Stanford Advisors

  • Yan Xia, Doctoral Dissertation Advisor (AC)

All Publications

  • Synthesis of Cyclobutadienoid-Fused Phenazines with Strongly Modulated Degrees of Antiaromaticity. Organic letters Teo, Y. C., Jin, Z., Xia, Y. 2018; 20 (11): 3300–3304


    The streamlined synthesis of a series of regioisomeric azaacene analogues containing fused phenazine and antiaromatic cyclobutadienoids (CBDs), using a catalytic arene-oxanorbornene annulation, followed by aromatization is reported. Controlling the fusion patterns allowed strong modulation of local antiaromaticity. Enhancing antiaromaticity in these regioisomeric azaacenes led to stabilized LUMO, reduced band gap, and quenched fluorescence. This synthetic strategy provides a facile means to fuse CBDs with variable degrees of antiaromaticity onto N-heteroarenes to tune their optoelectronic properties.

    View details for DOI 10.1021/acs.orglett.8b01190

    View details for PubMedID 29781279

  • Polycyclic conjugated hydrocarbons containing antiaromatic cyclobutadienoids enabled by efficient annulation Xia, Y., Chen, L., Jin, Z., Teo, Y. AMER CHEMICAL SOC. 2017
  • Streamlined Synthesis of Polycyclic Conjugated Hydrocarbons Containing Cyclobutadienoids via C-H Activated Annulation and Aromatization. Journal of the American Chemical Society Jin, Z., Teo, Y. C., Zulaybar, N. G., Smith, M. D., Xia, Y. 2017; 139 (5): 1806-1809


    The juxtaposition of fused cyclobutadienoid (CBD) with benzenoid creates intriguing alternating antiaromatic and aromatic conjugation. Synthetic accessibility of such molecules, however, has been challenging and limited in scope. We report a modular and streamlined synthetic strategy to access a large variety of polycyclic conjugated hydrocarbons with fused CBD. Synthesis was achieved through efficient palladium-catalyzed C-H activated annulation between abundant aryl bromides and oxanorbornenes, followed by aromatization under acidic conditions. The influence of four-membered ring was examined using spectroscopy, crystallography, and computation. This strategy will facilitate exploration on the chemical, structural, and electronic properties of such conjugated systems containing CBD.

    View details for DOI 10.1021/jacs.6b12888

    View details for PubMedID 28125224

  • Regioselective Synthesis of [3]Naphthylenes and Tuning of Their Antiaromaticity. Journal of the American Chemical Society Jin, Z., Teo, Y. C., Teat, S. J., Xia, Y. 2017; 139 (44): 15933–39


    Polycyclic conjugated hydrocarbons containing four-membered cyclobutadienoids (CBDs) are of great fundamental and technical interest due to the antiaromaticity brought by CBD circuits. However, their synthesis has been challenging, hampering the exploration and understanding of such systems. We report efficient synthesis of a series of unprecedented [3]naphthylene regioisomers in high yields, where three naphthalenoids are fused through two CBDs in linear, angular, and bent regioconnectivity. Their synthesis was enabled by exclusively regioselective catalytic arene-norbornene annulation (CANAL) between dibromonaphthalenes and benzooxanorbornadienes, followed by aromatization. [3]Naphthylene regioisomers exhibited distinct optoelectronic properties. Nucleus-independent chemical shift calculations, NMR spectroscopy, and X-ray crystallography revealed the strong effect of the fusion pattern on the local antiaromaticity and aromaticity in fused CBDs and naphthalenoids, respectively. Thus, our synthetic strategy allows facile access to extended CBD-fused π-systems with tunable local antiaromaticity and aromaticity.

    View details for DOI 10.1021/jacs.7b09222

    View details for PubMedID 28956438

  • Efficient Synthesis of Rigid Ladder Polymers via Palladium Catalyzed Annulation. Journal of the American Chemical Society Liu, S., Jin, Z., Teo, Y. C., Xia, Y. 2014; 136 (50): 17434-17437


    We report a new method to synthesize rigid ladder polymers using efficient palladium catalyzed annulation reactions with low catalyst loading (1 mol %). Rigid ladder polymers with benzocyclobutene backbone linkages can be synthesized from copolymerization of readily accessible aryl dibromides and norbornadiene or polymerization of AB type monomers bearing norbornene and aryl bromide or triflate moieties. High molecular weight (10-40 kDa) rigid ladder polymers can be obtained with complete monomer conversions. Diverse monomers also gave different, fixed ladder polymer conformations. The ladder polymers exhibited excellent thermal stability, high carbonization yield, and large intrinsic porosity.

    View details for DOI 10.1021/ja5110415

    View details for PubMedID 25423254

  • A donor-acceptor-donor conjugated molecule: twist intramolecular charge transfer and piezochromic luminescent properties CHEMICAL COMMUNICATIONS Guo, Z., Jin, Z., Wang, J., Pei, J. 2014; 50 (46): 6088-6090


    A donor-acceptor-donor molecule, , showed typical twist intramolecular charge transfer at the excited state and piezochromic property. XRD, DSC and computational researches revealed that the collapse of the crystalline structure upon applying pressure caused the piezochromic phenomenon, while the fluorescence was recovered by heating and solvent fuming.

    View details for DOI 10.1039/c3cc48980a

    View details for Web of Science ID 000336254000002

    View details for PubMedID 24473082

  • T-Shaped Donor-Acceptor Molecules for Low-Loss Red-Emission Optical Waveguide ORGANIC LETTERS Guo, Z., Lei, T., Jin, Z., Wang, J., Pei, J. 2013; 15 (14): 3530-3533


    A series of T-shaped polycyclic molecules with high fluorescence were developed as optical waveguide materials. Their emissions covered almost the whole visible range from 450 to 800 nm. Compound 3-1 showed an optical loss coefficient about 0.29 dB/μm in red-emission waveguide. Our investigations demonstrated that these molecules held great potential for organic optical waveguide due to the high fluorescence quantum efficiency and large Stokes' shift.

    View details for DOI 10.1021/ol4012025

    View details for Web of Science ID 000322210600012

    View details for PubMedID 23819876