Shouquan Huo

Associate Professor,
Inorganic and Organic Chemistry

Office: SZ 543
Phone: 252-328-9784
E-mail: huos@ecu.edu

• Senior Scientist (2003), Principal Scientist (2006), Eastman Kodak Company
• Senior Research Chemist, DSM Pharmaceuticals, Inc (2002
• Postdoctoral associate, Purdue University (1998)
• COE (Center of Excellence) Research Fellow, Hokkaido University, Japan (1996)
• Visiting Scientist, Institute for Molecular Sciences, Japan (1995)
• NNSF Postdoctoral fellow, Shanghai Institute of Organic Chemistry, China (1994)
• Ph.D. Chemistry, Nanjing University, China (1994)
• BS/MS Zhengzhou University, China (1988,1991)

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.

Organometallic 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.

Scheme 1

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 reactions.

Scheme 2

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 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 applications.

Scheme 3

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 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 applications.

Scheme 4

Book and Book Chapters

1. S. Huo and Yumin Li
   Phosphorescent Materials
   In The ACS In Focus Series, American Chemical Society, May, 2023.
2. S. Huo and Yumin Li
   Pt-Catalyzed C-C Bond Formation through C-H Functionalization
   In Handbook of C-H Functionalization, Maiti (Ed.). Wiley-VCH, October 1^st, 2022, published online, https://doi.org/10.1002/9783527834242.chf0096.
3. S. Huo and Yumin Li
   Pt-Catalyzed C-X (X=O, B, Si, Cl) Bond Formation through C-H Functionalization
   In Handbook of C-H Functionalization, Maiti (Ed.). Wiley-VCH, October 2^nd, 2022, published online, https://doi.org/10.1002/9783527834242.chf0095
4. 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.
5. S. Huo and E. 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, pp. 335-408.
6. E. Negishi and S. Huo
   Synthesis and Reactivity of Zirconocene Derivatives
   In Titanium and Zirconium in Organic Synthesis, Chapter 1, Marek, I., Ed., Wiley-VCH, 2002, pp. 1-49.
7. E. Negishi and S. Huo
   (-)-dichlorobis[(1,2,3,3a,7a-e)-1-[(1S,2S,5R)-5-methyl-2-(1-methylethyl)]cyclohexyl-1H-inden-1-yl]zirconium and its (+)-(1R,2R,5S)-isomer
   In e-EROS Electronic Encyclopedia of Reagents for Organic Synthesis, Paquette, L., Rigby, J., Roush, W., and Wipf, P., Ed., John Wiley & Sons, Inc., New York, 2001

Review Articles

1. S. Huo
   Platinum in Chemistry. An adventure from phosphorescent materials to catalytic C-H functionalization.
   The Chemical Record, invited personal account, 2018, 18, 1583-1595.
2. S. Huo, J. Carroll, and D. A. K. Vezzu
   Design, synthesis, and applications of highly phosphorescent cyclometalated platinum complexes
   Asian J. Org. Chem. 2015, 4, 1210-1245. Focus Review.
3. S. Huo, R. Mroz, and J. Carroll
   Negishi coupling in the synthesis of advanced electronic, optical, electrochemical, and magnetic materials
   Org. Chem. Frontiers. 2015, 2, 416-445.
4. E. Negishi and S. 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.
5. Y. Wu, S. Huo, J. Gong, X. Cui, L. Ding, K. Ding, C. Du, Y. Liu, and M. Song
   Studies on Cyclometallation of Ferrocenylimines
   J. Organomet. Chem. 2001, 637-639, 27-46. Invited review

Original Research Articles

1. A. Barham, J. Neu, C. L. Canter, R. D. Pike, Y. Li, S. Huo*
   Isomerization-Induced Multiple Reaction Pathways in Platinum-Catalyzed C−H Acylation Reaction of 2‑Aryloxypyridines.
   Organometallics 2021, 40, 3158-3169.

2. E. Warden, L. Bartolotti, S. Huo,* Y. Li*
   Theoretical Probe to the Mechanism of Pt-Catalyzed C−H Acylation Reaction: Possible Pathways for the Acylation Reaction of a Platinacycle.
   Inorg. Chem. 2020, 59, 555−562.

