We present a method to use long‐range CH coupling constants to derive the correct diastereoisomer from the molecular constitution of small molecules. A set of 792
Single crystal microwires of a well‐studied organic semiconductor used in organic solar cells, namely
- NSF-PAR ID:
- 10047054
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 28
- Issue:
- 4
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract J CHand3J CHvalues collected from a single HSQMBC experiment on a sample of strychnine were used in the CASE‐3D (computer‐assisted 3D structure elucidation) protocol. In addition to the most commonly used3J CHcoupling constants, the subset of 322J CHvalues alone showed an excellent degree of configuration selection. The study is mainly based on comparison of DFT‐calculated2,3J CHvalues with experimental ones, critical for the case of2J CH. But the configuration selection also works well using3J CHvalues predicted from a semi‐empirical Karplus‐based equation limited to H−C−C−C fragments. The robustness, shown using strychnine as a proof of concept, makes theJ ‐based CASE‐3D analysis a viable option for the application in fields such as peptide and carbohydrate research, organic synthesis, natural‐product identification and analysis, as well as medicinal chemistry. -
Abstract We present a method to use long‐range CH coupling constants to derive the correct diastereoisomer from the molecular constitution of small molecules. A set of 792
J CHand3J CHvalues collected from a single HSQMBC experiment on a sample of strychnine were used in the CASE‐3D (computer‐assisted 3D structure elucidation) protocol. In addition to the most commonly used3J CHcoupling constants, the subset of 322J CHvalues alone showed an excellent degree of configuration selection. The study is mainly based on comparison of DFT‐calculated2,3J CHvalues with experimental ones, critical for the case of2J CH. But the configuration selection also works well using3J CHvalues predicted from a semi‐empirical Karplus‐based equation limited to H−C−C−C fragments. The robustness, shown using strychnine as a proof of concept, makes theJ ‐based CASE‐3D analysis a viable option for the application in fields such as peptide and carbohydrate research, organic synthesis, natural‐product identification and analysis, as well as medicinal chemistry. -
Abstract Abundant transition metal borides are emerging as substitute electrochemical hydrogen evolution reaction (HER) catalysts for noble metals. Herein, an unusual canonic‐like behavior of the
c lattice parameter in the AlB2‐type solid solution Cr1–x Mox B2(x = 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) and its direct correlation to the HER activity in 0.5 M H2SO4solution are reported. The activity increases with increasingx , reaching its maximum atx = 0.6 before decreasing again. At high current densities, Cr0.4Mo0.6B2outperforms Pt/C, as it needs 180 mV less overpotential to drive an 800 mA cm−2current density. Cr0.4Mo0.6B2has excellent long‐term stability and durability showing no significant activity loss after 5000 cycles and 25 h of operation in acid. First‐principles calculations have correctly reproduced the nonlinear dependence of thec lattice parameter and have shown that the mixed metal/B layers, such as (110), promote hydrogen evolution more efficiently forx = 0.6, supporting the experimental results. -
Summary Factors that affect the respiration of organic carbon by marine bacteria can alter the extent to which the oceans act as a sink of atmospheric carbon dioxide. We designed seawater dilution experiments to assess the effect of
p CO2enrichment on heterotrophic bacterial community composition and metabolic potential in response to a pulse of phytoplankton‐derived organic carbon. Experiments included treatments of elevated (1000 p.p.m.) and low (250 p.p.m.)p CO2amended with 10 μmol L−1dissolved organic carbon fromEmiliana huxleyi lysates, and were conducted using surface‐seawater collected from the South Pacific Subtropical Gyre. To assess differences in community composition and metabolic potential, shotgun metagenomic libraries were sequenced from low and elevatedp CO2treatments collected at the start of the experiment and following exponential growth. Our results indicate bacterial communities changed markedly in response to the organic matter pulse over time and were significantly affected byp CO2enrichment. Elevatedp CO2also had disproportionate effects on the abundance of sequences related to proton pumps, carbohydrate metabolism, modifications of the phospholipid bilayer, resistance to toxic compounds and conjugative transfer. These results contribute to a growing understanding of the effects of elevatedp CO2on bacteria‐mediated carbon cycling during phytoplankton bloom conditions in the marine environment. -
Abstract A density functional theoretical (DFT) study is presented, implicating a1O2oxidation process to reach a dihydrobenzofuran from the reaction of the natural homoallylic alcohol, glycocitrine. Our results predict an interconversion between glycocitrine and an
iso ‐hydroperoxide intermediate [R(H)O+– O−] that provides a key path in the chemistry which then follows. Formations of allylic hydroperoxides are unlikely from a1O2‘ene’ reaction. Instead, the dihydrobenzofuran arises by1O2oxidation facilitated by a 16° curvature of the glycocitrine ring imposed by a pyramidalN ‐methyl group. This curvature facilitates the formation of theiso ‐hydroperoxide, which is analogous to theiso species CH2I+– I−and CHI2+– I−formed by UV photolysis of CH2I2and CHI3. Theiso ‐hydroperoxide is also structurally reminiscent of carbonyl oxides (R2C=O+– O−) formed in the reaction of carbenes and oxygen. Our DFT results point to intermolecular process, in which theiso ‐hydroperoxide's fate relates to O‐transfer and H2O dehydration reactions for new insight into the biosynthesis of dihydrobenzofuran natural products.