No abstract

A novel controlled-release formulation (CRF) of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was developed to reduce its negative environmental impacts by improving its herbicidal efficacy. The 2,4-D was chemically caged by coupling with photoremovable protecting groups (PRPGs) of coumarin derivatives. Photophysical studies of caged compounds showed that they all exhibited strong fluorescence properties. Controlled release of 2,4-D was achieved by irradiating the caged compounds using UV-vis light (310, 350, and 410 nm). The effect of various factors such as pH, solvent, and different substituents at the seventh position of coumarin moiety on the rate of photorelease was studied. The herbicidal activity of caged compounds and 4-(hydroxymethyl)-7-substituted coumarins was studied against Vigna radiata . The new formulation provided greater control over the release of 2,4-D by UV-vis light and also demonstrated the potential of the PRPGs not only to act as a delivery device but also to possess herbicidal activity after photorelease.

We report an excellent photoresponsive controlled release formulation based on a coumarin copolymer for pesticide 2,4-D.

We have introduced a series of nonionic photoacid generators (PAGs) for carboxylic and sulfonic acids based on N-hydroxyanthracene-1,9-dicarboxyimide (HADI). The newly synthesized PAGs exhibited positive solvachromatic emission (λ(max)(hexane) 461 nm, λ(max)(ethanol) 505 nm) as a function of solvent polarity. Irradiation of PAGs in acetonitrile (ACN) using UV light above 410 nm resulted in the cleavage of weak N-O bonds, leading to the generation of carboxylic and sulfonic acids in good quantum and chemical yields. Mechanism for the homolytic N-O bond cleavage for acid generation was supported by time-dependent density functional theory (TD-DFT) calculations. More importantly, using the PAG monomer N-(p-vinylbenzenesulfonyloxy)anthracene-1,9-dicarboxyimide (VBSADI), we have synthesized N-(p-vinylbenzenesulfonyloxy)anthracene-1,9-dicarboxyimide-methyl methacrylate (VBSADI-MMA) and N-(p-vinylbenzenesulfonyloxy)anthracene-1,9-dicarboxyimide-ethyl acrylate (VBSADI-EA) copolymer through atom transfer radical polymerization (ATRP). Finally, we have also developed photoresponsive organosilicon surfaces using the aforementioned polymers.

In recent times, nano-pesticide formulations have gained great popularity since they enableeffective usage of smaller quantities of the pesticides without creating much damage to the environment. The benefits of nano-pesticide formulation can be further expanded by adding to its arsenal both the tracking ability and precise control over the pesticide release. Recently, fluorescent photoresponsive nanocarriers have gained considerable momentum in the field of drug delivery since they can perform both as "fluorophore" for cell luminescence imaging and "phototrigger" for regulated drug release by external light stimuli. Hence, we report for the first time nano-pesticide formulation based on fluorescent photoresponsive organic nanoparticles, perylene-3-ylmethanol for regulated release of pesticide 2,4dichlorophenoxyacetic acid (2,4-D). Further, fluorescent nature of photoresponsive organic nanoparticles was used to study the morphological changes induced by 2,4-D inside the plant system using the confocal imaging studies. Additionally, the fluorescent colour change by photoresponsive organic nanoparticles before and after photo release was exploited for real time monitoring of 2,4-D release inside the plants. Bioassay experiments revealed that nano-pesticide, Pe-2,4-D efficiently delivered 2,4-D inside the plant tissues improving its herbicidal activity. Such photoresponsive multifunctional nanocarriers with good fluorescence, cellular uptake property and efficient photoregulated release ability will be of great benefit in the construction of nano-pesticides formulations.