This talk describes the enhancement of the quantum yield of electron transfer (eT) from a substituted zinc porphyrin (2-cyano-3-trans-(4-(2-(10,20-bis(2,6-di(n-hexoxy)phenyl)-15-(N,N-diphenylbenzenamine)ethynyl-porphyrinato-zinc(II)-5-yl) ethy- nyl)phenyl)acrylic acid),  abbreviated as �ZnP� to a CdSe quantum dot (QD) upon selective photoexcitation of the ZnP by linking the donor-acceptor pairs with  phenyl bis-dithiocarbamate (PBTC) molecules. Quantum yield of eT is defined as the fraction of photoexcited ZnP molecules that transfer an electron to a CdSe QD rather than decaying by another radiative or non-radiative pathway. PBTC links the ZnP to the QD by coordinating to Cd2+ on the surface of the QD through one of its dithiocarbamate groups and coordinating to the Zn metal center in ZnP with its second dithiocarbamate group.  The PBTC linking chemistry increases the fraction of QDs that participate in eT with ZnP by a factor of four over that for samples without added PBTC by increasing the average number of ZnP molecules adsorbed per QD. Use of the PBTC linker also increases the observed rate of eT by slowing the intersystem crossing of the ZnP (1*ZnP --> 3*ZnP) such that eT increasingly occurs through the faster singlet channel (1*ZnP --> 1(ZnP+-QD-)) rather than through the slower triplet channel (3*ZnP --> 3(ZnP+-QD-)).

Enhanced yield of charge separation in bis-dithiocarbamate-linked zinc porphyrin-CdSe quantum dot donor-acceptor complexes

248th National Meeting (2014)

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