Xu, Yunjie - University of Alberta - Department of Chemistry

个人简介

BSc in Chemistry and BSc in Mathematics, Xiamen U., China. PhD, UBC, Canada.

研究领域

Chirality and chiral discrimination are essential for living systems and are of fundamental importance in life sciences. Nearly all important biological molecules are chiral. In fact, the chemistry of life is built almost exclusively on L-enantiomers of amino acids and D-sugars, a pattern known as the "homochirality of life". Our research is focused on the spectroscopic and theoretical studies of this class of molecules. The main objective of the research is to obtain a detailed molecular level description of the interaction between chiral molecules. Specifically, we are interested in quantifying how the intermolecular forces come together in a stereo-specific way to enable a chiral molecule to recognize and to discriminate one enantiomer from the other. We use a combination of the molecular beam method with the cavity ring down spectroscopic technique. The molecular beam serves to synthesize and to stabilize the weakly bound homochiral (R·R' or S·S') and heterochiral (R·S' or S·R') diastereomers. The cavity ring down technique provides the ultrahigh sensitivity necessary to detect the infrared spectra of the chiral diastereomers. The state specific quantitative information from the spectra is used to derive structural and dynamical information about the system. These experimental analyses are complemented with high level ab initio calculations to construct the chiral recognition interaction surface and to provide insight into the specific roles of hydrogen-bonded networks and dispersion interactions in chiral discrimination. Another research direction is concerned with the measurements of vibrational circular dichroism spectra of chiral molecules. The experimental work is centered around developing new instruments that are capable of measuring optical properties of chiral molecules in the gas phase. The goal is to explore the link between molecular structure and optical activity and to assess the effects of solvation on optical properties of chiral molecules.

