Chemistry

Department of Chemistry, Carnegie Mellon University
Ph.D. Chemistry, Northwestern University, Illinois, 2003
Summary:

Our research focuses on fundamental science and engineering questions motivated by the creation of materials on the nanometer scale (1 nm=10-9 m). Our research themes include the synthesis, characterization, and applications of nanoparticles (typically 1-100 nm in size). We are developing chemical methods for synthesizing well defined nanoparticles, including atomically precise nanoclusters, shape- and size-controlled nanocrystals, hybrid nano-architectures, and inorganic/polymer nanocomposites. In-depth characterizations of the physical and chemical properties of nanoparticles and self-assembled nanomaterials are carried out with microscopy and spectroscopy techniques, such as electron microscopy, atomic force microscopy, X-ray crystallography, steady-state and ultrafast spectroscopies, etc. We also develop applications of nanoparticles in areas of catalysis, optics, chemo- and bio-sensing, and photovoltaics, etc.

Selected Publications: 
  1. “Correlating second harmonic optical responses of single Ag nanoparticles with morphology”, Jin, R.; Jureller, J.E.; Kim, H.Y.; Scherer, N.F. J. Am. Chem. Soc.127, 12482 (2005).
  2. “Synthesis of open-ended, cylindrical Au-Ag alloy nanostructures on a Si/SiOx surface”, Zhang, H.; Jin, R.; Mirkin, C.A. Nano Lett., 4, 1493 (2004).
  3. “Thermally-induced formation of atomic Au clusters and conversion into nanocubes”, Jin, R.; Egusa, S.; Scherer, N.F. J. Am. Chem. Soc.126, 9900 (2004).
  4. “Controlling anisotropic nanoparticle growth through plasmon excitation”, Jin, R.; Cao, Y.W.;  Hao, E.; Metraux, G.S.; Schatz, G.C.; Mirkin, C.A.; Nature425, 487 (2003).
  5. “Raman dye-labeled nanoparticle probes for proteins”, Cao, Y.C.; Jin, R.; Nam, J.M.; Thaxton, C.S.; Mirkin, C.A. J. Am. Chem. Soc.125, 14676 (2003).
Most Cited Publications
  1. "Photoinduced conversion of silver nanospheres to nanoprisms", R Jin, YW Cao, CA Mirkin, KL Kelly, GC Schatz, JG Zheng, science, 294, 1901 (2001).
  2. "Nanoparticles with Raman spectroscopic fingerprints for DNA and RNA detection", YWC Cao, R Jin, CA Mirkin, Science 297, 1536 (2002).
  3. "Controlling anisotropic nanoparticle growth through plasmon excitation", R Jin, YC Cao, E Hao, GS Métraux, GC Schatz, CA Mirkin, Nature 425, 487 (2003).
  4. "Correlating the crystal structure of a thiol-protected Au25 cluster and optical properties", M Zhu, CM Aikens, FJ Hollander, GC Schatz, R Jin, Journal of the American Chemical Society 130 , 5883 (2008).
  5. "What controls the melting properties of DNA-linked gold nanoparticle assemblies?", R Jin, G Wu, Z Li, CA Mirkin, GC Schatz, Journal of the American Chemical Society 125, 1643 (2003).
Recent Publications
  1. "Influence of Atomic-Level Morphology on Catalysis: The Case of Sphere and Rod-Like Gold Nanoclusters for CO2 Electroreduction", Shuo Zhao, Natalie Austin, Mo Li, Yongbo Song, Stephen D. House, Stefan Bernhard, Judith C. Yang, Giannis Mpourmpakis, and Rongchao Jin, ACS Catal., 8, 4996 (2018).
  2. "Sharp Transition from Nonmetallic Au246 to Metallic Au279 with Nascent Surface Plasmon Resonance", T Higaki, M Zhou, K Lambright, K Kirschbaum, MY Sfeir, R Jin, Journal of the American Chemical Society (2018).
  3. "Kernel Tuning and the Resulting Influence on Optical/Electrochemical Gaps of Bimetal Nanoclusters", R JIN, Acta Physico-Chimica Sinca (2018).
  4. "Toward Atomically Precise Nanoclusters and Nanoparticles", R JIN, Acta Physico-Chimica Sinca 34, 737 (2018).
  5. "Excited-State Behaviors of M1Au24 (SR) 18 Nanoclusters: The Number of Valence Electrons Matters", M Zhou, C Yao, MY Sfeir, T Higaki, Z Wu, R Jin, The Journal of Physical Chemistry C (2018).
  6. "Chiral Ag 23 nanocluster with open shell electronic structure and helical face-centered cubic framework", C Liu, T Li, H Abroshan, Z Li, C Zhang, HJ Kim, G Li, R Jin, Nature communications 9, 744 (2018).

