A series of sp(2) carbon materials with different specific surface area (SSA) and controlled pore size distribution (PSD) were synthesized at large scale through a facile and low-cost method. The SSA and PSD of these carbon materials were controlled by using different carbon sources and preparation methods. With different total and effective SSA (E-SSA) and PSD, the impacts on their capacitance performance were investigated thoroughly, which demonstrated that both E-SSA and PSD played the most important roles in their capacitance performance. Furthermore, theoretical modeling was performed, and the results are in agreement with the experimental results for the influence of E-SSA and PSD on their capacitance performance. Based on these, a general model using the slit/cylindrical NL-DFT approach is proposed for the estimation of the specific capacitance of sp(2) carbon materials, which offers a simple but reliable method to predict the capacitance performance of these materials, thus speeding up the design and screening of the materials for high-performance supercapacitor and other surface area related devices.

Racemic phenanthroindolizidine alkaloids tylophorine, antofine, and deoxytylophorinine, and optically pure alkaloids S-(+)-tylophorine and R-(-)-tylophorine were synthesized and evaluated for their antiviral activities against tobacco mosaic virus (TMV). Further salinization modifications based on tylophorine increased stability and water solubility and improved the antiviral activity in application. The bioassay results showed that most of these synthesized compounds showed higher antiviral activity against TMV in vitro and in vivo than commercial Ningnanmycin. Especially, tylophorine salt derivatives 10, 11, 13, 17, and 22 emerged as potential inhibitors of plant virus. These findings demonstrate that these phenanthroindolizidine alkaloids and their salt derivatives represent a new template for antiviral studies and could be considered for novel therapy against plant virus infection.

Heterocyclic compounds play an important role as the main sources of lead molecules of agrochemicals. Synthesis and biological activity of thiadiazole-containing 1,2,4-triazolo[3,4-b][1,3,4]-thiadiazoles were seldom reported. To find novel lead compounds with various biological activities, a series of 6-substituted-3-(4-methyl-1,2,3-thiadiazolyl)[1,2,4]triazolo[3,4-b][1,3,4]thiadizoles were rationally designed and synthesized according to the principle of combinations of bioactive substructures by the condensation of 3-(4-methyl-1,2,3-thiadiazolyl)-4-amino-1,2,4-triazole-5-thione with various carboxylic acids and phosphorus oxychloride. All newly synthesized compounds were identified by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), electroionization mass spectrometry (EI/MS), and elementary analysis. The crystal structure of 3-(4-methyl-1,2,3-thiadiazolyl)-6-(4-methylphenyl)[1,2,4]triazolo[3,4-b][1,3,4]thiadizole was determined by X-ray diffraction crystallography. In this crystal, two intermolecular hydrogen bonds (N2...H-C12 and N3...H-C13), a weak intermolecular interaction (S...S), and the weak ppi-ppi intermolecular interaction were observed. Fungicide screening indicated that all of the target compounds showed certain extent of growth inhibition against fungi tested. 3-(4-Methyl-1,2,3-thiadiazolyl)-6-n-propyl[1,2,4]triazolo[3,4-b][1,3,4]thiadizole and 3-(4-methyl-1,2,3-thiadiazolyl)-6-trichloromethyl[1,2,4]triazolo[3,4-b][1,3,4]thiadizole were found to have potential wide spectrum of fungicide activity. The median effective concentrations (EC(50)) detected for 3-(4-methyl-1,2,3-thiadiazolyl)-6-trichloromethyl[1,2,4]triazolo[3,4-b][1,3,4]thiadizole to six fungi were from 7.28 micromol/L against Pellicularia sasakii (Shirai) to 42.49 micromol/L against Alternaria solani . The results indicated that thiadiazole-containing 1,2,4-triazolo[3,4-b][1,3,4]-thiadiazoles were potential fungicide lead compounds.

Elicitors provide a broad spectrum of systemic acquired resistance by altering the physical and physiological status of the host plants and, therefore, are among the most successful directions in modern pesticide development for plant protection. To develop a novel elicitor with highly systemic acquired resistance, two series of thiazole- and oxadiazole-containing thiadiazole derivatives were rationally designed and synthesized according to the principle of combination of bioactive substructures in this work. Their structures were characterized by (1)H nuclear magnetic resonance (NMR), infrared (IR), high-resolution mass spectrometry (HRMS), or elemental analysis. Their potential systemic acquired resistance as an elicitor was also evaluated; bioassay results indicated that, among the 23 compounds synthesized, three compounds, 10a, 10d, and 12b, displayed better systemic acquired resistance than the positive control, tiadinil, a commercialized 1,2,3-thiadiazole-based elicitor. In addition, three other compounds, 10f, 12c, and 12j, exhibited a certain degree of fungus growth inhibition in vitro or in vivo. Our results demonstrated that, in combination of bioactive substructures is an interesting exploration for novel pesticide development, thiazole- and oxadiazole-containing thiadiazole derivatives are potential elicitors with good systemic acquired resistance.