近期论文

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Javix Thomas, Yunjie Xu*, "Structure and tunneling dynamics in a model system of peptide co-solvents: rotational spectroscopy of the 2,2,2-trifluoroethanol••water complex", J. Chem. Phys. 2014, 140, 234307. 30 day free access by JCP DOI: 10.1063/1.4883518. Christian Merten*, Christopher J. Berger, Robert McDonald, Yunjie Xu*, "Unique VCD signatures of dihydrogen bonding of a chiral amine borane complex in solution", Angew. Chem. Int. Ed. 2014, 53, 9940–9943. DOI: 10.1002/anie.201403690. Zahra Dezhahang, Mohammad Reza Poopari, Florencio Eloy Hernández, Carlos Diaz, Yunjie Xu*, "Diastereomeric preference of a triply axial chiral binaphthyl based molecule: a concentration dependent study by chiroptical spectroscopies", Phys. Chem. Chem. Phys. 2014, 16, 12959-12967. DOI:10.1039/c4cp01704h. Javix Thomas, Wolfgang Jäger, Yunjie Xu*, "Chirality induction and amplification in the 2,2,2-Trifluoroethanol••propylene oxide adduct", Angew. Chem. Int. Ed. 2014, 53, 7277–7280. DOI: 10.1002/anie.201403838. Javix Thomas, Yunjie Xu*,"Chirality Synchronization in Trifluoroethanol Dimer Revisited: The Missing Heterochiral Dimer", J. Phys. Chem. Lett. 2014, 5, 1850–1855. DOI: 10.1021/jz500718f. Xunchen Liu, Yunjie Xu*, "New rovibrational bands of the Ar–H2O complex at the mu2 bend region of H2O", J. Mol. Spectrosc. 2014, 301, 1-8. DOI: 10.1016/j.jms.2014.04.005. Christian Merten*, Robert McDonald, Yunjie Xu*, "Strong solvent-dependent preference of delta- and lambda-stereoisomers of a tris(diamine) nickel(II) complex revealed by vibrational circular dichroism spectroscopy", Inorg. Chem. 2014, 53, 3177-3182. DOI: 10.1021/ic4031766. Javix Thomas, Agapito Serrato III, Wei Lin, Wolfgang Jäger, Yunjie Xu*, "Perfluorobutyric acid and its monohydrate: a chirped pulse and cavity based Fourier transform microwave spectroscopic study", Eur. J. Chem. 2014, 20, 6148–6153. DOI: 10.1002/chem.201304321. Christian Merten*, Fee Li, Kenny Bravo-Rodriguez, Elsa Sanchez-Garcia, Yunjie Xu*, Wolfram Sander, "Solvent-induced conformational changes in cyclic peptides: A vibrational circular dichroism study ", Phys. Chem. Chem. Phys. 2014, 16, 5627-5633. DOI: 10.1039/C3CP55018D. Javix Thomas, Oleksandr Sukhorukov, Wolfgang Jäger, Yunjie Xu*, "Direct spectroscopic detection of unique free OH orientation in methyl lactate--(water)1,2 clusters: hydration of a chiral hydroxy ester", Angew. Chem. Int. Ed. 2014, 53, 1156–1159. DOI: 10.1002/anie.201308466. Christian Merten, Julien Bloino, Vincenzo Barone, Yunjie Xu*, "Anharmonicity Effects in the Vibrational CD Spectra of Propylene Oxide", J. Phys. Chem. Lett. 2013, 4, 3424-3428. DOI: 10.1021/jz401854y. Mohammad Reza Poopari, Zahra Dezhahang, Yunjie Xu*, "Identifying dominant conformations of N-acetyl-L-cysteine methyl ester and N-acetyl-L-cysteine in water: VCD signatures of the amide I and the C=O stretching bands", Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2013, pub. online Sep 6, 2013. DOI: 10.1016/j.saa.2013.08.118. (Invited for the Benjamin J. (van der Veken Special Issue). Christian Merten, Yunjie Xu*, "A comparative vibrational CD study of homo- and heteroleptic complexes of the type [Cu(trans-1,2-diaminocyclohexane)2L](ClO4)2", Dalton Trans. 2013, 42, 10572-10578. DOI: 10.1039/C3DT50459J. Javix Thomas, Jensen Yiu, Johannes Rebling, Wolfgang Jäger, Yunjie Xu*, "Chirped-pulse and cavity based Fourier transform microwave spectroscopy of a chiral epoxy ester: methyl glycidate", J. Phys. Chem. A. 2013, 117, 13249-13254. DOI: jp402552t. (Invited for the Terry Miller Special Issue). Javix Thomas, Oleksandr Sukhorukov, Wolfgang Jäger, Yunjie Xu*, "Chirped pulse and cavity based FTMW spectra of the methyl lactate-ammonia adduct: lock and key selectivity and internal rotation motions ", Angew. Chem. Int. Ed. 2013, 52, 4402–4405. DOI: 10.1002/anie.201300707. Zahra Dezhahang, Mohammad Reza Poopari, Yunjie Xu*, "Vibrational circular dichroism spectroscopy of three multidentate nitrogen donor ligands: Conformational flexibility and solvent effects ", Chem. Asian J. 2013, 8, 1205-1212. DOI: 10.1002/anie.201300707. (Featured on the inside cover of June 8 issue). Christian Merten, Yunjie Xu*, "Chirality transfer in the methyl lactate-ammonia complex observed by matrix-isolation vibrational circular dichroism spectroscopy", Angew. Chem. Int. Ed. 2013, 52, 2073–2076. DOI: 10.1002/anie.201300707 (Featured on the backcover of Feb. 11 issue. Graphic by W. Jäger) Fumie X. Sunahori, Guochun Yang, Elena N. Kitova, John S. Klassen, Yunjie Xu*, "Chirality recognition of the protonated serine dimer and octamer by infrared multiphoton dissociation spectroscopy", Phys. Chem. Chem. Phys. 2013, 15, 1873-1886. DOI: 10.1039/C2CP43296J. Mohammad Reza Poopari, Zahra Dezhahang, Yunjie Xu*, "A comparative VCD study of methyl mandelate in methanol, dimethyl sulfoxide, and chloroform: explicit and implicit solvation models", Phys. Chem. Chem. Phys. 2013, 15, 1655-1665. DOI: 10.1039/C2CP42722B. Christian Merten, Myung Ho Hyun, Yunjie Xu*, "Absolute configuration and predominant conformations of a chiral crown ether-based colorimetric sensor: A vibrational circular dichroism spectroscopy and DFT study of chiral recognition", Chirality 2013, 25, 294-300. DOI: 10.1002/chir.22147