scholarly journals Facile N-functionalization and strong magnetic communication in a diuranium(v) bis-nitride complex

2019 ◽  
Vol 10 (12) ◽  
pp. 3543-3555 ◽  
Author(s):  
Luciano Barluzzi ◽  
Lucile Chatelain ◽  
Farzaneh Fadaei-Tirani ◽  
Ivica Zivkovic ◽  
Marinella Mazzanti
Keyword(s):  
Small Molecules ◽  
Bond Formation ◽  
Antiferromagnetic Coupling ◽  
Ambient Conditions ◽  
C And N

A diuranium(v) bis-nitride complex supported by siloxide ligands displays remarkable reactivity in ambient conditions with small molecules such as CS2, CO2, CO and H2 resulting in N–C and N–H bond formation. The nitride linker also leads to an unusually strong antiferromagnetic coupling between uranium(v) ions.

Warming affects seasonal dynamics of microorganisms and reduces the N storage capacity of soil microbes in winter

2021 ◽  
Author(s):  
Philipp Gündler ◽  
Alberto Canarini ◽  
Sara Marañón Jiménez ◽  
Gunnhildur Gunnarsdóttir ◽  
Páll Sigurðsson ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Growth Rates ◽  
Seasonal Dynamics ◽  
Soil Microbes ◽  
Storage Capacity ◽  
Ambient Conditions ◽  
Soil Warming ◽  
Carbon Use Efficiency ◽  
Use Efficiency ◽  
C And N

<p>Seasonality of soil microorganisms plays a critical role in terrestrial carbon (C) and nitrogen (N) cycling. The asynchrony of immobilization by microbes and uptake by plants may be important for N retention during winter, when plants are inactive. Meanwhile, the known warming effects on soil microbes (decreasing biomass and increasing growth rates) may affect microbial seasonal dynamics and nutrient retention during winter.</p><p>We sampled soils from a geothermal warming site in Iceland (www.forhot.is) which includes three in situ warming levels (ambient, +3 °C, +6 °C). We harvested soil samples at 9 time points over one year and measured the seasonal variation in microbial biomass carbon (Cmic) and nitrogen (Nmic) and microbial physiology (growth and carbon use efficiency) by an <sup>18</sup>O-labelling technique.</p><p>We observed that Cmic and Nmic peaked in winter, followed by a decline in spring and summer. In contrast growth and respiration rates were higher in summer than winter. The observed biomass peak at lower growth rates, suggests that microbial death rates must have declined even more than growth rates. Soil warming increased biomass-specific microbial activity (i.e., growth, respiration, and turnover rates per unit of microbial biomass), prolonging the period of higher microbial activity found in summer into autumn and winter. Microbial carbon use efficiency was unaltered by soil warming. Throughout the seasons, warming reduced Cmic and Nmic, albeit with a stronger effect in winter than summer and restrained winter biomass accumulation by up to 78% compared to ambient conditions. We estimated a reduced microbial winter N storage capacity by 45.5 and 94.6 kg ha<sup>-1</sup> at +3 °C and +6 °C warming respectively compared to ambient conditions. This reduction represents 1.57% and 3.26% of total soil N stocks, that could potentially be lost per year from these soils.</p><p>Our results clearly demonstrate that soil warming strongly decreases microbial C and N immobilization when plants are inactive, potentially leading to higher losses of C and N from warmed soils over winter. These results have important implications as increased N losses may restrict increased plant growth in a future climate.</p>

scholarly journals Development and Mining of a Volatile Organic Compound Database

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Azian Azamimi Abdullah ◽  
Md. Altaf-Ul-Amin ◽  
Naoaki Ono ◽  
Tetsuo Sato ◽  
Tadao Sugiura ◽  
...  
Keyword(s):  
Small Molecules ◽  
Biological Activities ◽  
Biological Interactions ◽  
Ambient Conditions ◽  
Boiling Points ◽  
Volatile Organic ◽  
Care Field ◽  
High Vapor ◽  
Compound Database ◽  
Living Organisms

