Inorganic Chemistry Seminar, Dr. Hemamala Karunadasa, Stanford University

Tue, 2018-09-04 12:00 - 13:00
Speaker: 

Dr. Hemamala Karunadasa

Title

Between the sheets: The molecular chemistry of hybrid perovskites

Abstract

The tools of synthetic chemistry allow us to tune molecules with a level of precision not yet accessible with inorganic solids. We have investigated hybrid perovskites that couple organic small molecules with the optical and electronic diversity of extended inorganic solids. I will share our current understanding of these materials, whose technologically relevant properties are highly amenable to synthetic design.

The 3D lead-iodide perovskites have recently been identified as low-cost absorbers for high-efficiency solar cells. Although the efficiencies of devices with perovskite absorbers have risen at an impressive rate, the materials’ intrinsic instability and toxicity may impede their commercialization. I will discuss methods developed by our group to address these problems. The 2D hybrid perovskites have dramatically different properties from their 3D congeners. We discovered that some 2D perovskites emit broadband white light (similar to sunlight) when excited by UV light. I will discuss how these materials, which do not contain extrinsic dopants or obvious emissive sites, could emit every color of visible light. Although the organic molecules in hybrid perovskites have mostly played a templating role, we have investigated their role in engendering reactivity. I will describe reactions that occur between the inorganic sheets, which allow these nonporous solids to capture small molecules.

Brief Bio

Hema Karunadasa studied solid-state chemistry with Bob Cava at Princeton University and molecular catalysis with Jeff Long and Chris Chang at UC Berkeley and with Harry Gray at the California Institute of Technology. She joined Stanford Chemistry as an assistant professor in 2012. Her group synthesizes hybrid materials that harness the advantages of extended solids and discrete molecules.

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Attached Document: 

Host: Dr. Murray

inquiries rvargas@sas.upenn.edu

Inorganic Chemsitry Seminar: Dr. Matthew Kieber-Emmons, University of Utah

Tue, 2019-04-23 12:00 - 13:00
Speaker: 
Dr. Matthew Kieber-Emmons
Location: 

Carol Lynch Lecture Hall

Chemsitry Complex

Host: Tomson

Title & Abstract: TBA

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar; Dr. Xavier Roy, Columbia University

Tue, 2019-04-09 00:00 - 01:00
Speaker: 
Dr. Xavier Roy
Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Murray

Title & Abstract: TBA

inquiries rvargas@sas.upenn.edu

Organic Chemistry Seminar: Dr. David Nagib, Ohio State University

Mon, 2018-12-10 12:00 - 13:00
Speaker: 

Dr. David Naglib

C-H and C-O functionalization via radical chaperones

 


Our research is focused on harnessing the untapped reactivity of abundant chemical feedstocks to enable late-stage functionalization of medicinally relevant molecules. We have recently developed new approaches for selective C-H and C-O functionalization of alcohols, amines, and carbonyls, using a combination of radical (1e-) and closed shell (2e-) processes that act in concert with one another. These radical chaperone strategies have enabled discovery of new classes of reactivity to streamline the synthesis of complex molecules with biological and industrial significance.

Location: 

Carol Lynch Lectrue Hall

Chemistry Complex

Host: Dr. Walsh

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr. Milton Smith, MSU

Tue, 2018-12-04 12:00 - 13:00
Speaker: 

Dr. Milton Smith

 

 

Catalysts that Cleave C–H and N–H Bonds for Fine Chemical Synthesis and Energy Conversion

 

Catalytic transformations of C–H bonds are now common. This wasn’t always the case. Building from the first thermal, catalytic coupling of a borane and a hydrocarbon, our research group2 developed highly active iridium catalysts that exhibit unique regioselectivities for arene substitution and remarkable chemoselectivity for C–H functionalization. For example, sp2-C–X bonds (X = Cl, Br, and I) that are commonly cleaved in reactions with late transition metal complexes are remarkably inert to the Ir catalysts. From the roadmap we created many other groups in academia and industry have made important contributions to C–H borylations. Extensions to heterocyclic substrates and development of one-pot, catalytic reactions where the C–B bonds that result are further transformed make C–H borylation particularly attractive to synthetic chemists. Our recent work has emphasized ligand and reagent design to harness relatively weak interactions (e.g., hydrogen bonding) that are sufficiently strong to achieve  

