Charge transfer complexes of indole: Catechol type II

✍ Scribed by Hanna N. Borazan; Yousif H. Ajeena

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 401 KB
• Volume: 77
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.2600770618

✦ Synopsis

Charge transfer complexes between tryptamine:epinephrine, tryptamine:isoproterenol, tryptamine:catechol, and indo1e:catechol were demonstrated spectrophotometrically in aqueous solutions containing 0.1 M HCI. It was possible to make precise measurements and to calculate thermodynamic parameters and molar absorptivities. In general, the equilibrium constant was found to be quite low and ranged from 4.00 2 0.04 to 0.30 2 0.02 M -'. These interactions are exothermic and have relatively large standard enthalpy and entropy changes (AHo values ranged from -7.4 * 0.3 to -5.2 -r-0.4 kcal mol '; ASo ranged from -25 2 5.0 to -16 2 1.3 cal K-' mol-'). The similarity in AHo and A S o values for all the combinations indicates a similar interacting system. This result has led us to propose the involvement of the charge transfer effect, induced in the indo1e:catechol system, in the mechanism occurring in nerve conductions.