Research in Dr. Huo's Group
Our group is interested in the organometallic reactions, synthesis and characterization of functional organometallic materials, and biological applications of organometallic compounds. Current research pursues in the following three areas.
Selectivity in organometallic C-H bond activation. The control of selectivity in sp2/sp3 C-H bond activations is challenging, even with the intramolecular version of organometallic C-H bond activations. Recently we have discovered an interesting solvent-controlled switch of selectivity between sp2 and sp3 C-H bond activation by platinum (Scheme 1). We are examining underlying factors that contribute to the control of selective C-H activation and investigating reaction mechanisms. We are also studying an interesting cascade cyclometalation-selective acylation process.
Phosphorescent materials. Phosphorescent materials based on cyclometalated iridium and platinum compounds have been used as triplet emitters in organic light-emitting diode (OLED) devices to improve the devices' efficiency through harvesting both singlet and triplet excited states generated by electric excitations. Our group has designed, synthesized, and characterized a number of highly efficient phosphorescent platinum complexes based on tridentate and tetradentate ligands (Scheme 2). Some of the complexes are among the brightest Pt-based emitters. Through structural engineering of the complexes, emissions covering entire visible spectrum (blue to red) can be achieved. Our research in this area is focused on the structure-property relationship of phosphorescent materials and synthesis of tailor-made functional phosphorescent materials for optoelectronic and biological applications.
Organometallic anticancer agents and imaging materials. In collaboration with Professor Yan-Hua Chen at the Brody School of Medicine, we have screened a series of phosphorescent cyclometalated platinum compounds for their anticancer activities. The cellular uptake of those luminescent complexes is clearly demonstrated by the cell imaging (Scheme 3). A significant finding is the drastic difference in cytotoxicity between isomeric platinum complexes (N^C^N)PtCl and (C^N^N)PtCl (Scheme 4). The N^C^N-coordinated Pt complex demonstrated remarkably higher toxicity against a series of human lung cancer cells and a prostate cancer cell, probablyattributedto the trans effect of the carbon donor in N^C^N-coordinated complex. The screening has led us to the investigation of NCN-coordinated complexes as anticancer agents and other low cytotoxic complexes as imaging and/or labeling materials in biological applications.
Scheme 3 Scheme 4
Book Chapters and Reviews:
- Shouquan Huo and Ei-ichi Negishi
Palladium-Catalyzed Alkenyl-Aryl, Aryl-Alkenyl, and Alkenyl-Alkenyl Couplings
In The Handbook of Organopalladium Chemistry for Organic Synthesis, E. Negishi, Ed., J. Wiley & Sons, New York, Sect. III.2.6, 2002, 335-408.
- Ei-ichi Negishi and Shouquan Huo
Synthesis and Reactivity of Zirconocene Derivatives
In Titanium and Zirconium in Organic Synthesis, Chapter 1, Marek, I., Ed., Wiley-VCH, 2002, 1-49.
- Ei-ichi Negishi and Shouquan Huo
Zirconium-catalyzed Enantioselective Carboalumination of “Unactivated” Alkenes as a New Synthetic Tool for Asymmetric Carbon-carbon Bond Formation
Pure Appl. Chem. 2002, 74, 151-157.
Original Research Articles:
- Jeffrey Carroll, Hannah G. Woolard, Robert Mroz, Charles A. Nason, Shouquan Huo Regiospecific Acylation of Cycloplatinated Complexes: Scope, Limitations, and Mechanistic Implications. Organometallics 2016, 35, 1313-1322.
- Yumin Li, Jeffrey Carroll, Bradley Simpkins, Deepak Ravindranathan, Christopher M. Boyd, Shouquan Huo Computational and Experimental Study on Selective sp2/sp3 or
Vinylic/Aryl Carbon-Hydrogen Bond Activation by Platinum(II):
Geometries and Relative Stability of Isomeric Cycloplatinated Compounds. Organometallics 2015, 34, 3303-3313.
