Nobu Iguchi
From WikidChem
Nobuhito Iguchi
Yale College 10'
Chemistry Major
E-mail: nobuhito.iguchi@yale.edu
Address: 225 Prospect Street, New Haven, CT 06520-8107
Office: Klein Chemistry Laboratories (KCL) 9
Phone: (203) 432-5911
Fax: (203) 432-6144
[edit]Publications
[edit]Poster Presentation
6th Annual Yale Bouchet Conference on Diversity in Graduate Education (.pdf)
Research
Computational studies of TiO2 model surface functionalized with the siloxane, catechol, and acetylacetate (acac) linkers
Dye-sensitized solar cells are based on wide band-gap semiconductors electrodes (e.g., TiO2) surface-modified with molecular sensitizers for photoabsorption in the visible-range of the solar spectrum. Sensitizers are covalently attached to TiO2 thin-films by using Lewis base linkers that react with surface hydroxyl groups. These reactions form stable condensation products with TiO2 metal oxide and have been exploited for passivation of semiconductor. We have made significant progress in expanding our understanding of chemical bonding between siloxane, acac, and catechol adsorbates with TiO2 surface. In particular, we discovered that the siloxane linker attaches to trifunctional siloxanes form only two covalent bonds, in a ‘bridge’ mode with adjacent Ti4+ ions on the TiO2 surface. (cf. publication 1, published in Proc. SPIE 7034, 7034R 2008) The goal of this project is to further our understanding of the chemical reactions of the three adsorbates with TiO2 surface using Fourier transform (FT) infrared (IR) spectroscopy and electronic structure calculations based on density functional theory (DFT).
Computational studies of Mn terpyridine complexes covalently attached to TiO2 nanoparticles
Inexpensive water-splitting catalysts are needed to develop photocatalytic solar cells that mimic photosynthesis and produce fuel from sunlight and water. Di-μ-oxo dimanganese compound [H2O(terpy)MnIII(μ-O)2MnIV(terpy)H2O](NO3)3 is an efficient catalyst for water oxidation when activated with a primary oxidant (e.g., oxone) and is studied in the context of dye-sensitized solar cell and solar water splitting. Our collaborators in Brudvig group have successfully anchored the complex onto TiO2 surface and the resulting surface complex has been rigorously characterized by UV-visible spectroscopy, electrochemical, and computational studies. (cf. publication 2, submitted to Energy & Environ. Sci.) The aim of this project is to analyze the resulting complex by obtaining accurate binding enthalpy computations using ONIOM QM/MM methodology.
Analysis of the intermediate X of ribonucleotide reductase (RNR)
An intermediate X, responsible for the enzymatic reduction of ribonucleotides, produces the tyrosyl radical necessary for the reaction to take place. Rapid freeze quench methods have been used in conjunction with Mössbauer, ENDOR, EXAFS, and EPR spectroscopy to characterize X and, a short, 2.5 Å Fe-Fe vector and a 1.8 Å Fe-O interaction have been identified. There have been many computational models proposed for the structure intermediate X, but none of them has the characteristic short vector. Recently Batista lab has proposed a model that involves a Fe2O3 core with three μ-oxo bridges ligating the mixed valent Fe-dimmer and shows significant agreement with the experimental results. The aim of the project is to identify the structure of the intermediate X with further optimization of the current structure.
