IONA

Research & Publications

Kathleen E. Kristian's Research & Publications

Inorganic Chemistry Research

I. Metal Nitrosyl Chemistry

Overview

The many roles of nitric oxide (NO) in biological and environmental chemistry have led to intense research into its interaction with transition metals to form metal nitrosyls.  Detailed understanding of this class of molecules is important due to their involvement in biological reactions, intermediacy in the conversion of nitrogen oxide pollutants, and utility in organometallic and inorganic reactions.  Copper nitrosyls in particular are key intermediates in both biological reactions and NOx remediation through homogeneous and heterogeneous catalysis.

We are studying reductive nitrosylation reactions that produce secondary nitrosamines (R2NNO) via Cu(II) and NO, as well as the reverse reaction, denitrosylation of secondary nitrosamines.  In addition, we are developing syntheses of new stable or long-lived copper nitrosyl complexes.  Students working on these projects gain experience with organic and inorganic synthesis and purification, spectroscopic characterization methods, and experimental kinetics/reaction mechanisms.

Synthesis of Metal Nitrosyls

Both the biological production of NO by denitrosylation of S-nitrosothiols (RSNO) as well as the biological reduction of nitrite to nitric oxide occur at Cu sites in metalloproteins.  The latter process is catalyzed by copper nitrite reductase and is known to proceed through a copper nitrosyl (CuNO) intermediate.  Thermally stable or long-lived Cu–NO complexes are crucial for studying the reactivity of these intermediates.

We are developing syntheses of stable or long-lived mononuclear CuNO2+ complexes and studying their spectroscopic characteristics and thermal and/or photochemical reactivity.  The results of this work will contribute to fundamental understanding of Cu–NO structure and spectroscopy, which is a crucial factor in designing and improving useful environmental and biomedical applications.

Metal-catalyzed nitrosylation reactions

"Reductive nitrosylation" reactions (eq 1) involve the reduction of a metal center with concomitant nitrosylation of an amine or amido ligand to form secondary nitrosamines (R2NNO).

fig1

Understanding the mechanism of reductive nitrosylations furthers the development of catalytic systems that have both biochemical and environmental applications.  We are studying the nitrosylation of amines at Cu2+ centers to elucidate reaction mechanisms and lay the groundwork for catalytic reactions.

II.  N-Heterocyclic Carbene Transition Metal Complexes

Overview

Since the synthesis of the first stable free carbene, the use of N-heterocyclic carbenes  (NHCs, Scheme 1) as ligands for transition metal complexes has become its own field of research.  NHC ligands are oxidation resistant, are strong s-donor ligands that form very strong M–L bonds, and can be functionalized and/or built into a variety of chelating motifs.  These characteristics make them useful alternatives to phosphine ligands, particularly for oxidative chemistry that results in phosphine oxidation and catalyst degradation.  In the past twenty years, new NHC ligands have been synthesized in order to match the variety of available phosphine ligands, and determine the scope of NHC-metal complex reactivity.

Scheme 1

fig4

We are using this accumulated knowledge to identify promising NHC ligand candidates for copper in order to synthesize new complexes with interesting and useful reactivity.  Transition metal systems involving copper and NHC ligands have been successfully used for many important synthetic transformations, including (among others) hydrosilylation, conjugate additions, “click” reactions, carbon-carbon bond forming reactions (such as cross-coupling reactions, allylic substitutions, carbene transfers, carboxylations), and recently, C–H bond activation.

Aside from the significantly lower cost of copper (compared to expensive late transition metals like palladium and rhodium), the NHC-Cu systems have other advantages.  Due to the strong NHC–metal bond, the complexes are often air- and moisture-stable, and exhibit excellent thermal stability.  As the utility of NHC-Cu systems has become evident, rational design of new NHC-Cu complexes has become an active research area; the isolation and structural characterization of NHC-Cu complexes is crucial for developing new catalysts and reagents to more effectively carry out important transformations.


