Photoresponsive peptide and polypeptide systems. VIII. Synthesis and reversible photochromism of azo aromatic poly(L-ornithine)

✍ Scribed by Hiroyuki Yamamoto; Ayako Nishida; Tomoyuki Takimoto; Akira Nagai

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 401 KB
• Volume: 28
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/pola.1990.080280105

✦ Synopsis

Abstract

Poly(L‐ornithine) having azo aromatic side chain was synthesized by the water‐soluble carbodiimide procedure. The photochemical properties of the azo polypeptide poly[N^δ^‐p‐(phenylazo)benzoyl‐L‐ornithine] (PPABLO) was investigated by absorption and circular dichroism spectroscopy in hexafluoro‐2‐propanol (HFIP). The photochromism of the dichroic bands in the visible and ultraviolet wavelength regions was found to be reversible as a function of irradiation time at different wavelengths due to the photostationary state (about 70% trans)–cis photoisomerization of the azo aromatic moieties. The reversible photoinduced solubility change was also studied. On irradiation PPABLO is soluble under ultraviolet light (cis) and precipitate under visible light (70% trans) in HFIP–water. A discussion was presented that includes results on azo aromatic poly(L‐lysine).