Non-Covalent Supramolecular Donor-Acceptor Arrays With Nanocarbon Materials for Light-Harvesting

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Porphyrins and their analogues are well-known "pigments of life", which are involved in light-harvesting, oxygen transfer, and transformation of biological substrates. A variety of synthetic porphyrins have been studied as artificial light-harvesting materials with the best system providing >13% efficiency in the solar light-to-electricity conversion. Ferrocene-containing porphyrins, borondipyrromethenes (BODIPYs), and boronazadipyrromethenes (aza-BODIPYs) are prominent candidates for light-harvesting. Efficient use of such compounds in organic photovoltaics (OPV) requires non-covalent attachment of these molecules to the electron-acceptors such as fullerenes, nanotubes, and graphene. The pyrene group can facilitate such desired non-covalent interactions with nanocarbon materials. In proposed program, we will target new ferrocene (donor) - pyrene (non-covalent "glue") - porphyrin/BODIPY/aza-BODIPY (antennae) hybrids that have a potential to improve light-harvesting characteristics in OPVs.******Our short-term objectives are: (i) to prepare new ferrocene-pyrene-porphyrin/BODIPY/aza-BODIPY hybrids capable of forming strong non-covalent complexes with nanocabron materials. The ferrocene donor will be fully conjugated with the pi-system of the antennae to facilitate electron-transfer to the photoexcited chromophore. (ii) To characterize new materials with systematic variation in geometric and electronic properties by a variety of spectroscopic and (spectro)electrochemical methods, X-ray crystallography, and theoretical calculations in order to probe their photoinduced electron-transfer properties useful in OPVs. (iii) To study non-covalent complexes between new donor-acceptor hybrids and nanocarbon materials. The non-covalent complexes between light-harvesting dyads and nanocarbon materials will result in the formation of long-lived charge-separation states and improve the efficiency of OPV.******As a long-term objective, the systematic investigation of the new compounds will allow us to understand how and to what extent the nature of the chromophore, the through-bond and through-space distance between the redox centers, and the type of donor and acceptor conjugation with the antennae can control redox processes, stability, and photo-induced electron-transfer properties in these systems. The understanding of electronic interactions between donor, antennae, and nanocarbon acceptor is very important and likely will result in groundbreaking advances in preparation of nanoscale functional materials useful for light-harvesting. The specifically designed program is especially suitable for undergraduate and graduate students, who will receive unique training in the fields of inorganic and materials chemistry, spectroscopy, and computational chemistry, which will allow them to apply to positions that require highly desired skills. **