 

Highly Efficient Strategy for Constructing New Types of Peptide Macrocycles

  • By Burcu Ozden
  • 10 April 2018

Peng Liu and his colleagues report a highly efficient and generally applicable strategy for constructing new types of peptide macrocycles using palladium-catalyzed intramolecular C(sp3)–H arylation reactions on their newly published paper in Nature Chemistry. 

This strategy provides a powerful tool to address the long-standing challenge of size- and composition-dependence in peptide macrocyclization, and generates novel peptide macrocycles with uniquely buttressed backbones and distinct loop-type three-dimensional structures.

Department of Chemistry
PhD, Chemistry, Harvard University
Summary:

Raúl Hernández Sánchez's research group is interested in combining supramolecular, inorganic, and materials chemistry to synthesize functional systems that bridge the gap between nanoscale materials and molecular chemistry. Their research is focused on developing new synthetic methodologies to access well-defined nanometer-sized clusters where they can investigate surface structure-function relationships relevant in catalytic and magnetic materials. Other efforts in the Hernández Sánchez (HS) group are aimed at designing and synthesizing structural analogues of carbon nanotubes where exquisite control of the resulting framework allows for properties manipulation.

Students in the HS group will engage in synthetic chemistry and develop familiarity with a range of spectroscopic, electrochemical, crystallographic and magnetic techniques. While rooted in synthetic chemistry, research in the HS group will interface with materials, organic, theory, and physical chemistry.

Most Cited Publications
  1. "High total proton conductivity in large-grained yttrium-doped barium zirconate," Y Yamazaki, R Hernandez-Sanchez, SM Haile, Chemistry of Materials 21, 2755 (2009
  2.  "Cation non-stoichiometry in yttrium-doped barium zirconate: phase behavior, microstructure, and proton conductivity," Y Yamazaki, R Hernandez-Sanchez, SM Haile, Journal of Materials Chemistry 20, 8158 (2010)
  3. "Disulfide reductive elimination from an iron (III) complex,"Janice L Wong, Raúl Hernández Sánchez, Jennifer Glancy Logan, Ryan A Zarkesh, Joseph W Ziller, Alan F Heyduk, Chemical Science 4, 1906 (2013)
  4. "Probing the role of an Fe IV tetrazene in catalytic aziridination," SA Cramer, R Hernández Sánchez, DF Brakhage, DM Jenkins, Chemical Communications 50, 13967 (2014)
  5.  "Metal Atom Lability in Polynuclear Complexes," EV Eames, R Hernández Sánchez, TA Betley, Inorganic chemistry 52, 5006 (2013)
Recent Publications
  1.  "Molecular Materials for Nonaqueous Flow Batteries with a High Coulombic Efficiency and Stable Cycling," Margarita Milton, Qian Cheng, Yuan Yang, Colin Nuckolls, Raúl Hernández Sánchez, Thomas J Sisto, Nano Letters, 17, 7859 (2017)
  2. "Towards Catalytic Ammonia Oxidation to Dinitrogen: A Synthetic Cycle Using a Simple Manganese Complex,"Megan Keener, Madeline Peterson, Raúl Hernández Sánchez, Victoria F Oswald, Guang Wu, Gabriel Menard, Chemistry-A European Journal 23, 11479 (2017)
  3. "Single-Walled Carbon Nanotubes: Mimics of Biological Ion Channels,"Hasti Amiri, Kenneth L Shepard, Colin Nuckolls, Raúl Hernández Sánchez, American Chemical Society, 17, 1204 (2017)
  4. " Mechanistic insight into high-spin iron (I)-catalyzed butadiene dimerization," Heejun Lee, Michael G Campbell, Raúl Hernández Sánchez, Jonas Börgel, Jean Raynaud, Sarah E Parker, Tobias Ritter, American Chemical Society, 17, 2923 (2017)
  5. "Maximizing Electron Exchange in a [Fe3] Cluster," Raúl Hernández Sánchez, Amymarie K Bartholomew, Tamara M Powers, Gabriel Ménard, Theodore A Betle, American Chemical Society, 16, 2235 (2017)
Department of chemistry, University of Pittsburgh
Ph.D. in Chemistry: Cornell University,1997
Summary:

