Photoswitchable Multivalent Sugar Ligands:  Synthesis, Isomerization, and Lectin Binding Studies of Azobenzene−Glycopyranoside Derivatives

• Published in: Journal of the American Chemical Society 2002-03, Vol.124 (10), p.2124-2125
• Main Authors: Srinivas, Oruganti, Mitra, Nivedita, Surolia, Avadhesha, Jayaraman, Narayanaswamy
• Format: Article
• Language: English
• Subjects: Azo Compounds - chemical synthesis; Azo Compounds - chemistry; Azo Compounds - metabolism; Chemical reactivity; Chemistry; Exact sciences and technology; Glycosides - chemical synthesis; Glycosides - chemistry; Glycosides - metabolism; Isomerism; Kinetics; Ligands; Organic chemistry; Peanut Agglutinin - chemistry; Peanut Agglutinin - metabolism; Photochemistry; Reactivity and mechanisms; Spectrophotometry, Ultraviolet; Thermodynamics
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0173066

Coating of azobenzene chromophore with multivalent sugar ligands has been accomplished. Such sugar coating allows the study of the isomerization properties of this chromophore in aqueous solutions. The predominantly cis-isomer-containing photostationary state (PS) mixture of these azobenzene derivatives is found to be stable for hours. The rate constants for their isomerization, as well as the Arrhenius activation energies, are determined experimentally. An assessment of the lectin binding properties of the lactoside bearing isomeric azobenzene derivatives, by isothermal calorimetric methods, reveals the existence of an unusual cooperat ivity in their binding to lectin peanut agglutinin. Thermodynamic parameters evaluated for the trans and the PS mixture are discussed, in detail, for the lactoside bearing bivalent azobenzene derivative.