The findings were published in the Journal of the American Chemical Society on August 19, 2026.

"One of the biggest challenges has been developing photoswitches that respond efficiently to visible light without compromising their thermal stability," says Ryojun Toyoda, an assistant professor at Tohoku University's Graduate School of Science. "Our molecular antenna strategy overcomes this trade-off, allowing us to harvest visible light much more effectively while preserving the switching behavior that practical applications require."

For many real-world applications, photoswitches must function deep inside materials or biological tissues, where light loses intensity as it is scattered. Visible light is especially attractive because it penetrates these environments more effectively than ultraviolet light. However, most conventional azobenzene photoswitches are relatively insensitive to visible wavelengths, and previous efforts to improve their performance often reduced their stability.

To solve this problem, the researchers collaborated with Professor Shirin Faraji's group at Heinrich Heine University Düsseldorf to design azobenzene molecules equipped with dipyrrin complexes that act as highly efficient molecular antennae. These antennae absorb visible light before transferring the captured energy directly to the azobenzene unit, triggering its structural transformation.

The team developed two types of hybrid molecules. One linked azobenzene to a simple boron-based dipyrrin complex, while the other incorporated one-dimensional dipyrrin-zinc nanochains that transport energy along the molecular backbone. Through repeated separation processes, the researchers successfully isolated zinc nanochains of ten discrete lengths, enabling them to investigate how molecular size affects performance.

Using UV-visible absorption spectroscopy and proton nuclear magnetic resonance (¹H NMR), the researchers confirmed that the dipyrrin antennae efficiently transferred absorbed light energy to the azobenzene photoswitch. In the zinc nanochain structures, the chains acted as molecular energy highways, transporting excitation energy over long distances to the terminal azobenzene unit.

The new design produced some of the highest visible-light sensitivities reported for azobenzene photoswitches. The boron-based hybrid achieved a sensitivity of 7,500 M⁻¹ cm⁻¹, while the longest zinc nanochain reached 8,100 M⁻¹ cm⁻¹. Even more encouragingly, the researchers found that sensitivity increased as the nanochains became longer, suggesting that future designs could achieve even greater performance.

Unlike many previous strategies, the new molecular architecture also preserved the photoswitches' thermostable behavior, allowing them to maintain their switched state rather than rapidly reverting. Quantum chemical calculations further confirmed that the dipyrrin antennae efficiently harvest visible light and funnel the energy to the azobenzene core, validating the mechanism observed experimentally.

"This work provides a new design principle for highly sensitive molecular photoswitches," adds Toyoda. "We believe these molecular antennae will accelerate the development of molecular machines, smart materials, photopharmacology, and other technologies that rely on precise light-controlled molecular motion."

The researchers next plan to integrate these highly sensitive photoswitches into functional systems, including molecular robots, light-responsive smart surfaces, and technologies for manipulating DNA and proteins with light. They also hope the approach will contribute to the development of photopharmacology, in which medicines can be activated only at targeted locations within the body, reducing unwanted side effects.

Such technology could one day enable everything from smart materials that respond to their environment to drugs that can be activated only where and when they are needed.

Presentation Details:
Title: Molecular Antennae Enhance Visible-Light Sensitivity of Azobenzene Photoswitches
Authors: Yuta Chiba, Rio Shoji, Mira Kim, Shinya Takaishi, Ryota Sakamoto, Shirin Faraji*, Ryojun Toyoda*
Journal: Journal of the American Chemical Society
Link: 10.1021/jacs.6c12118

Contact:
Ryojun Toyoda
Graduate School of Science, Tohoku University
Email: ryojun.toyoda.a8 * tohoku.ac.jp
Website: https://web.tohoku.ac.jp/sakutai/

The findings were published in Science Advances on July 2, 2026.

"We demonstrated a fundamentally new way of creating two-dimensional quantum materials," says Takafumi Sato of Tohoku University's Advanced Institute for Materials Research (WPI-AIMR). "Rather than attempting to produce an unstable free-standing sheet of boron atoms, we exposed a naturally occurring honeycomb boron layer that already exists within a stable three-dimensional crystal called LaRh₃B₂.

