ABSTRACT
This chapter deals with each group of plant hormones and discusses the Ultraviolet (UV) spectral properties in relation to their chemical structure. Plant hormones, being naturally occurring materials, follow the same general rule. The type of substituents present in the gibberellins produces either weak absorption bands or complete transparency in the quartz region of the presently available commercial UV spectrophotometers. Other methods such as infrared, nuclear magnetic resonance, and mass spectrometry offer more information than that obtained by electronic absorption spectroscopy. However, the structural changes that take place in gibberellins when treated with different reagents can be readily detected by UV spectroscopy. UV spectroscopy has proved to be very useful in characterizing the products from reactions such as oxidation, hydrogenation, and dehydrogenation, studies that led to the determination of correct structure and stereochemistry of gibberellic acid. Among the spectroscopic techniques, UV played a major role in the structural elucidation of this family of growth-promoting substances.
