Photoremovable protecting groups (PRPGs) were demonstrated as a delivery device for controlled release of pheromone under both UV light (≥350 nm) and direct sunlight irradiation. In the present work, (Z)-11-hexadecen-1-ol (sex pheromone of Chilo infuscatellus Snellen) was chemically caged by four different photoremovable protecting groups (7-hydroxy-4-hydroxymethylcoumarin, 1-pyrenemethanol, 9-anthracenemethanol and 2-(hydroxymethyl)anthraquinone) individually. Photophysical studies showed that the caged pheromone with coumarin, pyrene and anthracene derivatives exhibited strong fluorescence. Controlled release of (Z)-11-hexadecen-1-ol was achieved by irradiating the caged compounds in aqueous ethanol both under UV and sunlight. Further, to mimic the environmental conditions, controlled release of (Z)-11-hexadecen-1-ol was also studied in soil medium under direct sunlight. Thermogravimetric analysis showed that caging of (Z)-11-hexadecen-1-ol by PRPGs significantly reduced its volatility. Bioassay experiments indicated that PRPGs are harmless to soil bacteria (Azotobacter sp. and Pseudomonas aeruginosa) and in vitro cytotoxicity studies on eukaryotic L929 cells showed that PRPGs are also non-toxic. Field bioassays were performed using caged pheromone against maize stalk borer (Chilo partellus) and the results showed that the caged alcohol is effective in a number of moths catches instead of free alcohol in a blend for a longer period of time. Our studies indicated that use of PRPGs as delivery device for controlled release of pheromone by sunlight holds great interest for field applications.

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) #& %#" Under a layer of 0.1M HCl in isopropanol, soft UV (365 nm) photolysis of the thiol?on? gold self?assembled monolayer (SAM) derived from the lipoic acid ester of α?hydroxy?1?acetylpyrene results in the expected removal of the acetylpyrene protecting group. By photolyzing through a mask this can be used to produce a patterned surface and, at a controlled electrochemical potential, it is then possible to selectively and reversibly electrodeposit copper on the photolyzed regions. Rather surprisingly, under these photolysis conditions, there is not only the expected photodeprotection of the ester but also partial removal of the lipoic acid layer which has been formed. In further studies, it is shown that this type of acid catalyzed photo?removal of SAM layers by soft UV is a rather general phenomenon and results in the partial removal of the thiol?on?gold SAM layers derived from other ω? thiolated carboxylic acids. However, this phenomenon is chain?length dependent. Under conditions in which there is a ~60% reduction in the thickness of the SAM derived from dithiobutyric acid, the SAM derived from mercaptoundecanoic acid is almost unaffected. The process by which the shorter chain SAM layers are partially removed is not fully understood since these compounds do not absorb significantly in the 365nm region of the spectrum! Significantly, this study shows that acid catalysis photolysis of thiol?on?gold SAMs needs to be used with caution.