3. E. Javed, J. D. Guthrie, J. Neu, G. S. Chirayath, S. Huo*
   Introducing an α‑Keto Ester Functional Group through Pt-Catalyzed Direct C−H Acylation with Ethyl Chlorooxoacetate.
   ACS Omega 2020, 5, 8393−8402.

4. B. J. Aguilar, Y. Zhao, H. Zhou, S. Huo, Y.-H. Chen, Qun. Lu*
   Inhibition of Cdc42-​intersectin interaction by small molecule ZCL367 impedes cancer cell cycle progression, proliferation, migration, and tumor growth.
   Cancer Biology & Therapy. 2019, 20, 740-749.

5. R. 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, 38, 171-182.

6. D. 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.

7. J. Carroll, H. G. Woolard, R. Mroz, C. A. Nason, S. Huo*
   Regiospecific acylation of cycloplatinated complexes. Scope, limitations, and mechanistic implications
   Organometallics, 2016, 35, 1313-1322.

8. Y. Li*, J. Carroll, B. Simpkins, D. Ravindranathan, C. M. Boyd, and S. 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.
9. D. A. K. Vezzu, Q. Lu, Y.-H. Chen,* and S. Huo*
   Cytotoxicity of cyclometalated platinum complexes based on tridentate NCN and CNN-coordinating ligands: Remarkable coordination dependence
   J. Inorg. Biochem. 2014, 134, 49-56.
10. J. Carroll, J. P. Gagnier, A. W. Garner, J. G. Moots, R. D. Pike, Y. Li, and S. 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.

11. C. F. Harris, D. A. K. Vezzu, L. Bartolotti, P. D. Boyle, and S. 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.

12. S. Huo*, C. F. Harris, D. A. K. Vezzu, J. P. Gagnier, M. E. Smith, R. D. Pike,  and Y. Li
    Novel phosphorescent tetradentate bis-cyclometallated C^C*N^N-coordinated platinum complexes: Structure, photophysics, and a synthetic adventure
    Polyhedron  2013, 52, 1030-1040. Werner special issue.

13. C. F. Harris, D. Ravindranathan, and S. Huo*
    Oxidative addition of heteroaromatic halides to Negishi reagent and subsequent cross-coupling reactions
    Tetrahedron Lett. 2012, 53, 5389-5392.

14. D. A.K. Vezzu, D. Ravindranathan, A.W. Garner, L. Bartolotti, M. E. Smith, P.D. Boyle, and S. Huo*
    Highly luminescent tridentate N^C*N platinum(II) complexes featured in fused five-six-membered metallacycle and diminishing concentration quenching
    Inorg. Chem. 2011, 50, 8261-8273.

15. G. Zhang, L. Ding, R. Reneger, X. Wang, Q. Lu, S. Huo, and Y.-H. Chen*
    Hydroxycamptothecin-loaded Fe3O4 nanoparticles induce human lung cancer cell apoptosis through caspase-8 pathway activation and disrupt tight junctions
    Cancer Sci. 2011, 102, 1216-1222.

16. A. W. Garner, C. F. Harris, D. A. K. Vezzu, R. D. Pike, and S. Huo*
    Solvent-controlled switch of selectivity between sp² and sp³ C-H bond activation by platinum (II)
    Chem. Commun. 2011, 47, 1902-1904.

17. J. C. Deaton*, R. H. Young, J. R. Lenhard, M. Rajeswaran, and S. Huo*
    Photophysical properties of the series fac- and mer-(1-phenylisoquinolinato-N^C^2¢)_x(2-phenylpyridinato-N^C^2¢)_3-xIridium(III) (x = 1 to 3)
    Inorg. Chem. 2010, 49, 9151-9161.

18. D. Ravindranathan, D. A. K. Vezzu, L. Bartolotti, P. D. Boyle, and S. Huo*
    Improvement in phosphorescence efficiency through tuning of coordination geometry of tridentate cyclometalated platinum (II) complexes
    Inorg. Chem. 2010, 49, 8922-8928.

