Triton-B-Catalyzed,Efficient, One-Pot Synthesis of Dithiocarbazates Through Alcoholic Tosylates

A quick, efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various tosylates of primary, secondary, and tertiary alcohols with a variety of substituted hydrazines using the benzyl–trimethylammonium hydroxide (Triton-B)/CS₂ system. The reaction conditions are mild with simpler workup procedures than the reported methods.     

An Efficient Synthesis of New Dispiropyrrolidine Derivatives via Three‐Component 1,3‐Dipolar Cycloaddition Reaction

A series of new dispiropyrrolidine derivatives were synthesized via the three‐component 1,3‐dipolar cycloaddition reaction of azomethine ylides generated in situ by the decarboxylative condensation of acenaphthenequinone and sarcosine or l ‐thioproline with 5‐benzylidene‐1,3‐dimethylpyrimidine‐2,4,6‐trione. The structures of the products were identified by IR, ¹H‐NMR, and HRMS spectra.     

A Convenient Method for the Preparation of 6,7-Methyl-Enedioxy-3-Alkyl-2-Hydroxy-1,4-Naphthoquinones from Natural Safrole and Carboxylic Acids

As part of our program to prepare substituted rtaphthoquinones with potential biological activity¹ we have synthetized 6, 7-methyleriedioxy-3-alky 1 lawsones (5a-g) from natural safrole (1) and carboxylic' acids (～50% overall yield).     

Efficient Method for Synthesis of the Derivatives of 5‐Arylidene Barbituric Acid Catalyzed by Aminosulfonic Acid With Grinding

Aminosulfonic acid is an environmentally friendly catalyst. Grinding a mixture of aromatic aldehydes, barbituric acid, and H₂NSO₃H at room temperature (without any solvent) gave 5‐arylidene barbituric acid in high yields, providing a simple and efficient route to synthesis of these compounds.     

Impact of the Synergistic Collaboration of Oligothiophene Bridges and Ruthenium Complexes on the Optical Properties of Dumbbell‐Shaped Compounds

The linear and non‐linear optical properties of a family of dumbbell‐shaped dinuclear complexes, in which an oligothiophene chain with various numbers of rings (1, 3, and 6) acts as a bridge between two homoleptic tris(2,2′‐bipyridine)ruthenium(II) complexes, have been fully investigated by using a range of spectroscopic techniques (absorption and luminescence, transient absorption, Raman, and non‐linear absorption), together with density functional theory calculations. Our results shed light on the impact of the synergistic collaboration between the electronic structures of the two chemical moieties on the optical properties of these materials. Experiments on the linear optical properties of these compounds indicated that the length of the oligothiophene bridge was critical for luminescent behavior. Indeed, no emission was detected for compounds with long oligothiophene bridges (compounds 3 and 4 , with 3 and 6 thiophene rings, respectively), owing to the presence of the ³π? π* state of the conjugated bridge below the ³MLCT‐emitting states of the end‐capping Ru^II complexes. In contrast, the compound with the shortest bridge ( 2 , one thiophene ring) shows excellent photophysical features. Non‐linear optical experiments showed that the investigated compounds were strong non‐linear absorbers in wide energy ranges. Indeed, their non‐linear absorption was augmented upon increasing the length of the oligothiophene bridge. In particular, the compound with the longest oligothiophene bridge not only showed strong two‐photon absorption (TPA) but also noteworthy three‐photon‐absorption behavior, with a cross‐section value of 4×10^?78 cm⁶ s² at 1450 nm. This characteristic was complemented by the strong excited‐state absorption (ESA) that was observed for compounds 3 and 4 . As a matter of fact, the overlap between the non‐linear absorption and ESA establishes compounds 3 and 4 as good candidates for optical‐power‐limiting applications.     

Aggregation Effects in Visible‐Light Flavin Photocatalysts: Synthesis,Structure, and Catalytic Activity of 10‐Arylflavins

A series of 10‐arylflavins (10‐phenyl‐, 10‐(2′,6′‐dimethylphenyl)‐, 10‐(2′,6′‐diethylphenyl)‐, 10‐(2′,6′‐diisopropylphenyl)‐, 10‐(2′‐tert‐butylphenyl)‐, and 10‐(2′,6′‐dimethylphenyl)‐3‐methylisoalloxazine ( 2 a – f )) was prepared as potentially nonaggregating flavin photocatalysts. The investigation of their structures in the crystalline phase combined with ¹H‐DOSY NMR spectroscopic experiments in CD₃CN, CD₃CN/D₂O (1:1), and D₂O confirm the decreased ability of 10‐arylflavins 2 to form aggregates relative to tetra‐O‐acetyl riboflavin ( 1 ). 10‐Arylflavins 2 a – d do not interact by π–π interactions, which are restricted by the 10‐phenyl ring oriented perpendicularly to the isoalloxazine skeleton. On the other hand, N3? H???O hydrogen bonds were detected in their crystal structures. In the structure of 10‐aryl‐3‐methylflavin ( 2 f ) with a substituted N3 position, weak C? H???O bonds and weak π–π interactions were found. 10‐Arylflavins 2 were tested as photoredox catalysts for the aerial oxidation of 4‐methoxybenzyl alcohol to the corresponding aldehyde (model reaction), thus showing higher efficiency relative to 1 . The quantum yields of 4‐methoxybenzyl alcohol oxidation reactions mediated by arylflavins 2 were higher by almost one order of magnitude relative to values in the presence of 1 .     

自由基引发八甲基丙烯酸酯基笼型倍半硅氧烷在多壁碳纳米管表面的可控包覆

以FeSO4/K2S2O8为反应的引发剂,通过均相和非均相聚合体系,制备了聚八甲基丙烯酸酯基笼型倍半硅氧烷(PMMA-POSS)包覆的多壁碳纳米管核-壳型纳米杂化材料.透射电子显微镜显示,在均相体系中可以得到包覆均匀且厚度可调的多壁碳纳米管杂化材料,包覆厚度在15~25 nm,35~50 nm之间,非均相体系中得到了PMMA-POSS微球悬挂在碳纳米管侧壁的杂化材料.通过傅里叶红外光谱(FTIR)、拉曼光谱(Raman)以及热重分析(TGA)对杂化材料进行了表征,并给出了可能的包覆机理.     

The asphericity of random 2‐dimensional complexes

We study random 2‐dimensional complexes in the Linial–Meshulam model and prove that for the probability parameter satisfying a random 2‐complex Y contains several pairwise disjoint tetrahedra such that the 2‐complex Z obtained by removing any face from each of these tetrahedra is aspherical. Moreover, we prove that the obtained complex Z satisfies the Whitehead conjecture, i.e. any subcomplex is aspherical. This implies that Y is homotopy equivalent to a wedge where Z is a 2‐dimensional aspherical simplicial complex. We also show that under the assumptions where c > 3 and , the complex Z is genuinely 2‐dimensional and in particular, it has sizable 2‐dimensional homology; it follows that in the indicated range of the probability parameter p the cohomological dimension of the fundamental group of a random 2‐complex equals 2. © 2013 Wiley Periodicals, Inc. Random Struct. Alg., 46, 261–273, 2015