Synthesis and biological evaluation of arylpyrazoles as fungicides against phytopathogenic fungi.

3-phenol-1H-pyrazoles (2), 4-halogeno-3-phenol-1H-pyrazoles (3) and 2-(1-phenol-1H-pyrazol-5-yl)phenols (4) were prepared by the condensation of (E)-3-(dimethylamino)-1-phenylprop-2-en-1-ones and hydrazine hydrate or phenylhydrazine in good yields. They were evaluated against five phytopathogens fungi, namely Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani and Fusarium solani in vitro. Most of the above-mentioned compounds exhibited activities. For example, 4-chloro-2-(1H-pyrazol-3-yl)phenol (3k) and 4-bromo-3-phenol-1H-pyrazole (3b) showed good and broad-spectrum antifungal properties against Cytospora sp., C. gloeosporioides, Botrytis cinerea, Alternaria solani and F. Solani with [Formula: see text] values ranging from 4.66 to 12.47 [Formula: see text]g/mL. The results showed that pyrazoles with one aryl group at 3-position (2 and 3) exhibited better antibacterial activity than those with two aryl substituents (4). In addition, the existence of an electron-withdrawing group, a substituent on the ortho-position of phenol ring or a halogen atom at the 4-position of the pyrazole enhanced the antifungal activity of pyrazoles 2 and 3. A series of arylpyrazole derivatives was facilely prepared and was evaluated against five phytopathogens fungi including Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani, and Fusarium solani in vitro. Most of those compounds exhibited remarkable antifungal activities and were superior to the positive control hymexazol.

Synthesis of pyrazolo[1,5-a]pyrimidine derivatives and their antifungal activities against phytopathogenic fungi in vitro.

5,6-Diarylpyrazolo[1,5-a]pyrimidines (3) and 6,7-diarylpyrazolo[1,5-a]pyrimidines (4) were chemoselectively synthesized by the condensation of isoflavone (1) and 3-aminopyrazole (2). 5,6-Diarylpyrazolo[1,5-a]pyrimidines (3) were obtained via microwave irradiation, and 6,7-diarylpyrazolo[1,5-a]pyrimidines (4) were obtained via conventional heating. In addition, the pyrimidine derivatives 3 and 4 were evaluated against five phytopathogenic fungi (Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani, and Fusarium solani) using the mycelium growth rate method. Some of them were effective in inhibiting the growth of the five phytopathogenic fungi. For instance, 6,7-diarylpyrazolo[1,5-a]pyrimidines (4j) inhibited the growth of A. solani with an [Formula: see text] value of 17.11 [Formula: see text], and 6,7-diarylpyrazolo[1,5-a]pyrimidines (4h) inhibited the growth of both Cytospora sp. and F. solani with [Formula: see text] values of 27.32 and 21.04 [Formula: see text], respectively. A chemoselective synthesis of 5,6-pyrazolo[1,5-a]pyrimidines 3 derivatives in excellent yields was performed under microwave irradiation and 6,7-pyrazolo[1,5-a]pyrimidines 4 were also prepared using heating method. The antifungal properties of 3 and 4 were tested against Cytospora sp., Colletotrichum gloeosporioides, Botrytis cinerea, Alternaria solani, and Fusarium solani.

Steady state fluorescence spectroscopy of the photosystem II core complex.

Spectroscopic properties within the core complex of photosystem II were investigated by studying the influence of the wavelength of excitation on the fluorescence emission spectrum. At two temperatures, when the core complex of PSII isolated from spinach was excited at six different excitation wavelengths ranging from 436 nm to 520 nm, there is no difference in the maxima of the emission spectra of the core complex, and when the core complex was excited at 480, 489, 495 and 507 nm respectively, fluorescence intensities of maxima decrease with increasing of the absorbance of the beta-carotene molecules at the four excitation wavelengths. The extent of change of the shoulder of the spectra beyond 700 nm depends on the kind of pigment molecule excited. The excitation wavelength can influence the way of energy transfer in the core complex of photosystem II. By Gaussian deconvolution analysis, at least seven groups of chlorophyll a molecules were discovered. They are Chl a(660), Chl a(670), Chl a(680), Chl a(682), Chl a(684), Chl a(687) and Chl a(690).