For years, scientists have been interested in borophene--a two-dimensional sheet of boron atoms--because its stronger electron interactions could produce exotic quantum phenomena not seen in graphene. However, borophene's ideal honeycomb structure is extremely unstable, making it almost impossible to manufacture.

Instead of trying to synthesize borophene directly, Sato and his colleagues took a different approach. They used the crystal structure of LaRh₃B₂, which naturally contains layers of boron atoms arranged in a honeycomb pattern. By exposing these layers at the crystal's surface, they created a stable two-dimensional electronic system with the properties of the elusive material.

Using angle-resolved photoemission spectroscopy (ARPES) at synchrotron radiation facilities, the team found an unusually high concentration of electrons near the material's Fermi level. This feature, known as a van Hove singularity, is important because it greatly strengthens interactions between electrons and can trigger unusual quantum behavior.

The researchers then combined these measurements with scanning tunneling microscopy and spectroscopy (STM/STS), which allowed them to observe the electrons in real space. Together, the two techniques showed that the electrons spontaneously aligned in one preferred direction, breaking the crystal's original six-fold symmetry and forming an "electronic nematic state"--a quantum state in which electrons behave similarly to molecules in a liquid crystal display.

"Instead of struggling to synthesize a fragile two-dimensional boron sheet from scratch, we looked inside a stable three-dimensional crystal that already contained a boron honeycomb lattice and exposed it on the material's surface," added Sato. "Observing this electronic liquid crystal state in a graphene-like material shows that carefully designing a material's electronic structure can unlock entirely new quantum phenomena."

A key aspect of the discovery was the combination of momentum-space and real-space imaging techniques. ARPES identified an electronic "hot spot" where the instability could emerge, while STM directly observed the resulting symmetry-breaking electronic pattern. By comparing the two sets of measurements, the researchers were able to explain how the electronic nematic state forms.

"Neither technique alone could have revealed the full picture," said Kosuke Nakayama, an assistant professor at Graduate School of Science. "By combining momentum-space information from ARPES with real-space observations from STM, we were able to connect the electronic instability with the emergence of the nematic state. This synergy was essential to understanding the physics behind this new quantum phase."

Because the crystal family used in this study allows many of its chemical elements to be substituted, researchers can readily adjust the number and behavior of electrons within the material. This flexibility provides a powerful platform for designing new quantum materials and could accelerate the development of next-generation superconductors and energy-saving quantum technologies.

Presentation Details:
Title: Realization of strongly correlated 2D honeycomb boron
Authors: Takemi Kato*, Tomonori Nakamura, Kosuke Nakayama*, Takumi Osumi, Seigo Souma, Asuka Honma, Alexandre Antezak, Pedro Rezende Gonçalves, Kiyohisa Tanaka, Miho Kitamura, Kenichi Ozawa, Koji Horiba, Hiroshi Kumigashira, Takashi Takahashi, Franck Fortuna, Andrés Felipe Santander-Syro, Rikio Settai, Yoshichika Onuki, Yoshinori Okada*, and Takafumi Sato*
Journal: Science Advances
Link: 10.1126/sciadv.aee3116

Contact:
Kosuke Nakayama、Takafumi Sato
Advanced Institute for Materials Research (WPI-AIMR), Tohoku University
Email: k.nakayama * arpes.phys.tohoku.ac.jp, t-sato * arpes.phys.tohoku.ac.jp
Website: https://arpes.phys.tohoku.ac.jp/index-e.html

The team achieved this by introducing dithiolate (SR'S) bridging ligands into an atomically precise gold-platinum (Au24Pt) alloy nanocluster protected by thiolate (SR) ligands. This new design allows the protective ligands to be removed at relatively low temperatures while preserving the nanocluster's precise structure.

In conventional alloy nanoclusters (Au24Pt(SR)18), the surface is covered by protective ligands that maintain structural stability but also block the active metal sites needed for catalytic reactions. Although weakening the bond between the ligands and the metal can make these active sites easier to expose, it also makes the nanocluster itself less stable, creating a long-standing trade-off between stability and catalytic activity.

