Organized and Sustainable Education Program for Drug Abuse Prevention by Yogo-teachers

　学校における喫煙・飲酒・薬物乱用防止教育の充実には，問題行動が顕在化する中学校期だけでなく小学校期 における指導の推進が重要であり，系統的な指導計画を立て，指導者や時間の確保，教材作成などに組織的に取 組み，継続可能なプログラム開発を行う必要がある。そこで，地区内12 校の養護教諭が協働して，発達段階に応 じた系統的・組織的かつ継続可能な地区共通の指導計画を開発し，各校の教育課程・年間計画に位置付けた実践 研究を行った。その結果，指導計画の実施状況は，小学校11 校中，学級活動10 校，ミニ保健指導10 校，長期 休業前指導6 校，広報活動9 校となり，特別支援学校1 校では広報活動のみを行うことができた。小学校におけ る喫煙・飲酒・薬物乱用防止教育の推進には，学校保健活動の中核的役割を担う養護教諭が専門性を活かし協働 して，系統的な指導計画を各校の教育課程に位置付け組織的で継続可能なプログラムとする取組が有効であった

Dual-Copper Catalytic Site Formed in CuMFI Zeolite Makes Effective Activation of Ethane Possible Even at Room Temperature

The role of dual-cation sites in zeolites has received a renaissance in chemistry and industry directed toward fixation and activation of various gases; such sites may be expected to be more efficient than a single-cation site. We aimed to clarify the real active centers in the copper-ion-exchanged MFI-type zeolite (CuMFI) for ethane (C₂H₆). A peculiar feature was found in the appearance of the characteristic IR bands at 2644 and 2582 cm^–1 when C₂H₆ was adsorbed on Cu⁺ formed in CuMFI. The existence of dual species composed of two Cu⁺ ions bridging C₂H₆ was clearly indicated by extended X-ray absorption fine structure (EXAFS) data. Density functional theory calculations gave clear evidence that the two IR bands are distinctly due to C₂H₆ adsorbed on the dual-Cu⁺ site and not on a single site; this agrees with the EXAFS data. These data lead us to conclude that the dual-Cu⁺ site in the CuMFI sample is indispensable for efficient activation of C₂H₆ through the simultaneous interaction of C₂H₆ with two Cu⁺ ions

Further Evidence for the Existence of a Dual-Cu⁺ Site in MFI Working as the Efficient Site for C₂H₆ Adsorption at Room Temperature

We have recently clarified the following point: a dual-type site, which is composed of a pair of monovalent copper ions (Cu⁺) formed in a copper-ion-exchanged MFI-type zeolite (CuMFI), functions as the active center for strong ethane (C₂H₆) adsorption even at room temperature rather than a single-type site composed of a Cu⁺ ion. However, the character of the dual-Cu⁺ site in a CuMFI is not yet fully understood. In this study, we have elucidated the nature of the active sites for C₂H₆ based on infrared (IR) and calorimetric data. On the basis of the results obtained, we came to the conclusion that the dual-Cu⁺ site composed of Cu⁺ ions giving the adsorption energy of 100 kJ mol^–1 and the absorption band at 2151 cm^–1 for carbon monoxide (used as a probe molecule) at room temperature functions as an adsorption site for C₂H₆. We also evaluated, for the first time, the interaction between the dual-Cu⁺ site and C₂H₆ energetically, by the direct measurement of heat of adsorption. The value of 67 kJ mol^–1 that we recorded was higher than that for the single-Cu⁺ site in this sample and also for other samples, such as NaMFI and HMFI

Potential for Fixation of N₂ at Room Temperature Utilizing a Copper-Ion-Exchanged MFI-Type Zeolite As an Adsorbent: Evaluation of the Bond Dissociation Energy of Adsorbed NN and the Bond Strength of the Cu⁺−N(N) Species

A peculiar N₂ adsorption was found on a copper-ion-exchanged MFI-type zeolite (CuMFI); the N₂ adsorption was established within 20 s at 300 K. Related to this fact, the bond dissociation energy of NN in a stable Cu⁺−NN species in CuMFI was, for the first time, evaluated to be 9.11 eV from the characteristic bands at 2295, 2654, and 4553 cm⁻¹, which correspond to the fundamental, combination, and overtone vibrations of NN adsorbed on Cu⁺ of CuMFI, respectively. The vibrational frequency of Cu⁺−N in the Cu⁺−NN formed in CuMFI was also determined to be ∼360 cm⁻¹, together with the energy for the formation of a Cu⁺−N bond; the Cu⁺−NN species is stable enough to maintain a N₂ molecule on MFI at 300 K. DFT calculations reasonably explain the experimental data and also the N₂ adsorption model based on the three-coordinate Cu⁺ site in CuMFI

