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Three complexes [Fe(L)2](ClO4)2 (1)、[Ni(L)2](ClO4)2 (2) and [Co(L)2](ClO4)2 (3) were synthesized by the reaction of N,N’-(4-methylpyridin-2-yl)pyrazine-2,6-diamine (L) with Fe(ClO4)2·6H2O, (Ni(ClO4)2·6H2O or Co(ClO4)2·6H2O) at room temperature, respectively. They were characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The catalytic behavior of the complexes for the synthesis of propylene carbonate from propylene oxide and carbon dioxide were studied. The results show that all of them showed excellent catalytic activities with TOF as high as 2104 h-1, 2824 h-1 and 2605 h-1, respectively. Complex 2 that exhibit higher catalytic activity was taken to explore the influence of time, pressure and temperature to optimize the reaction condition in detail.

Element doping is effective to improve the photoelectrochemical (PEC) performance of photoelectrodes, as it can increase the carrier density and then enhance electrical conductivity for efficient charge transfer. In this study, titanium (Ti) was selectively doped into the bottom and/or top layer of the double layered hematite (α-Fe2O3/α-Fe2O3) nanorod arrays grown on conductive transparent substrate (F:SnO2, FTO) via a two-step hydrothermal method to optimize the electron donor distribution and improve the charge separation efficiency for a remarkable enhancement in PEC water splitting. It was demonstrated that, by selectively doping Ti into the bottom layer, the obtained FTO/α-Fe2O3:Ti/α-Fe2O3 nanorod photoanode showed the highest PEC performance for water splitting, with photocurrent density reaching 1.69 mA/cm2 at 1.9 V vs. RHE under AM 1.5G illumination, which was 4.3 times that of undoped α-Fe2O3/α-Fe2O3 nanorod film (0.39 mA/cm2) and even much higher than the top layer and double layer doped α-Fe2O3 nanorod films (FTO/α-Fe2O3/α-Fe2O3:Ti and FTO/α-Fe2O3:Ti/α-Fe2O3:Ti). By introducing the Ti electron donor dopants into α-Fe2O3, the electron density will be increased in the α-Fe2O3:Ti layer, raising the Fermi level. For the FTO/α-Fe2O3:Ti/α-Fe2O3 nanorod film, the band realignment will create a terraced band structure and then build an internal electric field at the interface of the bottom and top layers. As a result, the photoexcited electrons and holes will transfer to the FTO substrate and the photoanode surface, respectively, as driven by the internal electric field. This study demonstrated an alternative approach to the design of novel photoanodes with improved PEC performances, by engineering the electron density distribution and the band structure for efficient charge carrier separation.

Based on the ligand H4Salen-8tBu (salen-4), a new dinuclear cobalt complex (salen-4)[Co(III)TFA]2 (salen-4 = 3,5-di-tert-butylsalicylaldehyde-3,3&prime, diaminobiphenylamine, TFA = trifluoroacetic acid) has been firstly synthesized and characterized. It shows high catalytic activity for the copolymerization of propylene oxide (PO) and carbon dioxide (CO2), yielding regioregular poly(propylene carbonate) (PPC) with little generation of propylene carbonate (PC) by-product. It has been found that (salen-4)[Co(III)TFA]2 shows higher activity at milder conditions, generating a polymer with maximum Mn of 293 kg/mol and a narrow molecular weight distribution PDI of 1.35. The influences of reaction time, CO2 pressure, reaction temperature, nature of the cocatalyst, catalyst dosage and substrate concentration on the molecular weight, yield and selectivity of the polymer were explored in detail. The results showed that the (salen-4)[Co(III)TFA]2/[PPN]TFA catalyst system demonstrated a remarkable TOF as high as 735 h&ndash, 1. In addition, a hypothetical catalytic reaction mechanism was proposed based on density functional theory (DFT) calculations and the catalytic reaction results of the (salen-4)[Co(III)TFA]2.

A series of Salen cobalt complexes have been successfully synthesized and they show high catalytic activity for the copolymerization of propylene oxide (PO) and carbon dioxide (CO2), yielding poly(propylene carbonate) (PPC). After optimizing the reaction conditions such as temperature, pressure and reaction time, the catalytic system achieved excellent conversion (99.47%) and showed high catalytic activity with an initial TOF up to 483.18 h−1. The content of carbonate chain of the PPC and head-to-tail connection are 88.92% and 86.79% respectively. PPC starts to decompose at 230°C and completely decomposed at 260°C. The Mn of the PPC is 109.898 kg/mol, and the PDI is 1.65295.

