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Battery Tackling Fire Hazard, Volume, and Weight Simultaneously
<(From Left) Professor Hye Ryung Byon, Ph.D candidate Rak Hyeon Choi, Professor Chang Yun Son>
Lithium-metal batteries are garnering attention as the next-generation high-energy battery set to replace existing lithium-ion batteries. However, commercialization has been difficult due to the high fire risk associated with using flammable liquid electrolytes. As an alternative to solve this, 'organic solid electrolytes' with flexibility were proposed, but their slow lithium-ion transfer rate at room temperature limited their practical application. Korean researchers have succeeded in developing a solid electrolyte that enhances lithium-ion mobility by 100 times and operates at room temperature.
KAIST announced on November 4th that a research team led by Professor Hye Ryung Byon from KAIST Department of Chemistry, in collaboration with Professor Chang Yun Son's team from Seoul National University, has developed a new organic solid electrolyte film that operates stably even at room temperature.
The research team fabricated a solid electrolyte about 1/5 the thickness of a human hair using a new material called 'Covalent Organic Framework (COF)', which has a porous structure with uniformly arranged holes.
The developed COF electrolyte features a porous crystalline structure similar to the Metal Organic Framework (MOF), which won the 2025 Nobel Prize in Chemistry, but with significantly enhanced chemical stability in the battery operating environment.
The team meticulously arranged lithium-ion transporting functional groups at regular intervals, designing the structure so that lithium ions, which previously only moved at high temperatures, could rapidly move along these functional groups even at room temperature. This implemented a solid electrolyte structure where the lithium-ion migration path can be precisely controlled at the molecular level.
Specifically, the research team introduced a 'dual sulfonated functional group' into the nanopores to facilitate the easy detachment (dissociation) and movement of lithium ions, creating a channel that allows lithium ions to move rapidly along the shortest linear path. Molecular Dynamics (MD) simulations confirmed that this structure lowers the energy required for lithium ion movement, enabling fast migration with less energy and stable operation even at room temperature.
The fabricated electrolyte film is made via a 'Self-assembly' method, resulting in a very smooth surface and uniform structure. Consequently, it adheres perfectly to the lithium metal electrode, allowing ions to move more stably when traveling between electrodes.
<Figure 1. Synthesis process and structural/electrochemical properties of ultrathin covalent organic framework (COF) films according to thickness.(a) Synthesis process of ultrathin COF solid electrolyte, (b) Changes in thickness and surface roughness of COF films according to monomer concentration,(c) Changes in crystallinity of COF solid electrolytes with variations in morphology and thickness, (d) Ionic conductivity characteristics of COF solid electrolytes depending on morphology and thickness,(e) Rate capability of lithium metal–lithium iron phosphate (LiFePO₄) batteries, (f) Cycle life characteristics of lithium metal–lithium iron phosphate batteries >
As a result, the developed electrolyte showed a lithium-ion migration speed 10 to 100 times faster than conventional organic solid electrolytes. When applied to a lithium-iron phosphate battery based on lithium metal, it maintained over 95% of its initial capacity even after 300 charge/discharge cycles, demonstrating high stability with almost no energy loss (Coulombic efficiency of 99.999%).
<Figure 2. Molecular dynamics simulation analysis of the lithium-ion conduction mechanism in the COF solid electrolyte. (a) Lithium-ion (turquoise spheres) conduction pathways through two distinct ionic conduction subchannels within the COF, (b) Two-dimensional free energy landscape of each migration pathway obtained from metadynamics simulations >
Professor Hye Ryung Byon stated, "This research represents a step forward in the commercialization of lithium-metal batteries by realizing an organic solid electrolyte capable of fast lithium-ion migration even at room temperature," adding, "Combining it in a hybrid form with inorganic solid electrolytes could improve interfacial stability issues."
The first author of this research is Rak Hyeon Choi, a graduate student in the KAIST Chemistry Department, and the results were published in the international journal Advanced Energy Materials (October 5, 2025 issue).
Paper Title: Room-Temperature Single Li⁺ Ion Conducting Organic Solid-State Electrolyte with 10⁻⁴ S cm⁻¹ Conductivity for Lithium Metal Batteries, DOI: 10.1002/aenm.202504143
This achievement was supported by LG Energy Solution and KAIST's Frontier Research Laboratory (FRL), as well as the National Research Fou
2025.11.05 View 128 -
KAIST Develops AI That Automatically Designs Optimal Drug Candidates for Cancer-Targeting Mutations
< (From left) Ph.D candidate Wonho Zhung, Ph.D cadidate Joongwon Lee , Prof. Woo Young Kim , Ph.D candidate Jisu Seo >
Traditional drug development methods involve identifying a target protin (e.g., a cancer cell receptor) that causes disease, and then searching through countless molecular candidates (potential drugs) that could bind to that protein and block its function. This process is costly, time-consuming, and has a low success rate. KAIST researchers have developed an AI model that, using only information about the target protein, can design optimal drug candidates without any prior molecular data—opening up new possibilities for drug discovery.
