Molecular recognition of nucleolipid amphiphile octadecanoyl ester of 1-(2-carboxyethyl) adenine to the complementary nucleobases. Part I: characterization of the monolayer behavior at the air/water interface and photodimerization in the Langmuir–Blodgett film matrix under ultraviolet irradiation

Abstract

Molecular recognition capabilities of a novel nucleolipid amphiphile, octadecanoyl ester of 1-(2 carboxyethyl) adenine, to the complementary nucleobases at the air/water interface were investigated by surface pressure–area ( π–A) isotherms and UV spectra measurements. All of the observations show that molecular recognition through complementary base pairing takes place at the air/water interface between the adenine moiety in the headgroup of the nucleolipid amphiphile and the dissolved complementary nucleobase substrates in the subphase. On the surface of pure water, the monolayer gave a limiting molecular area of 29.3 Å 2 and collapse pressure at about 62 mN/m while on the subphase of aqueous 5 mM thymidine and uridine solution, the limiting molecular area and collapse pressure are 42.0 Å 2 and 77 mN/m, 39.7 Å 2 and 79 mN/m, respectively. In the Langmuir–Blodgett (LB) matrix, the constituent molecules are arranged regularly, which facilitates the photodimerization of the thymine moieties and uracil moieties that transferred into solid substrates along with the surface monolayer of the nucleolipid amphiphile as a result of the formation of the base–base complex, the photodimerization accomplished in 6 and 4 h for the thymine and uracil rings in the LB films under irradiation of a 254-nm ultraviolet light at room temperature, respectively.