Photoswitchable dipeptides containing the azobenzene chromophore undergo photoactivated molecular changes when exposed to UV and visible light. In this presentation, we discuss our results on the photodynamics of azobenzene-dipeptide conjugates. It is known that solvent polarity can affect azobenzene photoisomerization but the literature contains a paucity of data on amino acid substituent effects. Chambers and Hayworth reported an unexpected stabilization of the cis-azobenzene isomer in aqueous solution for azobenzene-Pro-Leu. We have prepared similar azobenzene dipeptide conjugates to study this effect more closely. We hypothesize that micellar aggregation may play a role in this unusual stability of the cis isomer. Our research initially seeks to study the effect of amino acid sequence, solvent, and added surfactant on the kinetics of thermal cis-trans isomerization. We have introduced ortho-fluorine substituents to facilitate diagnosis of aggregation and microenvironment characteristics via 19F NMR. We will report methods for the synthesis of fluoroazobenzene peptide conjugates and studies of the aggregation dynamics via NMR, UV-Vis spectroscopy and tensiometry.

Photodynamics of azobenzene-dipeptide (Pz-dipeptide) conjugates

249th National Meeting (2015)

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