KAIST (President Kwang Hyung Lee) announced on the 10th that a research team led by Professor Woo Youn Kim in the Department of Chemistry has developed an AI model named BInD (Bond and Interaction-generating Diffusion model), which can design and optimize drug candidate molecules tailored to a protein’s structure alone—without needing prior information about binding molecules. The model also predicts the binding mechanism (non-covalent interactions) between the drug and the target protein.
The core innovation of this technology lies in its “simultaneous design” approach. Previous AI models either focused on generating molecules or separately evaluating whether the generated molecule could bind to the target protein. In contrast, this new model considers the binding mechanism between the molecule and the protein during the generation process, enabling comprehensive design in one step. Since it pre-accounts for critical factors in protein-ligand binding, it has a much higher likelihood of generating effective and stable molecules. The generation process visually demonstrates how types and positions of atoms, covalent bonds, and interactions are created simultaneously to fit the protein’s binding site.
<Figure 1. Schematic of the diffusion model developed by the research team, which generates molecular structures and non-covalent interactions based on protein structures. Starting from a noise distribution, the model gradually removes noise (via reverse diffusion) to restore the atom positions, types, covalent bond types, and interaction types, thereby generating molecules. Interacting patterns are extracted from prior knowledge of known binding molecules or proteins, and through an inpainting technique, these patterns are kept fixed during the reverse diffusion process to guide the molecular generation.>
Moreover, this model is designed to meet multiple essential drug design criteria simultaneously—such as target binding affinity, drug-like properties, and structural stability. Traditional models often optimized for only one or two goals at the expense of others, but this new model balances various objectives, significantly enhancing its practical applicability.
The research team explained that the AI operates based on a “diffusion model”—a generative approach where a structure becomes increasingly refined from a random state. This is the same type of model used in AlphaFold 3, the 2024 Nobel Chemistry Prize-winning tool for protein-ligand structure generation, which has already demonstrated high efficiency.
Unlike AlphaFold 3, which provides spatial coordinates for atom positions, this study introduced a knowledge-based guide grounded in actual chemical laws—such as bond lengths and protein-ligand distances—enabling more chemically realistic structure generation.
<Figure 2. (Left) Target protein and the original bound molecule; (Right) Examples of molecules designed using the model developed in this study. The values for protein binding affinity (Vina), drug-likeness (QED), and synthetic accessibility (SA) are shown at the bottom.>
Additionally, the team applied an optimization strategy where outstanding binding patterns from prior results are reused. This allowed the model to generate even better drug candidates without additional training. Notably, the AI successfully produced molecules that selectively bind to the mutated residues of EGFR, a cancer-related target protein.
This study is also meaningful because it advances beyond the team’s previous research, which required prior input about the molecular conditions for the interaction pattern of protein binding.
Professor Woo Youn Kim commented that “the newly developed AI can learn and understand the key features required for strong binding to a target protein, and design optimal drug candidate molecules—even without any prior input. This could significantly shift the paradigm of drug development.” He added, “Since this technology generates molecular structures based on principles of chemical interactions, it is expected to enable faster and more reliable drug development.”
Joongwon Lee and Wonho Zhung, PhD students in the Department of Chemistry, participated as co-first authors of this study. The research results were published in the international journal Advanced Science (IF = 14.1) on July 11.
● Paper Title: BInD: Bond and Interaction-Generating Diffusion Model for Multi-Objective Structure-Based Drug Design
● DOI: 10.1002/advs.202502702
This research was supported by the National Research Foundation of Korea and the Ministry of Health and Welfare.
2025.08.12 View 2496 -
Anti-Neuroinflammatory Natural Products from Isopod-Related Fungus Now Accessible via Chemical Synthesis
<(From left) Professor Sunkyu Han, Ph.D candidate Yoojin Lee, Ph.D candidate Taewan Kim>
"Herpotrichone" is a natural substance that has been evaluated highly for its excellent ability to suppress inflammation in the brain and protect nerve cells, displaying significant potential to be developed as a therapeutic agent for neurodegenerative brain diseases such as Alzheimer's disease and Parkinson's disease. This substance could only be obtained in minute quantities from fungi that are symbiotic with isopods. However, KAIST researchers have succeeded in chemically synthesizing this rare natural product, thereby presenting the possibility for the development of next-generation drugs for neurodegenerative diseases.
*Chemical Synthesis: A process of creating desired substances using chemical reactions.
KAIST (President Kwang Hyung Lee) announced on the 31st of July that a research team led by Professor Sunkyu Han of the Department of Chemistry successfully synthesized the natural anti-neuroinflammatory substances 'herpotrichones A, B, and C' for the first time.
