Molecular Size and Electronic Structure Combined Effects on the Electrogenerated Chemiluminescence of Sulfurated Pyrene‐Cored Dendrimers

Abstract

The electrochemistry, photophysics, and electrochemically generated chemiluminescence (ECL) of a family of polysulfurated dendrimers with a pyrene core have been thoroughly investigated and complemented by theoretical calculations. The redox and luminescence properties of dendrimers are dependent on the generation number. From low to higher generation it is both easier to reduce and oxidize them and the emission efficiency increases along the family, with respect to the polysulfurated pyrene core. The analysis of such data evidences that the formation of the singlet excited state by cation-anion annihilation is an energy-deficient process and, thus, the ECL has been justified through the triplet-triplet annihilation pathway. The study of the dynamics of the ECL emission was achieved both experimentally and theoretically by molecular mechanics and quantum chemical calculations. It has allowed rationalization of a possible mechanism and the experimental dependence of the transient ECL on the dendrimer generation. The theoretically calculated Marcus electron-transfer rate constant compares very well with that obtained by the finite element simulation of the whole ECL mechanism. This highlights the role played by the thioether dendrons in modulating the redox and photophysical properties, responsible for the occurrence and dynamics of the electron transfer involved in the ECL. Thus, the combination of experimental and computational results allows understanding of the dendrimer size dependence of the ECL transient signal as a result of factors affecting the annihilation electron transfer.

Enhancing Electrogenerated Chemiluminescence on Platinum Electrodes through Surface Modification

“…Chronoamperometric ECL experiments (Figure ) further demonstrate the superior properties of Pt@pPPy with respect to ECL generation without any damage of Pt@pPPy. The decrease of the ECL transient for Pt@pPPy is commonly observed in potential step experiments and is due to reactants diffusion . At the Pt electrode, the “catalytic route” described by mechanism 2 determines the ECL resulting in a steady‐state but low signal.…”

“…The decrease of the ECL transient for Pt@pPPy is commonly observed in potential step experiments and is due to reactants diffusion. [32][33][34] At the Pt electrode, the "catalytic route" described by mechanism 2 determines the ECL resulting in a steady-state but low signal. Thus, the modification of the Pt microelectrode surface leads to a substantial enhancement of the sensitivity to ECL emission.…”

Redox Properties and Interchromophoric Electronic Interactions in Isoalloxazine−Anthraquinone Dyads

“…In order to shine light on such an important behavior of MQ and MA cyclophanes a quantum chemical study paralleled the voltammetric investigation …”

Competition between Arene–Perfluoroarene and Charge‐Transfer Interactions in Organic Light‐Harvesting Systems

“…c) Energy-level diagrams of pyrene,[22] TPF, and TCNB, and d) the corresponding PL spectra. b) FM images of pyrene-TFPm icrowiresu pon excitation with 365 nm;T CNB doping concentrations are 0, 0.5, 1, 3, and 100 %( from left to right).…”

“…b) FM images of pyrene-TFPm icrowiresu pon excitation with 365 nm;T CNB doping concentrations are 0, 0.5, 1, 3, and 100 %( from left to right). c) Energy-level diagrams of pyrene,[22] TPF, and TCNB, and d) the corresponding PL spectra. Insets are the corresponding photographs excited by UV lamp.…”