Transient absorption spectroscopy of the electron transfer step in the photochemically activated polymerizations of N-ethylcarbazole and 9-phenylcarbazole

Abstract

The polymerization of photoexcited N-ethylcarbazole (N-EC) in the presence of an electron acceptor begins with an electron transfer (ET) step to generate a radical cation of N-EC (N-EC+.). Here, the...

A Transparent, High‐Performance, and Stable Sb2S3 Photoanode Enabled by Heterojunction Engineering with Conjugated Polycarbazole Frameworks for Unbiased Photoelectrochemical Overall Water Splitting Devices

“…[ 41,53 ] In addition, as shown in Figure S31a (Supporting Information), a broad peak between 600 and 700 nm can be observed in the TA spectra of the CPF‐TCzB photoanode, which is attributed to the absorption of photoinduced electrons in the CPF‐TCzB. [ 54 ] This photoinduced absorption was not observed in the TA spectra of the CPF‐TCzB/Sb 2 S 3 photoanode, implying that the photogenerated electrons in the CPF‐TCzB can be rapidly consumed by the holes extracted from the Sb 2 S 3 (Figure S31b, Supporting Information).…”

Photoredox-HAT Catalysis for Primary Amine α-C–H Alkylation: Mechanistic Insight with Transient Absorption Spectroscopy

“…The TEAS data were collected using an ultrafast laser system at the University of Bristol, whereas TVAS data over extended time ranges from sub-picosecond to microsecond were obtained using the LIFEtime facility at the STFC Rutherford-Appleton Laboratory (RAL). , The experimental methods used for TEAS and TVAS have been reported previously, ,,,,,,− and are described in Section S1 in the Supporting Information, together with the methods used for steady-state spectroscopic characterization of samples.…”

“…Analysis of transient absorption spectroscopy data used the KOALA software package for spectral decomposition (as described in Section S4 in the Supporting Information). 54 The interpretation of experimental transient absorption spectra made use of predictions from DFT calculations 36,37 to support the assignment of spectral bands in TEAS or TVAS data. All DFT calculations used the Gaussian 09W software package.…”

“…The interpretation of experimental transient absorption spectra made use of predictions from DFT calculations , to support the assignment of spectral bands in TEAS or TVAS data. All DFT calculations used the Gaussian 09W software package…”

“…In recent studies, we applied two variants of transient absorption spectroscopy, denoted here as transient electronic absorption spectroscopy (TEAS) and transient vibrational absorption spectroscopy (TVAS), to study the mechanisms of photoredox and other reaction cycles over femtosecond to microsecond timescales. ,,,− Here, we use these methods to examine the multistep mechanism proposed by Cresswell and co-workers for the photoredox-HAT-catalyzed α-C–H alkylation of cyclohexylamine (CHA) with methyl acrylate (Figure a) . From the TEAS and TVAS measurements, we identify reactive intermediates involved in steps 1–3 (Figure b) and determine their reaction kinetics.…”