Herpotrichone natural products are substances obtainable only in minute quantities from 'Herpotrichia sp. SF09', a symbiotic pill bug fungus, and possess a unique 6/6/6/6/3 pentacyclic framework consisting of five fused rings (four six-membered and one three-membered ring).
Interestingly, this substance exhibits excellent anti-neuroinflammatory effects that suppress brain inflammatory reactions. Recently, its mechanism of action to protect nerve cells by inhibiting ferroptosis (iron-mediated cell death) was also reported, raising expectations for its potential as a therapeutic drug for brain diseases.
Professor Han's research team devised a biosynthetically inspired strategy to chemically synthesize herpotrichoneS. The key to success was a named chemical reaction "Diels-Alder (DA) reaction". This reaction forms a six-membered ring by creating new bonds between carbon-based partners, much like two puzzle pieces interlocking to form a single ring.
<Figure 2. Key Synthetic Strategy for Hypotricon A, B, and C Based on Hydrogen Bonding>
Furthermore, the research team focused on a weak attractive phenomenon between molecules called "hydrogen bonding". By delicately designing and controlling this hydrogen bond, they were able to precisely induce the reaction to occur chemo-, regio- and stereoselectively, thereby synthesizing herpotrichone. Notably, without the pivotal hydrogen bond, only a small amount of the target natural product was formed or only undesirable byproducts were generated.
The configuration of the C2’ hydroxyl moiety was essential in directing the desired transition states leading to the target natural products.
Thanks to this induced hydrogen bonding, the reacting molecules approached the correct positions and went through an ideal transition state, allowing for the synthesis of herpotrichone C. This reaction principle was also successfully applied to herpotrichone A and B, enabling the successful synthesis of these natural products.
During the key Diels-Alder reaction conducted in the laboratory, new molecular structures not yet discovered in nature were also formed. Some of these have a high probability of being novel natural products with excellent pharmacological activity, thus doubling the significance of this research for anticipating natural products through synthesis.
Indeed, while Professor Han's research team conducted synthetic studies on herpotrichone A and B based on a 2019 paper by Chinese researchers who discovered and elucidated their structures, the research team observed the formation of undesired byproducts.
Interestingly, in 2024, the same Chinese research team that discovered herpotrichones A and bn reported the discovery of a new natural product called herpotrichone C, which turned out to be the same substance as the major byproduct previously obtained by Professor Han's team en route to herpotrichones A and B.
Professor Han stated, "This is the first total synthesis of a rare natural product with pharmacological activity related to neurodegenerative diseases and systematically presents the principle of biomimetic synthesis of complex natural products." He added, "It is expected to contribute to the development of novel natural product-based anti-neuroinflammatory therapeutics and biosynthesis research of this group of natural products."
This research outcome, with Yoojin Lee, a master's and Ph.D. integrated course student in the Department of Chemistry, as the first author, was published on July 16th in the Journal of the American Chemical Society (JACS), one of the most prestigious academic journals in the field of chemistry.
This research was supported by the National Research Foundation of Korea (NRF) Mid-career Researcher Support Program, the KAIST UP Project, the KAIST Grand Challenge 30 Project, and the KAIST Trans-Generational Collaborative Research Laboratory Project.
2025.08.04 View 2061 -
KAIST Designs a New Atomic Catalyst for Air Pollution Reduction
<(From Left)Professor Jong Hun Kim from Inha University, Dr. Gyuho Han and Professor Jeong Young Park from KAIST>
Platinum diselenide (PtSe2) is a two-dimensional multilayer material in which each layer is composed of platinum (Pt) and selenium (Se). It is known that its excellent crystallinity and precise control of interlayer interactions allow modulation of various physical and chemical properties. Due to these characteristics, it has been actively researched in multiple fields, including semiconductors, photodetectors, and electrochemical devices. Now, a research team has proposed a new design concept in which atomically dispersed platinum on the surface of platinum diselenide can function as a catalyst for gas reactions. Through this, they have proven its potential as a next-generation gas-phase catalyst technology for high-efficiency carbon dioxide conversion and carbon monoxide reduction.
KAIST (President Kwang Hyung Lee) announced on July 22 that a joint research team led by Endowed Chair Professor Jeong Young Park from the Department of Chemistry, along with Professor Hyun You Kim's team from Chungnam National University and Professor Yeonwoong (Eric) Jung's team from the University of Central Florida (UCF), has achieved excellent carbon monoxide oxidation performance by utilizing platinum atoms exposed on the surface of platinum diselenide, a type of two-dimensional transition metal dichalcogenide (TMD).
To maximize catalytic performance, the research team designed the catalyst by dispersing platinum atoms uniformly across the surface, departing from the conventional use of bulk platinum. This strategy allows more efficient catalytic reactions using a smaller amount of platinum. It also enhances electronic interactions between platinum and selenium by tuning the surface electronic structure. As a result, the platinum diselenide film with a thickness of a few nanometers showed superior carbon monoxide oxidation performance across the entire temperature range compared to a conventional platinum thin film under identical conditions.
