2031 Pure Appl. Chem., Vol. 79, No. 11, pp. 2031–2038, 2007. doi:10.1351/pac200779112031 © 2007 IUPAC Arjunolic acid: A renewable template in supramolecular chemistry and nanoscience* Braja Gopal Bag ‡ and Shaishab Kumar Dinda Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore (W), India Abstract: Arjunolic acid, a triterpenoid, renewably resourced from Terminalia arjuna saw- dust, has the potential of being used as a structural molecular framework in supramolecular chemistry and nanoscience. The nanosized chiral triterpenoid on derivatization could immo- bilize varieties of organic solvents at low concentrations. The low-molecular-mass organic compounds self-assembled in organic media to form fibrous network structures having fibers of nano- to micrometer diameters. A dual-component supramolecular gelation has been demonstrated, exhibiting interesting thermochromic property. An arjunolic acid-derived crown ether showed efficient binding to monovalent cations, including a primary ammonium ion paving the way for chiral recognition of amino acids. Keywords: arjunolic acid; renewable; template; nanoscience; thermochromes; terpenes; self- assembly; soft-materials; organogel; Terminalia. INTRODUCTION Primary plant metabolites such as sugars, amino acids, and nucleotides are essential to the life of the plant. Secondary metabolites stored in plants may not be essential to the life of the plant, but may play an important role in self-defenses against harmful organisms, coloring petals, and fruits, etc. [1]. Many of these plant secondary metabolites are used as medicines for the treatment of various physiological disorders [2]. The triterpenoids are an important class of plant secondary metabolites derived from C 30 precursors [3]. In spite of the abundance of many naturally occurring chiral triterpenes having well-de- fined three-dimensional structures, there is little activity in the use of those in the general area of supramolecular chemistry and nanoscience. *Pure Appl. Chem. 79, 1831–2100. An issue of reviews and research papers based on lectures presented at the 1 st International IUPAC Conference on Green–Sustainable Chemistry, held in Dresden, Germany, 10–15 September 2006. ‡ Corresponding author