Synthesis and spectral-luminescence properties of the conjugate of 24-epibrassinolide with porphyrin

The synthesis of a previously unknown conjugate of 24-epibrassinolide with porphyrin is described. Four molecules of 24-epibrassinolide are bonded to a molecule of porphyrin by selective formation of cyclical boric ethers in diol groups of the side chain. Electronic spectra of the synthesized conjugate of 24-epibrassinolide with porphyrin are measured and analyzed. The spectral and luminescence characteristics of the initial porphyrin and the conjugate are found to be similar. The quantum yield and fluorescence lifetime of the conjugate in tetrahydrofuran are 0.06 and 10.6 ns, respectively. The extinction coefficient of the conjugate in tetrahydrofuran is 385,000 (Mbullet operatorcm)-1 at a wavelength of 418 nm. © 2009 Springer Science+Business Media, Inc.