In particular, carbon monoxide and oxygen were evenly adsorbed on the surface in similar proportions, increasing the likelihood that they would encounter each other and react, which significantly enhanced the catalytic activity. This improvement is primarily attributed to the increased exposure of surface platinum atoms resulting from selenium vacancies (Se-vacancies), which provide adsorption sites for gas molecules.
The research team confirmed in real-time that these platinum atoms served as active adsorption sites during the actual reaction process, using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) conducted at the Pohang Accelerator Laboratory. This high-precision analysis was enabled by advanced instrumentation capable of observing surfaces at the nanometer scale under ambient pressure conditions. At the same time, computer simulations based on density functional theory (DFT) demonstrated that platinum diselenide exhibits distinct electronic behavior compared to conventional platinum.
*Density Functional Theory (DFT): A quantum mechanical method for calculating the total energy of a system based on electron density.
Professor Jeong Young Park stated, “This research presents a new design strategy that utilizes platinum diselenide, a two-dimensional layered material distinct from conventional platinum catalysts, to enable catalytic functions optimized for gas-phase reactions.” He added, “The electronic interaction between platinum and selenium created favorable conditions for the balanced adsorption of carbon monoxide and oxygen. By designing the catalyst to exhibit higher reactivity across the entire temperature range than conventional platinum, we improved its practical applicability. This enabled a high-efficiency catalytic reaction mechanism through atomic-level design, a two-dimensional material platform, and precise adsorption control.”
This research was co-authored by Dr. Gyuho Han from the Department of Chemistry at KAIST, Dr. Hyuk Choi from the Department of Materials Science and Engineering at Chungnam National University, and Professor Jong Hun Kim from Inha University. The study was published on July 3 in the world-renowned journal Nature Communications.
Paper Title: Enhanced catalytic activity on atomically dispersed PtSe2 two-dimensional layers
DOI: 10.1038/s41467-025-61320-0
This research was supported by the Mid-Career Researcher Program of the Ministry of Science and ICT, the Core Research Institute Program of the Ministry of Education, the National Strategic Technology Materials Development Project, the U.S. National Science Foundation (NSF) CAREER Program, research funding from Inha University, and the Postdoctoral Researcher Program (P3) at UCF. Accelerator-based analysis was conducted in cooperation with the Pohang Accelerator Laboratory and the Korea Basic Science Institute (KBSI).
2025.07.22 View 2113 -
Distinguished Professor Sukbok Chang Donates His Prize Money
The honoree of the 2019 Korea Best Scientist and Technologist Award, Distinguished Professor Sukbok Chang donated his prize money of one hundred million KRW to the Chemistry Department Scholarship Fund and the Lyu Keun-Chul Sports Complex Management Fund during a donation ceremony last week.
Professor Chang won the award last month in recognition of his pioneering achievements and lifetime contributions to the development of carbon-hydrogen activation strategies, especially for carbon-carbon, carbon-nitrogen, and carbon-oxygen formations. Professor Chang, a world renowned chemist, has been recognized for his highly selective catalytic systems, allowing the controlled defunctionalization of bio-derived platform substrates under mild conditions and opening a new avenue for the utilization of biomass-derived platform chemicals.
“All my achievements are the results of my students’ hard work and dedication. I feel very fortunate to have such talented team members. I want to express my sincere gratitude for such a great research environment that we have worked together in so far,” said Professor Chang at the ceremony.
KAIST President Sung-Chul Shin said, “Not only will Professor Chang’s donation make a significant contribution to the Department of Chemistry, but also to the improvement of the Lyu Keun-Chul Sports Complex’s management, which directly links to the health and welfare of the KAIST community.”
Professor Chang currently holds the position of distinguished professor at KAIST and director of the Center for Catalytic Hydrocarbon Functionalizations in the Institute for Basic Science (IBS). He previously received the Kyung-Ahm Academic Award in 2013 and the Korea Toray Science Award in 2018. All these prize money also went to the school.
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2019.08.26 View 11788 -
New Catalyst for Synthesizing Chiral Molecules Selectively
(from left: Dr. Yoonsu Park and Professor Sukbok Chang from the Department of Chemistry)
Molecules in nature often have “twin” molecules that look identical. In particular, the twin molecules that look like mirror images to each other are called enantiomers. However, even though they have the same type and number of elements, these twin molecules exhibit completely different properties.
Professor Sukbok Chang and Dr. Yoonsu Park from the Department of Chemistry developed a new catalyst capable of selectively synthesizing only one of the two enantiomers. Using this catalyst, the have succeeded in manufacturing the chiral lactam, an essential ingredient in pharmaceuticals, from a hydrocarbon compound.
