A charge density study of π-delocalization and intermolecular interactions.

The compound trans-4,4'-azo-1,2,4-triazole (atrz) is a planar molecule with two planar triazole rings bridged by an azo group. The molecule is a good donor ligand and has an interesting π-delocalized character. In addition, intermolecular interactions in the crystalline state through π-π stacking are found between triazole rings with a very short inter-planar distance of 3.17 Å. The electron density distribution is obtained from both high resolution X-ray diffraction data at 100 K and density functional theory (DFT) calculations using the ωB97X-D functional. Bond characterization is performed in terms of the charge density distribution and the associated topological properties. The Laplacian distribution around each atom reveals the shape of the valence-shell charge concentration and demonstrates a sp(2) hybrid orbital shape for each atom in the molecule. The π-delocalization of the planar molecule is further illustrated by the Fermi-hole distribution. The weak intermolecular π-π interactions and hydrogen bonds are further illustrated by the Hirshfeld surface. The energies of weak intermolecular π-π interactions and hydrogen bonds have been calculated using ωB97X-D/6-311++G(3df,2p) at experimental geometry.

The hypoglycemic effect of the crude drug prescription resources from Taiwan on experimental diabetic-mellitus (II)--the antihyperglycemic effect of tang-niao-tung no. 2 and no. 3.

The water extracts of crude drugs of Taiwan Tang-Niao-Tung (T.N.T.) No. 2 and No. 3 were administered to normal and diabetic rats for investigating the antihyperglycemic effect of these two prescriptions. It was found that the blood glucose level in normal rats was temporarily increased after T.N.T. No. 2 and No. 3 administration; this may be caused by the starch content of the drugs component. In contrast, the diabetic rats have shown a significant decrease (P less than 0.01) of blood glucose in 2, 4, 6 hours after T.N.T. No. 2 and No. 3 have been given. The blood glucose percentage at 6 hours was 78.1% of T.N.T. No. 2 and 79.2% of T.N.T. No. 3 as compared to the original level. The hypoglycemic effect of T.N.T. No. 2 and No. 3 on alloxan-induced diabetic rats have suggested that action mechanism might not mediate through the release of insulin or positive feedback of glucose to insulin, neither acted on insulin receptor. It might be possible by the indirect promoting of enzyme activity. However, the pharmacological effect of some drugs could elucidate the hypoglycemic action of these prescriptions. Temporary promotion of blood glucose in normal rats will decline to normal level by 12 hours after T.N.T. No. 2 and No. 3 administration. The pharmacological effect of these herb prescriptions for diabetic rats is valuable for further study.