High-yield Formation Research Articles

A facile and high-yield formation of dipyrrin-boronic acid dyads and triads: a light-harvesting system in the visible region based on the efficient energy transfer.

Artificial light-harvesting systems, Ar,O-BODIPY dyads and triads conjugated with a light harvester, were synthesized in high yield by the reaction of an N2O2-type dipyrrin with boronic acids. Dyad 2 having a pyrene unit underwent quantitative Förster resonance energy transfer (FRET) from the antenna unit, pyrene, to the fluorophore unit, Ar,O-BODIPY. Triads 3·5 and 4·5 were quantitatively prepared by mixing pyridine-appended compounds 3 and 4 with saloph·Zn complex 5, respectively. Triad 4·5 underwent efficient FRET from the saloph·Zn complex unit to the fluorophore unit at the rate of 2.0 × 10(11) s(-1). Interestingly, the fluorescence quenching process in the excited state of the triad 3·5 took place following the energy transfer event. Thus, appropriate positioning of the energy donor and acceptor is necessary to construct a highly efficient FRET system.

Stabilization of the potent odorant 2-acetyl-1-pyrroline and structural analogues by complexation with zinc halides.

2-Acetyl-1-pyrroline (2AP) and the structurally similar compounds 6-acetyl-2,3,4,5-tetrahydropyridine (ATHP, along with its tautomer 6-acetyl-1,2,3,4-tetrahydropyridine), 2-propionyl-1-pyrroline (2PP), and 2-acetyl-2-thiazoline (2A2T) are well-known potent odorants in various food products. However, due to the highly unstable nature of these compounds, especially 2AP and ATHP, they are scarcely used commercially in flavor formulations. A novel and attractive method for the stabilization of these potent odorants in dry powder form is presented. Coordination of 2AP, ATHP, 2PP, and 2A2T to zinc ions (ZnI2, ZnBr2, or ZnCl2) resulted in the formation in high yields of stable crystalline complexes, which upon hydration release the free odorant. Infrared spectroscopy was used to study the coordination complexes. 2AP contains donor atoms, which coordinate (with covalent character) through both the heterocyclic nitrogen and carbonyl oxygen atoms to the zinc ion. This is also the case for ATHP and 2PP, but not for 2A2T, because the sulfur group in 2A2T provides a third possible donor site. Stability studies showed that the 2AP-ZnI2 complex (with 14% loading) maintained >94% retention of 2AP after 3 months of storage at ambient temperature in a dry environment. Meanwhile, the ATHP-ZnI2 complex was similarly stable and retained 89% of the ATHP after 3 months of storage. This stabilization technology may enable the commercial use of this powerful aroma compound as a flavoring agent.

α-nitroacrylates in reactions with malonic and acetylaminomalonic esters

Reactions of α-nitroacrylates of aromatic series with malonic and acetylaminomalonic esters proceed in the presence of sodium alcoholates and lead to the formation in high yields of Michael adducts, precursors of modified analogs of γ-aminobutyric and glutamic acids.

High-yield formation of substituted tetracyanobutadienes from reaction of ynamides with tetracyanoethylene.

A high-yielding sequence of [2+2] cycloaddition-retroelectrocyclization of ynamides with tetracyanoethylene (TCNE) is described. The reaction provided tetracyanobutadiene (TCBD) species, which were characterized by various techniques. DFT and TD-DFT calculations were also performed to complement experimental findings.

New ω-bromoacylisatins and isoindigos derived therefrom

Isatin is a widely known natural compound occurring in various plant species, e.g., Isatis tinctoria L. and Couropita guianancis aubl. [1, 2]. Isatin was also isolated as a human adrenaline metabolite [3]. Extensive studies on the synthesis and reactivity of isatins have led to the discovery of new diverse aspects of organic reactions. Numerous methods for the preparation of various heterocyclic systems have been developed starting from isatin; in particular, spiro pyrrolidines, quinolines, indoles, β-lactams, oxindoles, and other heterocycles possessing a considerable potential of biological activity have been obtained [4, 5]. Isatin derivatives containing a reactive bromoalkyl fragment have recently attracted strong interest. These compounds were used to synthesize various conjugates with known biologically active compounds (including medicinal agents) which also showed high antibacterial [6–8], antiviral [9], and antitumor activity [10, 11]. The existing methods for the preparation of N-bromoalkylisatins are few in number and are not free from disadvantages related to side formation of alkylenediisatins. In the present communication we describe a new synthetic approach to 1-(ω-bromoacyl)isatins, which is based on acylation of isatin sodium salt (I) with ω-bromoalkanoyl chlorides II and III. The reactions were carried out in anhydrous benzene at 15°C, and the corresponding 1-(ω-bromoacyl)isatins IV and V were obtained in high yields (88–89%). Compound IV was converted into isoindigo derivative VI according to the procedure described by us previously [12]. Almost quantitative formation of hexaethylphosphoric triamide (according to the P NMR data) and high yield of VI indicated that the reaction is not accompanied by side quaternization of initial phosphorous triamide.

