A series of new herbicidal sulfonylurea compounds were investigated aiming at developing a three-dimen-sional quantitative structure-activity relationship (3D-QSAR) model using the CoMFA technique. On this base, some molecular structures were modified to improve their activities. A model of the target acetolactate syntheses (ALS) en-zyme was established for the first time, which is useful to design and synthesis of new ALS enzyme inhibitor.

The single-crystal structure of neodymium chloride-ribopyranose pentahydrate, NdCl3·C5H10O5··5H2O was determined to have Mr=490.80, a=9.138(11), b=8.830(10), c=9.811(11) Å,β=94.087(18)°, V=789.7(16) Å3, P21, Z=2,μ=0.71073 Å and R=0.0198 for 2075 observed reflections. The ligand of the title complex was observed in a disordered state and two molecular configurations of NdCl3·C5H10O5 ·5H2O were found in the single crystal as a pair of isomers. Both ligand moieties of the two molecules are ribopyranose forms, providing three hydroxyl groups in ax-eq-ax orientation for coordination. One ligand of the pair of isomers is b-D-ribopyranose in the 1C4 conformation, and the other is a-D-ribopyranose in the 4C1 conformation. The Nd3+ion is nine-coordinated with five Nd-O bonds from water molecules, three Nd-O bonds from hydroxyl groups of the ribopyranose and one Nd /Cl bond from chlorideion. The hydroxyl groups, water molecules, chlorideions form an extensive hydrogen-bond network. The IR spectral C-C,O-H,C-O and C-O-H vibrations were observed to be shifted in the complex and the IR results are in accordance with those of X-ray spectroscopy.

Some series of 2-alkyl (alkythio)-5-((4-chloro)-3-ethyl-1-methyl-1H-pyrazole-5-yl)-1,3,4-oxadiazoles (thiadiazoles) were prepared as potential fungicides. Their fungicidal activity was evaluated against rice sheath blight, which is a major disease of rice in China. Structure-activity relationships for the screened compounds were evaluated and discussed. It was found that 5-(4-chloro-3-ethyl-1-methyl-1H-pyrazole-5-yl)-1,3,4-thiadiazole-2-thione has the higher fungicidal activity.

A study of some sulfonylureamolecules with consideration of watermolecules as its solvent was undertaken. The influence of the water molecules on the structure-activity relationship of the 35 sulfony-lurea molecules was discussed. By supper-imposition of structural sulfonylmolecules, a molecular RM S was correlated with p I 50, which denotes that the configuration difference in water solution is one of the reasons which causes the difference in bioactivity.

In search of new ALS inhibitors without the previous knowledge of receptor crystal structure, DISCO module was appfied to produce 3D-pharmacophore models, which provided information to design novel molecules by 3D-datahase searching. Then a number of molecules were synthesized. Several of them have some ALS inhibitory activities.