Saxena Group is focused on developing Fourier Transform electron spin resonance and its application to otherwise inaccessible problems in biophysics. The coupling of electron spin angular momentum to its environment—as revealed by the ESR spectrum—provides rich information about the electronic, structural and dynamical properties of the molecule. Saxena group creates the methods that measure the precise distance between two units in a protein, in order to determine their folding patterns and conformational dynamics. These ESR Spectroscopic Rulers— based on multiple quantum coherences and double resonance experiments—are unique in that they resolve distances in the 1-16 nm length scale even on bulk amorphous materials. Much of this work is based on the use of first-principles theory to develop new experimental protocols and to analyze experimental results.

His group continues to develop applications of these spectroscopic rulers that range from capturing the essence of structural changes - such as misfolding - in proteins, to measuring the atomic-level details of ion-permeation in a ligand gated ion-channel. The main projects of his group include:

  • Pulsed ESR methods to measure distance constraints in systems containing paramagnetic metals
  • Measurement of structural and dynamical determinants of the protein-DNA interactions and functional dynamics in pentameric ligand gated ion-channels.
  • Application of the spectroscopic ruler to measure and predict global structures of nanostructured materials.
  • Role of metals in aggregation of Amyloid-β peptide.
Most Cited Publications
  1. "Nonlinear-least-squares analysis of slow-motion EPR spectra in one and two dimensions using a modified Levenberg–Marquardt algorithm," D. E. Budil, S. Lee, S. Saxena, J. H. Freed, Journal of Magnetic Resonance, Series A 120, 155 (1996)
  2. "Amplification of xenon NMR and MRI by remote detection," A. J. Moulé, M. M. Spence, S. I. Han, J. A. Seeley, K. L. Pierce, S Saxena, A. Pines. Proceedings of the National Academy of Sciences 100, 9122 (2003)
  3. "Double quantum two-dimensional Fourier transform electron spin resonance: distance measurements," S. Saxena, J. H. Freed, Chemical physics letters 251,102 (1996)
  4. "Direct evidence that all three histidine residues coordinate to Cu (II) in amyloid-β1− 16," B. Shin, S. Saxena, Biochemistry 47, 9117 (2008)
  5. "Theory of double quantum two-dimensional electron spin resonance with application to distance measurements," J Freed, S. Saxena, Jounal of Chemiical Physics 107, 1317-1340 (1997).
Recent Publications
  1. “ESR shows that the C-terminus of Ligand Free Human Glutathione S-Transferase A1-1 exists in two conformations,” M. J. Lawless, J. R. Pettersson, G. S. Rule, F. Lanni, S. SaxenaBiophysical Journal 114, 592 (2018)
  2. “The Cu(II)-nitrilotriacetic acid complex improves loading of a-helical double-histidine sites for precise distance measurements by pulsed ESR,” S. Ghosh, M. J. Lawless, G. S. Rule, S. SaxenaJ. Magn. Reson., 286, 163 (2018)
  3. “On the use of Cu(II)-iminodiacetic acid complex in double-Histidine based distance measurements by pulsed electron spin resonance,” M. J. Lawless, S. Ghosh, T. F. Cunningham, A. Shimshi, and S. SaxenaPhys. Chem. Chem. Phys., 19, 20959 (2017)
  4. “An analysis of nitroxide based distance measurements by pulsed ESR spectroscopy in cell-extract and in-cell,” M. J. Lawless, A. Shimshi, T. F. Cunningham, M. Kinde, P. Tang, and S. SaxenaChemPhysChem., 18, 1653 (2017)
  5. “Nucleotide-independent Cu(II)-based distance measurements in DNA by pulsed ESR,” M. J. Lawless, J. L. Sarver, S. Saxena, Angew Chem, 56, 2115 (2017)