Chemical Education

I.  Analysis of Hg by Cold Vapor Atomic Absorption Spectroscopy in Upper Level Undergraduate Labs

Due to their well-documented effects on human health, the levels of mercury and organomercury species in commercial seafood are tracked and tabulated by the FDA.  Mercury levels can be measured by atomic spectroscopy, which is a fundamental part of the undergraduate analytical chemistry/instrumental analysis curricula.

We have developed a protocol for the measurement of total mercury in commercial fish samples by cold vapor atomic absorption spectroscopy (CVAAS) that has been validated by analytical spiking experiments.  Analysis of a variety of fish by this method yields reproducible results that are in good agreement with those reported by the FDA.

An experiment utilizing our digestion method and analytical protocol for the Varian AA240 atomic absorption spectrometer with VGA-77 cold vapor generator was successfully incorporated into CHM 322:  Instrumental Analysis during the Spring 2013 semester.

II.  Inorganic Chemistry Curricula

A foundational course, CHM 327:  Inorganic and Bioinorganic Chemistry, has been developed to introduce students to fundamental principles of inorganic chemistry through bioinorganic systems.  Iona College awarded Dr. Kristian a CELTIC Excellence in Teaching Award (CETA) in 2012 to develop a group project assignment for this course that promotes collaboration through information technology resources.

III.  Scientific Writing

Strong academic writing is the hallmark of well-educated and successful students at any college and in any field. Dr. Kristian has a long-standing interest in developing methods for teaching scientific writing and using writing as a teaching tool at the undergraduate level. At Iona, her work in this area includes revisions to the scientific writing component of the laboratory curricula, and implementation of a Learning Community composed of her section of CHM 109: General Chemistry Laboratory I and a section of ENG 120: Writing I.

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Undergraduate Research Participants

Dr. Kristian’s work is completed in collaboration with undergraduate students from all class years.  If you are interested in working with Dr. Kristian in the field of inorganic chemistry or in chemical education, please contact her by email.

Undergraduate Research Participants

Student Research Topic Years Program
Eugene Picone ‘16
  • Synthesis of NHC-metal complexes
  • Synthesis of metal nitrosyls
2014 - B.S. Chemistry
Scott Friedbauer ‘15
  • Synthesis of metal-NHC complexes
  • Synthesis of metal nitrosyls
  • Development of a digestion protocol for analysis of Hg in fish
2012-present B.S. Chemistry
Jennifer Gomez ‘15
  • Synthesis of metal nitrosyls
  • Analysis of Hg in fish by CVAAS
2011-present B.S. Chemistry
Jennifer Barajas ‘14
  • Analysis of Hg in fish by CVAAS
  • FAAS analysis of Cu in rat liver and bile
2012-2014 B.S. Chemistry
Kristen Ferencz ‘14
  • Analysis of Hg in fish by CVAAS
  • FAAS analysis of Cu in rat liver and bile
2012-2014 B.S. Chemistry
Donika Kabashi ‘14
  • Development of a digestion protocol for analysis of Hg in fish
  • FAAS analysis of Cu in rat liver and bile
2012-2014 B.S. Chemistry
Kelly O’Brien ‘14
  • Analysis of Hg in fish by CVAAS
  • Assessment of laboratory curricula
2011-2013 B.S. Chemistry MST Education
Tenesha Canzius ‘12
  • Development of a digestion protocol for analysis of Hg in fish
  • Development of GC-MS curriculum for Instrumental Analysis Lab
2011-2012 B.S. Chemistry

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NY ACS Inorganic Topical Group

Inorganic and Organometallic Topical Group of the NY ACS Local Section

Dr. Kristian is a co-chair of the Inorganic and Organometallic Topical Group of the NY ACS Local Section.  In collaboration with co-chair Dr. James Camara of Yeshiva University, Dr. Kristian organizes events for the inorganic chemistry community in the NY metro area.
 
