Language：English   Publisher：Advanced Materials  

Photon upconversion (UC) from red or near-infrared (NIR) light to blue light is promising for in vivo optogenetics. However, the examples of in vivo optogenetics have been limited to lanthanide inorganic UC nanoparticles, and there have been no examples of optogenetics without using heavy metals. Here the first example of in vivo optogenetics using biocompatible heavy metal-free TTA-UC nanoemulsions is shown. A new organic TADF sensitizer, a boron difluoride curcuminoid derivative modified with a bromo group, can promote intersystem crossing to the excited triplet state, significantly improving TTA-UC efficiency. The TTA-UC nanoparticles formed from biocompatible surfactants and methyl oleate acquire water dispersibility and remarkable oxygen tolerance. By combining with genome engineering technology using the blue light-responding photoactivatable Cre-recombinase (PA-Cre), TTA-UC nanoparticles promote Cre-reporter EGFP expression in neurons in vitro and in vivo. The results open new opportunities toward deep-tissue control of neural activities based on heavy metal-free fully organic UC systems.

DOI： 10.1002/adma.202405509

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Language：English   Publisher：Physical Chemistry Chemical Physics  

Strong light-matter interactions have attracted much attention as a means to control the physical/chemical properties of organic semiconducting materials with light-matter hybrids called polaritons. To unveil the processes under strong coupling, studies on the dynamics of polaritons are of particular importance. While highly condensed molecular materials with large dipole density are ideal to achieve strong coupling, the emission properties of such films often become a mixture of monomeric and excimeric components, making the role of excimers unclear. Here, we use amorphous neat films of a new bis(phenylethynyl anthracene) derivative showing only excimer emission and investigate the excited-state dynamics of a series of strongly coupled microcavities, with each cavity being characterised by a different exciton-photon detuning. A time-resolved photoluminescence study shows that the excimer radiatively pumps the lower polariton in the relaxation process and the decay profile reflects the density of states. The delayed emission derived from triplet-triplet annihilation is not sensitive to the cavity environment, possibly due to the rapid excimer formation. Our results highlight the importance of controlling intermolecular interactions towards rational design of organic exciton-polariton devices, whose performance depends on efficient polariton relaxation pathways.

DOI： 10.1039/d4cp00255e

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Physical Chemistry C  

Chiral molecule-based organic thin films are of increasing interest in optoelectronics and light technologies, where the development of isotropic neat films of chiral molecules is important for practical applications. Understanding the chiroptical responses of dense molecular aggregates often becomes challenging due to the reflection or scattering of light arising from significant reflectivity changes at the excitonic transition. Furthermore, the combination of linear birefringence (LB) and linear dichroism (LD) from micro- to mesoscopic ordering is a potential source of artifacts. Here, we report the circular dichroism (CD) of optically isotropic neat films of a new BODIPY-BINOL conjugate (O-BODIPY), which reveals a negligible LD-LB contribution as measured with both conventional methods and Mueller polarimetry. A 5-fold increase in the anisotropy factor in the neat film relative to the solution is explained by intermolecular exciton coupling. Time-dependent density functional theory calculations of possible intermolecular geometries induced in the film indicate the formation of short-ordered structures in the isotropic film with the help of combined chiral units. These results provide insight into chiral light-matter interactions, which are currently at the core of many fundamental discussions and promising chiroptical applications.

DOI： 10.1021/acs.jpcc.3c04212

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Materials Chemistry A  

Sustainable photonics applications of solid-state triplet-triplet annihilation photon upconversion (TTA-UC) are limited by a small UC spectral window, low UC efficiency in air, and non-recyclability of polymeric materials used. In a step to overcome these issues, we have developed new recyclable TTA-UC bioplastics by encapsulating TTA-UC chromophores liquid inside the semicrystalline gelatin films showing broad-spectrum upconversion (red/far-red to blue) with high UC efficiency in air. For this, we synthesized a new anionic annihilator, sodium-TIPS-anthracene-2-sulfonate (TIPS-AnS), that combined with red/far-red sensitizers (PdTPBP/Os(m-peptpy)2(TFSI)2), a liquid surfactant Triton X-100 reduced (TXr) and protein gelatin (G) formed red/far-red to blue TTA-UC bioplastic films just by air drying of their aqueous solutions. The G-TXr-TIPS-AnS-PdTPBP film showed record red to blue (633 to 478 nm) TTA-UC quantum yield of 8.5% in air. The high UC quantum yield has been obtained due to the fluidity of dispersed TXr containing chromophores and oxygen blockage by gelatin fibers that allowed efficient diffusion of triplet excited chromophores. Further, the G-TXr-TIPS-AnS-Os(m-peptpy)2(TFSI)2 bioplastic film displayed far-red to blue (700-730 nm to 478 nm) TTA-UC, demonstrating broad-spectrum photon harvesting. Finally, we demonstrated the recycling of G-TXr-TIPS-AnS-PdTPBP bioplastics by developing a downstream approach that gives new directions for designing future recyclable photonics bioplastic materials.

DOI： 10.1039/d2ta04810h

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Inorganic Chemistry  

Os(II) complexes showing singlet-to-triplet absorption are of growing interest as a new class of triplet sensitizers that circumvent energy loss during intersystem crossing, and they enable effective utilization of input photon energy in various applications, such as photoredox catalysis, photodynamic therapy, and photon upconversion. However, triplet excited-state lifetimes of Os(II) complexes are often too short (τ < 1 μs) to transfer their energy to neighboring molecules. While the covalent conjugation of chromophores has been known to extend the net excited-state lifetimes through an intramolecular triplet energy transfer (IMET), heavy-atom effects of the central metals on the attached chromophore units have rarely been discussed. Here, we investigate the relationship between the spin-density contribution of the heavy metals and the net triplet excited-state lifetimes for a series of Os(II) and Ru(II) bis(terpyridine) complexes modified with perylene units. Phosphorescence lifetimes of these compounds strongly depend on the lifetimes of the perylenyl group-localized excited states that are shortened by the heavy-atom effect. The degree of heavy-atom effect can be largely circumvented by introducing meta-phenylene bridges, where the perylene unit retains its intrinsic long excited-state lifetime. The thermal activation to the short-lived excited states is suppressed, thanks to sufficient but still small energy losses during the IMET process. Involvement of the metal center was also confirmed by the prolonged lifetime by replacing Os(II) with Ru(II) that possesses a smaller spin-orbit coupling constant. These results indicate the importance of ligand structures that give a minimum heavy-atom effect as well as the sufficient energy gap among the excited states and fast IMET for elongating the triplet excited-state lifetime without sacrificing the excitation energy.

DOI： 10.1021/acs.inorgchem.1c03129

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Responsible for pages： p. 86-89   Language：Japanese  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：日本大学理工学部　船橋キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：日本大学理工学部　船橋キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：日本大学理工学部　船橋キャンパス   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Type：Competition, symposium, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：4

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：4