Rapid, benign, and additive-free thiolysis of epoxides under ultrasonic/aqueous conditions

An environmentally friendly and efficient procedure is developed for ring opening of various epoxides with thiols under non-thermal conditions. Reactions take place by ultrasonic irradiation of the two reactants suspended in an additive-free aqueous medium. Consequently, high-yield formation of various β-hydroxy sulfides is quickly observed.

Synthesis of A New Class of Pyridazin-3-one and 2-Amino-5-arylazopyridine Derivatives and Their Utility in the Synthesis of Fused Azines

A general route for the synthesis of a novel class of pyridazin-3-one derivatives 3 by the reaction in acetic anhydride between 3-oxo-2-arylhydrazonopropanals 1 and some active methylene compounds like p-nitrophenylacetic acid and cyanoacetic acid was established. Under these conditions the pyridazin-3-one derivatives 3 were formed as the sole isolable products in excellent yield. The 6-acetyl-3-oxopyridazine derivative 3l was reacted with DMF-DMA to afford the corresponding enaminone derivative 4, which reacts with a variety of aminoazoles to afford the corresponding azolo[1,5-a]pyrimidine derivatives 5–7. Also, in order to explore the viability and generality of a recently uncovered reaction between 3-oxo-2-arylhydrazonopropanals and active methylene compounds, a variety of 2-amino-6-aryl-5-arylazo-3-aroylpyridines 16–19 were prepared by reacting 3-oxo-2-arylhydrazonopropanals with miscellaneous active methylene compounds like 3-oxo-3-phenylpropionitrile, hetaroylacetonitriles and cyanoacetamides. These 2-aminopyridine derivatives undergo smooth reactions with cyanoacetic acid that led to the formation in high yield of a new class of 1,8-naphthyridine derivatives 24. The structures of all new substances prepared in this investigation were determined by the different analytical spectroscopic methods, in addition to the X-ray crystallographic analysis.

Кормовые бобы - перспективная зернобобовая кормовая культура

The articles offers the results of studies on the effect of sowing methods, seeding rates and backgrounds supply on yield and economic efficiency of broad bean cultivation for seeds. Increase seeding rate of 0.4 to 0.8 million units per hectare, regardless of sowing methods, increased the content of crude protein at 2.5-3.3 %. Similar changes occurred in the sugar content of the grain. In contrast, with increasing seeding rate, in wide-space sowing and calculated doses of fertilizers usage, resulted in a decrease of crude fiber, fat and ash. Adding the calculated doses of mineral fertilizers at planting in wide-space sowing with a rowing space of 45 cm and seeding rate of 0.6 million units per hectare provides about 10 thousand rubles per hectare, and the profitability level was 78 percent. Formation of high yields of green mass (41.0 tons per hectare) and grain ( 2.34 tons per hectare) of broad bean noted, when adding calculated doses of mineral fertilizers at wide-space sowing method with a seeding rate of 0.6 million units per hectare. I this way, we can see the high net income ( 9742.8 rubles per hectare), the level of profitability (78.0 %) and the cost of 1 ton of grain (5336.4 rubles per ton). The calculations of economic efficiency of fodder beans cultivation for grain showed that a high profitability obtained by making calculated doses of fertilizers, with a rowing method of sowing and seed rate of 0.7 million units per hectare was 59.4 %, while in wide-space sowing (45 and 60 cm) with a seeding rate of 0.6 million units per hectare was 78.0%.

