Professional Education


  • Bachelor of Science, Zhejiang Institute Of Technology (2009)
  • Doctor of Philosophy, Zhejiang University (2014)

Stanford Advisors


All Publications


  • Quadruple H-Bonding Cross-Linked Supramolecular Polymeric Materials as Substrates for Stretchable, Antitearing, and Self-Healable Thin Film Electrodes JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Yan, X., Liu, Z., Zhang, Q., Lopez, J., Wang, H., Wu, H., Niu, S., Yan, H., Wang, S., Lei, T., Li, J., Qi, D., Huang, P., Huang, J., Zhang, Y., Wang, Y., Li, G., Tok, J., Chen, X., Bao, Z. 2018; 140 (15): 5280–89

    Abstract

    Herein, we report a de novo chemical design of supramolecular polymer materials (SPMs-1-3) by condensation polymerization, consisting of (i) soft polymeric chains (polytetramethylene glycol and tetraethylene glycol) and (ii) strong and reversible quadruple H-bonding cross-linkers (from 0 to 30 mol %). The former contributes to the formation of the soft domain of the SPMs, and the latter furnishes the SPMs with desirable mechanical properties, thereby producing soft, stretchable, yet tough elastomers. The resulting SPM-2 was observed to be highly stretchable (up to 17 000% strain), tough (fracture energy ∼30 000 J/m2), and self-healing, which are highly desirable properties and are superior to previously reported elastomers and tough hydrogels. Furthermore, a gold, thin film electrode deposited on this SPM substrate retains its conductivity and combines high stretchability (∼400%), fracture/notch insensitivity, self-healing, and good interfacial adhesion with the gold film. Again, these properties are all highly complementary to commonly used polydimethylsiloxane-based thin film metal electrodes. Last, we proceed to demonstrate the practical utility of our fabricated electrode via both in vivo and in vitro measurements of electromyography signals. This fundamental understanding obtained from the investigation of these SPMs will facilitate the progress of intelligent soft materials and flexible electronics.

    View details for DOI 10.1021/jacs.8b01682

    View details for Web of Science ID 000430642000052

    View details for PubMedID 29595956

  • Near-Infrared-Emissive Self-assembled Polymers via the Implementation of Molecular Tweezer/Guest Complexation on a Supramolecular Coordination Complex Platform CHINESE JOURNAL OF POLYMER SCIENCE Gao, Z., Wei, C., Han, Y., Yuan, M., Yan, X., Wang, F. 2018; 36 (3): 399–405
  • Universal Selective Dispersion of Semiconducting Carbon Nanotubes from Commercial Sources Using a Supramolecular Polymer. ACS nano Chortos, A., Pochorovski, I., Lin, P., Pitner, G., Yan, X., Gao, T. Z., To, J. W., Lei, T., Will, J. W., Wong, H. P., Bao, Z. 2017

    Abstract

    Selective extraction of semiconducting carbon nanotubes is a key step in the production of high-performance, solution-processed electronics. Here, we describe the ability of a supramolecular sorting polymer to selectively disperse semiconducting carbon nanotubes from five commercial sources with diameters ranging from 0.7 to 2.2 nm. The sorting purity of the largest-diameter nanotubes (1.4 to 2.2 nm; from Tuball) was confirmed by short channel measurements to be 97.5%. Removing the sorting polymer by acid-induced disassembly increased the transistor mobility by 94 and 24% for medium-diameter and large-diameter carbon nanotubes, respectively. Among the tested single-walled nanotube sources, the highest transistor performance of 61 cm(2)/V·s and on/off ratio >10(4) were realized with arc discharge carbon nanotubes with a diameter range from 1.2 to 1.7 nm. The length and quality of nanotubes sorted from different sources is compared using measurements from atomic force microscopy and Raman spectroscopy. The transistor mobility is found to correlate with the G/D ratio extracted from the Raman spectra.

    View details for DOI 10.1021/acsnano.7b01076

    View details for PubMedID 28528552

  • Photophysical Properties of Organoplatinum(II) Compounds and Derived Self-Assembled Metallacycles and Metallacages: Fluorescence and its Applications. Accounts of chemical research Saha, M. L., Yan, X., Stang, P. J. 2016: -?

