title: Understanding the relationship between photolysis efficiency and metal binding using ArgenCast photocages.
abstract: ArgenCast-1 (1), a photocage for silver utilizing acyclic polythioether 3,6,12,15-tetrathia-9-azaheptadecane receptor and 4,5-dimethoxy-2-nitrobenzyl (DMNB) chromophore has been prepared using trimethylsilyl trifluoromethanesulfonate-assisted electrophilic aromatic substitution. Metal binding studies with ArgenCast-1 reveal interactions with Ag(+), Hg(2+) and Cu(+), but only Ag(+) coordinates in both aqueous and organic solvents. The uncaging mechanism of ArgenCast-1 metal complex involves a photoreaction that converts the nitrobenzydrol into the electron withdrawing nitrosobenzophenone that participates in a resonance interaction with a metal-bound aniline nitrogen atom. The structural change following photolysis decreases availability of the nitrogen lone pair for Ag(+) coordination, but strong interactions between Ag(+) and the thioether ligands mitigates metal ion release. A resonance interaction with a key aci-nitro intermediate reduces the photolysis quantum yield of ArgenCast-1, so several naphthyl-based nitrobenzyl groups were screened as alternatives to DMNB. The naphthyl Ag(+) photocages, ArgenCast-2 and -3, exhibit nearly identical quantum yield to ArgenCast-1 owing to the dominance of resonance between aci-nitro intermediate and the aniline nitrogen atom.
authors.affiliation: Department of Chemistry, University of Connecticut, Storrs, CT, USA.
authors.forename: Hannah W
authors.initials: HW
authors.lastname: Mbatia
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Kennedy
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burdette
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D008628:Mercury / Q000737:chemistry; D008698:Mesylates / Q000737:chemistry; D010782:Photolysis; D012834:Silver / Q000737:chemistry*; D012997:Solvents; D013057:Spectrum Analysis; D014297:Trimethylsilyl Compounds / Q000737:chemistry; D014867:Water
chemical_list: D000814:Aniline Compounds; D056831:Coordination Complexes; D005456:Fluorescent Dyes; D008024:Ligands; D008698:Mesylates; D012997:Solvents; D014297:Trimethylsilyl Compounds; D014867:Water; C053353:trimethylsilyl trifluoromethanesulfonate; D012834:Silver; D003300:Copper; D008628:Mercury