To overcome this challenge, the researchers designed a new ligand structure that strengthens the nanocluster's outer "staple" framework. They used a relatively weakly bound thiolate ligand (TBBT) together with dithiolate (TDT) bridging ligands, which reinforce the staple structure while allowing the weaker ligands to be removed more easily.

As a result, the newly developed alloy nanocluster, ([Au24Pt(TBBT)12(TDT)3]⁰, combines excellent structural stability with ligand removal at relatively low temperatures. When supported on cerium oxide (CeO₂) and activated through pretreatment, the catalyst showed significantly higher low-temperature CO oxidation activity than the conventional monothiolate-protected alloy nanocluster [Au24Pt(PET)18]⁰, reducing the temperature required to achieve 50% CO conversion by 39 °C.

The findings demonstrate that advanced ligand engineering can directly control nanocluster structure while greatly improving the activity of thermal catalysts.

The research was published in Nano Letters, published by the American Chemical Society, on Month 29, 2026.

Atomically precise metal nanoclusters have attracted considerable attention as catalysts because their geometric and electronic structures can be precisely tailored. However, the protective ligands covering their surfaces, while essential for maintaining structural integrity, also prevent reactant molecules from reaching the active metal sites.

To expose these active sites, researchers typically use thermal, chemical, or electrochemical pretreatments to remove the ligands. Previous studies have shown that removing the ligands can greatly improve catalytic activity. However, the high temperatures often required can cause the nanoclusters to aggregate and leave sulfur-containing residues on the catalyst support, reducing performance. This has created an urgent need for methods that remove ligands under milder conditions.

To address this challenge, the research group developed a ligand engineering strategy using a gold-platinum alloy nanocluster (Au24Pt). While conventional Au24Pt(SR)18 nanoclusters rely on strongly bound ligands that limit catalytic activity, simply replacing them with weaker ligands compromises structural stability. Instead, the team reinforced the nanocluster by bridging the weaker thiolate ligands with dithiolate groups. This strengthened the outer staple motifs while lowering the temperature required to remove the weaker ligands and activate the catalyst.

The researchers synthesized the alloy nanocluster [Au₂₄Pt(TBBT)₁₂(TDT)₃]⁰ through ligand exchange, replacing some of the original PET (2-phenylethanethiolate) ligands with TBBT (4-tert-butylbenzenethiolate) and TDT (thiodithiolate). Structural analysis showed that the new nanocluster retained almost exactly the same metal core as the original [Au₂₄Pt(PET)₁₈]⁰, while the addition of the dithiolate ligands strengthened the surrounding staple structure.

To understand how the ligands detached during heating, the researchers used direct insertion probe mass spectrometry (DIP-MS). The analysis showed that the conventional nanocluster lost PET ligands through the breaking of either sulfur-carbon or gold-sulfur bonds. In contrast, the new nanocluster selectively released only the monothiolate TBBT ligands by breaking the gold-sulfur bonds, leaving the reinforcing dithiolate framework intact.

The nanoclusters were then supported on CeO₂ at a loading of just 0.5 wt% and tested as catalysts for CO oxidation. Without pretreatment, CO oxidation began at approximately 236 °C for [Au₂₄Pt(PET)₁₈]⁰/CeO₂ but at a lower temperature of 215 °C for [Au₂₄Pt(TBBT)₁₂(TDT)₃]⁰/CeO₂.

After oxidative pretreatment at 250 °C for 30 minutes, CO oxidation started at 128 °C for the conventional catalyst and at only 110 °C for the newly designed catalyst. The temperature required to achieve 50% CO conversion also fell from 301 °C to 262 °C - a reduction of 39 °C. These results suggest that subtle differences in how ligands detach from nanoclusters can influence the structure of the supported catalyst and ultimately improve its catalytic performance.

This study demonstrates that reinforcing the staple motifs with dithiolate groups makes it possible to incorporate weaker gold-sulfur bonds without sacrificing structural stability. As a result, the nanoclusters can be activated more easily while maintaining their precise atomic structure, leading to higher catalytic activity.