19. D. A. K. Vezzu, J. C. Deaton, J. S. Jones, L. Bartolotti, C. F. Harris, A. P. Marchetti, M. Kondakova, R. D. Pike,  and S. Huo*
    Highly luminescent tetradentate bis-cyclometalated platinum complexes: Design, synthesis, structure, photophysics, and electroluminescence application
    Inorg. Chem. 2010, 49, 5107-5119.

20. D. A. K. Vezzu, J. C. Deaton, M. Shayeghi, Y. Li and S. Huo*
    Acridinone/amine(carbazole)-based bipolar molecules: Efficient Hosts for fluorescent and phosphorescent emitters
    Org. Lett. 2009, 11, 4310-4313.

21. M. Rajeswaran, W. J. Begley, L. P. Olson, and S. Huo
    Steric effects of substituted quinolines on lithium coordination geometry
    Polyhedron 2007, 26, 3653-3660.

22. J. C. Deaton, S. Huo, B. Lussier, C. T. Brown, J. C. Garnett, D. B. Blondell, and M. 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.

23. S. Huo,* J. C. Deaton, M. Rajeswaran, and W. 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.

24. Z. Tan, B. Liang, S. Huo, J. Shi, E. Negishi
    Zirconium-catalyzed asymmetric carboalumination (ZACA reaction) of 1,4-dienes
    Tetrahedron: Asymmetry  2006,  17(4),  512-515.

25. S. Huo*
    Highly efficient, general procedure for the preparation of alkylzinc reagents from unactivated alkyl bromides and chlorides
    Org. Lett. 2003, 5, 423-425.

26. S. Huo, J. Shi, and E. Negishi
    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.
27. T. Takahashi, M. Ishikawa, and S. 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.
28. E. Negishi, S. Liu, C. Xu, and S. Huo
    A novel, highly selective, and general methodology for the synthesis of 1,5-diene containing oligoisopenoids of all possible geometrical combinations exemplified by an efficient synthesis of coenzyme Q₁₀
    Org. Lett. 2002, 4, 261-264.

29. S. Huo and E. 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.
30. K. Sato, Y. Nishihara, S. Huo, Z. Xi, and T. Takahashi
    Preparation and reaction of monocyclic bis(cyclopentadienyl)titanacyclopentenes and –pentadienes
    J. Organomet. Chem. 2001, 633, 18.
31. Takahashi, Y. Liu, C. Xi, and S. Huo
    Grignard reagent mediated reaction of Cp₂Zr(II)-ethylene complex with imines
    Chem. Commun. 2001, 1(1), 31-32.
32. R. Hara, Y. Ura, S. Huo, K. Kasai, N. Suzuki, and T. Takahashi
    Allene formation by coupling of propargylic ethers with olefins via b-alkoxide elimination of zirconacycle intermediates
    Inorg. Chim. Acta 2000, 300-302, 741-748.