More information about the NY ACS and the Inorganic and Organometallic Topical Group is available at:  www.newyorkacs.org
 
Past Events
 
2013
 
2nd Annual “Frontiers of Inorganic and Organometallic Chemistry” Lecture Symposium
 
The 2nd annual lecture symposium featured a keynote address by Prof. Pat Holland of Yale University and symposium speakers Mark Biscoe (City College of CUNY), Jack R. Norton (Columbia University), Lynn Francesconi (Hunter College of CUNY), and Ahmad Moini (BASF Corp).

Dr. Kristian and Iona College chemistry majors Ross Giacomini '15, Michelle Muzzio '15, and Scott Friedbauer '15 volunteer at the 2013 Frontiers of Inorganic and Organometallic Chemistry Lecture Symposium.

2012
 
1st Annual “Frontiers of Inorganic and Organometallic Chemistry” Lecture Symposium
 
The inaugural “Frontiers of Inorganic and Organometallic Chemistry” lecture symposium in 2012 attracted more than 70 academic and industrial chemists.  It featured four prominent inorganic/organometallic chemists from the NY region as well as a keynote address by Prof. Paul Chirik of Princeton University. 

fig4
Dr. Kristian and Iona College chemistry majors Scott Friedbauer '15 and Jennifer Gomez '15 volunteer at the 2012 Frontiers of Inorganic and Organometallic Chemistry Lecture Symposium (not pictured:  biology major Fawaz Abdulkarim '14).

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Publications and Presentations

Publications
The names of undergraduate co-authors are underlined.
 
Bakac, A.; Durfey, B. L; Pestovsky, O.; Kristian, K. E.  Kinetics and Thermodynamics of Nitric Oxide Binding to Transition Metal Complexes.  Relationship to Dioxygen Binding.  Chemical Science, 2013, 4, 2185.
 
Li, L.; Kristian, K. E.; Han, A.; Norton, J. R.; Sattler, W.  Synthesis and Structural Characterization of Cp2- and (CpMe)2-ligated Titanaaziridines and Titanaoxiranes with Fast Enantiomer Interconversion Rates.  Organometallics, 2012, 31, 8218-8224.
 
Kristian, K. E.; Bakac, A.  Reduction of nitrous acid with a macrocyclic rhodium complex that acts as a functional model of nitrite reductase.  Inorganic Chemistry, 2012, 51(8), 4877–4882.
 
Song, W.; Kristian, K. E.; Bakac, A.  Visible Light-Induced Release of NO From a Nitrosyl Rhodium Complex. Chemistry: A European Journal, 2011, 17(16), 4513-4517.
 
Kristian, K. E.; Song, W.; Bakac, A.  Preparation, Crystal Structure, and Unusually Facile Redox Chemistry of a Macrocyclic Nitrosylrhodium Complex.  Inorganic Chemistry, 2010, 49(15), 7182–7187.
 
Kristian, K. E.; Iimura, M.; Cummings, S. A.; Norton, J. R.; Janak, K. E.; Pang, K.  Mechanism of the Reaction of Alkynes with a “Constrained Geometry” Zirconaaziridine. PMe3 Dissociates More Rapidly from the Constrained Geometry Complex than from its Cp2 Analogue.  Organometallics, 2009, 28(2), 493–498.
 
Pasternack, R. F.; Gibbs, E. J.; Sibley, S.; Woodard, L.; Hutchinson, P.; Genereux, J.; Kristian, K.  Formation Kinetics of Insulin-Based Amyloid Gels and the Effect of Added Metalloporphyrins.  Biophysical Journal 2006, 90, 1033-1042.
 
Kristian, K.; Medina-Emmanuelli, N.; Ortíz, O.; González, A.; González, J.; De Jesús, J.; Vargas, I.; Weiner, B.; Morell, G.  Study of the Effects of Heavy Ion Radiation on Nanocomposite Carbon Films.  Materials Research Society Symposium Proceedings, 2003, 77 (T8.8).
 
