Three calcium coordination compounds, [Ca(CPA)(H2O)4]·(CPA), 1, [Ca(MCPA)2(H2O)2]·H2O, 2, and [Ca(TCPA)2(H2O)3]·2H2O, 3 [HCPA = 3-chlorophenoxyacetic acid, HMCPA = 2-methyl-4-chlorophenoxyacetic acid, and HTCPA = 2,4,6-trichlorophenoxyacetic acid], have been synthesized by the microwave method with advantages that include shorter reaction times, lower energy consumption, and higher product yield. The structures have been characterized by IR, elemental analysis, and single-crystal X-ray diffraction. Influences on the crystal structures by changing the number and position of chlorine substituent group in phenoxyacetic acid are discussed. Steric hindrance effects involving the Cl and an ability to form the O–H⋯Cl hydrogen bonds enrich the structure diversity. TG analysis reveals that the thermostability for the three compounds is 3 > 1 > 2, which could be influenced by the existence of hydrogen bonds (O–H⋯Cl and O–H⋯O).
Hit, Lead & Candidate Discovery To discover succinate dehydrogenase inhibitors with a novel structure, we introduced cinnamic acid structure to optimize the lead structure 1 and synthesized four series of cinnamon–pyrazole carboxamide derivatives. The bioassay data showed that compounds (E)-N-(1-[4-chlorophenyl]-4-cyano-1H-pyrazol-5-yl)-3-(2-fluorophenyl) acrylamide ( 5III-d) and (E)-3-(2-chlorophenyl)-N-(1-[4-chlorophenyl]-4-cyano-1H-pyrazol-5-yl) acrylamide ( 5III-f) showed the significant antifungal activity against three fungi. In addition, 5III-d and 5III-f exhibited the excellent inhibitory effect against succinate dehydrogenase (SDH) enzymes with IC 50 values ranging from 19.4 to 28.7 μM. The study demonstrates that the chlorine substituent group is present on both the phenyl and pyrazole rings that have a very good effect on the antifungal effect, and the compounds 5III-d and 5III-f can act as potential SDH inhibitors (SDHI) and throw a sprat for a new generation of SDHI.