Dr Yi-Lin Wu

Publication

• Date
• Type

Research

● Heavy Metal-free Organic Redox Photosensitizer/Photocatalyst
Light-induced chemical transformation is ubiquitous in nature and central to the function of many life processes. In these reactions, sustainable solar power activates substrates to form the high-energy intermediates, leading to novel products or targets degradation that cannot be achieved otherwise. To enable such a possibility under mild conditions, the involvement of a light-absorbing photosensitizer is required. Whilst the traditional choice of photosensitizers has been limited to transition-metal materials, we are developing metal-free organic alternatives based on fundamental quantum chemical considerations. We introduce small functional groups into commercial dyes to bias the orbital orientation and the electron density distribution. This general strategy guarantees fast triplet formation with minimal energy loss from the spin-flipping process, providing photosensitizers tailorable for specific chemical reactions.

● Organic Room-temperature Phosphors
The development of purely organic materials displaying room-temperature phosphorescence (RTP) will expand the toolbox of inorganic phosphors for imaging, sensing or display applications. On the one hand, this challenging task is associated with the low formation yields of phosphorescent triplet states in organic materials; on the other hand, it is deeply rooted in the relatively rapid structural dynamics in the excited molecules, resulting in non-radiative energy dissipations. To address these issues, we introduce functional groups that can facilitate triplet formation and engage in non-covalent interactions simultaneously. The multivalent and directional non-covalent interactions restrict the molecular motions and make the RTP process kinetically favourable. Furthermore, we are interested in identifying the critical molecular motions that need to be suppressed through molecular modelling and structural engineering. Such information will suggest the most efficient strategy to implement non-covalent interactions for excited-state conformation and electronic control.

● Functional Porous Materials
Since the properties of most real-life materials are a function of the degree of molecular aggregation, we exploit the platform of porous architecture to modulate the intermolecular interactions in the condensed phase. The molecular components can be far separated from each other, thus maintaining the monomeric behaviour such as light absorption or chemical reactivity. The components can also be arranged through aromatic stacking. In this situation, new properties emerge due to strong intermolecular interactions; enhanced exciton and electron mobilities or stabilised high-energy intermediates are often observed. Reliable structural tuning between these two extremes is of utmost importance; innovated materials can be expected from molecular assemblies with spatially uniform or gradient structural/compositional features. Additionally, we are particularly interested in developing methods to create crystalline porous solids through non-covalent chemistry or amorphous polymers with intrinsically non-planar and non-stackable backbones. Such methodologies allow for the ease of mass production and recyclability of these materials. 

● New Reaction Development and Mechanistic Investigation
Organic sulfur compounds have long been postulated as the key to link the inorganic (H2S, SO2 and iron-sulfur clusters) and organic chemistry from the prebiotic era, with which Nature accomplishes complex syntheses and metabolism known to date. Their versatility originates from the moderate bond energy and rich redox states in these chemicals. They can thus serve as the catalysts or mediators to facilitate efficient transformations that are otherwise difficult to achieve. With strong connections to our other research programs, we are interested in developing bond-formation methods involving, but not limited to, thiocarbonyl, thioester and thioamide functionalities. We apply these methods for novel chromophore synthesis, efficient polymerisation and bioorthogonal conjugation with a clear mechanistic understanding of these reactions.

Biography

Yi-Lin was born in Taipei and received his B.S. in Chemistry from National Taiwan University (2005) under the tutelage of Professor Tien-Yau Luh. After the military service, he moved to Switzerland to pursue his M.Sc. (2008) and Ph.D. (2012) degrees at ETH Zürich with Professor François Diederich. At ETH, he was involved in a wide range of physical organic projects ranging from the mechanistic investigation of click-type syntheses to photo-switchable systems for cholesteric liquid crystal induction. His graduate work was recognized by the Excellence Scholarship of ETH Zurich, Novartis M.Sc. Fellowship, and the Scholarship Fund of the Swiss Chemical Industry.

Following his Ph.D., he was awarded the Swiss National Science Foundation (SNF) Fellowship to start his postdoctoral research (2012) in the group of Professor Michael Wasielewski at Northwestern University, where he was subsequently promoted as the Research Assistant Professor (2014) and Research Associate Professor (2017) in Chemistry. At Northwestern, he took the synthetic and spectroscopic approaches simultaneously to interrogate the interplay between the self-assembly nanostructures and excited-state electron/spin/energy dynamics of biology- and photovoltaics-relevant materials.

Yi-Lin took the post of Lecturer in Materials Chemistry at Cardiff University in January 2019.

Appointment:

2019–present: Lecturer in Materials Chemistry, Cardiff University
2017–2018: Research Associate Professor, Northwestern University
2014–2017: Research Assistant Professor, Northwestern University

Education and Training:

2012−2013: SNF Postdoctoral Fellow, Northwestern University (with Prof. M. R. Wasielewski)
2008–2012: Ph.D. in Chemistry, ETH Zurich (with Prof. F. Diederich)
2007–2008: M.Sc. in Chemistry, ETH Zurich (with Prof. F. Diederich)
2002–2005: B.S. in Chemistry, National Taiwan University (with Prof. T.-Y. Luh)