C–H borylations with high regioselectivities.1,2

More recently, our research group has initiated a program to tap the potential for using ammonia to store, distribute, and release hydrogen gas. Specifically, we have targeted the oxidation ammonia to dinitrogen gas, protons, and electrons.3,4 Combining ammonia oxidation with ammonia synthesis from dinitrogen—the most abundant component of Earth’s atmosphere—and renewable hydrogen, a groundwork for a closed, zero-carbon fuel cycle based on nitrogen gas would be established. We recently have designed the first molecular catalyst that oxidizes NH3 to N2, six “protons,” and six electrons at room temperature. This is the anodic reaction in electrocatalytic NH3 “splitting” to N2 and H2.

 


 

 

(1) Chattopadhyay, B.; Dannatt, J. E.; Andujar-De Sanctis, I. L.; Gore, K. A.; Maleczka, R. E., Jr; Singleton, D. A.; Smith, M. R., III. J. Am. Chem. Soc. 2017, 139, 7864–7871.

(2) Smith, M. R., III; Bisht, R.; Haldar, C.; Pandey, G.; Dannatt, J. E.; Ghaffari, B.; Maleczka, R. E., Jr.; Chattopadhyay, B. ACS Catal. 2018, 8, 6216–6223.

(3) Little, D. J.; Smith, M. R., III; Hamann, T. W. Energy Environ. Sci. 2015, 8, 2775–2781.

(4) Little, D. J.; Edwards, D. O.; Smith, M. R., III; Hamann, T. W. ACS Appl. Mater. Interfaces 2017, 9, 16228–16235.

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Mindiola

inquiries rvargas@sas.upenn.edu

Inorganic Chemistry Seminar: Dr. Katherine J. Franz, Duke

Tue, 2019-02-19 12:00 - 13:00
Speaker: 

Dr. Katherine Franz

Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Tomson/ Dmochowski

Title & Abstract TBA

inquires rvargas@sas.upenn.edu

Joe Francisco Joins Penn

Joseph Francisco has joined Penn as the President's Distinguished Professor of Earth & Environmental Sciences. Prof. Francisco will have a secondary appointment in the Chemistry Department. 

 

Joseph S. Francisco

Photo: 
First Name: 
Joseph S.
Last Name: 
Francisco
Official Title: 
President’s Distinguished Professor
Additional Titles: 
Professor of Chemistry
Professor of Earth & Environmental Sciences
Contact Information
Email: 
frjoseph@sas.upenn.edu
Phone: 
215-573-3164
Education: 

B.S.: Chemistry, University of Texas at Austin, 1977

 

Ph.D.: Chemical Physics, Massachusetts Institute of Technology, 1983.

 

Research Fellow: University of Cambridge, 1983-1985

 

Provost Postdoctoral Fellow: Massachusetts Institute of Technology, 1985-1986

Research Interests: 

Research in our laboratory focuses on basic studies in spectroscopy, kinetics and photochemistry of novel transient species in the gas phase, in aerosol and at the ice-quasi liquid layer. These species play an important role in atmospheric processes. Yet questions dealing with how structures correlate to reactivity and photochemical mechanisms have not been addressed for these systems. These problems are addressed by research efforts in our laboratory. Specific research areas of interest are: 1) Spectroscopic determinations of electronic and vibrational transitions in free radicals; 2) Kinetics of individual gas-phase reaction steps involving free radicals in complex reaction mechanisms involved in the gas phase and at interfaces; 3) Characteristics of primary photo chemical processes that free radicals can undergo in the gas phase and at interfaces; 4) Atmospheric chemistry and dynamics at the air/water interface chemistry; and 5) Atmospheric chemistry and dynamics at the ice-quasi liquid layer.

 

 

Our goal is to use state-of-the-art molecular orbital methods to predict properties that can be used as a guide in the experimental search. We aim to predict spectroscopic properties for these novel species in the gas phase and at the air/water interface, that would facilitate their full experimental characterization. 

