ABSTRACT
Photorelease and photoisomerization of trans-cinnamic acid in aqueous CTAB solutions induces a bulk solution viscosity increase and decrease, respectively, triggered by orthogonal irradiation wavelengths.
Subject(s)
Water/chemistry , 2,2'-Dipyridyl/analogs & derivatives , 2,2'-Dipyridyl/chemistry , Cetrimonium , Cetrimonium Compounds/chemistry , Cinnamates/chemistry , Electron Transport , Isomerism , Magnetic Resonance Spectroscopy , Organometallic Compounds/chemistry , ViscosityABSTRACT
Photoinduced mediated electron transfer to N-alkylpicolinium(NAP)-based esters has previously been shown to induce release of carboxylate anions. In this mechanism, electrons are shuttled between a good electron donor through a sensitizer/mediator to the NAP group which subsequently induces C-O bond cleavage. Previous studies have used UV-absorbing mediators to initiate substrate release with high photorelease efficiencies, but require long irradiation periods for quantitative deprotection. The current study improves upon previous systems by using lower energy visible light absorbing mediators that induce substrate release over shorter irradiation periods (i.e. higher overall photolytic efficacies).
Subject(s)
Carboxylic Acids/chemistry , Coloring Agents/chemistry , Coumarins/chemistry , Electrons , Light , Electron Transport , Esters , Photolysis , Picolines/chemistry , Quantum TheoryABSTRACT
A new aqueous-compatible photoinduced electron transfer based photolabile protecting group has been developed for the release of carboxylic acids. The reduction potential of this group is more positive than previous systems, thereby allowing the use of sensitizers with modest oxidation potentials. Release of several carboxylic acids has been demonstrated using tris(bipyridyl)ruthenium(II) as both a direct sensitizer and a mediator for electron transfer between a good donor and the protecting group.
ABSTRACT
Visible-light-absorbing citrate-stabilized gold nanoparticles and tryptophan-dithiane-conjugate-stabilized gold nanoparticles have been used to mediate electron transfer between dithiothreitol (DTT), a good electron donor, and an N-methylpicolinium ester in aqueous solution. Quantitative yield of the free carboxylate has been obtained with quantum yields of release, Phirel, ranging from 0.5 to 4.5.
