Molecular ferroelectrics with high-temperature reversible phase-transition behaviors are very rare and have currently become one of the hotspots in the field of ferroelectric materials. Herein we display two new crown ether clathrates possessing unusual high-temperature ferroelectric phase-transition behaviors, cyclohexyl ammonium 18-crown-6 tetrafluoroborate (or perchlorate), [Hcha-(18-crown-6)](+) [BF4](-) (1) and [Hcha-(18-crown-6)](+)[ClO4](-) (2) (Hcha = protonated cyclohexyl ammonium). We have proven their reversible structural phase transitions by variable-temperature PXRD measurements and temperature evolutions of Raman bands. Both clathrates exhibit clear ferroelectric phase transitions at about 397 and 390 K, respectively, revealed by the thermal anomalies of differential scanning calorimetry (DSC) measurements, together with abrupt dielectric anomalies in the heating and cooling processes. The measurements on ferroelectric properties using the single crystals showed optimized spontaneous polarization (Ps) of ca. 3.27 μC cm(-2) for 1 and 3.78 μC cm(-2) for 2.

Hydrothermal reaction of three-connecting ligands 1,3,5-tris(1-imidazolyl) benzene (tib) and MnSO4 or CoSO4·7H2O provides two new metal-organic frameworks, {[Mn(tib)2(H2O)4]SO4}n (1) and {[Co(tib)2(H2O)4]SO4}n (2). Single-crystal X-ray diffraction studies reveal that complexes 1 and 2 belong to the polar point group 3m, and have the same two-dimensional honeycomb networks with (6, 3) topology. The ferroelectric behavior investigation indicates that both compounds are typical ferroelectrics with an electric hysteresis loop showing a remnant polarization (P(r)) of ca. 0.586 μC cm(-2) and a coercive field (E(c)) of 2000 V cm(-1) for 1 and P(r) of ca. 0.208 μC cm(-2) and a coercive field (E(c)) of 2600 V cm(-1) for 2.

No abstract

No abstract

Resveratrol contributes to a plant’s tolerance of various abiotic and biotic stresses and is highly beneficial to human health. A search for elite alleles affecting resveratrol production was undertaken to find useful grapevine germplasm resources. Resveratrol levels in both berry skins and leaves were determined in 95 grapevine accessions (including 50 wild Chinese grapevine accessions and 45 cultivars) during two consecutive years. Resveratrol contents were higher in berry skins than in leaves and in wild Chinese grapevines than in grapevine cultivars. Using genotyping data, 79 simple sequence repeat (SSR) markers linked to 44 stilbene synthase (STS) genes were detected in the 95 accessions, identifying 40 SSR markers with higher polymorphisms. Eight SSR marker loci, encompassing 19 alleles, were significantly associated with resveratrol content on (P < 0.001), and 5 SSR loci showed repeated associations. Locus Sh5 had four associations: three positive for allele 232 (including leaves in the 2 years) and one negative for allele 236 in four environments. Loci Sh9 and Sh56 for a total of 7 alleles exhibited positive effects in berry skins in the 2 years. In berry skins, locus Sh56 with positive effects was closely linked to VvSTS27, and locus Sh77 with negative effects to VvSTS17, importantly, the two candidate genes both were located on Chromosome 16. The SSR marker loci and candidate genes identified in this study will provide a useful basis for future molecular breeding for increased production of natural resveratrol and its derivatives.