, three series of oligoacene dioxides are considered as follows: 1) middle insertion by 1–2 benzene rings; 2) single‐side expansion using 1–2 benzene rings; 3) double‐side expansion using two benzene rings. On the basis of density functional theory and complete active space self‐consistent field (CASSCF) calculations, we reveal that oligoacene dioxides in the middle insertion series have a triplet ground state, whereas those in the single‐side expansion series and the double‐side expansion series have open‐shell broken‐symmetry singlet diradical ground states except for their common origin naphthalene‐1,5‐dioxide whose ground state is triplet and which is also viewed as the origin of the middle insertion series. Magnetic coupling interactions of these oligoacene dioxides are also determined. This work should help people toward an atomistic understanding of the electronic structures and properties of possible intermediates or products and even the oxidation mechanism of graphene sheets, and provides a reasonable strategy of designing novel graphene‐oxide‐based magnetic materials.     

1,5-二取代六氢三嗪-2-N-硝基亚胺的合成和杀虫活性的测定

以S-甲基-N-硝基异硫脲、取代苄胺为原料,依次经过亲核取代反应,Mannich反应合成了12个未见文献报道的1,5-二取代六氢三嗪-2-N-硝基亚胺(2a～21),结构经1H NMR,IR和元素分析确证.初步的杀虫活性测试表明,该类化合物在500mg/L时对稻飞虱具有较好的杀虫活性.     

Metal-Mediated Directional Capping of Rod-Packing Metal–Organic Frameworks

Two new rod-packing metal–organic frameworks (RPMOF) are constructed by regulating the in situ formation of the capping agent. In CPM-s7, carboxylate linkers extend 1D manganese-oxide chains in four additional directions, forming 3D RPMOF. The substitution of Mn²⁺ with a stronger Lewis acidic Co²⁺, leads to an acceleration of the hydrolysis-prone sulfonate linker, resulting in presence of sulfate ions to reduce two out of the four carboxylate-extending directions, and thus forming a new 2D rod-packing CPM-s8. Density functional theory calculations and magnetization measurements reveal ferrimagnetic ordering of CPM-s8, signifying the potential of exploring 2D RPMOF for effective low-dimensional magnetic materials.     

In-situ cation exchange enhances room temperature phosphorescence of a family of metal-organic frameworks

The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn₂(4,5-ImDC)₂]M₂(NKU-132,M=(CH₃)₂NH₂or(CH₂CH₃)₂NH₂),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry.