The Physicochemical Science Group of Asahi Laboratory consists of two subgroups: the "Physical Chemistry Group" and the "Electrochemistry Group." The Physical Chemistry Group focuses on research into the "chirality of materials in the solid state," while the Electrochemistry Group centers on "biosensor, chemical sensor, and optical device applications using conductive mesoporous thin films."
The main laboratory (2nd and 3rd floors) and student rooms (3rd floor) are Tokyo Women's Medical University and Waseda University Joint Institution for Advanced Biomedical Sciences (TWIns, Building No. 50), Waseda University. Research is conducted by making effective use of facilities both on campus — including the Material Characterization Central Laboratory (Building No. 55, B1F), the Nanotechnology Research Center (Building No. 121, 2F), and the Kagami Memorial Research Institute for Materials Science and Technology (Building No. 42) — and off campus at institutions such as the National Institute for Materials Science (NIMS) and the National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba, Ibaraki. We also actively engage in collaborative research with universities and research institutions both domestically and internationally, as well as with private companies, with a view toward contributing our research results to society.
We introduce below some of the research conducted in our group. The Physicochemical Science Group of Asahi Laboratory also accepts master's and doctoral students from other universities. Those interested are encouraged to contact Professor Asahi (tasahi at waseda.jp).
【Physical Chemistry Group】
The left-right asymmetry that pervades nature — known as "chirality" — raises many profound questions for humanity. For example, amino acids exist as two mirror-image forms (D- and L-enantiomers), yet proteins in living organisms contain only the L-form. Similarly, while sugars also have mirror-image forms, the sugars found in DNA consist exclusively of the D-form. This phenomenon is known as the homochirality of life, and the question of why life is built using L-amino acids and D-sugars remains an unsolved mystery closely tied to the origin of life itself. For this reason, it is important to know the chirality of compounds — such as pharmaceuticals, seasonings, sweeteners, and fragrances — that act on homochiral biological systems.
The Physical Chemistry Group of Asahi Laboratory focuses primarily on research into the "chirality of chiral materials in the solid state." Our group has developed a unique spectroscopic instrument capable of measuring chiroptical properties in the solid state — the Generalized-High Accuracy Universal Polarimeter (G-HAUP) — and uses it to approach the "mysteries" of chirality in solid-state organic and inorganic chiral materials from a uniquely original perspective.
Research Topics
① Physicochemical Study of the Chiral Drug Thalidomide
Thalidomide, a representative chiral drug, was marketed as an analgesic and sedative, but was withdrawn after severe teratogenic side effects were reported in pregnant women. In recent years, however, thalidomide has regained attention as its therapeutic efficacy against several intractable diseases — including Hansen's disease and multiple myeloma — has been reported, leading to renewed market approval.
The pharmacological effects of thalidomide differ markedly depending on its chirality. Furthermore, since the chirality of thalidomide can invert under certain conditions, it is essential from a safety standpoint to evaluate under what conditions chiral inversion occurs. Despite the fact that thalidomide is sold and consumed in the solid state, almost all research on its chirality has been conducted in solution; solid-state studies are extremely rare.
In this research, we use the G-HAUP — an optical measurement instrument developed uniquely by our group — to evaluate the chirality of solid-state thalidomide "in situ," thereby striving to more accurately elucidate the physicochemical properties of solid-state thalidomide, including its stability and reactivity (chiral inversion and hydrolysis).
We grew thalidomide crystals by solvent evaporation, and through single-crystal X-ray structure analysis and quantum chemical calculations, we were the first in the world to demonstrate that differences in physicochemical properties such as melting point and solubility originate from differences in crystal structure [1]. We also determined the absolute structure of the thalidomide metabolite CBG, which had not previously been established [2], and elucidated the hydrolysis and dehydration reaction mechanisms among metabolites including thalidomide and CBG [3–5]. Furthermore, we developed a crystal growth method by sublimation and experimentally demonstrated the possibility of chiral inversion of thalidomide in the gas phase [6, 7]. We were the first in the world to measure the temperature dependence of enantiomeric and racemic crystals, revealing that a distinct difference in thermal expansion behavior arises due to a subtle symmetry difference in the dimers [8].
Related Publications
[1] T. Suzuki, T. Asahi et al., Phase Transitions, 83, 223–234 (2010).
[2] K. Otogawa, T. Asahi et al., Acta Cryst. E, 71, 107–109 (2015).
[3] Y. Ogino, T. Asahi et al., J. Theor. Biol., 373, 117–131 (2015).
[4] Y. Ogino, T. Asahi et al., Chirality, 29, 282–293 (2017).
[5] T. Taniguchi, T. Asahi et al., Chem. Lett., 50, 1388–1391 (2021).
[6] M. Kira, Y. Shiga, K. Nakagawa, T. Asahi et al., Cryst. Growth Des., 24, 3133–3139 (2024).
[7] K. Nakagawa, M. Kira, T. Asahi, Monthly Saibo (in Japanese), 56, 1009–1013 (2024).
Press release
Press coverage
[1] Kagaku Shimbun “Structural change of thalidomide crystal due to temperature elucidated” May 16, 2025 (Printed on page 4)
② Symmetry Breaking in Copper-Oxide High-Temperature Superconductors
Superconductivity is expected to enable dramatic energy savings across a wide range of fields, including power, transportation, industry, and information technology. However, since superconductivity occurs only at extremely low temperatures, there is currently no clear path toward its practical application at room temperature. This is largely because the mechanism underlying high-temperature superconductivity has not yet been elucidated, which means there are no established guidelines for designing and synthesizing materials with even higher superconducting transition temperatures (Tc). To elucidate this mechanism, it is necessary to clarify the "special order" possessed by superconductors, but the debate surrounding this order has yet to be resolved.
In our laboratory, we aim to clarify the nature of the order formation in the pseudogap phase of copper-oxide high-temperature superconductors by using the G-HAUP — our unique optical measurement instrument — to determine whether symmetry breaking exists in the pseudogap phase. The G-HAUP is the only polarimetric spectroscopy method capable of simultaneously measuring optical activity, circular dichroism, linear birefringence, and linear dichroism.
Despite the extremely small lattice constant anisotropy along the a- and b-axes of the cleavable copper-oxide high-temperature superconductor Bi2Sr2CaCu2O8+δ (Bi2212) crystal, we discovered — surprisingly — that anomalous dispersion of linear birefringence and peaks in linear dichroism are observed at 345 and 330 nm, respectively [1]. We also grew Bi2−xPbxSr2CaCu2O8+δ single crystals with various Pb contents by the floating-zone method, and clarified that the origin of the optical anisotropy is related to the "superstructure modulation" (incommensurate modulation) [2].
We are currently constructing a new G-HAUP capable of cooling measurement samples to low temperatures. Going forward, we aim to measure optical activity, circular dichroism, and optical anisotropy in the pseudogap phase using this low-temperature G-HAUP, thereby clarifying whether symmetry breaking exists in the pseudogap phase and ultimately revealing the special order of high-temperature superconductors.
Related Publications
[1] K. Zhang, K. Nakagawa, T. Asahi et al., J. Phys. Soc. Jpn., 90, 113702 (2021).
[3] K. Zhang, K. Okano, T. Asahi, K. Nakagawa, Sci. Rep., 16, 22052 (2026).
Press release
Press coverage
③ Chiroptical Measurements in the Solid State Using G-HAUP
Quantitative evaluation of the chirality of materials is extremely important. Techniques for evaluating chirality include measuring the difference in refractive index (optical activity) and the difference in absorbance (circular dichroism) for left and right circularly polarized light. Polarimeters and circular dichroism spectrometers have been commonly used as standard methods for measuring chiroptical properties. However, these techniques can only be applied to isotropic materials such as solutions and amorphous thin films. In anisotropic materials such as crystals and oriented thin films, optical anisotropy in the form of birefringence and linear dichroism coexists, making it impossible to quantitatively measure chirality using conventional polarimeters or circular dichroism spectrometers.
In 1983, Kobayashi et al. developed a groundbreaking optical measurement instrument — the High Accuracy Universal Polarimeter (HAUP) [1-2] — enabling simultaneous measurement of chiroptical properties and optical anisotropy in anisotropic materials. Our laboratory, which follows in the tradition of Kobayashi, developed the Generalized-HAUP (G-HAUP) [3,6,8,14] as a further evolution of HAUP, and has used it to measure optical activity in chiral crystals composed of achiral molecules [4,8,10,14], optical activity in amino acid crystals [4,8-9,14], chiroptical properties of organic dye molecules intercalated into layered inorganic crystals [3], optical activity in laminated collagen thin films as biomaterials [5-6,11], and chiroptical properties of chiral photomechanical crystals [7-8,14], thereby revealing various valuable insights unobtainable from any other physical measurement. We also extended our research from chiral optics into the magneto-optics field, and by modifying the G-HAUP optical system to allow application of a magnetic field to the sample, we achieved the world's first precise measurement of Faraday rotation perpendicular to the optical axis [12,14].
