Our mission is inspired by the way in which photosynthesis combines the energy of two or more photons to perform chemistry that is otherwise strongly uphill at equilibrium. We will employ light harvesting and advances in solar photochemistry to enable unprecedented photoinduced crosscoupling reactions that valorize abundant molecules. The energy input required to transform stable and abundant molecules to valuable products is greatly reduced by the use of catalysts. A fundamental aim in catalysis is to devise new ways to convert plentiful and unreactive molecules to valuable ones for energy-relevant applications. The research proposed for the BioLEC Energy Frontier Research Center (EFRC) will expand our fundamental understanding of both solar photochemistry and photosynthetic systems to enable sophisticated photoinduced cross-coupling chemistry. The resulting breakthroughs will lead to valuable chemicals, fuels, and materials. At the frontier of this endeavor, we aim to catalyze reactions that have prohibitive energy barriers for equilibrium chemistry������������������reactants are more stable than products. The reactions that we target are presently inconceivable using the leading edge of modern synthetic chemistry. Our approach is inspired by the way in which nature combinesthe energy of multiple photons to ramp up redox capability beyond that achievable with the energy from a single photon. To succeed, BioLEC brings together scientific communities that rarely interact������������������organic synthesis, structural and molecular biology, and physical chemistry.

The proposed research is composed of two parallel lines of inquiry addressing fundamental aspects of photo-induced energy transfer processes as they relate to the emerging topic of solar photon wavelength upconversion achieved through the regenerative photochemical process of sensitized triplet-triplet annihilation (TTA). The concepts developed in this proposal address topics and processes central to solar energy conversion while being cognizant of sustainable sensitizer design and compatibility of the proposed photochemical processes within aqueous environments. First, we seek to translate sensitized TTA-based upconversion into more sustainable formats using highly abundant elements in sensitizer design. Two representative molecular designs will be developed to promote intramolecular triplet state generation for use in upconversion schemes: (1) new CuI charge transfer sensitizers designed to possess markedly extended excited state lifetimes using pendant triplet acceptors to intramolecularly produce either ����������������pure��������������� organic triplets or equilibrated excited states based on the triplet reservoir effect; and (2) high extinction coefficient SnIV porphyrin sensitizers covalently tethered to energetically appropriate acceptors/annihilators in their axial positions, thereby circumventing the limitations imposed by bimolecular triplet sensitization. As a result, the typical sequence of two consecutive bimolecular reactions, triplet sensitization and annihilation, becomes reduced to only the latter which will then take place between two energized acceptor/annihilator molecules located on two distinct porphyrins. The second series of proposed investigations address a key criterion for potential integration into solar fuels producing schemes, namely, photochemical upconversion that decisively functions in water. In order to promote regenerative upconversion photochemistry in water: (1) we will directly address the problem by evaluating the photochemical interactions occurring between water-soluble phthalocyanine triplet sensitizer donors and acceptors/annihilators initially based on high fluorescence quantum efficiency perylenediimide (PDI) dyes, affording near-IR-tovisible light conversions; (2) micellar nanoreactors will be used to host/encapsulate various hydrophobic upconversion pairs in water, absorbing low energy light and radiating higher energy photons into the immediately adjacent aqueous solution; and (3) mesoporous silica nanoparticles will be used to examine upconversion occurring in nanoporous environments either between surface-anchored sensitizers and freely diffusing acceptors/annihilators or between chromophores loaded/adsorbed into the pores of the material. The nature of the micellar nanoreactors and mesoporous silica will permit detailed photophysical/photochemical examinations of these materials in water.

The mission of the Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE) is to evaluate molecule/materials hybrids for cooperative sunlight-driven generation of liquid fuels from CO2, H2O, and N2. The CHASE approach relies on fundamental mechanistic studies to develop and evaluate technological advances that harness the individual strengths of molecules and materials to cooperatively overcome longstanding challenges in the robust and selective conversion of abundant feed-stocks to liquid fuels and O2 driven by sunlight. This approach requires a diverse and deeply collaborative research Hub. Led by a core team at the University of North Carolina at Chapel Hill (UNC), CHASE features strategic satellite teams at proximal institutions. The team structure will provide scientific expertise and research infrastructure to: (a) synthesize new atomically and morphologically precise molecule/ materials hybrids for solar energy conversion, (b) address questions of unparalleled depth about structure, dynamics, and mechanism in complex hybrids, and (c) rapidly build on discoveries to expand basic energy science knowledge and prepare the next generation of solar fuels scientists. The fundamental challenges in liquid solar fuels generation are now clear, thanks in part to JCAP research. The CHASE approach, defined by precise molecule/materials hybrids and comprehensive mechanistic inquiry through sophisticated theory and advanced photophysical, photochemical, and catalysis studies, will provide ever-deeper understanding and design principles to overcome these challenges and make liquid solar fuels a reality.

We propose a quantum spin technology to image biochemical pathways in the rhizosphere with unprecedented chemical detail and sensitivity. Specifically, the proposed technology transfers the quantum entangled nuclear spin order of hydrogen gas, to metabolites, including nitrate, amino acids, nitrogen and pyruvate, to enable molecular imaging of their metabolic transformations without any penetration depth limitations such that molecular turnover and metabolism can be observed directly in soil.

Advanced spectroscopies with the state-of-the-art light sources provide unprecedented opportunities for capturing correlated electronic/nuclear motions in real time and mapping out excited state trajectories on the potential energy landscape. In particular, it is important to understand the impact of coherent electron and nuclear motions in energy and electron transfer processes that lead to chemical reactions, and how to control these motions to steer the reaction in desirable directions. The proposed work aims at directly measuring vibronic coherence in molecular systems and their effects in energy transfer processes in supramolecular systems or aggregates based on Pt(II) dimer molecules.