Tethering of ANS Based Fluorescent Probes to Cyclodextrin Hosts with Potential Applications as a Fluorescent Sensor

The ultimate goals of this Masters project were to synthesize a reusable, fluorescent molecular sensor and to evaluate its potential effectiveness. The molecular sensor was to be synthesized from an anilino naphthalenesulfonic acid (ANS) based fluorescent probe and a β-cyclodextrin (β-CD) host, either natural or modified. As a means of enhancing the effectiveness of the molecular sensor, it was determined that there should be a very large difference in intensity in the "on" and "off" positions, thus making it very easy to identify the sensors position.

Intermolecular studies were conducted involving several different ANS based fluorescent probes and dimethyl-β-CD and β-CD. It was identified that 2-toluidino 6-naphthalenesulfonic acid (2,6-TNS) would be the most effective probe to use due to its strong affinity to form inclusion complexes with β-CDs and the very large increase in fluorescence emission intensity upon inclusion.

Several synthetic techniques were investigated. Attempts were made to brominate 2,6-TNS and to protect the amine group of 2,6-TNS to be followed with further work to brominate the protected 2,6-TNS. These attempts were unsuccessful.

Attempts were also made to modify the CD before attaching the probe. These attempts were made with β-CD. Investigations were made into attaching an alkyl chain, which would act as the tether between the host and guest molecules, onto the larger secondary rim of β-CD, but attempts to do so were unsuccessful. Investigations were also made into modifying the primary rim of β-CD. β-CD was successfully mono-tosylated.

The mono-tosylated β-CD was reacted with 2,6-TNS and evidence suggests that the host and guest molecules are tethered via a single carbon alkyl chain.