Difference of Characteristics of Photosynthesis, Matter Production and Translocation between Indica and Japonica Super Rice

This study was to reveal the difference of characteristics of dry matter accumulation and photosynthetic production between indica and japonica super rice. Field experiments were conducted by using five representative super hybrid indica combinations and five conventional japonica super rice varieties planted on a large scale in Jiangsu region with rice-wheat double cropping rotation. Dry matter accumulation, distribution and translocation, leaf area, leaf area duration(LAD), crop growth rate(CGR), net assimilation rate(NAR), seedling quality and leaf type were analyzed systematically. Results showed that, dry matter accumulation, LAD, CGR, and NAR at the early growth stage(from transplanting to jointing), leaf length, leaf base angle, angle between stem and leaf and drooping angle in top three leaves, leaf area decreasing per day after heading and harvest index of japonica rice were less than those of indica rice significantly, while dry matter accumulation, LAD, CGR, and NAR at the middle and later growth stages(from jointing to maturity), ratio of leaf area of productive tillers, ratio of leaf area of top three leaves, grain-leaf ratio(spikelets per cm2 leaf area, filled grains per cm2 leaf area and grain weight per cm2 leaf area), maximum leaf area index, total filling, grain yield, biological yield, maximum output and apparent output and their ratio were larger than those ofindica rice significantly. Although dry matter weight per stem of japonica rice at the main growth stages was lower than that of indica rice, the superiority of population quantity suggested that japonica rice would possess higher dry matter accumulation and leaf area. With the advancement of growth and development, the superiority of photosynthesis and matter production of japonica rice was increasing, with a higher dry matter accumulation more than that of indica rice 25 d after heading approximately. The growth potential of japonica rice remained strong at the late period of grain-filling(from milky stage to maturity), while stored matter kept in the stem and sheath exported appropriately at the early period of grain-filling(from heading to milky stage), ensuring the security of efficient photosynthetic layer and the enrichment of high accumulation yield sink. Therefore, balanced formation of high biological yield, stable-increasing-slow-decreasing tendency of leaf area, and the large amounts of high efficient photosynthate production from jointing to maturity are the important characteristics and causes for the efficient and sustainable output of photosynthetic systems, more grain-filling and high yield formation in japonica rice.

Role of end-groups and catalyst in polyester cyclodepolymerization and cycle-chain equilibria

The influence of polyesters end-groups on cyclic oligoester formation is investigated using a series of hydroxy-, carboxy- and methylester-terminated aliphatic polyesters, in the presence of various ester interchange catalysts. The presence of hydroxy end-groups is the preponderant factor on cyclodepolymerization kinetics. This indicates that the main reaction is the intramolecular hydroxy–ester interchange reaction between hydroxy end-groups and ester functions in the chain. Carboxy-ester and ester–ester interchanges play a minor role, as the cycle-chain equilibrium is reached only very slowly when carboxy- or ester-terminated polyesters are reacted. High temperature and the presence of tin catalysts are also favorable factors, while, as expected, dilution shifts the equilibrium toward the formation of high yields of cyclic oligoesters. A mechanism is proposed, based on the reverse of the “coordination-insertion” mechanism established for the ring-opening polymerization of lactones.

High yield formation of lipid bilayer shells around silicon nanowires in aqueous solution

The combination of nanoscaled materials and biological self-assembly is a key step for the development of novel approaches for biotechnology and bionanoelectronic devices. Here we propose a route to merge these two subsystems and report on the formation of highly concentrated aqueous solutions of silanized silicon nanowires wrapped in a lipid bilayer shell. We developed protocols and investigated the dynamics of lipid films on both planar surfaces and silicon nanowires using fluorescence recovery after photobleaching, demonstrating fully intact and fluid bilayers without the presence of a lipid molecule reservoir. Finally, the experimental setup allowed for in situ observation of spontaneous bilayer formation around the nanowire by lipid diffusion from a vesicle to the nanowire. Such aqueous solutions of lipid coated nanowires are a versatile tool for characterization purposes and are relevant for newly emerging bioinspired electronics and nanosensorics.

High Yield Formation and Its Eco-Physiological Characteristics of Cast-Trans¬planting Rice