To contribute molecular diversity for novel fungicide development, a series of novel thiazole carboxamides were rationally designed, synthesized, and characterized with the succinate dehydrogenase (SDH) as target. Bioassay indicated that compound 6g showed the similar excellent SDH inhibition as that of Thifluzamide with IC 50 of 0.56 mg/L and 0.55 mg/L, respectively. Some derivatives displayed improved in vitro fungicidal activities against Rhizoctonia cerealis and Sclerotinia sclerotiorum with EC 50 of 1.2−16.4 mg/L and 0.5−1.9 mg/L. Surprisingly, 6g showed promising in vitro fungicidal activities against R. cerealis and S. sclerotiorum with EC 50 of 6.2 and 0.6 mg/L, respectively, which was superior to Thifluzamide with the EC 50 of 22.1 and 4.4 mg/L, respectively. Additionally, compounds 6c and 6g displayed excellent in vivo fungicidal activities against S. sclerotiorum on Brassica napus L. leaves with protective activity of 75.4% and 67.3% at 2.0 mg/L, respectively, while Thifluzamide without activity at 5.0 mg/L. Transcriptomic analysis of S. sclerotiorum treated with 6g by RNA sequencing indicated the down-regulation of succinate dehydrogenase gene SDHA and SDHB, and the inhibition of the TCA-cycle.

In searching for novel fungicidal leads, the novel bioactive succinate dehydrogenase inhibitor (SDHI) derivatives were designed and synthesized by the inversion of carbonyl and amide groups. Bioassay indicated that compound 5i stood out with a broad spectrum of in vitro activity against five fungi. Its EC50 value (0.73 μg/mL) was comparable to that of boscalid (EC50 of 0.51 μg/mL) and fluxapyroxad (EC50 of 0.19 μg/mL) against Sclerotinia sclerotiorum. For Rhizoctonia cerealis, 5i and 5p with EC50 values of 4.61 and 6.48 μg/mL, respectively, showed significantly higher activity than fluxapyroxad with the EC50 value of 16.99 μg/mL. In vivo fungicidal activity of 5i exhibited an excellent inhibitory rate (100%) against Puccinia sorghi at 50 μg/mL, while the positive control boscalid showed only a 70% inhibitory rate. Moreover, 5i showed promising fungicidal activity with a 60% inhibitory rate against Rhizoctonia solani at 1 μg/mL, which was better than that of boscalid (30%). Compound 5i possessed better in vivo efficacy against P. sorghi and R. solani than boscalid. Molecular docking showed that even the carbonyl oxygen atom of 5i was far from the pyrazole ring. It could also form hydrogen bonds toward the hydroxyl hydrogen and amino hydrogen of TYR58 and TRP173 on SDH, respectively, which consisted of the positive control fluxapyroxad. Fluorescence quenching analysis and SDH enzymatic inhibition studies also validated its mode of action. Our studies showed that 5i was worthy of further investigation as a promising fungicide candidate.

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Strobilurin fungicides play a crucial role in protecting plants against different pathogens and securing food supplies. A series of 1,2,3-thiadiazole and thiazole-based strobilurins were rationally designed, synthesized, characterized, and tested against various fungi. Introduction of 1,2,3-thiadiazole greatly improved the fungicidal activity of the target molecules. Compounds 8a, 8c, 8d, and 10i exhibited a relatively broad spectrum of fungicidal activity. Compound 8a showed excellent activities against Gibberella zeae, Sclerotinia sclerotiorum, and Rhizoctonia cerealis with median effective concentrations (EC) of 2.68, 0.44, and 0.01 μg/mL, respectively; it was much more active than positive controls enestroburin, kresoxim-methyl, and azoxystrobin with EC between 0.06 and 15.12 μg/mL. Comparable or better fungicidal efficacy of compound 8a compared with azoxystrobin and trifloxystrobin against Sphaerotheca fuliginea and Pseudoperonspera cubensis was validated in cucumber fields at the same application dosages. Therefore, compound 8a is a promising fungicidal candidate worthy of further development.