Molecular Phenotypes of Structurally Homologous ETS Transcriptions Factors

Speaker(s): 
Gregory Poon
Dates: 
Thursday, September 28, 2017 - 4:30pm

 ETS transcription factors comprise an evolutionarily related family of genetic regulators that are ubiquitous in animals and control a myriad of physiologically critical processes. ETS proteins are united by a highly conserved DNA-binding domain, with overlapping target DNA preferences on the one hand, but are functionally diverse and non-redundant on the other. This so-called ìspecificity conundrumî besets not only our understanding of ETS homologs but also the structure-activity relationships of eukaryotic transcription factors in general. Translationally, it hampers efforts to develop...

Department of Chemistry, University of Pittsburgh
Ph.D., Physical Chemistry, University of Wisconsin-Madison, 2013
Summary:

In the Laaser Lab, we are interested in developing a physical understanding of how changes at the molecular level translate to the macroscopic properties of responsive polymeric materials. For example, how does a change in charge spacing affect the interactions between charged polymers, and at what point do the polymers stop behaving like isolated chains in solution and start behaving like part of a bulk material? How do orientational changes in single polymer chains propagate through a material to achieve macroscopic ordering? And how do polymeric networks transduce force, to achieve things like mechanochemical responses?

We explore these questions by a number of optical and spectroscopic methods, such as light scattering and Raman and infrared spectroscopy, along with classical materials characterization methods like rheology and electron microscopy. Together, these methods allow us to develop new understanding of the structure and dynamic properties of responsive polymeric materials, and offer students the opportunity to gain broad experience in both physical chemistry and polymer science.