The researchers expect that this ligand engineering strategy will contribute to the development of supported metal nanocluster catalysts with improved activity, selectivity, and durability. Future studies will investigate how different ligand desorption pathways influence the structural evolution of supported nanocluster catalysts during catalytic reactions.

Presentation Details:
Title: Ligand Engineering of Dithiolate-Protected Au₂₄Pt Nanoclusters for Improved Thermocatalytic Activity
Authors: Riki Nakatani, Tokuhisa Kawawaki, Sara Yoshikawa, Chaoqi Chen, Taishi Suzuki, Soichi Kikkawa, Satoshi Anada, Seiji Yamazoe and Yuichi Negishi
Journal: Nano Letters (Nano Lett.)
Link: 10.1021/acs.nanolett.6c01977

Contact:
Yuichi Negishi,
Institute of Multidisciplinary Research for Advanced Materials
Email: yuichi.negishi.a8 * tohoku.ac.jp
Website: https://www2.tagen.tohoku.ac.jp/lab/negishi/html/

For the first time ever, the Super-Kamiokande Collaboration found an indication of the Diffuse Supernova Neutrino Background (DSNB), which is an integrated flux of neutrinos originating from many different supernovae over time. This international collaboration group involving approximately 250 researchers from 60 universities and research institutions has made a ground-breaking achievement that provides an important clue for deepening our understanding of the history of cosmic star formation and nucleosynthesis.

The research results were presented on June 25, 2026, at Neutrino 2026: XXXII International Conference on Neutrino Physics and Astrophysics, held at the University of California, Irvine, USA.

The DSNB is the accumulation of neutrinos emitted by all core-collapse supernovae throughout cosmic history, from the early universe to the present. Capturing the DSNB would provide a definitive observational means to quantitatively unravel the history of nucleosynthesis and star formation in the universe, and to test theoretical models. However, neutrinos arriving from vast distances are diffuse, and their signals are extremely faint and challenging to detect. Undertaking this observation is like straining to hear the "faint whispers" of supernova explosions engraved in cosmic history.

To tune in to these "whispers", the research team conducted a detailed analysis of approximately 5,000 days of observational data, combining two phases of data collection involving either ultrapure water or ultrapure water with the addition of Gadolinium (which improves detection). Super-Kamiokande detects Cherenkov light produced when neutrinos interact with water, using a 50,000-ton tank of ultrapure water and approximately 13,000 photomultiplier tubes installed underground. This level of dedication is required just to be able to potentially detect neutrinos and minimize background noise such as cosmic rays.

Ultimately, the team identified a statistically significant excess signal in the neutrino energy range from 13.3 to 81.3 MeV. The significance of the excess signal was 2.6 sigma (99.5% confidence level). Although it cannot be explained as a random fluctuation, it does not yet meet the discovery threshold (5 sigma or higher) and is therefore currently described as an indication rather than a definitive detection.

"We are already planning on incorporating ongoing observations at Super-Kamiokande together with its successor detector, Hyper-Kamiokande, to further improve sensitivity in future collaborative studies," says Yosuke Ashida, Assistant Professor at Tohoku University.

The current results are anticipated to contribute to a better understanding of the formation processes of neutron stars and black holes, as well as the chemical evolution of the universe.

Regarding this result, Hiroyuki Sekiya, Associate Professor at the University of Tokyo, and spokesperson for the Super-Kamiokande experiment, commented: "Observing the world's first indication of the Diffuse Supernova Neutrino Background is a deeply meaningful achievement and has been a long-cherished goal since the beginning of the Super-Kamiokande project."

Presentation Details:
Title: Supernova Neutrinos in Super-Kamiokande
Presenter: Hiroyuki Sekiya (ICRR, The University of Tokyo)
Conference Name: Neutrino 2026: XXXII International Conference on Neutrino Physics and Astrophysics
Date: June 25, 2026
Link: https://indico.global/event/15740/contributions/155621/

Contact:
Yosuke Ashida
Department of Physics
Email: yosuke.ashida.a1 * tohoku.ac.jp
Website: https://epx.phys.tohoku.ac.jp/eeweb/?lang=en