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Title: Fundamental studies of energy-and hole/electron- transfer in hydroporphyrin architectures

The long-term objective of the Bocian/Holten/Lindsey research program is to design, synthesize, and characterize tetrapyrrole-based molecular architectures that absorb sunlight, funnel energy, and separate charge with high efficiency and in a manner compatible with current and future solar-energy conversion schemes. The synthetic tetrapyrroles include porphyrins and hydroporphyrins; the latter classes of molecules encompass analogues of the naturally occurring chlorophylls and bacteriochlorophylls (e.g., chlorins, bacteriochlorins, and their derivatives). The attainment of the goals of the research program requires the close interplay of molecular design and synthesis (Lindsey group), static and time-resolved optical spectroscopic measurements (Holten group), and electrochemical, electron paramagnetic resonance, and resonance Raman studies, as well as density functional theory calculations (Bocian Group). The proposed research encompasses four interrelated themes: (1) Determination of the rates of ground-state hole/electron transfer between (hydro)porphyrins in multipigment arrays as a function of array size, distance between components, linker type, site of linker connection, and frontier molecular orbital composition. (2) Examination of excited-state energy transfer among hydroporphyrins in multipigment arrrays, including both pairwise and non-adjacent transfer, with a chief aim to identify the relative contributions of through-space (Förster) and through-bond (Dexter) mechanisms of energy transfer, including the roles of site of linker connection and frontiermore » molecular orbital composition. (3) Elucidation of the role of substituents in tuning the spectral and electronic properties of bacteriochlorins, with a primary aim of learning how to shift the long-wavelength absorption band deeper into the near-infrared region. (4) Continued development of the software package PhotochemCAD for spectral manipulations and calculations through the compilation of a database of spectra for naturally occurring and synthetic hydroporphyrins. The availability of such data should augment efforts in the design of light-harvesting systems where spectral coverage in the red and near-infrared regions is desired. Collectively, the proposed studies will provide fundamental insights into molecular properties, interactions, and processes relevant to the design of molecular architectures for solar-energy conversion. The accomplishment of these goals is only possible through a highly synergistic program that encompasses molecular design, synthesis, and characterization.« less
Authors:
 [1]
  1. University of California, Riverside, CA (United States)
Publication Date:
OSTI Identifier:
1150022
Report Number(s):
DOE UC RIVERSIDE 15660
DOE Contract Number:
FG02-05ER15660
Resource Type:
Technical Report
Research Org:
University of California, Riverside, CA (United States).The Regents of the University of California,
Sponsoring Org:
USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY Solar energy; energy transfer; hole/electron transfer; hydroporphyrin