1. THE CHEMISTRY OF AUTUMN COLORS
Martin Drastík

2. Why would I like to speak about this topic?
Sad but beautiful

3. Pigments Chlorophyll – green Carotene – orange
Anthocyanin – red, purple

4. Chlorophyll Molecule is large (C55H70MgN4O6)
Porphyrin ring + magnesium
Situated in leafs – organelles

5. Chlorophyll Chloroplasts Not soluble in the aqueous solution of cells
Photosynthesis of sugars and starches

6. Chlorophyll
Why do the leaves seem to be green?
Absorption
spectrum

7. Chlorophyll Not a very stable compound; decomposed by bright sunlight
Continuously synthesized in leaves (requires sunlight and  temperatures) until autumn

8. Carotene Large molecule (C40H36) Situated in the chloroplasts
Function: accessory absorber - energy transferred to chlorophyll

9. Carotene Absorption spectrum Much more stable than chlorophyll
Carotene persists in
leafs even when
chlorophyll has
disappeared

10. Anthocyanin Various structures – diff. is „B“ benzenoid ring
Disolved in the aqueous solu-
tion of cells

11. Anthocyanin Absorption spectrum
Color is sensitive to the pH of the cell sap

12. Anthocyanin If the sap is acidic – bright red
If the sap is neutral – purple
If the sap is alkaline – orange
alkaline; neutral; acidic

13. Anthocyanin
Formed by a reaction between sugars and certain proteins in cell. Occurs when concentration of sugar in the sap is high enough.
Requires light
Red side insolate

14. Conclusion
Summer:
Autumn: stop of producing chlorophyll, storing energy in fruit
and nuts
changing color of leaves

15. Thank you for your attention
The biggest source of information:
Prof. Shakhashiri, University of Wisconsin-Madison Chemistry: Chemical of the Week
Pictures – internet