Brown, Rodney T. and Fletcher, Nicholas Charles and Danos, Eleftherios and Halcovitch, Nathan Ross (2019) A Tripodal Ruthenium(II) Polypyridyl Complex with pH Controlled Emissive Quenching. European Journal of Inorganic Chemistry, 2019 (1). pp. 110-117. ISSN 1434-1948
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Abstract
A tripodal podand has been prepared and complexed to ruthenium(II) creating a metal complex with C3-symmetry and an enclosed cavity. The complex shows the anticipated enhanced emission when compared to [Ru(bipy)3]2+ in acetonitrile. The emission from this cryptand like structure is invariant to the introduction of monovalent cations in aqueous solution, but a significant drop in the emission was observed with increasing pH over a very broad pH range (3 to 12). This is attributed to an N to t2g electron transfer in the excited-state in the unprotonated form with a transfer rate of the order of 4.2 x 105 s-1. The crystal structure indicates the inclusion of water within the cavity suggesting that the protonation of a tertiary amine can be effectively moderated by a water molecule held in close proximity within a rigid cavity