Research in Dr. Huo's Group
Our group is interested in the
organometallic reactions and catalysis, synthesis and characterization of
functional organometallic materials, and biological applications of
organometallic compounds. Current research pursues in the following directions.
C-H bond activation and functionalization. The
control of selectivity in competing sp2/sp3 C-H bond activations is
challenging, even with the intramolecular version of organometallic C-H bond activations. Our group
discovered an interesting solvent-controlled switch of selectivity between sp2
and sp3 C-H bond
activation by platinum (Chem. Commun. 2011, 47,
1902-1904). As shown in Scheme 1,
the reaction of the bipyridine ligand with K2PtCl4 in
acetic acid produced predominantly sp3 C-H activation products, while
in acetonitrile (MeCN) gave selectively sp2 C-H activation products. sp2 C-H activation products can
thermally isomerize to their corresponding sp3 C-H activation products in
acetic acid. This is a classical
example of thermodynamic and kinetic control of reactions.
During the study on the
selective C-H bond
activation, we discovered an unprecedent regiospecific acylation of
cycloplatinated complexes in which the acylation occurs at the metalated carbon
(Organometallics, 2016, 35, 1313-1322). More recently, this process has been developed into
an efficient Pt-catalyzed C-H
acylation reaction (Scheme 2) (Org. Lett. 2017, 19, 1606-1609). This reaction distinguish itself from other
metal-catalyzed acylation reactions by the fact that no oxidant and other
additives are needed and a broader range of acyl groups can be introduced. We
are currently expanding our research in this area by investigating the scope,
limitations, and mechanistic aspects of this reaction and other related
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 many highly efficient phosphorescent
platinum complexes based on tridentate and tetradentate ligands (Scheme 3, Inorg. Chem. 2010, 49, 5107-5119). 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
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
4). A significant finding is the drastic difference in cytotoxicity between
isomeric platinum complexes (N^C^N)PtCl and (C^N^N)PtCl (J.
Inorg. Biochem. 2014, 134, 49-56). The N^C^N-coordinated Pt complex demonstrated
remarkably higher toxicity against a series of human lung cancer cells and a
prostate cancer cell, probably attributed to 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
Book Chapters and Reviews:
- S. Huo,Carboalumination Reactions, In The Chemistry of Organoaluminum Compounds in PATAI’s
Chemistry of Functional Groups, L. Micouin, I. Marek, Z. Rappoport and Eds,
John Wiley and Sons, Chichester, May, 2017, pp. 253- 316
- 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:
Mroz, D. A. K. Vezzu, B. Wallace, D. Ravindrananthan, J. Carroll, R. D. Pike,
S. Huo*. A comparative
study on phosphorescent cycloplatinated complexes based on tridentate
C^N^N-coordinating ligands and phenylethynyl or phenyl ligand. Chin. J.
Org. Chem. 2018,
C. McAteer, E. Javed, L. Huo, and S. Huo* Platinum-catalyzed double acylation of 2-(aryloxy)pyridines via direct C-H activation Org. Lett. 2017, 19, 1606-1609.
- 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" style="">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