Self-assembly and photoinduced electron transfer in a donor- $$\upbeta $$ β -cyclodextrin-acceptor supramolecular system $$^{\S }$$ §

Abstract

Equimolar amounts of native β-cyclodextrin (β-CD), pyrene-linked adamantane (PYAD) and tert-butylpyromellitic diimide (PMDI) when dissolved in water self-assembled to form the supramolecular donor-acceptor system PYAD β-CD PMDI. The high affinity of adamantane derivatives for inclusion binding in the β-CD cavity and the propensity of PMDI to undergo rim-binding at the narrow rim of β-CD led to the formation of PYAD β-CD PMDI. The ternary complex PYAD β-CD PMDI was thoroughly characterized using various spectroscopic techniques. β-CD performs three functions in the self-assembled complex: (1) encapsulate the adamantane unit and keep the pyrene (PY) moiety above the secondary rim, (2) rim-bind PMDI and keep it at the primary rim, and (3) act as a spacer between pyrene and PMDI. Thus, the ternary complex can function as a donor-spacer-acceptor system capable of undergoing photoinduced electron transfer (PET). Upon excitation of the pyrene moiety in PYAD β-CD PMDI an electron is transferred from the excited pyrene to the PMDI ground state. Steady state and time resolved fluorescence experiments were carried out to study the PET in PYAD β-CD PMDI. Existence of the ternary system and PET processes taking place within it are further supported by laser flash photolysis experiments.

Pyrenyl Carbon Nanotubes for Covalent Bilirubin Oxidase Biocathode Design: Should the Nanotubes be Carboxylated?

“…A small over‐potential requirement but still yielding high current densities from BOD electrocatalysis is more advantageous than a precious Pt metal catalyst . Hence, the application of BOD as biocathode for fuel cells and other energy devices has gained considerable interests .…”

“…In this study, we examined at the influence of chemically functionalized (carboxylation) and unfunctionalized carbon nanotube surfaces for pyrene linking and BOD attachment toward the resulting level of O 2 reduction currents. Although the pyrene linkers for pi‐pi stacking with carbon nanostructures to immobilize BOD is a known approach , the effect of underlying nanotubes’ chemical functionality in such pyrene‐nanostructure architectures is not well understood and is thus tested in the present study.…”

“…Unfunctionalized MWNT (>95 %, outside diameter: 30–50 nm, inside diameter: 5–12 nm, length: 10–20 μm (TEM), specific surface area: >60 m 2 /g (BET), electrical conductivity: >100 s/cm) and carboxylated MWNT (>95 %, content of −COOH: 0.73 wt %, outside diameter: 30–50 nm, inside diameter: 5–12 nm, length: 10–20 μm, specific surface area: >60 m 2 /g, electrical conductivity: >100 s/cm, manufacturing method: chemical vapor deposition) were purchased from US Research Nanomaterials, Inc. (Houston, TX, USA). BOD ( Myrothecium verrucaria) was purchased from Amano Enzyme Inc. (Nagoya, Aichi, Japan) and purified by hydrophobic interaction chromatography method by using a HiTrap TM Phenyl HP hydrophobic column (GE Healthcare) . Py, EDC, and NHS were purchased from Sigma‐Aldrich (St. Louis, MO, USA).…”