- Shouquan Huo, Jeffrey Carroll, Dileep A.K. Vezzu. Design, Synthesis, and Applications of Highly Phosphorescent Cyclometalated Platinum Complexes. Asian J. Org. Chem. 2015, 4, 1210-1245
- Shouquan Huo*, Robert Mroz, and Jeffrey Carroll Negishi coupling in the synthesis of advanced electronic, optical, electrochemical, and magnetic materials. Org. Chem. Front. 2015, 2, 416-445.
- Dileep A.K. Vezzu, Qun Lu, Yan-Hua Chen,* and Shouquan Huo* Cytotoxicity of Cyclometalated Platinum Complexes Based on Tridentate NCN and CNN-coordinating ligands: Remarkable Coordination Dependence. J. Inorg. Biochem. 2014,134, 49-56.
- Jeffrey Carroll, Joshua P. Gagnier, Alexander W. Garner, Justin G. Moots, R. D. Pike, Yumin Li, and Shouquan Huo* Reaction of N-isopropyl-N-phenyl-2,2'-bipyridin-6-amine with K2PtCl4: Selective C-H bond activation, C-N Bond Cleavage, and Selective Acylation. Organometallics 2013, 32, 4828-4836.
- Caleb F. Harris, Dileep A. K. Vezzu, Libero Bartolotti, Paul D. Boyle, and Shouquan Huo* Synthesis, Structure, Photophysics, and a DFT Study of Phosphorescent C*N^N- and C^N^N-Coordinated Platinum Complexes. Inorg. Chem. 2013, 52, 11711-11722.
- Shouquan Huo, Caleb F. Harris, Dileep A.K. Vezzu, Joshua P. Gagnier, Meredith E. Smith, Robert D. Pike, Yumin Li, Novel phosphorescent tetradentate bis-cyclometalated C^C*N^N-coordinated platinum complexes: Structure, photophysics, and a synthetic adventure. Polyhedron, 2013, 52, 1030-1040.
- Caleb F. Harris, Deepak Ravindranathan, Shouquan Huo, Oxidative addition of heteroaromatic halides to Negishi reagent. Tetrahedron Letters, 2012, 53, 5389-5392.
- Dileep A. K. Vezzu, Deepak Ravindranathan, Alexander W. Garner, Libero Bartolotti, Meredith E. Smith, Paul D. Boyle, Shouquan Huo, Highly Luminescent Tridentate N^C*N Platinum(II) Complexes Featured in Fused Five-Six-membered Metallacycle and Diminishing Concentration Quenching. Inorganic Chemistry, 2011, 50, 8261-8273.
- Gen Zhang, Lei Ding, Randall Reneger, Xuemei Wang, Qun Lu, Shouquan Huo, Yan-Hua Chen, Hydroxycamptothecin-loaded Fe3O4 nanoparticles induce human lung cancer cell apoptosis through apoptosis through caspase-8 pathway activation and disrupt tight junctions. Cancer Science, 2011, 102, 1216-1222.
- Alexander W. Garner, Caleb F. Harris, Dileep A. K. Vezzu, Robert D. Pike, Shouquan Huo, Solvent-controlled switch of selectivity between sp2 and sp3 C-H bond activation by platinum(II). Chemical Communications, 2011, 47, 1902-1904.
- Joseph C. Deaton, Ralph H. Young, Jerome R. Lenhard, Manju Rajeswaran, Shouquan Huo, Photophysical properties of the series fac- and mer-(1-phenylisoquinolinato-N C2')x(2-phenylpyridinato-N C2')3-xiridium(III) (x = 1-3). Inorganic Chemistry, 2010, 49, 9151-9161.
- Deepak Ravindranathan, Dileep A. K. Vezzu, Libero Bartolotti, Paul D. Boyle, Shouquan Huo, Improvement in Phosphorescence Efficiency through Tuning of Coordination Geometry of Tridentate Cyclometalated Platinum(II) Complexes. Inorganic Chemistry, 2010, 49, 8922-8928.
