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 bindingin 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 canfunction 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 tothe 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.
Volume 133, 2021
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