2D sp2 Carbon-Conjugated Porphyrin Covalent Organic Framework for Cooperative Photocatalysis with TEMPO.

2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon-conjugated porphyrin-based covalent organic framework (Por-sp2 c-COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light-emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π-conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 -C=C- double bonds linkage ensures the stability of Por-sp2 c-COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por-sp2 c-COF is pivotal for cooperative photocatalysis with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.

Selective aerobic oxidation of sulfides by cooperative polyimide-titanium dioxide photocatalysis and triethylamine catalysis.

The selective aerobic oxidation of sulfides is highly attractive for modern organic and pharmaceutical synthesis. Thus, there is an urgent need for exploring new photocatalytic system on this reaction. In this work, we investigated the polyimide-titanium dioxide (Aeroxide P25 TiO2, denoted as P25) photocatalyst in visible light-driven selective aerobic oxidation of sulfides. Polyimide-P25 shows enhanced absorption of visible light. Subsequently, this makes polyimide-P25 exhibits observable photocatalytic activity on visible light-driven selective aerobic oxidation of sulfides while pure polyimide and P25 individually have none. Aided by triethylamine (TEA), the yield of sulfoxide by polyimide-P25 photocatalysis reaches more than 3 folds compared to that without TEA, highlighting the remarkable cooperative effect between polyimide-P25 photocatalysis and TEA catalysis. Moreover, a plausible mechanism is figured out based on the quenching control experiments, kinetic studies and in-situ electron paramagnetic resonance (EPR) tests. This work could provide useful guidance for the rational design of hybrid photocatalysts to undertake challenging selective chemical transformations.

2D and 3D Porphyrinic Covalent Organic Frameworks: The Influence of Dimensionality on Functionality.

The construction of 2D and 3D covalent organic frameworks (COFs) from functional moieties for desired properties has gained much attention. However, the influence of COFs dimensionality on their functionalities, which can further assist in COF design, has never been explored. Now, by selecting designed precursors and topology diagrams, 2D and 3D porphyrinic COFs (2D-PdPor-COF and 3D-PdPor-COF) are synthesized. By model building and Rietveld refinement of powder X-ray diffraction, 2D-PdPor-COF crystallizes as 2D sheets while 3D-PdPor-COF adopts a five-fold interpenetrated pts topology. Interestingly, compared with 2D-PdPor-COF, 3D-PdPor-COF showed interesting properties, including 1) higher CO2 adsorption capacity; 2) better photocatalytic performance; and 3) size-selective photocatalysis. Based on this study, we believe that with the incorporation of functional moieties, the dimensionality of COFs can definitely influence their functionalities.

Designed Synthesis of a 2D Porphyrin-Based sp2 Carbon-Conjugated Covalent Organic Framework for Heterogeneous Photocatalysis.

The construction of stable covalent organic frameworks (COFs) for various applications is highly desirable. Herein, we report the synthesis of a novel two-dimensional (2D) porphyrin-based sp2 carbon-conjugated COF (Por-sp2 c-COF), which adopts an eclipsed AA stacking structure with a Brunauer-Emmett-Teller surface area of 689 m2 g-1 . Owing to the C=C linkages, Por-sp2 c-COF shows a high chemical stability under various conditions, even under harsh conditions such as 9 m HCl and 9 m NaOH solutions. Interestingly, Por-sp2 c-COF can be used as a metal-free heterogeneous photocatalyst for the visible-light-induced aerobic oxidation of amines to imines. More importantly, in comparison to imine-linked Por-COF, the inherent structure of Por-sp2 c-COF equips it with several advantages as a photocatalyst, including reusability and high photocatalytic performance. This clearly demonstrates that sp2 carbon-linked 2D COFs can provide an interesting platform for heterogeneous photocatalysis.

Cu(OAc)2-Mediated Reaction of [60]Fullerene with Aldehydes and Primary Amines for the Synthesis of Fulleropyrrolines.

The facile one-step reaction of [60]fullerene with aldehydes and primary amines in the presence of cheap and easily available Cu(OAc)2·H2O afforded a series of new types of fulleropyrrolines with trisubstituted C═C bonds in good to excellent yields, which would be difficult to prepare by known methods. The formed fulleropyrroline under the assistance of Pd(OAc)2 and CuCl2·2H2O could be further converted to 1-fulleropyrrolidine by the chlorohydroxylation reaction of C═C bond. Subsequent elimination reaction of 1-fulleropyrrolidine with the aid of TsOH·H2O generated the scarce 1-fulleropyrroline derivative.

A Protocol for the Preparation of 2,5-Diaryl Fulleropyrrolidines: Thermal Reaction of [60]Fullerene with Aromatic Aldehydes and Arylmethanamines.

Thermal reaction of [60]fullerene with various arylmethanamines in the presence of aromatic aldehydes under air conditions afforded a series of rare 2,5-diaryl fulleropyrrolidines. Intriguingly, the obtained fulleropyrrolidines exhibited different stereoselectivity. N-unsubstituted arylmethanamines exclusively produced 2,5-diaryl fulleropyrrolidines as cis isomers, while N-substituted arylmethanamines with rare exceptions always gave 2,5-diaryl fulleropyrrolidines as trans isomers. Theoretical calculations at the level of B3LYP/6-31G (d,p) were employed to elucidate the stereoselectivity of N-substituted 2,5-diaryl fulleropyrrolidines as trans isomers by investigating the transition-state structures of different cycloaddition pathways.

