Synthesis of Water Soluble Nitrogen Heterocyclic Compounds for Applications in Molecular Recognition I. Preparation of Water Soluble Bispyrrole-bipyridine Derivatives for Recognition of Metal Ions in Water II Synthesis of Water Soluble Bispyrrole-naphthyridine Derivatives and The Binding Study in Two-Phase System

This thesis consists of two parts. The first part is to prepare water soluble bispyrrole-bipyridine derivatives for recognition of metal ions in water; the second part is to synthesize water soluble bispyrrole-naphthyridine derivatives, and the binding study in two-phase system is also attempted.
Part I: Preparation of water soluble bispyrrole-bipyridine derivatives for recognition of metal ions in water
By introduction of ethylene glycol moiety to the pyrrole ring of BPBP molecule, the solubility of such BPBP derivative in water is enhanced, thus sensing metal ions in water becomes possible. The synthesis of a water-soluble BPBP derivative is carried out, and the BPBP compound showed binding affinity toward silver(I), copper(II), and mercury(II) ions in aqueous solution ( CH3CN/H2O = 1: 99 ). The BPBP receptor shows shifts in the UV-Vis spectra on binding with appropriate metal ions.
Part II: Synthesis of water soluble bispyrrole-naphthyridine derivatives and the binding study in two-phase system
Bispyrrole-naphthyridine molecule BPN (2,7-bis(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine) is a fluorescent molecule designed to bind selectively with octyl glucopyranoside in our lab. The excellent photophysical properties make BPN a highly sensitive probe for monitoring glucopyranoside to a detection limit of 100 pM. However, BPN has poor water solubility, thus we have to use alkyl glucopyranoside for the binding study in organic solvents. We thus attempted to incorporate ethylene glycol group to BPN to render an enhanced solubility in water. We also attempted to examine the binding of BPN with sugar in two-phase system. However, the blank tests showed that even little water extracted in dichloromethane would interfere with the fluorescence intensity of BPN.