More recently, to overcome the limitations of the conventional HAUP method, we developed a new measurement principle based on an optical configuration in which the transmitted light intensity is maximized (diagonal position). The conventional HAUP method uses a configuration in which transmitted light intensity is minimized (extinction position), resulting in a decreased signal-to-noise (S/N) ratio for strongly absorbing samples or at wavelengths where light source intensity is low. In contrast, the new diagonal-position principle eliminates the need for the two-dimensional measurements required by the conventional method, and it was clarified that the influence of systematic errors arising from the imperfection of the linear polarizer can also be eliminated. This principle was applied to the non-absorbing uniaxial crystal MgF2 and the strongly absorbing copper-oxide superconductor Bi2Sr2CaCu2O8+δ (Bi2212). The LB and LD values obtained from measurements near the diagonal position agreed with high accuracy with results from the conventional method [13,15], and it was also demonstrated that the measurement time can be shortened [16].
Related Publications
[1] J. Kobayashi et al., J. Appl. Cryst., 16, 204–211 (1983).
[2] J. Kobayashi, T. Asahi et al., Phys. Rev. B, 53, 11784 (1996).
[3] M. Tanaka, T. Asahi et al., J. Phys. D: Appl. Phys., 45, 175303–175311 (2012).
[4] K. Ishikawa, T. Asahi et al., Chem. Commun., 48, 6031–6033 (2012).
[5] K. Nakagawa, T. Asahi et al., Chem. Commun., 50, 15086–15089 (2014).
[6] T. Asahi, Y. Ogino, K. Nakagawa et al., Kagaku Kogyo (in Japanese), 66, 97–108 (2015).
[7] A. Takanabe, H. Koshima, T. Asahi, J. Am. Chem. Soc., 138, 15066–15077 (2016).
[8] T. Asahi, K. Nakagawa, K. Ishikawa, A. Takanabe, H. Koshima et al., J. Synth. Org. Chem. Jpn. (in Japanese), 75, 530–537 (2017).
[9] K. Ishikawa, T. Asahi et al., J. Phys. Chem. Solids, 104, 257–266 (2017).
[10] K. Nakagawa, B. Kahr, T. Asahi et al., J. Phys. Chem. C, 121, 25494–25502 (2017).
[11] K. Nakagawa, T. Asahi, J. Jpn. Assoc. Cryst. Growth (in Japanese), 45, 06-1–06-8 (2018).
[13] K. Zhang, K. Nakagawa, T. Asahi et al., J. Phys. Soc. Jpn., 90, 113702 (2021).
[16] K. Zhang, K. Okano, T. Asahi, K. Nakagawa, Sci. Rep., 16, 22052 (2026).
④ Novel Communication Devices Using Metasurface Materials
The diversification of communication devices, the proliferation of services delivered via communication networks such as the Internet of Things (IoT), and the rapid spread of artificial intelligence (AI) have caused an exponential increase in the volume of data to be processed by IT equipment and the power consumed within networks. For future networks capable of handling large-volume communications, dramatic miniaturization and integration of packages and chips are critically important. There is currently rapidly growing interest in and demand for all-photonic networks, which enable large-capacity, low-power-consumption, and low-latency communications.
In this research, we are conducting collaborative research with multiple companies toward the development of novel communication devices using metasurface materials.
⑤ Research for Improving Quality of Life (QOL) in Space for General Civilians
Currently, human activities in space are carried out primarily by astronauts, and the Environmental Control and Life Support System (ECLSS) has been designed and developed mainly to sustain the lives of astronauts who have undergone rigorous selection and long-term training. Meanwhile, with the advancement of space tourism for general civilians and commercial space station concepts, private activities in low Earth orbit are expected to expand significantly in the future. In such circumstances, it is essential not only to maintain life and health, but also to ensure a safe and comfortable environment in space.
We aim to establish technologies for comprehensive and continuous measurement and analysis of external environmental information — such as temperature, humidity, oxygen concentration, carbon dioxide concentration, and cosmic radiation — as well as internal biological information, such as body temperature, heart rate, brain waves, and hormone levels. This will enable early detection of minor changes in physical condition and early signs of health abnormalities, thereby preventing health risks from materializing. Furthermore, we will develop measurement technologies and analytical models adapted to the unique constraints of space — including microgravity, limited space, power, and communication environments — and build foundational technologies to enable general civilians to stay safely and comfortably in space.
Press release
⑥ Thermal Energy Conversion Using Liquid Crystals
Liquid crystals or mesophases that combine fluidity with long-range orientational order underpin technologies ranging from displays and thermometers to pharmaceutical formulations. Among them, chiral liquid crystals are of particular interest because their broken inversion symmetry enables the conversion of thermal energy into directed mechanical motion. Such systems offer a promising route for harvesting low-grade waste heat, including that generated by high-performance computing, and could contribute to more sustainable energy technologies.