Through a pyrazine and naphthyridine-containing diamino ligand, N2,N7-di(pyrazin-2-yl)-1,8-naphthyridine-2,7-diamine (H2dpznda), defective extended metal atom chain complexes with one chromium(II) metal absent in centre, [Cr5(μ5-dpznda)4Cl2] (1) and [Cr5(μ5-dpznda)4(NCS)2] (2) were obtained. An electrochemistry research showed that the pentachromium(II) complexes were quite resistant to reduction although accessible to oxidation, with two reversible redox couples at E1/2 = +0.59 and +0.30 V.

A series of Ti/Li/Al ternary layered double hydroxides (TiLiAl-LDHs) with different Ti:Li:Al molar ratios were prepared by a coprecipitation method for photocatalytic CO2 reduction. It was demonstrated that the contents of anions between the layers of Ti/Li/Al-LDHs greatly determined the photocatalytic activity for CO2 reduction. With Ti:Li:Al molar ratios optimized to be 1:3:2, the largest contents of $${{\bf{CO}}}_{{\bf{3}}}^{{\bf{2}}}$$ CO 3 2 − anion and hydroxyl group were obtained for the Ti1Li3Al2-LDHs sample, which exhibited the highest photocatalytic activity for CO2 reduction, with CH4 production rate achieving 1.33 mmol h−1 g−1. Moreover, the theoretical calculations show that Ti1Li3Al2-LDHs is a p-type semiconductor with the narrowest band gap among all the obtained TiLiAl-LDHs. After calcined at high temperatures such as 700 °C, and the obtained TiLiAl-700 sample showed much increased photocatalytic activity for CO2 reduction, with CH4 production rate reaching about 1.59 mmol h−1 g−1. This calcination induced photocatalytic enhancement should be related to the cystal structure transformation from hydrotalcite to mixed oxides containing high reactive oxygen species for more efficient CO2 reduction.

A series of Ti/Li/Al ternary layered double hydroxides (TiLiAl-LDHs) with different Ti:Li:Al molar ratios were prepared by a coprecipitation method for photocatalytic CO2 reduction. It was demonstrated that the contents of anions between the layers of Ti/Li/Al-LDHs greatly determined the photocatalytic activity for CO2 reduction. With Ti:Li:Al molar ratios optimized to be 1:3:2, the largest contents of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\bf{CO}}}_{{\bf{3}}}^{{\bf{2}}}$$\end{document}CO32− anion and hydroxyl group were obtained for the Ti1Li3Al2-LDHs sample, which exhibited the highest photocatalytic activity for CO2 reduction, with CH4 production rate achieving 1.33 mmol h−1 g−1. Moreover, the theoretical calculations show that Ti1Li3Al2-LDHs is a p-type semiconductor with the narrowest band gap among all the obtained TiLiAl-LDHs. After calcined at high temperatures such as 700 °C, and the obtained TiLiAl-700 sample showed much increased photocatalytic activity for CO2 reduction, with CH4 production rate reaching about 1.59 mmol h−1 g−1. This calcination induced photocatalytic enhancement should be related to the cystal structure transformation from hydrotalcite to mixed oxides containing high reactive oxygen species for more efficient CO2 reduction.

To improve the charge carrier transfer ability in the bulk and at the surface of α-Fe2O3 and accelerate the water oxidation kinetics at the photoanode/electrolyte interface, herein, starting with Ti-doped α-Fe2O3 nanorods, a nitrogen (N) doped carbon (C) nanolayer was coated on the surface of nanorods through a facile hydrothermal method, following a thermal treatment in Ar atmosphere. It was revealed that the N-doped C nanolayer, acting as the passivation layer and/or the water oxidation catalyst, could efficiently extract and collect photoexcited holes from the bulk of α-Fe2O3 and then inject them into the electrolyte for the accelerated water oxidation reaction, by inhibiting both the bulk and surface charge carrier recombination. As a result, the photocurrent density of Ti-doped α-Fe2O3 nanorods coated with N doped C nanolayer was increased by ∼2.7 folds at 1.8 V vs. RHE, as compared with the pristine one.

Based on the ligand 2,2′-dipyridylamine (Hdpa) and di（2-pyrazyl）amine（Hdpza）, neutral molecular complexes [Co(Hdpa)2(NCS)2] (1) and [Co(Hdpza)2(NCS)2] (2) were synthesized. The DFT calculation of complex 1 was carried out to analyze the electron density distribution. Magnetic results indicate that a gradual decrease in χMT over the entire temperature range indicates strong zero-field splitting for the high-spin Co(II) ion in 1. The complex was used for the cycloaddition reaction of CO2 and propylene oxide, and compared with the reported complex 2 [Co(Hdpza)(NCS)2], the catalytic activity was 1 > 2. The Complex 1 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 5040 h−1.

