Design and synthesis of molecular sensors for biogenic amines and anions

Abstract

Design and synthesis of selective and sensitive chromogenic and luminometric molecular sensors for biological, clinical and environmental important ions, anions, and neutral species is one of the main fields of supramolecular chemistry. There have been a number of reviews describing the chemistry of molecular sensing especially for anion recognition and host molecules for anions. Most of the molecular sensors are generally consist of two parts which are receptors and chromophores. In this thesis, two types of chromogenic sensors are described; they are (i) NH-based hydrogen bonding with anion receptors attached directly to the chromophores; (ii) a coordination–based competitive displacement approach in which specific analytes compete with luminometric indicators for binding with receptor metal complexes. In Chapter 1, a brief introduction to molecular sensors based on binding integration approach and competitive displacement approach is given. In Chapter 2, the synthesis, characterization and spectroscopic properties of a series of neutral N-(p-substituted-phenyl)aryl-urea and thiourea receptors (substituent = -NO2 and -OCH3) for anion recognition are reported. These urea and thiourea receptors were attached to substituted aryl moieties and anion recognition was effected via hydrogen bonding interaction. Absorption spectra of these receptors in a binary mixture of aqueous DMF were found to produce a bathochromic shifts in the presence of selected anions. In Chapter 3, a coordination–based competitive displacement approach of chemosensing of biogenic amines and ammonia based on a series of Ru(II) - Ln(III) heterobimetallic donor-accepter chemodosimetric ensembles is reported. The series of cyano-bridged heterobimentallic complexes K{[Ru(tBubpy)(CN)4]2-Ln(H2O)4}(where tBubpy = 4,4’-di-tert-butyl-2,2’-bipyridine; Ln = Eu, Nd, Tb and Gd) functioned as chemodosimetric ensembles for specific luminometrict detection of biogenic amines and ammonia. Synthesis, X-ray crystal characterization and spectroscopic properties of these chemodosimeters are reported. Binding properties of these chemodosimeters with common gases revealed that these heterobimetallic complexes are very selective to amine containing molecules with binding constant about log K = 4.

Date of Award	3 Oct 2006
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Hon Wah Michael LAM (Supervisor)