Cast-Transplanting rice has a low cost, easy operation, high and stable yield potential advantage, Depth study of the seedings throwing is very important to develop the light and simple cultivation of rice. The purpose of this study is to explore the high yield formation and its eco-physiological characteristics of cast-transplanting rice. Under the rice-wheat cropping systems, conventional japonica cultivar Nanjing 44 and japonica hybrid rice cultivar Yongyou 8 were used to investigate the characteristics of high yield formation including tillering dynamic, LAI, photosynthetic potential, dry matter production and the eco-physiological basis, such as post-root activity, photosynthetic characteristics, material accumulation and translocation, with three cast-transplanting methods of transplanted seedlings (TS), pointed seedlings (PS), and broadcasted seedlings (BS) in contrast with the manually transplanting of seedlings with roots washed beforehand (MTS), which could provide the theoretical and practical basis for the high and stable yield of the cast-transplanting rice. The results showed that the yields of three methods were 21.9%, 18.3%, and 13.2% higher than MTS for Yongyou 8, and 18.3%, 14.1%, and 9.87% higher than MTS for Nanjing 44, respectively. The yields of two cultivars both showed the trend of TS PS BS MTS. Although the filled-grain percentage and 1000-grain weight of cast-transplanting rice were significantly or very significantly lower than those of MTS, the total number of spikelets of cast-transplanting rice was conformably higher than that of MTS at a significant or very significant degree. The increased yield was mainly due to the higher total spikelet number. Compared to MTS, the cast-transplanting rice had more peak seedling tillers, higher or equivalent ratios of productive tillers to total tillers, an enough number of ultimate effective panicles, higher LAI and LAD, and thus a more robust population quality. According to these results, we could give the conclusion of the eco-physiological basis of high and stable yield of cast-transplanting rice. After transplantation, there were earlier tillering, more leaf tillering positions, stronger tillering capability, and higher quality and enough quantity of tillering. At the heading stage, they had suitable plant height, stouter stems and sheaths, efficient leaf configurations, preferable air ventilation and light transmission conditions, higher biomass accumulation, a more coordinated sink-source relationship, and hence a higher yield potential. In the late growth period, the cast-transplanting rice had stronger roots, slower senescence of leaves, more powerful photosynthesis, more coordinated dry matter accumulation and translocation of stem and sheath, higher filling ratios, being more conducive to the higher yield. TS and PS have evident advantages than MTS, and are more favorable in achieving higher yield.

High Yield Formation and Its Eco-Physiological Characteristics of Cast-Trans¬planting Rice

High Yield Formation and Its Eco-Physiological Characteristics of Cast-Trans¬planting Rice

Dibenzosilanorbornadienyl Cations and Their Fragmentation into Silyliumylidenes

The terphenyl-substituted dibenzosilanorbornadienyl cation 11 was synthesized and isolated in the form of its [B(C6F5)4](-) salt. The salt was characterized by NMR spectroscopy supported by quantum mechanical computations and by an XRD analysis of a corresponding acetonitrilium salt. The thermal fragmentation of 11[B(C6F5)4] in benzene results in the high-yield formation of diphenylterphenylsilylium borate 17[B(C6F5)4]. High-lying intermediates in this process are solvent-complexed terphenylsilyliumylidene 8 and the hydrogen- and phenyl-substituted silylium ion 20. The formation of silylium ion 20 by reaction of silyliumylidene 8 with the solvent benzene demonstrates the high potential of this four valence electron species in C-H bond activation reactions. In addition, the instability of the hydrogen-substituted silylium ion 20 in benzene opens new mechanistic perspectives particular for dihydrogen activation by silyl cationic frustrated Lewis pairs and in general for the dihydrogen activation by strong Lewis acids.

Design, microwave assisted synthesis and pharmacological activities of substituted pyrimido[2,1-b][1,3]benzothiazole-3-carboxylate derivatives

Background and aimThe current need for the discovery and development of new lead compounds exhibiting optimal antitumor potency as well as anti-inflammatory activity. Due to biological activity of significant number of compounds containing condensed pyrimidine ring system and our interest in MCRs reactions, we wish to report the synthesis of 4H-pyrimido[2,1-b][1,3]benzothiazole-3-carboxylate. MethodA novel one pot multi-component reaction of substituted benzaldehyde, ethyl cyanoacetate, 2-amino benzothiazole to give pyrimido[2,1-b][1,3]benzothiazole-3-carboxylate was described. The operational simplicity, environmental friendly conditions, regioselective formation of target product and high yield in significantly very short reaction time were major benefits. Result and discussionStructural assignments based on spectroscopic data (FT-IR, 1H NMR, mass spectra). Compounds evaluated for in vitro on panel of 60 different human tumor cell lines derived from nine neoplastic cancer types at NCI, and for the in vitro anti-inflammatory activity. Compound ethyl(4R)-2-amino-6,9-dimethyl-4-[4-(dimethylamino)phenyl]-4H-pyrimido[2,1-b][1,3]benzothiazole-3-carboxylate (4i) was found to possess good antiproliferative activity and compound ethyl(4R)-2-amino-6-chloro-4-(3,4,5-trimethoxyphenyl)-4H-pyrimido[2,1-b][1,3]benzothiazole-3-carboxylate (4g) was found to posses potent anti-inflammatory activity and compounds 4a, 4b, 4h also found to be significant anti-inflammatory activity. ConclusionThe obtained results prove the necessity for further investigations to clarify the features underlying the antitumor potential of tested compounds and had potential to design lead for anti-inflammatory activity.