González, A.; Huang, D.; Medina-Emmanuelli, N.; Kristian, K.; Ortíz, O.; González, J.; De Jesús, J.; Vargas, I.; Weiner, B.; Morell, G.  Effects of Heavy Ion Radiation on the Electron Field Emission Properties of Sulfur Doped Nanocomposite Carbon Films.  Diamond and Related Materials, 2004, 13(2), 221-225.
 
Presentations
The names of undergraduate co-authors are underlined.
 
Kristian, K. E. “Teaching collaboration skills through a wiki-based inorganic chemistry group project”.  Oral presentation, 248th American Chemical Society National Meeting, San Francisco, CA, August 2014, paper CHED-507.
 
Friedbauer, S.; Kabashi, D.; Kristian, K. E. “A Protocol for the Analysis of the Mercury Content of Commercial Fish Samples by CVAAS in Undergraduate Labs”.  Poster presentation at the 2013 Northeast Regional Meeting of the American Chemical Society (NERM), New Haven, CT, October 2013, paper NERM-1186
 
Barajas, J.; Ferencz, K.; Kabashi, D.; Friedbauer, S.; O’Brien, K.; Gomez, J.; Kristian, K. E.
 “Determination of the Mercury Content of Commercial Fish Samples by Cold Vapor AAS”.  Poster presentation at the 2013 Northeast Regional Meeting of the American Chemical Society (NERM), October 2013, New Haven, CT, paper NERM-1236.
 
Kabashi, D.; Friedbauer, S.; O’Brien, K.; Kristian, K. E.  “Development of a Protocol for the Analysis of the Mercury Content of Commercial Fish Samples in Undergraduate Labs”.  Oral presentation at the 61st Annual Undergraduate Research Symposium of the New York ACS Local Section, City College of CUNY, New York, NY, April 2013.
 
Friedbauer, S.; Kabashi, D.; O’Brien, K.; Kristian, K. E.  “Development of a Protocol for the Analysis of the Mercury Content of Commercial Fish Samples in Undergraduate Labs”.  Poster presentation at Iona College Undergraduate Research Day, Iona College, New Rochelle, NY, April 2013.
 
Barajas, J.; Ferencz, K.; Kabashi, D.; Friedbauer, S.; O’Brien, K.; Gomez, J.; Kristian, K. E.  “Development of a Protocol for the Analysis of the Mercury Content of Commercial Fish Samples in Undergraduate Labs”.  Poster presentation at Iona College Undergraduate Research Day, Iona College, New Rochelle, NY, April 2013.
 
“Formation and Disproportionation of a Rhodium(II) Complex of Nitrous Acid”.  Oral presentation at 244th American Chemical Society National Meeting, Philadelphia, PA, August 2012, paper INOR-617.
 
“Mechanism of Formation of a Rhodium Nitrosyl from Rh(II) and HNO2”.  Poster presentation at Inorganic Reaction Mechanisms Gordon Research Conference, Galveston, TX, March 2011.
 
“Chemistry of NO Release From a Rhodium Nitrosyl Complex”.  Oral presentation at Iowa State University Postdoctoral Association Research Day, Ames, Iowa, May 2010. 
 
“Mechanism of Insertion of Unsaturated Electrophiles into a ‘Constrained Geometry’ Zirconaaziridine”.  Oral presentation at 235th American Chemical Society National Meeting, New Orleans, LA, March 2008, paper INOR-586; and at 40th Middle Atlantic Regional Meeting of the ACS, Queens, NY, May 2008, paper MRM-527.
 
“Double Discovery at Columbia University:  Scientists and Educators Sharing Perspectives”.  Poster presentation at 235th American Chemical Society National Meeting, New Orleans, LA, March 2008, paper CHED-143.

“The Science of Tutoring Scientific Writers”.  Oral presentation at International Writing Center Association/National Conference on Peer Tutoring in Writing Annual Conference, Hershey, PA, October 2003.
 
“The Effects of Space Radiation on the Surface Morphology and Chemical Composition of Nanocomposite Carbon Thin Films”.  Poster presentation at 225th American Chemical Society National Meeting, New Orleans, LA, March 2003, paper CHED-809.

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