Selected Publications: 

M. Kumar, and J.S. Francisco, Mechanistic Insight into Ion-Pair Particle Formation from Methanesulfonic Acid-Amines Chemistry at the Air-Water Interface,  Proc. Natl. Acad. Sci. USA., 114, 12401-12406 (2017).

 

L. Artiglia, J. Edebeli,  F. Orlando, S. Chen, P. C. Arroyo, A. Gilgen, T. Bartels-Rausch, A. Kleibert, M. Vazdar, M. A. Garegnano, J.S. Francisco,  P.B. Shepson, I. Gladich, and M. Ammann, A Surface-Stabilized Ozonide Triggers Bromide Oxidation at the Aqueous Solution-Vapor Interface, Nature Communications8, 700 (2017).

 

C.Q. Zhu, J. Zhong, M. Kumar, J.S. Francisco, X.C. Zeng, New Mechanistic Pathways for Creigee-Water Chemistry at the Air/Water Interface,  J. Am. Chem. Soc., 138, 11164-11169 (2016).

 

R. Hoehn, M.A. Carignano, S. Kais,  J.S. Francisco, and  I. Gladich, Hydrogen Bonding and Orientation Effects on the Accommodation of Methylamine at the Air-Water Interface, J. Chem. Phys.144, 214701 (2016).

 

M. Kumar, A. Sinha, and J. S. Francisco, Role of Double Hydrogen Atom Transfer Reactions in Atmospheric Chemistry, Acc. Chem. Res., 49, 877- 833 (2016).

 

M. Kumar and J.S. Francisco, Red-Light Induced Decomposition of Organic Peroxy Radical: A New Source of the HO2Radical, Angew. Chem. Int. Ed.54, 15711-15714 (2015).

 

J.M. Anglada, M. Martins-Costa, M.F. Ruiz-Lopez, J.S. Francisco, Spectroscopic Signatures of Ozone at the Air/Water Interface and Photochemistry Implications, Proc. Natl. Acad. Sci. USA., 111, 11618-11623 (2014).

Karen Goldberg Elected to National Academy

Karen Goldberg, the Vagelos Professor of Energy Research, has been elected to the National Academy of Sciences. Prof. Goldberg joined Penn in 2017 from the University of Washington, where she was the Nicole A. Boand Endowed Professor in Chemistry. She received her A.B. degree from Barnard College, Columbia University and her Ph.D. from the University of California, Berkeley.

Physical Chemistry Seminar: Dr. Josh Vura- Weis, University of Illinois

Thu, 2019-01-17 13:00 - 14:00
Speaker: 

Dr. Josh Vura-Weis

Ultrafast extreme ultraviolet spectroscopy reveals short-lived states in transition metal complexes and organohalide perovskite semiconductors



University of Illinois at Urbana/Champaign, 600 S Mathews Ave, Urbana, IL USA    X-ray absorption near edge spectroscopy (XANES or NEXAFS) is a powerful technique for electronic structure determination.  However, widespread use of XANES is limited by the need for synchrotron light sources with tunable x-ray energy. Recent developments in extreme ultraviolet (XUV) light sources using the laser-based technique of high-harmonic generation have enabled core-level spectroscopy to be performed on femtosecond to attosecond timescales.  We have extended the scope of tabletop XUV spectroscopy and demonstrated that M2,3-edge XANES, corresponding to 3p→3d transitions, can reliably measure the electronic structure of first-row transition metal coordination complexes with femtosecond time resolution.  We use this ability to track the excited-state relaxation pathways of photocatalysts and spin crossover complexes.  In semiconductors such as CH3NH3PbI3, distinct signals are observed for photoinduced electrons and holes, allowing the dynamics of each carrier to be tracked independently.  This work establishes extreme ultraviolet spectroscopy as a useful tool for mainstream research in inorganic, organometallic, and materials chemistry.  
Location: 

Carol Lynch Lecture Hall

Chemistry Complex

Host: Dr. Subotnik

inquiries rvargas@sas.upenn.edu

Department of Chemistry

231 S. 34 Street, Philadelphia, PA 19104-6323

215.898.8317 voice | 215.573.2112 fax | web@chem.upenn.edu

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