Radiation grafting on natural films

Different methods of polymer grafting using gamma irradiation are reported in the present study for the preparation of newly functionalized biodegradable films, and some important properties related to their mechanical and barrier properties are described. Biodegradable films composed of zein and poly(vinyl alcohol) (PVA) were gamma-irradiated in presence of different ratios of acrylic acid (AAc) monomer for compatibilization purpose. Resulting grafted films (zein/PVA-g-AAc) had their puncture strength (PS=37–40Nmm−1) and puncture deformation (PD=6.5–9.8mm) improved for 30% and 50% PVA in blend, with 5% AAc under 20kGy. Methylcellulose (MC)-based films were irradiated in the presence of 2-hydroxyethyl methacrylate (HEMA) or silane, in order to determine the effect of monomer grafting on the mechanical properties of films. It was found that grafted films (MC-g-HEMA and MC-g-silane) using 35% monomer performed higher mechanical properties with PS values of 282–296Nmm−1 and PD of 5.0–5.5mm under 10kGy. Compatibilized polycaprolactone (PCL)/chitosan composites were developed via grafting silane in chitosan films. Resulting trilayer grafted composite film (PCL/chitosan-g-silane/PCL) presented superior tensile strength (TS=22MPa) via possible improvement of interfacial adhesion (PCL/chitosan) when using 25% silane under 10kGy. Finally, MC-based films containing crystalline nanocellulose (CNC) as a filling agent were prepared and irradiated in presence of trimethylolpropane trimethacrylate (TMPTMA) as a grafted plasticizer. Grafted films (MC-g-TMPTMA) presented superior mechanical properties with a TS of 47.9MPa and a tensile modulus (TM) of 1792MPa, possibly due to high yield formation of radicals to promote TMPTMA grafting during irradiation. The addition of CNC led to an additional improvement of the barrier properties, with a significant 25% reduction of water vapor permeability (WVP) of grafted films.

ChemInform Abstract: Antiselective Three‐Component Mannich Reactions in Thiopyran‐4‐one System.

The one-pot, three-component Mannich reactions of thiopyran-4-one 1 with different aromatic aldehydes and aniline derivatives in the presence of catalytic quantities of ZrOCl2.8H2O (15 mol %) led to rapid and high yield formation of various 3-methylamino substituted derivatives of 1 at room temperature. Spectroscopic and X-ray analyses of the products suggested the formation of the anti stereoisomers as the major product of the reactions.

Synthesis and structure of cobalt(II) iodide bearing a bulky N-heterocyclic carbene ligand, and catalytic activation of bromoalkanes

A divalent cobalt iodine complex bearing 1,3-bis(mesityl)imidazol-2-ylidene and pyridine ligands was synthesized and its structure was determined. The cobalt center has a typical d7-tetrahedral geometry, as expected. Catalytic application of this cobalt complex with bromoalkanes and Grignard reagents demonstrated high-yield formation of alkenes as a result of β-hydrogen elimination; in sharp contrast, the activation of alkyl halides was not successful using the larger N-heterocyclic carbene ligand, 1,3-bis(2,6-diisopropyl-phenyl)imidazol-2-ylidene. In the presence of styrene, Heck reaction proceeded with trans selectivity. The reaction of a substrate containing a bromobenzyl moiety yielded a homocoupling product.

Ultrafast exciton dynamics in colloidal aluminum phosphide nanocrystals

The primary exciton dynamics of colloidal indirect bandgap AlP nanocrystals are characterized with ultrafast transient absorption spectroscopy. A 400-nm excitation results in a high yield formation of an emissive exciton with a ∼1-ns lifetime and a 50-nm bandwidth red-shifted emission. Multi-wavelength target analysis is used to decompose the measured signals into sequential and parallel models, which interpret the measured data as an emissive exciton with a 1.2-ns decay time and a dark exciton which is attributed to surface trapping. Reconstructed nonlinear absorption spectra resolve a broad optical gain persisting for >1ns. The 15% emission yield demonstrates that colloidal AlP nanocrystals are useful as a potential broadband, high efficiency optoelectronics material.

Antiselective Three‐Component Mannich Reactions in Thiopyran‐4‐one System

The one‐pot, three‐component Mannich reactions of thiopyran‐4‐one 1 with different aromatic aldehydes and aniline derivatives in the presence of catalytic quantities of ZrOCl2.8H2O (15 mol %) led to rapid and high yield formation of various 3‐methylamino substituted derivatives of 1 at room temperature. Spectroscopic and X‐ray analyses of the products suggested the formation of the anti stereoisomers as the major product of the reactions.