Enantiomerism or chirality is considered very important for drug development. Biomaterials, such as DNAs and proteins also have chiral properties, but they exhibit different physiological activities depending on the types of drugs. One type of the enantiomer could be useful while the other is toxic. Hence, the technology for selective synthesizing (i.e. asymmetric synthesis) is required, but it is still regarded as a great challenge faced by modern chemistry to date.
The researchers solved this problem by developing a new catalyst. Earlier they presented their research on developing an iridium catalyst that converts hydrocarbons into high value γ-lactam compounds, and published it in Science in March 2018. However, the developed catalyst still had a limitation that both types of enantiomers are obtained without selectivity.
In this study, they found that among dozens of other catalyst candidates, iridium catalysts with chiral diamine scaffolds were able to select the correct enantiomer with a selectivity of 99% or more. This novel catalyst can be used to synthesize the various chiral γ-lactam as required. A left-handed γ-lactam and a right-handed γ-lactam can be produced using a left-handed iridium catalyst and a right-handed iridium catalyst, respectively.
They analyzed the reason for the high selectivity through computational chemistry simulations. They identified that temporal hydrogen bonding occurred between the chiral diamine catalysts and the hydrocarbon compound during the reaction. As a result of the hydrogen bonding, the formation of the left-handed lactam was boosted.
With their new catalyst, they also succeeded in synthesizing chiral lactam compounds with different structures. By using inexpensive and readily available feedstock hydrocarbons, the researchers produced a group of chiral lactams in different shapes. As their chirality and diverse structures enable lactams to function as an active compound in the body for antibiotic, anti-inflammatory, or anti-tumoral functions, this study may facilitate the development of potential drugs in a more efficient and cheaper way.
Professor Chang said, “We hope that our research on selectively producing core units of effective drugs will lead to developing new drugs that demonstrate fewer side-effects and higher efficacy. There are also economic advantages of this research because it uses hydrocarbon compounds, which can be abundantly found in nature, to produce high-value raw materials.
This research was published in Nature Catalysis(10.1038/s41929-019-0230-x) on February 19, 2019.
Figure 1. Asymmetric formation of chiral γ-lactam
Figure 2. Outline of research outcome
2019.03.05 View 9067 -
A Novel Material for Transparent and Flexible Displays
(Research team led by Professor Sang Youl Kim from the Department of Chemistry)
The next generation of flexible and transparent displays will require a high-performing and flexible polymeric material that has the optical and thermal properties of glass. The material must be transparent to visible light and have a low coefficient of thermal expansion (CTE). Unfortunately, such a polymeric material has not been available. A KAIST research team has succeeded in making a new polymeric material with an exceptionally low CTE value while retaining high transparency and excellent thermal and mechanical properties. The method developed for amorphous polymers with a controlled CTE can be applied to control the thermal expansion of organic materials as well.
Most of objects expands upon heating and shrinks by cooling, and organic polymers have a relatively large CTE compared to that of ceramics or metals. Thin, light-weight planar substrates for semiconductor devices should have a similar CTE of ceramics. Otherwise, the device can be cracked due to the stress caused by thermal expansion and contraction. Therefore, matching the CTE of the semiconductor device and the substrate is crucial for successful manufacturing of display devices. Forming a network structure by connecting polymer chains is a well-known method of reducing the CTE of amorphous polymers. However, polymers with a network structure eventually lose their flexibility and becomes brittle.
As an alternative method, Professor Sang Youl Kim from the Department of Chemistry and his team chose to adjust the distance and interaction between polymer chains. Thermal expansion and contraction of polymer films can be minimized by introducing interaction forces between the polymer chains and by arranging the direction of the force perpendicularly. The team successfully implemented this approach by appropriately designing the chemical structure of a transparent polymeric material. It is called poly (amide-imide) film, which is a transparent, flexible, and high-performing polymeric material. It is thermally stable enough to be used in the AMOLED (active-matrix organic light-emitting diode) fabrication process (stable at >400℃) with a low CTE (4ppm/℃).
The team made IGZO TFT (Indium Gallium Zinc Oxide Thin Film Transistor) devices on the newly synthesized transparent poly(amide-imide) film, and confirmed that the device could indeed operate normally even when it is folded down to a radius of 1mm.
Professor Kim said, “Our results suggest a way of controlling the thermal expansion of amorphous polymers similar to a level of glass without chemical cross-linking, which has long been regarded as a challenging problem. At the same time, we succeeded in making the polymer transparent and flexible. We expect that it can be applied to controlling the thermal expansion of various organic materials.”