Most previous studies have focused on behaviours near phase-transition temperatures for experimental convenience. However, these states exist only within a narrow temperature window, limiting practical deployment under fluctuating conditions. To overcome this challenge, we are developing phase-separated liquid-crystal colloids capable of operating across a broad temperature range. By dispersing liquid-crystal domains in a special alcohol matrix, we have achieved stable operation from 0 to 100°C, greatly extending the accessible temperature range.
We are also exploring how geometry and topology influence energy-conversion efficiency. When confined within a liquid matrix, liquid crystals develop complex topological textures that strongly modify their collective behaviour. By harnessing these emergent soft-matter states, we aim to establish new mechanisms for thermal-energy transduction and ultimately create heat-harvesting devices that approach the Carnot limit.
Related Publications
[1] S. Takano, T. Nakanishi, K. Nakagawa, T. Asahi, Phys. Rev. E, 2025, 112, 055429.
[2] S. Takano, T. Asahi, I. I. Smalyukh, Nat. Photon., 2025, 19, 659–661.
【Electrochemistry Group】
In recent years, increasing attention has been paid to the development of technologies that enable the creation of innovative functional materials by precisely controlling the nanoscale structure of matter and the nanoscale spaces generated thereby. "Conductive mesoporous membranes" are inorganic structures (metals or conductive inorganic materials) that possess many controlled, fine spaces (pores) with diameters of approximately 2–50 nm, while also having electrical conductivity. Compared to conventional inorganic porous materials such as zeolites and mesoporous silica, they offer overwhelming advantages in terms of high electrical conductivity and various electrical, magnetic, optical, and catalytic properties that emerge in nanoscale spaces.
Asahi Laboratory conducts advanced research based on "unique measurement technologies" — including electrochemical analysis systems and newly developed optical systems — to analyze and understand the relationship between nanostructures with diverse architectures and their physicochemical properties, and aims to contribute to the creation of "dream materials" by applying these to sensor devices and optical devices.
Research Topics
① Development of High-Sensitivity Sensor Devices Using Mesoporous Membranes
③ Development of Biosensor Devices for Mobilization of Healthcare
① Development of High-Sensitivity Sensor Devices Using Mesoporous Membranes
"Mesoporous membranes," due to their extremely large specific surface area (high specific surface area effect), are applied in a wide variety of uses such as catalysts, adsorbents, and electrode materials for electric double-layer capacitors. In addition to these characteristics, conductive mesoporous membranes have pore sizes sufficiently small relative to the wavelength of light, such that a high-intensity electric field is formed inside and around the pores due to plasmonic effects, enabling optical enhancement.
In this research, we aim to develop highly practical biomedical and chemical sensor devices — capable of detecting target substances in smaller amounts at lower concentrations than existing methods, with higher sensitivity — by leveraging the high specific surface area effect and plasmonic effects of conductive mesoporous membranes, targeting the sensing of important chemical substances related to life phenomena (in particular, substances that cause diseases or appear when disease occurs).
② Control of Optical Properties Utilizing Nanopores of Mesoporous Membranes and Development of Optical Devices
To enhance the performance of optical devices, there has been growing interest in recent years in achieving improvements not only through the materials themselves, but also through characteristic structures such as nanostructuring and multilayer film formation. The characteristic nanopores of "conductive mesoporous membranes" can be precisely designed by controlling synthesis conditions in terms of pore size, thickness, and density; by exploiting these characteristic nanopores, it may be possible to efficiently control optical properties.
In this research, we aim to clarify the detailed operating mechanisms of optical devices based on mesoporous materials, and to develop optical devices that efficiently control optical properties through the entirely new concept of controlling the pores of mesoporous membranes — by evaluating the optical and electrical properties of mesoporous membranes synthesized under various conditions using independently constructed evaluation systems.
③ Development of Biosensor Devices for Mobilization of Healthcare
Extending healthy life expectancy is an important policy challenge, and maintaining health requires early treatment through early diagnosis. In recent years, there has also been a demand for solutions to social challenges such as labor shortages and rising medical costs in the healthcare and nursing care sectors. For this reason, the mobilization of medical equipment and devices through point-of-care testing (POCT) devices — which enable testing close to the patient — is anticipated.
In this research, with the aim of realizing mobilization of healthcare, we focus on electrode chip-type biosensors and are engaged in collaborative research with companies to develop novel biosensor devices that combine Asahi Laboratory's unique expertise in "design of biomolecules" and "control of electrode surfaces."