Research

2016 – present(PI : Michael S. Strano, MIT)

2D Material Enabled Colloidal Electronic Systems

Two-dimensional-material-enabled nanoelectronic circuits can be grafted onto or embedded within colloidal microparticles coupled to an energy source, creating autonomous and semi-autonomous state machines in particulate form. The resulting devices operate as particulate systems capable of logical computation,^[1] remote sensing, and information storage.^[2]

Syncell3

In this context, we reported two parallel fabrication strategies to construct such colloidal electronic systems. One of them is based on traditional top-down photolithography,^[1] the other one is a bottom-up method we recently introduced as “autoperforation”.^[2] In particular, this “autoperforation” technique utilizes a method of controlled brittle fracture at the nanometer scale as a means of spontaneous assembly of surfaces comprised of 2D electronic materials.

[1]Nature Nanotechnology 2018, 13, 819-827.
[2]Nature Materials 2018, 17, 1005-1012.

2014 – 2016(PI : Michael S. Strano, MIT)

Novel Energy Harvesting Methodologies Based on Low Dimensional Materials

Next‐generation off‐the‐grid electronic systems call for alternative modes of energy harvesting. The wide spectrum of low dimensional carbon materials with exceptional electronic properties provide an ideal platform for electrical energy harvesting across many length scales. We have developed, within the past few years, several mechanistically distinct strategies for electricity generation within the liquid,^[1]^, ^[2] solid,^[3] and vapor^[4] phases, that taps into each pair of unique material-environment interactions.

Syncell3

Energy harvesting from molecular interactions between the environment and the interfacing nanostructured materials has attracted growing scientific attention. The surge in the amount of efforts have boosted the power densities of such devices by orders of magnitude.^[4] The diversity of energy sources and various types of molecular interactions are especially intriguing, as these energy harvesting strategies are considered prime candidates to power next‐generation colloidal nano‐electronic systems, which need to draw energy from all kinds of environments.^[5]

[1]J. Am. Chem. Soc. 2017, 139, 15328-15336.
[2]Energy Environ. Sci. 2016, 9, 1290-1298.
[3]Advanced Materials 2016, 28, 9752-9757.
[4]Advanced Energy Materials 2018, 8, 1802212.
[5]Nature Comm. 2018, 9, 664.

2012 – 2014(PI : Gregory C. Fu, Caltech)

Ni-based Homogeneous Stereo-convergent Reaction Development

Alkylboron compounds are an important family of target molecules, serving as useful intermediates, as well as end points, in fields such as pharmaceutical science and organic chemistry. Facile transformation of carbon-boron bonds into a wide variety of carbon-X bonds (where X is, for example, carbon, nitrogen, oxygen, or a halogen), with stereochemical fidelity, renders the generation of enantioenriched alkylboronate esters a powerful tool in synthesis.

Boron

In this project, we showed that nickel complexes can catalyze asymmetric alkylation of carbon centers adjacent to boron.^[1] This protocol creates chiral alkylboronates that function as stable precursors to numerous complex molecules. The reaction proceeds in stereo-convergent fashion—forming a single product from either mirror image of the α-haloboronate reagent. Successive reactions can also create chains of adjacent chiral alkyl centers with stereochemistry set by the configuration of the ligand bound to nickel.

[1]Science 2016, 354, 1265-1269.

2014 (Jun. – Oct.)(PI : Stacey I. Zones, Chevron)

Computationally Guided Synthesis of SSZ-52: A Zeolite for Engine Exhaust Clean-up

Small-pore cage-based zeolites such as SSZ-13 (CHA) serve as commercial catalysts in several important reactions including the selective catalytic reduction of NOx-species and in the conversion of methanol to light olefins. Structural similarities between SSZ-52 (SFW) and CHA suggest SSZ-52 will be of similar utility in these applications. However, wide usage and manufacture of this unique material has been hindered to-date by the difficulty of its synthesis.

Boron

In fact, the only disclosed method for making SSZ-52 requires use of an organic structure directing agent (SDA) that is highly time intensive to synthesize and therefore cost prohibitive. In this study,^[1] through a combination of de novo design computations and experimental efforts, three alternative SDAs have been identified that are inexpensive and easily synthesized from commercially available reagents.

[1]Chemistry of Materials 2016, 28, 708-711.

2013 – 2014(PI : John H. Seinfeld, Caltech)

Transient Partitioning and Reaction of a Condensing Vapor Species in a Droplet

The general overall atmospheric gas-to-droplet conversion process comprises: (1) gas-phase diffusion from the bulk gas to the surface of a droplet; (2) absorption into the droplet; and (3) simultaneous diffusion and reaction inside the droplet.

Boron

In this study, we solved the exact analytical solution of the transient equation of gas-phase diffusion of a condensing vapor to, and diffusion and reaction in, an aqueous droplet.^[1] Droplet-phase reaction is represented by first-order chemistry. The solution facilitates study of the dynamic nature of the vapor uptake process as a function of droplet size, Henry’s law coefficient, and first-order reaction rate constant for conversion in the droplet phase.

[1]Atmospheric Environment 2014, 89, 651-654.

2010 – 2013(PI : John D. Roberts, Caltech)

Conformational Equilibria of Small Organic Molecules Resolved Using NMR Spectroscopy

Simple 1,2-disubstituted ethane systems (XCH₂CH₂Y), with staggered conformers corresponding to gauche and trans conformational isomers,^[1] can provide insight into the intramolecular forces that stabilize functional groups.

Boron

Specifically, the conformational preferences of N,N-dimethylsuccinamic acid and its Li⁺ salt were estimated by comparing the respective experimental NMR vicinal proton–proton coupling constants to semiempirical coupling constants for each staggered conformer as derived by the Haasnoot–De Leeuw–Altona method.^[2] We then extended this analytical methodology to other chelating molecular systems.^[3]^,^[4]

[1]Mag. Res. Chem. 2013, 51, 701-704.
[2]Organic Letters 2013, 15, 760-763.
[3]J. Phys. Chem. A 2014, 118, 1965-1970.
[4]J. Org. Chem. 2013, 78, 11765-11771.