This research, led by researchers Sun Dal Kim and Byungyoung Lee, was published in Science Advances on October 26. (DOI: 10.1126/sciadv.aau1956v)
2019.01.24 View 8692 -
Novel Strategies to Transform a Commercially Available Iboga Alkaloid to Post-Iboga Alkaloids
(PhD candidate HyeonggeunLim, Professor Sunkyu Han, PhD candidate Sikwang Seong)
KAIST chemists have synthesized seven different iboga and post-iboga natural products from commercially available catharanthine by mirroring nature’s biosynthetic post-modification of the iboga skeleton. They devised a novel strategy to biosynthesize the natural products via a series of selective and efficient oxidation and rearrangement reactions. This will serve as a stepping stone for developing therapeutic medications against cancer and narcotics addiction.
The research team, led by Professor Sunkyu Han, conceptualized and coined the term “Post-Iboga” alkaloids to describe the natural products that are biosynthetically derived from iboga-type alkaloids, which are composed of rearranged indole and/or isoquinuclidine backbones.
Iboga alkaloids have attracted significant attention from the scientific community due to their intriguing polycyclic structures and potential therapeutic uses against drug addictions. Nature has evolved to add architectural repertoires to this family of secondary metabolites by diversifying the iboga frameworks.
Notable examples are the FDA-approved anticancer drugs vinblastine and vincristine, both derived by the oxidative dimerization of catharanthine and vindoline subunits. Admittedly, synthetic foci toward the biosynthetic iboga-derivatives have historically been on these aforementioned dimeric natural products.
Recent natural product isolation studies on Tabernaemontana corymbosa and Ervatamia officinalis species have resulted in discoveries of various secondary metabolites that are biosynthetically derived from iboga alkaloids. These recent outbursts of iboga-derived natural product isolation reports have kindled interests toward these family of natural products.
The research team utilized (+)-catharanthine, the starting material for the industrial production of the anticancer drug Navelbine®. Well-orchestrated oxidations at the C19 position and the indole moiety of the catharanthine derivative, followed by differential rearrangements under acidic conditions, provided synthetic samples of voatinggine and tabertinggine respectively.
On the other hand, opportune oxidations at the C19 position and the alpha position of the tertiary amine moiety of the catharantine derivative, followed by a transhemiaminalization, produced the first synthetic sample of chippiine/dippinine-type natural product, dippinine B.
It is important to note that the chippiine and dippinine-type alkaloids have been targeted among synthetic chemists for over 30 years but had not succumbed to synthesis prior to this report.
Professor Han believes that their study will serve as a blueprint for further explorations of the synthesis, biosynthesis, and pharmacology of this emerging family of natural products. This study was published in Chem on November 15, 2018 (DOI: 10.1016/j.chempr.2018.10.009).
2018.11.16 View 7293 -
Effective Drug Delivery to Heart with Tannic Acid
(Professor Haeshin Lee from the Department of Chemistry) Typical methods of drug delivery to the heart require surgical procedures involving incisions in the chest wall and bones. To efficiently treat cardiovascular and related vascular diseases without surgery, a KAIST research team developed a heart-targeting drug delivery technology using tannin acid via intravenous systemic injection. This method can be applied to the development of a variety of new protein-based drugs.
Cardiovascular-circulatory disease is currently the second leading cause of death in Korea. A typical example of this disease is myocardial infarction caused by poor oxygen and nutrient supply due to narrowed coronary arteries and poor blood flow to the heart.
Although there have been numerous research projects to develop chemotherapeutic drugs and therapeutic proteins, clinics still rely on surgical procedures. Drug delivery can be an alternative, but it is quite challenging because ceaseless dynamic cycles of the heart and massive exchanges of blood mean administered therapeutics do not stay inside the heart very long.
Professor Haeshin Lee from the Department of Chemistry and his team employed tannic acid (TA), which is known for giving bitter taste to wines. It is one of the most abundant polyphenols and can be easily found in plants, such as fruits, vegetables, cacao, and others. TA has also been used as a multifunctional coating molecule.
Using these properties of TA, the team complexed protein and peptide therapeutics with tannic acid and succeeded in targeting protein and peptide therapeutics to the heart. TA, coated on the surface of a granulated protein complex, helps maintain cardiac function because it adheres to extracellular matrices, elastin, and collagens in heart tissues allowing the protein to stay attached to the heart tissue for a longer period.
The team confirmed that these Tannic-acid-modified proteins stay in blood vessels five days longer than with protein-only injections. Additionally they found that TA-protein complexes do not show any cardiac toxicity and do not cause noticeable pathology.
The team has been continuously developing biomaterials for medical applications by testing various polyphenolic materials that feature adhesive and coating properties, including tannic acid. They have injected a mixture of TA and fibroblast growth factors (FGF) into animal models with myocardial infarctions. After four weeks, they confirmed that the infarction was reduced and the left ventricular pressure and cardiac output were almost normalized.
Professor Lee said, “Although there have been numerous drugs related to heart disease, so far there has not been efficient drug delivery to the heart so this technology will be able to reformulate existing drugs into new and more efficient drugs.”
This research, jointly led by Dr. Ki-Suk Kim from the Predictive Model Research Center, was published in Nature Biomedical Engineering on April 30 ( http://www.nature.com/articles/s41551-018-0227-9 ).