We aimed to develop new effective catalysts for the synthesis of propylene carbonate from propylene oxide and carbon dioxide. A kind of Mx+LClx coordination complex was fabricated based on the chelating tridentate ligand 2,6-bis[1-(phenylimino)ethyl] pyridine (L). The obtained products were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. It was found that the catalytic activity of the complexes with different metal ions, the same ligand differed and co-catalyst, where the order of greatest to least catalytic activity was 2 &gt, 3 &gt, 1. The catalytic system composed of complex 2 and DMAP proved to have the better catalytic performance. The yields for complex 2 systems was 86.7% under the reaction conditions of 100 &deg, C, 2.5 MPa, and 4 h. The TOF was 1026 h&minus, 1 under the reaction conditions of 200 &deg, C, 2.5 MPa, and 1 h. We also explored the influence of time, pressure, temperature, and reaction substrate concentration on the catalytic reactions. A hypothetical catalytic reaction mechanism is proposed based on density functional theory (DFT) calculations and the catalytic reaction results.

Based on the ligand H2dpPzda (1), a novel cobalt complex [Co(H2dpPzda)(NCS)2]&middot, CH3OH(2) has been synthesized and characterized. The Complex 2 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 29,200 h&minus, 1. The catalytic system also showed broad substrate scope of epoxide. Additionally, the catalyst could be recycled to maintain the integrity of the structure and remained equal to the level of its catalytic activity even after seven catalytic rounds. Additionally, a possible catalytic mechanism was proposed due to the high catalytic activity which might be owing to the synergism of Lewis acidic metal centers and N group.

Seven kind of graft copolymerization Konjac Glucomannan with quaternary ammonium group have been prepared, using Konjac Glucomannan (KGM) and methacryloxylethyl alkyl dimethyl ammonium bromide with c8–c18 alkyl and benzyl in water, ceric ammonium nitrate as initiator, the reaction temperature of 348 K, and the reaction period of 3 h. The structures were confirmed by FTIR. The 15 min inhibitory rates of all the graft copolymerization KGM against Escherichia coli and Staphylococcus aureus reached 99.99%, against Candida albicans somewhat lower, but 30 min inhibitory rate still reached 99.02% for graft copolymerization KGM with quaternary ammonium group having 14 alkyl. The antibacterial mechanism of the graft copolymerization KGM has been investigated by adsorption ability to E. coli, measure of 260 nm absorbing materials and SEM micrographs. Firstly, the bacteria were fastly adsorbed by graft copolymerization KGM. Interactions between bacterial membranes and antibacterial product cause fundamental changes in both membrane structure and function, induced leakage of cytoplasmic contents is a classic indication of damage to the bacterial cytoplasmic membrane. The loss of the connection between the outer membrane and the underlying peptidoglycan induces the abnormality of nodular structures and bleb formation of the cell envelope of E. coli. The antibacterial mechanism is in accordance with microbiologic findings identifying surface blebbing as the first morphologic change occurring in the permeability barrier of gram-negative bacteria under mild heat stress and laser irradiation, etc. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Chitosans with different average molecular weight (1,500-156 kDa) were prepared under optimal conditions based on our previous research by the depolymerization of initial chitosan using hydrogen peroxide, with maintaining the native structure of natural chitosan as principal consideration. Nitrogen and Carbon components of initial chitosan and degraded products were analyzed by BUCHI fully automatic nitrogen determination system and Liquid total organic carbon (TOC) analyzer respectively. Fourier transform infrared (FTIR), 13C nuclear magnetic resonance (13C NMR), X-ray diffraction and circular dichroism (CD) analyses were used to characterize the structure properties of samples. The results indicated that the maximum standard deviations of carbon content and nitrogen content and the degree of deacetylation (DD) of degraded products with the corresponding values of the initial chitosan are 2.4%, 2.3% and 6.9% respectively. Besides, the differentiations of the nitrogen content and DD value of the degraded product with the corresponding values of the initial chitosan are narrowed with the increase in the reaction time. FTIR spectra of resulting products are similar to that of initial chitosan in terms of peak number and position, indicating that there are no other functional groups formed during the degradation. 13C-NMR analyses of initial chitosan and degraded products revealed that the chemical structures of resulting chitosans are not changed to any noticeable extent. X-ray diffraction patterns of initial chitosan and degraded chitosans are alike and show characteristic peaks at 2theta = 10. 4 degrees and 19.8 degrees under the condition that the initial chitosan was disposed as degraded chitosans. Circular dichroism analyses showed that all the samples exhibit a broad negative band located at about 210 nm assigned to n --pi* electronic transition of the --NH--CO-- chromophore on a glycosidic ring in acidic media, which demonstrated that degraded chitosans maintain their natural conformation in liquid state substantially. All these confirmed that the degraded chtiosans maintain their natural structure and conformation, and the breakage of beta-1,4-glucoside bonds in macromolecule is the basic process under optimal degradation conditions.