33. Z. Xi, S. Huo, Y. Noguchi, and T. Takahashi
    Formation of zirconacyclohexadienes from zirconacyclopentadienes and LiCHClSiR₃
    Chem. Lett. 2000, 218.
34. E. Negishi, S. Liu, C. Xu, and S. Huo
    A general method for the synthesis of E and/or Z oligoisoprenoids based on Pd-catalyzed homoallyl-alkenyl and homopropargyl-alkenyl cross coupling and Zr-catalyzed carboalumination
    Polyhedron 2000, 19, 592.
35. T. Takahashi, S. Huo, R. Hara, Y. Noguchi, K. Nakajima, and W. 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.
36. B. Ji, Y. Shen, Y. Wu, K. Ding, and S. Huo
    The molecular and crystal structure of an inclusion compound formed between acetylferrocence pyridine-2,6-diformylhydrazone and ethanol
    Jiegou Huaxue 1998, 17, 319-324.
37. T Takahashi, Z. Xi, R. Fischer, S. Huo, C. Xi, and K. Nakajima
    Intermolecular coupling reaction of alkynes with vinyl bromide with selective skeletal rearrangement
    J. Am. Chem. Soc. 1997, 119, 4561.
38. C. Xi, S. Huo, T. Afifi, R. Hara, and T. Takahashi
    Remarkable effect of copper chloride on diiodination of zirconacyclopentadienes
    Tetrahedron Lett. 1997, 38, 4099.
39. T. Takahashi, Y. Nishihara, S. Huo, and M. Kotora
    Highly regio- and distereoselective allylation and benzolation of zirconacyclopentane using copper salt
    Chem. Commun. 1997, 1599-1600.
40. T. Takahashi, Z. Xi, Y. Nishihara, S. Huo, K. Kasai, K. Aoyagi, V. Denisor, and E. Negishi
    Convenient preparative method of a, b-disubstituted cyclopentenone by zirconium promoted intermolecular coupling of an alkyne, EtMgBr or ethylene, and CO
    Tetrahedron  1997, 53, 9123.
41. Y. Nishihara, T. Ishida, S. Huo, and T. Takahashi
    Preparation and reactions of Cp₂HfRCl, Cp₂HfRR’ and hafnacyclopent-2-enes
    J. Organomet. Chem. 1997, 547, 209-216.
42. T. Takahashi, R. Hara, S. Huo, Y. Ura, M. P. Leese, and N. Suzuki
    Allene formation by the reaction of olefins with propargyl silyl ethers mediated by a zirconocene complex
    Tetrahedron Lett. 1997, 38, 8723.
43. Y. Liu, Y. Wu, S. Huo, and H. Z. Yuan
    Symmetrization reaction of mercurated ferrocenylimines. X-ray crystal structure of [Hg{(h⁵-C₅H₅)Fe(h⁵-C₅H₃CPh=NC₆H₄-4-Br)}₂]
    J. Organomet. Chem. 1997, 534, 7-13.
44. Y. Liu, Z. Yu, S. Huo, and Y. Wu
    IR and chromatographic features of ferrocenylimines and their mercurated derivatives
    Gaodeng Xuexiao Huaxue Xuebao 1996, 17, 901-905.
45. Y. Wu, S. Huo, and H. Yuan
    Secondary interaction and n-p conjugation in ferrocenylimine derivatives of mercury as probed by Hg-199 resonance
    Main Group Chemistry, 1996, 1, 253-256.
46. Y. Wu, S. Huo, L. Yang, and C. Du
    Carbon-13 NMR spectra of cyclomercurated ferrocenylimines: Substituent effects and conformations in the ferrocenes
    J. Organomet. Chem. 1995, 490, 249-254.
47. S. Huo, Y. Zhu, and Y. Wu
    Crystal structures of anil of benzoylferrocene and its derivatives of mercury: Specific arrangement of the ferroceny and phenyl groups around the C=N bond
    J. Organomet. Chem. 1995, 490, 243-247.
48. Y. Wu, S. Huo, and Y. Zhu
    Crystal and molecular structure of [1-[(4-chlorophenyl)imino]ethyl]ferrocene and a structural comparison with Its cyclometallated derivatives
    J. Organomet. Chem. 1995, 485, 161-164.
49. S. Huo, Y. Wu, X. Mao, and H. Yuan
    Synthesis and mercuration of anils of benzoylferrocene
    Tetrahedron 1994, 50, 10467-10476.
50. S. Huo, Y. Wu, C. Du, Y. Zhu, H. Yuan, and X. Mao
    Synthesis, characterization and structure of cyclopalladated ferrocenylketimines
    J. Organomet. Chem. 1994, 483, 139-146.
51. Y. Wu, S. Huo, Y. Zhu, and L. Yang
    Studies on the cyclomercuration of [1-(arylimino)ethyl]ferrocenes and related structure-reactivity relationship
    J. Organomet. Chem. 1994, 481, 235-242.
52. Y. Wu, S. Huo, and Z. Yu
    Studies on the synthesis of heteroannularly substituted ferrocenesYuji Huaxue (Chinese J. Org. Chem.)  1994, 46, 38-43.

US Patents and Patent Applications