RESUMO
[figure: see text] Photochemical reaction pathways during direct irradiation of stilbene analogues (1a-1d) can be switched completely by adjusting the concentration of hydrochloric acids. Competitive ring opening and acid-catalyzed hydrolysis processes are responsible for this novel selectivity.
RESUMO
The ground and excited state interactions between p-methoxy-2-styrylquinoline (2-StQ-OMe) and different protic acids with various acid concentrations were studied in different media. Emission bands due to the hydrogen bonding complex, protonation complex and aggregation or solid complex were observed for the first time, in n-hexane. The different reaction pathways were controlled by the solvent polarity and the concentrations of the protic acid. The acidity of acid was also important to the acid-base complex.
Assuntos
Ácidos/química , Quinolinas/química , Ligação de Hidrogênio , Estrutura Molecular , Solventes/química , Espectrofotometria UltravioletaRESUMO
Chounghwamycin A, a new antitumor antibiotic produced by a strain of Streptomyces sp. No. PL-D-5, was isolated and characterized. It appeared to belong to the actinomycin group of antibiotics from physico-chemical studies and has an empirical formula of C63H88N11O21. The antibiotic is extractable into an organic solvent from the fermentation broth, possessing potent antileukemic activity against P388 mouse leukemia in mice and antimicrobial activity against Gram-positive bacteria with MIC values about 0.1-0.4 microgram/ml, but showed no activity on Gram-negative bacteria, yeast and fungi tested.