Figure 1. Schematic for the heart-targeting mechanism of TANNylated protein nanocomplexes: (1) size-dependent permeation, (2) phenolic (that is, TA), and (3) internalization by internalization by myoblasts
Figure 2. Effect of TA based protein complexes on cardiac cell transport efficiency and viral gene expression efficiency and therapeutic function in animal models with myocardial infarction
2018.09.18 View 6645 -
Visualizing Chemical Reaction on Bimetal Surfaces
Catalysts are the result of many chemists searching to unravel the beauty of molecules and the mystery of chemical reactions. Professor Jeong Young Park from the Department of Chemistry, whose research focuses on catalytic chemical reactions, is no exception. His research team recently made breakthroughs in addressing long-standing questions for understanding reaction mechanisms on bimetal catalysts.
During the studies reported in Science Advances, following a publication in Nature Communications this month, Professor Park’s research team identified that the formation of metal–oxide interfaces is the key factor responsible for the synergistic catalytic effect in bimetal catalysts. The team confirmed this fundamental reaction mechanism through in situ imaging of reaction conditions. This is the first visualization of bimetal surfaces under reaction conditions, signifying the role of metal–oxide interfaces in heterogeneous catalysis.
Bimetallic materials have outstanding catalytic performance, which opens a new pathway for controlling electronic structures and binding energy in catalysts. Despite considerable research on various catalytic reaction efficiencies, there are yet unanswered questions on the underlying principles behind the improved performance. Even more, it was very hard to figure out what led to the efficiency because the structure, chemical composition, and oxidation state of bimetallic materials change according to reaction conditions.
Recently, some research groups suggested that oxide–metal interfacial sites formed by the surface segregation of bimetallic nanoparticles might be responsible for the increased catalytic performance. However, they failed to present any definitive evidence illustrating the physical nature or the fundamental role of the oxide–metal interfaces leading to the improved performance.
To specifically address this challenge, the research team carried out in situ observations of structural modulation on platinum–nickel bimetal catalysts under carbon monoxide oxidation conditions with ambient pressure scanning tunneling microscopy and ambient pressure X-ray photoelectron spectroscopy.
The team observed that platinum–nickel bimetal catalysts exhibited a variety of different structures depending on the gas conditions. Under ultrahigh vacuum conditions, the surface exhibited a platinum skin layer on the platinum–nickel alloyed surface, selective nickel segregation followed by the formation of nickel oxide clusters using oxygen gas, and finally the coexistence of nickel oxide clusters on the platinum skin during carbon monoxide oxidation. The research team found that the formation of interfacial platinum–nickel oxide nanostructures is responsible for a highly efficient step in the carbon monoxide oxidation reaction.
These findings illustrate that the enhancement of the catalytic activity on the bimetallic catalyst surface originates from the thermodynamically efficient reaction pathways at the metal–metal oxide interface, which demonstrates a straightforward process for the strong metal–support interaction effect. The formation of these interfacial metal–metal oxide nanostructures increases catalytic activity while providing a thermodynamically efficient reaction pathway by lowering the heat of the reactions on the surface. [J. Kim et al. Adsorbate-driven reactive interfacial Pt-NiO1-x nanostructure formation on the Pt3Ni(111) alloy surface, Science Advances (DOI: 10.1126/sciadv.aat3151 ]
Professor Park said that one way to monitor catalysts is to detect hot electrons associated with energy dissipation and conversion processes during surface reactions. His team led the real-time detection of hot electrons generated on bimetallic PtCo nanoparticles during exothermic hydrogen oxidation. The team successfully clarified the origin of the synergistic catalytic activity of PtCo nanoparticles with corresponding chemicurrent values.
By estimating the chemicurrent yield, the research team conclude that the catalytic properties of the bimetallic nanoparticles are strongly governed by the oxide–metal interface, which facilitates hot electron transfer. [H. Lee et al. Boosting hot electron flux and catalytic activity at metal–oxide interfaces of PtCo bimetallic nanoparticles, Nature Comm, 9, 2235 (2018)].
Professor Park explained, “We feel that the precise measurement of hot electrons on catalysts gives insight into the mechanism for heterogeneous catalysis, which can help with the smart design of highly reactive materials. The control of catalytic activity via electronic engineering of catalysts is a promising prospect that may open the door to the new field of combining catalysis with electronics, called “catalytronics.” He added that the study also establishes a strategy for improving catalytic activity for catalytic reactions in industrial chemical reactors.
Professors Park and Yousung Jung from the Department of Chemical and Biomolecular Engineering and the Graduate School of EEWS conducted this research in collaboration with Professor Bongjin Mun from the Department of Physics at GIST.
Figure 1. Evolution of surface structures of PtNi bimetal surfaces under various ambient conditions.
