1806 



SPECTROSCOPY AND FLUORESCENCE OF PIGMENTS CHAP. 37C 



of the bands at 518 and 585 m/z (in a), and at 565 and 635 m^ (in &), in- 

 dicates that they belong to two different forms of reduced chlorophyll; 

 Evstigneev and Gavrilova suggested that the "long- wave" bands belong 

 to nondissociated semiquinones (derived from the chlorophylls by one-step 

 reduction, cf. Krasnovsky's hypothesis on p. 1503), and the ''short-wave" 

 bands to their ions. 



T — ' — I — ' — I — ' — I — ' — 1 — ■ — I — I — r 



220 260 300 340 380 420 460 500 540 580 620 660 700 740 780 820 



TT\/jL 



Fig. 37C.12. Absorption spectrum of methyl bacteriochlorophyllide in ether (after Holt 



and Jacobs 1954). 



(6) Bacteriochlorophyll and Derivatives 



New measurements have been made in the absorption spectrum of 

 bacteriochlorophyll, by Manten (1948), Krasnovsky and Vojnovskaja 

 (1951), Weigl (1952) and Holt and Jacobs (1954^). Fig. 37C.12 shows 

 the absorption spectrum of methyl bacteriochlorophyllide in ether. The 

 main red peak is located, according to Weigl, at 772 m^u in ether, 771 mju 

 in acetone and methanol, and 782 mju in benzene; and according to Holt 

 and Jacobs, at 769 m^ in ether, all in satisfactory agreement with fig. 

 21.25. Weigl noted a striking effect of polar solvents on the "orange" 

 band: it is found at 575 mn (577 mii according to Holt and Jacobs) in 

 ether, 580 mn in acetone, and 581 mju in benzene, but is shifted to 609 mn 

 in methanol. (French, as well as Manten, reported a similar position — 

 605 m/i.) Weigl converted bacteriochlorophyll to bacteriopheophytin, 