    Abstract

    Over the past couple of decades, coordination-driven self-assembly has evolved as a broad multidisciplinary domain that not only covers the syntheses of aesthetically pleasing supramolecular architectures but also emerges as a method to form new optical materials, chemical sensors, theranostic agents, and compounds with light-harvesting and emissive properties. The majority of these applications depend upon investigations that reveal the photophysical nature and electronic structure of supramolecular coordination complexes (SCCs), including two-dimensional (2D) metallacycles and three-dimensional (3D) metallacages. As such, well-defined absorption and emission spectra are important for a given SCC to be used for sensing, bioimaging, and other applications with molecular fluorescence being an important component. In this Account, we summarize the photophysical properties of some bis(phosphine)organoplatinum(II) compounds and their discrete SCCs. The platinum(II) based organometallic precursors typically display spectral red-shifts and have low fluorescence quantum yields and short fluorescence lifetimes compared to their organic counterparts because the introduction of metal centers enhances both intersystem crossing (ISC) and intramolecular charge transfer (ICT) processes, which can compete with the fluorescence emissions. Likewise ligands with conjugation can also increase the ICT process; hence the corresponding organoplatinum(II) compounds undergo a further decrease in fluorescence lifetimes. The use of endohedral amine functionalized 120°-bispyridyl ligands can dramatically enhance the emission properties of the resultant organoplatinum(II) based SCCs. As such these SCCs display emissions in the visible region (ca. 400-500 nm) and are significantly red-shifted (ca. 80-100 nm) compared to the ligands. This key feature makes them suitable as supramolecular theranostic agents wherein these unique emission properties provide diagnostic spectroscopic handles and the organoplatinum(II) centers act as potential anticancer agents. Using steady state and time-resolved-spectroscopic techniques and quantum computations in concert, we have determined that the emissive properties stem from the ligand-centered transitions involving π-type molecular orbitals with modest contributions from the metal-based orbitals. The self-assembly and the photophysics of organoplatinum(II) ← 3-substituted pyridyl based SCCs are highly diverse. Subtle changes in the ligands' structures can form molecular congener systems with distinct conformational and photophysical properties. Furthermore, the heterometallic SCCs described herein possess rich photophysical properties and can be used for sensing based applications. Tetraphenylethylene (TPE) based SCCs display emissions in the aggregated state as well as in dilute solutions. This is a unique phenomenon that bridges the aggregation caused quenching (ACQ) and aggregation induced emission (AIE) effects. Moreover, a TPE based metallacage exhibits solvatoluminescence, including white light emission in THF solvent, and can act as a fluorescence-sensor for structurally similar ester compounds.

    View details for PubMedID 27736060

  • Immobilizing Tetraphenylethylene into Fused Metallacycles: Shape Effects on Fluorescence Emission JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Zhou, Z., Yan, X., Saha, M. L., Zhang, M., Wang, M., Li, X., Stang, P. J. 2016; 138 (40): 13131-13134

    Abstract

    Herein, we describe the selective formation of a discrete fused metallarhomboid and a triangle by the careful control of the shape and stoichiometry of the building blocks. A tetraphenylethylene (TPE)-based tetrapyridyl donor is exploited as the bridging component, and coordination immobilization of the TPE unit within the rigid metallacyclic frameworks efficiently suppresses its intramolecular rotational motions. As a result, the fused polygons are innately emissive in dilute solution, representing an alternative to aggregation-induced emission. Upon further molecular aggregation, these metallacycles display aggregation-induced enhanced emissions. Interestingly, the fused rhomboid 7 shows a weaker fluorescence in dilute solutions relative to that of the fused triangle 8, while a reversal of emission intensities was observed in the aggregated state. These markedly different fluorescence efficiencies are likely due to the differences in the shapes of the fused polygons. Thus, this work shows that the properties of supramolecular coordination complexes can be affected by subtle structural factors, which can be controlled easily and precisely at the molecular level.

    View details for DOI 10.1021/jacs.6b07173

    View details for Web of Science ID 000385469600009

    View details for PubMedID 27672700