Volatile organic compounds (VOCs) are small molecules that exhibit high vapor pressure under ambient conditions and have low boiling points. Although VOCs contribute only a small proportion of the total metabolites produced by living organisms, they play an important role in chemical ecology specifically in the biological interactions between organisms and ecosystems. VOCs are also important in the health care field as they are presently used as a biomarker to detect various human diseases. Information on VOCs is scattered in the literature until now; however, there is still no available database describing VOCs and their biological activities. To attain this purpose, we have developed KNApSAcK Metabolite Ecology Database, which contains the information on the relationships between VOCs and their emitting organisms. The KNApSAcK Metabolite Ecology is also linked with the KNApSAcK Core and KNApSAcK Metabolite Activity Database to provide further information on the metabolites and their biological activities. The VOC database can be accessed online.

scholarly journals Iterative Synthesis of Pluripotent Thioethers through Controlled Redox Fluctuation of Sulfur

Synlett ◽  
2018 ◽  
Vol 29 (10) ◽  
pp. 1329-1333 ◽  
Author(s):  
Abraham Mendoza ◽  
Kilian Colas
Keyword(s):  
Small Molecules ◽  
Redox State ◽  
Bond Formation ◽  
Building Blocks ◽  
Constructive Alignment ◽  
Boronic Esters ◽  
Type C ◽  
Iterative Synthesis

Target- and diversity-oriented syntheses are based on diverse building blocks, whose preparation requires discrete design and constructive alignment of different chemistries. To enable future automation of the synthesis of small molecules, we have devised a unified strategy that serves the divergent synthesis of unrelated scaffolds such as carbonyls, olefins, organometallics, halides, and boronic esters. It is based on iterations of a nonelectrophilic Pummerer-type C–C coupling enabled by turbo-organomagnesium amides that we have recently reported. The pluripotency of sulfur allows the central building blocks to be obtained by regulating C–C bond formation through control of its redox state.

Recent Advances for the C–C and C–N Bond Formation in the Synthesis­ of 1-Phenethyl-tetrahydroisoquinoline, Aporphine, Homoaporphine­, and β-Carboline Alkaloids

Synthesis ◽  
2017 ◽  
Vol 49 (20) ◽  
pp. 4535-4561 ◽  
Author(s):  
Carlos Puerto Galvis ◽  
Vladimir Kouznetsov
Keyword(s):  
Small Molecules ◽  
Control Strategies ◽  
Bond Formation ◽  
Biological Properties ◽  
Physical Activities ◽  
Organic Transformations ◽  
Reaction Step ◽  
Critical Step ◽  
Metal Catalyzed ◽  
Made In

Among the existing methods for the synthesis of bioactive and/or complex small molecules, organic transformations such as C–C and C–N bond formation have been significantly developed and exploited for the synthesis of diverse synthetic and natural fused aza-polycycles. The abundance and biological and physical activities of 1-phenethyl-tetrahydroisoquinolines, aporphines, homoaporphines, and β-carbolines have inspired many organic chemists to seek sustainable and efficient protocols for their preparation. However, these methodologies involve multiple steps and in most cases the key reaction step is based on the formation of new C–C and/or C–N bonds, and this is usually the critical step that lowers the yields and selectivity. This review is focused on the advances made in recent years regarding the synthesis of these selected natural fused aza-polycycles, overviewing the substrate scope, limitations, regioselectivity, and chemoselectivity, as well as related control strategies of these reactions, concentrating on developments from 2010 to 2016.1 Introduction2 1-Phenethyl-tetrahydroisoquinolines; Dysoxylum Alkaloids3 Aporphines, Homoaporphines, and Semisynthetic Derivatives4 Harmala and Eudistomin Alkaloids and Their Biological Properties5 Metal-Catalyzed C–C Bond Formation6 Pd-Catalyzed C–C and C–N Bond Formation7 Metal-Catalyzed C–N Bond Formation8 [4+2] Cycloaddition in the Synthesis Of Aporphines9 Tandem C–N/C–C Bond Formation: The Pictet–Spengler Reaction10 Miscellaneous Methods11 Conclusions

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