SUMMARYSeed size in higher plants is coordinately determined by the growth of the embryo, endosperm and maternal tissue, but relatively little is known about the genetic and molecular mechanisms that set final seed size. We have previously demonstrated that Arabidopsis DA1 acts maternally to control seed size, with the da1-1 mutant producing larger seeds than the wild type. Through an activation tagging screen for modifiers of da1-1, we have identified an enhancer of da1-1 (eod3-1D) in seed size. EOD3 encodes the Arabidopsis cytochrome P450/CYP78A6 and is expressed in most plant organs. Overexpression of EOD3 dramatically increases the seed size of wild-type plants, whereas eod3-ko loss-of-function mutants form small seeds. The disruption of CYP78A9, the most closely related family member, synergistically enhances the seed size phenotype of eod3-ko mutants, indicating that EOD3 functions redundantly with CYP78A9 to affect seed growth. Reciprocal cross experiments show that EOD3 acts maternally to promote seed growth. eod3-ko cyp78a9-ko double mutants have smaller cells in the maternal integuments of developing seeds, whereas eod3-1D forms more and larger cells in the integuments. Genetic analyses suggest that EOD3 functions independently of maternal factors DA1 and TTG2 to influence seed growth. Collectively, our findings identify EOD3 as a factor of seed size control, and give insight into how plants control their seed size.

A high-molecular weight bio-based polycarbonate was successfully synthesized by breaking the hydrogen bond of endo-OH group using an ionic liquid.

Green synthesis of poly­(isosorbide carbonate) (PIC) with remarkable properties is a huge challenge in industrial applications due to low molecular weight and harsh reaction conditions. We reported a novel pathway to synthesize high molecular weight PIC through melt polymerization of isosorbide (ISB) and dimethyl carbonate (DMC), which are derived from the biomass and CO2, respectively. The effects of metal ion-containing compound catalyst on chemical structures, terminal groups, and molecular weight of PIC in the process of melt polycondensation were studied. Compared with the best reported catalyst lithium acetylacetonate, the weight-average molecular weight (M w) of PIC was increased by using our preferred catalyst sodium tert-butoxide from 46 500 to 55 100 with the ISB conversion up to 99.0%, and the reaction time was decreased from 12 h to only 2.5 h, as far as we know, which is the highest M w value and the most efficient catalyst achieved by one-step method. According to the results of the experiment and simulation, we found that high catalytic performance was ascribed to the weak interaction energy of anion–cation of catalyst and the strong proton acceptance ability of the anion of the catalyst. Meanwhile, increasing the interaction energy of anion–cation of the catalyst could inhibit the occurrence of the methylation side reaction and interestingly the activated endohydroxyl groups of ISB were found to be more easily methylated. Finally, based on the captured and detected intermediates of the two-stages of the reaction, a possible mechanim for the synergetic effects of cation–anion through hydrogen bond formation was proposed.

The balance between band structure, composition, and defect is essential for improving the optoelectronic properties of ternary and quaternary quantum dots and the corresponding photovoltaic performance. In this work, ascorbic acid (AA) as capping ligand is introduced into the reaction system to prepare green Zn–Cu–In–Se (ZCISe) quantum dots. Results show that the addition of AA can increase the Zn content while decrease the In content, resulting in enlarged band gap, high conduction band energy level, and suppressed charge recombination. When AA/Cu ratio is 1, the quantum dots possess the largest band gap of 1.49 eV and the assembled quantum dot-sensitized solar cells exhibit superior photovoltaic performance with ∼17% increment mainly contributed by the dramatically increased current density. The new record efficiencies of 10.44 and 13.85% are obtained from the ZCISe cells assembled with brass and titanium mesh-based counter electrodes, respectively.

The structure-controllable imidazole-based dicationic ionic liquids were used to precisely adjust the molecular weight and thermal properties of isosorbide-based polycarbonate.

Binding two quadruply bonded dimolybdenum units [Mo(2)(DAniF)(3)](+) (DAniF=N,N'-di-p-anisylformamidinate) with two chalcogen atoms generated two molecules with a central core composed of a cyclic six-membered [Mo(2)](2)(μ-EH)(2) species (E=S in 1 and O in 3, and [Mo(2)] is a quadruple-bonded [Mo(2)(formamidinate)(3)] unit). Aerobic oxidation of 1 and 3 followed by concomitant deprotonation gave rise to the corresponding [Mo(2)](2)(μ-E)(2) compounds 2 and 4. The latter show a striking coplanarity and near-bond equalization of the Mo/E cluster. The oxidized species 2 and 4 are diamagnetic in the measured temperature range of 5 to 300 K, which is somewhat unexpected for molecules that have dimetal units with a σ(2)π(4)δ(1) electronic configuration. This suggests there are strong interactions between the dimolybdenum units through the E atoms. The large electronic delocalization of the δ electrons over the entire Mo/E core is supported by the exceptionally large potential separation for the two successive one-electron reductions of the linked Mo(2)(5+) units from the oxidized species (ΔE(½)=1.7 V for the sulfur analogue). This large electronic delocalization has an important effect on the NMR spectroscopic signals for the two sets of methine (N-(CH)-N) protons from the DAniF ligands. Those essentially parallel to the core, H(∥), and those essentially perpendicular to the core, H(⊥), exhibit downfield and upfield chemical shifts, respectively, that are separated by δ=1.32 ppm. The structural, electronic, magnetic, and chemical behaviors for 2 and 4 are consistent with aromaticity, with the [Mo(2)E(2)Mo(2)] cores that resemble the prototypical benzene molecule. Theoretical studies, including DFT calculations, natural bond orbital (NBO) analyses, and gauge-independent atomic orbital (GIAO) NMR spectroscopic calculations, are also consistent with the aromaticity of the [Mo(2)](2)(μ-E)(2) units being promoted by d(δ)(Mo(2))-p(π)(E) π conjugation. The cyclic π conjugation of the central moiety in 2 and 4 involves a total of six electrons with 2e from δ(Mo(2)) and 4e from p(π)(E) orbitals, thereby conforming to Hückel's rule when electrons in the MOs with δ character are considered part of the delocalized system.

A synthetic strategy for bio-based polycarbonate was developed via one-pot polymerization of renewable monomer isosorbide and dimethyl carbonate using eco-friendly organo-catalysts.

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