- Dileep A. K. Vezzu, Joseph C. Deaton, James S. Jones, Libero Bartolotti, Caleb F. Harris, Alfred P. Marchetti, Marina Kondakova, Robert D. Pike, Shouquan Huo, Highly Luminescent Tetradentate Bis-Cyclometalated Platinum Complexes: Design, Synthesis, Structure, Photophysics, and Electroluminescence Application. Inorganic Chemistry, 2010, 49, 5107-5119.
- Dileep A. K. Vezzu, Joseph C. Deaton, Mohammed Shayeghi, Yumin Li, Shouquan Huo, Acridinone/Amine(carbazole)-Based Bipolar Molecules: Efficient Hosts for Fluorescent and Phosphorescent Emitters. Organic Letters, 2009, 11, 4310-4313.
- Manju Rajeswaran, William J. Begley, Leif P. Olson, and Shouquan Huo, Steric effects of substituted quinolines on lithium coordination geometry. Polyhedron 2007, 26, 3653-3660.
- Joseph C. Deaton, Shouquan Huo, Barbara Lussier, Chrostopher T. Brown, Joy C. Garnett, Debra B. Blondell, and Michael R. Landry, Vapor Pressures of Homo- and Heteroleptic Orthemetalated Complexes of iridium. Digest of Technical Papers-Society for Information Display International Symposium, 2006, 37 (Bk. 1), 939-941.
- Shouquan Huo, Joseph C. Deaton, Manju Rajeswaran, and William C. Lenhart, Highly Efficient, Selective, and General Method for the Preparation of Meridional Homo- and Heteroleptic Tris-cyclometalated Iridium Complexes. Inorg. Chem. 2006, 45, 3155-3157.
- Ze Tan, Bo Liang, Shouquan Huo, Ji-Cheng Shi, Ei-Ichi Negishi, Zirconium-catalyzed asymmetric carboalumination (ZACA reaction) of 1,4-dienes. Tetrahedron: Asymmetry 2006, 17(4), 512-515.
- Shouquan Huo, Highly Efficient, General Procedure for the Preparation of Alkylzinc Reagents from Unactivated Alkyl Bromides and Chlorides. Org. Lett. 2003, 5, 423-425.
- Shouquan Huo, Ji-cheng Shi, and Ei-ichi Negishi, 3.0.CO;2-2/abstract">A New Protocol for The Enantioselective Synthesis of Methyl-Substituted Alkanols and Their Derivatives via Hydroalumination-Zirconium-Catalyzed Alkylalumination Tandem Process. Angew. Chem. Int. Ed. 2002, 41, 2141-2143.
- Tamotsu Takahashi, Masanori Ishikawa, and Shouquan Huo, Reaction of A Double Bond of Zirconacyclopentadienes: Formation of 1,2,3,5-Tetrasubstituted Benzenes via The C-C Bond Cleavage. J. Am. Chem. Soc. 2002, 124, 388-389.
- Shouquan Huo and Ei-ichi Negishi, A Convenient and Asymmetric Protocol for The Synthesis of Natural Products Containing Chiral Alkyl Chains via Zr-Catalyzed Asymmetric Carboalumination of Alkenes. Synthesis of Phytol and Vitamins E and K, Org. Lett. 2001, 3, 3253.
- Tamotsu Takahashi, Shouquan Huo, Ryuichiro Hara, Yoshinori Noguchi, Kiyohiko Nakajima, and Wen-Hua Sun, Reaction of Zirconacyclopentadienes with CO in The Presence of n-BuLi. Selective Formation of Cyclopentenone Derivatives from Two Alkynes and CO. J. Am. Chem. Soc. 1999, 121, 1094.
US Patents and Patent Applications
US 6,835,835 B1
US 6,824,895 B1
US 7,029,766 B2
US 7,417,146 B2
US 7,476,739 B2
US 5,517,984 B2
US 7,553,556 B2
US 7,579,090 B2
US 7,597,967 B2
US 7,718,276 B2
US 7,736,756 B2
US 7,767,316 B2
US 7,842,406 B2
US 2006134461 A1
US 2006134459 A1