FUNCTIONALIZATION OF THE MOLECULE BY HYDROGEN BONDING AND PHOTOREACTION DYNAMICS

点击翻译按钮获取中文摘要

The effect of inter- and intramolecular hydrogen bonding on the photochemical behaviors of aromatic compounds have been studied. Firstly, we have prepared a series of olefins with a pyrrole ring and a hetero aromatic ring such as pyridine or phenanthroline ring. In these olefins only the cis isomer forms intramolecular hydrogen bonding and showed intramolecular hydrogen atom transfer in the excited singlet state exhibiting fluorescence emission at considerably long wavelength region. Due to the hydrogen atom transfer only the trans→cis one-way photoisomerization has been observed. Secondly, we have revealed that intramolecular hydrogen bonding can control the efficiency and the mode of isomerization. Thus, 2'-hydroxychalcone, where both cis and trans isomers form 0-H : 0 intramolecular hydrogen bonding, exhibited intramolecular hydrogen atom transfer in the excited triplet state and finally resulted in one-way cis→trans isomerization around the C=C double bond. Thirdly, we have prepared a photochromic compound utilizing intramolecular hydrogen bonding exhibiting color change between reddish orange and greenish yellow by alternate irradiation with 366 nm and 546 nm light. Finally, we have prepared a series of donor-acceptor systems having 2-ureido-4 [1H]-pyrimidinone part which has very high association constant. In these systems photoinduced charge transfer interaction can take place even at very low concentration of the compounds by the aid of intramolecular hydrogen bonding.