Figure 2. Formation of Pt-CoO interface leads to the catalytic enhancement of PtCo bimetal catalysts.
2018.07.25 View 12548 -
Lead-free, Efficient Perovskite for Photovoltaic Cells
(Clockwise from left: Post-doc Researcher Lamjed Debbichi, Master’s Candidate Songju Lee, Professor Min Seok Jang and Professor Hyungjun Kim)
A KAIST research team has proposed a perovskite material, Cs2Au2I6 that serves as a potential active material for highly efficient lead-free thin-film photovoltaic devices. This material is expected to lay the foundation to overcome previously known limitations of perovskite including its stability and toxicity issues.
As strong candidates for next-generation high-efficiency photovoltaic cells, perovskite photovoltaic cells have a maximum photoconversion efficiency of 22%, comparable to high-performance crystalline silicon photovoltaic cells. In addition, perovskite-based cells can be fabricated at low temperatures, thereby bringing about dramatic cost reductions.
However, it has been noted that conventional organic-inorganic hybrid perovskite materials exhibit low stability, eventually degrading their performance and making them unfit for continued use. Moreover, their inclusion of lead has undermined their environmental friendliness.
In light of this, a joint team led by Professor Hyungjun Kim from the KAIST Department of Chemistry and Professor Min Seok Jang from the School of Electrical Engineering has analyzed a previously discovered perovskite material, Cs2Au2I6, consisting of only inorganic substances and investigated its suitability for application in thin-film photovoltaic devices. Theoretical investigations suggests that this new perovskite material is not only as efficient but also more stable and environment friendly compared to the conventional perovskite materials. For this analysis, the team developed multiscale multiphysics simulation frameworks. Atomic-scale first-principle quantum calculations were carried out to study the optical properties of the proposed material, and device-scale electromagnetic simulations were conducted to suggest that the material could indeed serve as a promising photovoltaic substance at the device level.
From this point onward, the research team plans to extend the study in two directions: an empirical study to apply the perovskite material in real-world photovoltaic cells and a theoretical analysis to find the optimal and highly stable material for photovoltaic cells. The team said, “Perovskite materials are highly efficient, but in order to completely replace the conventional solar cells, their stability and toxicity issues must first be resolved.” They added that this research is expected to accelerate related studies in pursuit of high-efficiency, environment-friendly perovskite materials.
This research, led by post-doc researcher Lamjed Debbichi and master’s candidate Songju Lee, was selected as the front cover article of Advanced Materials on March 22.
Figure 1. Cover of Advanced Materials
Figure 2. Schematic of full solar cell device structure
2018.06.08 View 11525 -
Fast-Charging Lithium-Oxygen Batteries
(Professor Hye Ryung Byon)
KAIST researchers have paved the way for fast-charging lithium-oxygen batteries.
Professor Hye Ryung Byon from the Department of Chemistry and Professor Yousung Jung from the Graduate School of EEWS led a joint research team to develop lithium-oxygen batteries exhibiting 80% round-trip efficiency even at high charging rates, solving the problem of existing lithium-oxygen batteries which generally showed drastically lower efficiencies when the charge current rate was increased.
This study exploits the size and shape lithium peroxide, a discharge product, which is known to cause the very problems mentioned above. In doing so, the researchers have lowered the overpotential, which is the difference between the thermodynamic reversible potential and the measured potential, and simultaneously improved battery efficiency. Of particular interest is the fact that these high-performance lithium-oxygen batteries can be realized without costly catalysts.
One remarkable property of lithium-oxygen batteries is that they can accommodate three to five times the energy density of lithium-ion batteries commonly used today. Therefore, lithium-oxygen batteries would render longer driving distance to electric vehicles or drones, which operate on the continued use of electrical power.
However, their weakness lies in that, during charge, the lithium peroxide remains undecomposed at low overpotential, resulting in eventually compromising the battery’s overall performance. This is due to the poor ionic and electrical conductivity of lithium peroxide.
To tackle this issue, the researchers could form one-dimensional amorphous lithium peroxide nanostructures through the use of a mesoporous carbon electrode, CMK-3. When compared against non-mesoporous electrodes, CMK-3 showed exceptionally lower overpotential, thereby enhancing the round-trip efficiency of lithium-oxygen batteries.
The amorphous lithium peroxide produced along the electrode has a small volume and a large surface area contacting electrolyte solution, which is presumably endowed with high conductivity to speed up the charging of the lithium-oxygen batteries.
This research underpins the feasibility of overcoming the fundamental limitations of lithium-oxygen batteries even without the addition of expensive catalytic materials, but rather by the re-configuration of the size and shape of the lithium peroxide.
The findings of this research were published in Nature Communications on February 14.
Figure 1. Transmission electron microscopy (TEM) images
Figure 2. Galvanostatic rate capability
Figure 3. Density functional calculation and Bader charge analysis
2018.05.30 View 12310