[Study of Paints and Drawing Techniques of Fine Brushwork Yunlong Ripples Painting in Qing Dynasty].

In order to study the paints and techniques of decorative patterns of dragon among clouds and water waves, the materials based on a Qing Dynasty meticulous painting were measured by three-dimensional video microscopy, Raman microscopy and energy dispersive X-ray fluorescence spectroscopy. The results showed that the green clothes was firstly colored by Paris green, the decorative patterns of dragon among clouds and water waves were then painted by hematite, the edge was delineated by brass powder at last. The dark yellow area within the decorative patterns was presented due to the interaction of green and red paints. In addition, ultramarine blue was checked in the painting. According to the first synthesized time of ultramarine blue and Paris green, we can make sure the time limit of the painting finished.

Synthesis and Functionalization of Symmetrical 2,5-Diaryl Fulleropyrrolidines: Ferric Perchlorate-Mediated One-Step Reaction of [60]Fullerene with Arylmethanamines.

A series of scarce N-unsubstituted 2,5-diaryl fulleropyrrolidines as cis isomers could be prepared via the facile one-step reaction of [60]fullerene with N-unsubstituted arylmethanamines promoted by cheap and easily available ferric perchlorate. Nevertheless, the reaction of N-substituted arylmethanamines with [60]fullerene under the same conditions gave different experimental results. N-Methylbenzylamine formed N-methyl 2,5-diphenyl fulleropyrrolidine as a trans isomer, and N,N-dibenzylamine unexpectedly afforded the N-unsubstituted 2,5-diphenyl fulleropyrrolidine as a cis isomer. Intriguingly, high stereoselectivity for all 2,5-diaryl fulleropyrrolidines could be observed although both cis and trans isomers were possibly formed. N-Unsubstituted fulleropyrrolidine could be further converted to N-substituted fulleropyrrolidines under the assistance of an acid chloride or an isocyanate. A possible reaction pathway leading to 2,5-diaryl fulleropyrrolidines is also proposed.

[Non-Destructive Identification of Pigments Printed on the Bank Bill Issued in 1945].

Three-dimensional video microscopy, Raman spectrometer and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) were employed to analyze the pigments of various colors on a sample of bank bill issued in 1945. The results indicated that organic pigments including C. I. Pigment Red 146 and C. I. Pigment Red 53∶1, and inorganic pigments such as cinnabar, parareaglar, χ-phase of realgar, carbon black and Prussian blue were used in printing; the brown-black handwriting letters were speculated to be formed from the fading black-blue ink. Most areas of the bank bill were in one single color with one pigment, but two areas of orange-red seals were checked to be colored with cinnabar and two different phases of realgar, and the parareaglar, and χ-phase of realgar were found to be used as printing pigments firstly. This study shows that combining with three technologies above-mentioned is viable and it has great application potential in non-destructive identification of organic and inorganic pigments on paper-based cultural heritage.

[A Non-Destructive Study of Printing Materials of an Imperial China Green Engraved Coiling Dragon Stamp].

Non-destructive measurement methods including video microscopy (VM), Raman spectrometer (RS), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) were employed to analyze the printing materials of a green curled-up dragon stamp sample from the late Qing Dynasty in terms of the paper and ink. The results indicated that the plate-making process of the sample belonged to handcrafted gravure while the slender and dense paper fiber with no coating, watermark, or gumming. Elements of Al and Si were inspected in fillers of paper, therefore, it could be inferred that kaolin (Al2O3·2SiO2·2H2O) was the filler of paper. Green ink was made up of blue pigment Prussian Blue (Fe4[Fe(CN)6]3·14-16H2O) and yellow pigment Lead(II) chromate(PbCrO4). According to theories of additive color and subtractive color, ink presented green color due to the effect of Prussian blue and Lead chromate mixed together. Elements of Na, Mg, S, Cl, K, Ca, V, Zn and Ba were measured from fillers of the ink and it could be inferred that MgCO3, BaSO4, CaCO3 and other substances might be contained in ink fillers. This study with three techniques mentioned above is viable and it has a broad application in non-destructive analysis of printing and paper-based artwork.

Synthesis of Fullerene-Fused Dioxanes/Dioxepanes: Ferric Perchlorate-Mediated One-Step Reaction of [60]Fullerene with Diols.

The facile one-step reaction of [60]fullerene with various diols in the presence of ferric perchlorate afforded a series of rare fullerene-fused dioxanes/dioxepanes. Nevertheless, the reaction of [60]fullerene with diethylene glycol, triethylene glycol, and tripropylene glycol promoted by ferric perchlorate unexpectedly generated fullerene-fused dioxanes instead of the anticipated fullerene-fused crown ethers. A plausible reaction mechanism is proposed to explain the formation of fullerene-fused dioxane/dioxepane products.