Evidence for Interfacial Halogen Bonding

Abstract

A homologous series of donor-π-acceptor dyes was synthesized, differing only in the identity of the halogen substituents about the triphenylamine (TPA; donor) portion of each molecule. Each Dye-X (X=F, Cl, Br, and I) was immobilized on a TiO2 surface to investigate how the halogen substituents affect the reaction between the light-induced charge-separated state, TiO2 (e(-) )/Dye-X(+) , with iodide in solution. Transient absorption spectroscopy showed progressively faster reactivity towards nucleophilic iodide with more polarizable halogen substituents: Dye-F < Dye-Cl < Dye-Br < Dye-I. Given that all other structural and electronic properties for the series are held at parity, with the exception of an increasingly larger electropositive σ-hole on the heavier halogens, the differences in dye regeneration kinetics for Dye-Cl, Dye-Br, and Dye-I are ascribed to the extent of halogen bonding with the nucleophilic solution species.

A Low‐Energy‐Gap Thienochrysenocarbazole Dye for Highly Efficient Mesoscopic Titania Solar Cells: Understanding the Excited State and Charge Carrier Dynamics

“…[45][46][47] The method is described in the experimental section of the Supporting Information whereas the processed data are tabulated in Table 3. [45][46][47] The method is described in the experimental section of the Supporting Information whereas the processed data are tabulated in Table 3.…”

“…Subsequently,w ei mplemented nanosecondl aser flash photolysis measurements to study the interfacial charge-transfer reactions between the photo-oxidized dye molecules (D + )a nd the charged titania or the cobalt species in the electrolyte. [45][46][47] The method is described in the experimental section of the Supporting Information whereas the processed data are tabulated in Table 3. Figure 6a-c shows that all three electrochemically oxidized dye molecules on titania feature strong electron- ic absorptions in the near-infraredr egion.W ei nitially used ad ye-grafted titania film in contact with acetonitrile to acquire time constants (t 1/2 )o natime scale of millisecond (Figure 6d-f), which were connected with the back-electron transfer from the negatively chargedt itania to D + .W et hen investigated C294 with variousc obalt-based electrolytes.…”

Non‐classical Design of High‐Efficiency Sensitizers for Dye‐Sensitized Solar Cells

“…Furthermore, a recent study by Swords et al . revealed that an oxidized dye cation ([Dye‐X] + , X = F, Cl, Br, I) with a more polarizable halogen substituent (polarization: F < Cl < Br < I) on the phenyl ring of the triphenyl amine donor shows progressively higher reactivity toward iodide ion and therefore the corresponding DSSC has higher efficiency.…”

Preise 2016 des Chemical Institute of Canada und der Canadian Society for Chemistry

“…Sein Forschungsprogramm umfasst Solarzellen, Solartreibstoffe, Energiespeicherung und Katalyse. In der Angewandten Chemie hat er über Halogenbrückenbindungen an Grenzflächen berichtet …”