Refernces
10.1021/ol302742g
The research aims to modulate the photoisomerization efficiency of N,C-chelate boryl chromophores, which are photoresponsive materials with potential applications in molecular electronics, optical data storage, molecular switching, and logic technologies. The study focuses on understanding the role of triplet acceptors, such as naphthalene, pyrene, and anthracene, in controlling the photoisomerization process and establishing the involvement of a photoactive triplet state in the isomerization of these photochromic compounds. The researchers synthesized a series of compounds (1-3) incorporating a photochromic boryl chromophore and different aromatic acceptors with varying triplet energies. They found that the photoisomerization quantum yield can be modulated by controlling the triplet energy of the acceptor, with compounds 1 and 2 undergoing quantitative conversion to their dark isomers with different quantum yields, while compound 3 showed suppressed isomerization. The study concluded that the photoisomerization of N,C-chelate dimesitylboranes likely proceeds via a triplet state, and the photoreactivity can be effectively modulated by controlling the triplet-triplet energy gap between the photochromic unit and the triplet acceptor chromophore. This finding has significant implications for the design of photochromic N,C-chelate boron compounds, suggesting that the photoisomerization can be sensitized or quenched using appropriate triplet sensitizers or acceptors.
10.1016/S0040-4020(01)86171-8
The research investigates the complexation and catalytic properties of water-soluble calixarenes, specifically those with dialkylamino and carboxyethyl groups. The study aims to understand how these calixarenes form host-guest complexes with various hydrocarbons and their catalytic effects on the acid-catalyzed hydrolysis of N-benzoyl-1,4-dihydroxybenzene. The researchers synthesized a series of water-soluble calixarenes by introducing amino and carboxyethyl groups at the "upper rim" of the calixarene structure using methods like Mannich bases and quaternization. They found that the calix[6]arene was particularly effective in forming complexes with hydrocarbons like pyrene and anthracene, and it also showed significant catalytic activity in the hydrolysis reaction. The study concludes that the dimensions of the hydrocarbon guest molecules and the "lower rim" of the calixarene play a crucial role in complexation, and the calixarenes' flexibility affects their catalytic efficiency. The chemicals used in the process include p-(diallylamino)calixarenes, p-(carboxyethyl)calixarenes, various hydrocarbons like pyrene and anthracene, and reagents for the synthesis such as formaldehyde, secondary amines, and sodium borohydride.
10.1021/ja906162u
The study focuses on creating amphiphilic dendrimers that can encapsulate hydrophobic guest molecules and release them in response to an enzymatic trigger. The micellar behavior of the dendrimers was studied using pyrene as a probe, and it was found that the critical aggregation concentrations (CACs) decreased with increasing dendrimer generation. Dynamic light scattering (DLS) studies showed that the size of the dendrimers decreased upon exposure to porcine liver esterase (PLE), indicating disassembly. Fluorescence studies confirmed the release of pyrene from the dendrimers upon enzymatic disassembly. The rate of disassembly and guest release was found to be generation-dependent, with higher-generation dendrimers showing slower kinetics due to steric protection of the ester functionalities. Pentaethylene Glycol (PEG) is a linear polyether with multiple ethylene oxide units. PEG is used as the hydrophilic unit in the dendrimers to enhance water solubility and to prevent nonspecific interactions with biological systems. It also helps in stabilizing the micellar structure.The study demonstrates the potential of these enzyme-responsive dendrimers for targeted drug delivery and biosensing applications.
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