Abstract

The state of aggregation of chlorophylls a and b, pyrochlorophyll a, bacteriochlorophyll, pheophytin a and pyropheophytin a in a variety of nonpolar solvents has been deduced from molecular weight measurements made by vapor-phase osmometry. In carbon tetrachloride and benzene solution, chlorophyll a and pyrochlorophyll a exist predominately as dimers over a wide concentration range, although there is evidence for oligomer formation in concentrated solutions. In aliphatic or cycloaliphatic hydrocarbon solvents, chlorophyll a can form oligomers with aggregation numbers as large as 20. In even the most dilute cyclohexane solutions studied, chlorophyll a exists as a tetramer. Chorophyll b and bacteriochlorophyll aggregate more strongly. The basic unit for these tow chlorophyll is the trimer which has a strong tendency to form hexamer and higher oligomers in aliphatic hydrocarbon solvents. Infrared spectra for solutions of chlorophyll of known states of aggregation are presented.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call