Fe(phen)₃²⁺-modified zeolite particles and their energetic studies

Chemically modified zeolite Y (NaY) particles and their resulting modified electrodes were prepared with acridinium (AcH⁺), iron(II) and 1,10-phenanthroline (phen) for energetic studies. According to diffuse reflectance absorption spectroscopy and cyclic voltammetry, AcH⁺ and Fe(phen)₃²⁺ were successfully entrapped in the zeolite particles. Transient emission spectra measurements showed that the lifetime of AcH⁺* in the zeolite particles (to 35 ns; λ_ex 365 nm; λ_em 500 nm) was greatly reduced upon incorporating Fe(phen)₃²⁺ and Fe²⁺. The fast decay of AcH⁺*(NaY) suggested that a reductive quench was likely to take place in the zeolite particle. Probably due to a size-exclusion effect, the bulky electron donor, N,N-diethyl-2-methy 1-1,4-phenylene diamine (DEPD), revealed a difficulty in reaching the photosensitizer, AcH⁺, inside the zeolite particle. As a consequence, the insignificant photocurrent for the oxidation of DEPD was from the NaY|AcH⁺ electrode. However, if Fe²⁺ and Fe(phen)₃²⁺ were incorporated, the photocurrent would become more significant. Closer examinations, in addition, showed that the photooxidaton of DEPD occurred more rapidly on the NaY|AcH ⁺|Fe(phen)₃²⁺ electrode, compared to the NaY|AcH⁺|Fe²⁺ electrode. This difference apparently results from a greater gap in energetics between DEPD and Fe(phen) ₃³⁺_(NaY) than that between DEPD and Fe ³⁺_(NaY). Due to this effect, a greater amount of indophenol blue, derived from the coupling reaction of the oxidized DEPD with 1-naphthol, was formed and deposited on the NaY|AcH⁺|Fe(phen) ₃²+ modified electrode. Thanks to this photo-induced charge-transfer reaction, the NaY|AcH⁺|Fe(phen)₃ ²⁺ particle showed an application potential in image recording.