Most Cited Publications
  1. "Adding a dimension to the infrared spectra of interfaces using heterodyne detected 2D sum-frequency generation (HD 2D SFG) spectroscopy," Wei Xiong, Jennifer E. Laaser, Randy D. Mehlenbacher, and Martin T. Zanni, PNAS 108, 20902 (2011)
  2. "Transient 2D IR Spectroscopy of Charge Injection in Dye-Sensitized Nanocrystalline Thin Films," Wei Xiong, Jennifer E. Laaser, Peerasak Paoprasert, Ryan A. Franking, Robert J. Hamers, Padma Gopalanand Martin T. Zanni, J. Am. Chem. Soc. 131,18040 (2009)
  3. "Time-Domain SFG Spectroscopy Using Mid-IR Pulse Shaping: Practical and Intrinsic Advantages," Jennifer E. Laaser, Wei Xiong, and Martin T. Zanni, J. Phys. Chem. B 115, 2536 (2011)
  4. "Two-Dimensional Sum-Frequency Generation Reveals Structure and Dynamics of a Surface-Bound Peptide," Jennifer E. Laaser, David R. Skoff, Jia-Jung Ho, Yongho Joo, Arnaldo L. Serrano, Jay D. Steinkruger, Padma Gopalan, Samuel H. Gellman, and Martin T. Zanni, J. Am. Chem. Soc. 136, 95 (2014)
  5. "Bridge-Dependent Interfacial Electron Transfer from Rhenium−Bipyridine Complexes to TiO2 Nanocrystalline Thin Films," Peerasak Paoprasert, Jennifer E. Laaser, Wei Xiong, Ryan A. Franking, Robert J. Hamers, Martin T. Zanni, J. R. Schmidt and Padma Gopalan, J. Phys. Chem. C 114, 9898 (2010)
Recent Publications
  1. "Equilibration of Micelle–Polyelectrolyte Complexes: Mechanistic Differences between Static and Annealed Charge Distributions," Jennifer E. Laaser, Michael McGovern, Yaming Jiang, Elise Lohmann, Theresa M. Reineke, David C. Morse, Kevin D. Dorfman, and Timothy P. Lodge, J. Phys. Chem. B, 121, 4631 (2017)
  2. "Architecture-Dependent Stabilization of Polyelectrolyte Complexes between Polyanions and Cationic Triblock Terpolymer Micelles," Jennifer E. Laaser, Elise Lohmann, Yaming Jiang, Theresa M. Reineke, and Timothy P. Lodge, Macromolecules 49, 6644 (2016)
  3. "Tuning Cationic Block Copolymer Micelle Size by pH and Ionic Strength," Dustin Sprouse, Yaming Jiang, Jennifer E. Laaser, Timothy P. Lodge, and Theresa M. Reineke, Biomacromolecules 17, 2849 (2016)
  4. "Interpolyelectrolyte Complexes of Polycationic Micelles and Linear Polyanions: Structural Stability and Temporal Evolution," Jennifer E. Laaser, Yaming Jiang, Shannon R. Petersen, Theresa M. Reineke, and Timothy P. Lodge, J. Phys. Chem. B 119, 15919 (2015)
  5. "Probing Site-Specific Structural Information of Peptides at Model Membrane Interface In Situ," Bei Ding, Afra Panahi, Jia-Jung Ho, Jennifer E. Laaser, Charles L. BrooksIII, Martin T. Zanni, and Zhan Chen, J. Am. Chem. Soc. 137, 10190 (2015)

ACS Launches Chemistry Preprint Server

  • By Aude Marjolin
  • 15 August 2016

Authors can deposit draft chemistry papers in online archive before publication. The American Chemical Society announced today that it will create a preprint server for chemistry research to promote sharing of early scientific results.

Preprint servers allow researchers to publish draft papers or preliminary data online to get feedback from the larger research community before a paper goes through a journal’s more formal peer review process. “A preprint server dedicated to chemists will help speed the dissemination of research results, solicit valuable feedback, and foster international collaboration,” says Kevin Davies, a vice president in ACS’s Publications Division who is spearheading the effort.

ACS is currently seeking collaborators to join in development of the server, which is tentatively called ChemRxiv. The joint undertaking between two of ACS’s divisions—CAS and Publications—is expected to launch in the next few months.

Intermolecular Potentials from the Iterated Stockholder Atoms Approach

Speaker(s): 
Alston Misquitta
Dates: 
Friday, July 8, 2016 - 2:00pm

The Iterated Stockholder Atom (ISA) algorithm [1] is proving to be one of the most interesting methods for atoms‐in‐a‐molecule (AIM): it leads to a unique definition of the atoms which are guaranteed to be maximally spherical while allowing for the effects of charge movement as a result of chemical bonding. Through a basis‐space, or BS‐ISA, algorithm [2] we are able to calculate the ISA solution at the basis‐set...

Nanostructure-Controlled Heterogeneous Catalysts with Superior Catalytic Properties

Speaker(s): 
Wenyu Huang
Dates: 
Thursday, April 7, 2016 - 4:00pm to 5:30pm

Dr. Huang received a B.S. in Chemistry from Nanjing University, China in 2000. After receiving an M.S. in 2002 also from Nanjing University, he started his Ph.D. research with Professor Mostafa A. El-Sayed at Georgia Institute of Technology and received his Ph.D. in 2007. Dr. Huang then began postdoctoral research with Professor Gabor A. Somorjai at University of California,...

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