Photochemistry and Transmission Pump–Probe Spectroscopy of 2-Azidobiphenyls in Aqueous Nanocrystalline Suspensions: Simplified Kinetics in Crystalline Solids

Abstract

Aqueous nanocrystalline suspensions provide a simple and efficient medium for performing transmission spectroscopy measurements in the solid state. In this Letter we describe the use of laser flash photolysis methods to analyze the photochemistry of 2-azidobiphenyl and several aryl-substituted derivatives. We show that all the crystalline compounds analyzed in this study transform quantitatively into carbazole products via a crystal-to-crystal reconstructive phase transition. While the initial steps of the reaction cannot be followed within the time resolution of our instrument (ca. 8 ns), we detected the primary isocarbazole photoproducts and analyzed the kinetics of their formal 1,5-H shift reactions, which take place in time scales that range from a few nanoseconds to several microseconds. It is worth noting that the high reaction selectivity observed in the crystalline state translates into a clean and simple kinetic process compared to that in solution.

Photophysical Tuning of σ-SiH Copper-Carbazolide Complexes To Give Deep-Blue Emission

“…1-Methylcarbazole and 1,3-di­(trifluoromethyl)­carbazole were prepared by modified literature with 3-bromo-2-nitrotoluene, phenylboronic acid, and 1-bromo-2-nitrobenzene,3,5-bis­(trifluoromethyl)­phenylboronic acid, respectively . NMR spectra for 1-methylcarbazole and 1,3-di­(trifluoromethyl)­carbazole were consistent with NMR spectra reported in the literature. , …”

“…18 NMR spectra for 1-methylcarbazole and 1,3-di(trifluoromethyl)carbazole were consistent with NMR spectra reported in the literature. 41,42 Synthesis of (Si H P 2 )Cu(3,6-dichlorocarbazolide) (2). Potassium bis(trimethylsilyl)amide (1 M in THF, 500 μL, 500 μmol) was added dropwise to a solution of 3,6-dichlorocarbazole (118 mg, 500 μmol) in 5 mL of THF at −30 °C and stirred for 30 min at RT.…”

Mechanistic Studies of Adamantylacetophenones with Competing Reaction Pathways in Solution and in the Crystalline Solid State

“…), stable suspensions of crystalline particles with an average size in the submicrometer regime can be prepared. We term such mixtures nanocrystalline suspensions, which have been shown to be amenable to spectroscopic analysis using standard solution-phase methods. ,− For each derivative, nanocrystalline suspensions were prepared using a 0.04 mM CTAB surfactant solution and stock solutions in acetonitrile. For ketone 4 , 0.2 mL of a 2.5 mg/mL acetonitrile solution was added dropwise to ∼20 mL of a vortexing surfactant solution.…”

Unraveling the Solid-State Photoreactivity of Carbonylbis(4,1-Phenylene)dicarbonazidate with Laser Flash Photolysis

“…A nanocrystal suspension of 1 was prepared by dissolving 1 (30 mg) in acetone (203 mL) and adding 250 mL of water. 26 The size of the nanocrystals was measured by using dynamic light scattering (DLS, see Supporting Information), which showed 77% of the nanocrystals were less than 486 nm. The nanosuspension was irradiated for 20 min, and 1 H NMR spectra of the reaction mixture showed the formation of 3 and 4 in the ratio of ∼1:1.…”