US EPA

7854204 

Journal Article 

Electron-donor-acceptor complex formation by compounds of biological interest. II. The association constants of various I,4-dinitrobenzene-phenothiazine drug complexes 

Foster, R; Fyfe, CA 

1966 

112 

3 

490-495 

English 

5912018 

10.1016/0926-6585(66)90251-2 

1. 1. Reversible attachment of drugs at a biological site may in some cases be at least partly due to electron-donor-acceptor complex formation (so-called "charge-transfer" complexes). This possibility has led us to measure the stabilities of some complexes of drugs with an electron-acceptor molecule. 2. 2. A nuclear magnetic resonance method has been used to measure the association constants of complexes of 1,4-dinitrobenzene with: 10-methylphenothiazine, promazine, chlorpromazine, diethazine, promethazine, ethopropazine and trimeprazine. 3. 3. The results show that every phenothiazine complex measured is more stable than the corresponding complex of N,N-dimethylaniline (known to be strong donor). Electron-withdrawing groups in the phenothiazine reduce the complexing ability of the molecule. The presence of a long aliphatic side-chain in the 10-position also decreases the stability of the complex. It is suggested that this is the result of steric hindrance. © 1966.