Material Exhibiting Efficient CO₂ Adsorption at Room Temperature for Concentrations Lower Than 1000 ppm: Elucidation of the State of Barium Ion Exchanged in an MFI-Type Zeolite

Carbon dioxide (CO₂) gas is well-known as a greenhouse gas that leads to global warming. Many efforts have been made to capture CO₂ from coal-fired power plants, as well as to reduce the amounts of excess CO₂ in the atmosphere to around 400 ppm. However, this is not a simple task, particularly in the lower pressure region than 1000 ppm. This is because the CO₂ molecule is chemically stable and has a relatively low reactivity. In the present study, the CO₂ adsorption at room temperature on MFI-type zeolites exchanged with alkaline-earth-metal ions, with focus on CO₂ concentrations <1000 ppm, was investigated both experimentally and by calculation. These materials exhibited a particularly efficient adsorption capability for CO₂, compared with other presented samples, such as the sodium-form and transition-metal ion-exchanged MFI-type zeolites. Ethyne (C₂H₂) was used as a probe molecule. Analyses were carried out with IR spectroscopy and X-ray absorption, and provided significant information regarding the presence of the M²⁺–O^2––M²⁺ (M²⁺: alkaline-earth-metal ion) species formed in the samples. It was subsequently determined that this species acts as a highly efficient site for CO₂ adsorption at room temperature under very low pressure, compared to a single M²⁺ species. A further advantage is that this material can be easily regenerated by a treatment, e.g., through the application of the temperature swing adsorption process, at relatively low temperatures (300–473 K)

Combined Experimental and Computational Approaches To Elucidate the Structures of Silver Clusters inside the ZSM‑5 Cavity

A combination of experimental and computational analyses suggested the presence of Ag₃ or Ag₄ clusters inside a nanometer-sized cavity in Ag–ZSM-5 zeolites, which were formed from H–ZSM-5 using the conventional ion-exchange method in an aqueous silver nitrate solution. During the experimental analyses, we investigated the structural and absorption properties of Ag–ZSM-5 through UV–vis diffuse reflectance and X-ray absorption fine structure (XAFS) measurements. The results from the extended XAFS (EXAFS) analysis indicated that clusters contained in the ZSM-5 cavity have Ag–Ag separations of approximately 2.6 Å. The UV–vis measurements indicated that the clusters located in the cavity present three prominent absorption bands centered at approximately 255, 287, and 331 nm for the sample treated at 473 K. The Ag–ZSM-5 treated at 573 or 673 K presents new UV–vis bands at approximately 303 and 319 nm. The experimental results regarding the structural and absorption properties of Ag–ZSM-5 could be well-reproduced by DFT calculations when a model large enough to represent a 10-membered ring of ZSM-5 was used. DFT optimization indicated that the ZSM-5 cavity can accommodate a triangular Ag₃ cluster and a butterfly Ag₄ cluster whose Ag–Ag separations range from 2.7 to 2.9 Å. According to time-dependent DFT calculations, these clusters have electronic transitions from a completely symmetric 5s-based orbital to a 5s-based orbital with one node. The electronic excitations between the 5s-based orbitals are modulated by the ZSM-5 encapsulation through the resulting deformation of the cluster and interactions between the cluster and framework oxygen atoms. The electronic transitions between the 5s-based orbitals that appropriately explain the UV–vis absorption properties would become fingerprints for identifying the shapes and sizes of clusters inside a zeolite cavity. Our multidisciplinary analyses conclusively determined the origin of the absorption peaks in Ag–ZSM-5 and successfully obtained atomistic information about the states of silver clusters inside a ZSM-5 cavity. The findings of this study will provide useful information for elucidating the structures of active sites in Ag-ZSM-5 and their important role in catalytic reactions such as C–H bond activation in hydrocarbons

Success in Making Zn⁺ from Atomic Zn⁰ Encapsulated in an MFI-Type Zeolite with UV Light Irradiation

For the first time, the paramagnetic Zn⁺ species was prepared successfully by the excitation with ultraviolet light in the region ascribed to the absorption band resulting from the 4s–4p transition of an atomic Zn⁰ species encapsulated in an MFI-type zeolite. The formed species gives a specific electron spin resonance band at <i>g</i> = 1.998 and also peculiar absorption bands around 38,000 and 32,500 cm^–1 which originate from 4s–4p transitions due to the Zn⁺ species with paramagnetic nature that is formed in MFI. The transformation process (Zn⁰ → Zn⁺) was explained by considering the mechanism via the excited triplet state (³P) caused by the intersystem crossing from the excited singlet state (¹P) produced through the excitation of the 4s–4p transition of an atomic Zn⁰ species grafted in MFI by UV light. The transformation process was well reproduced with the aid of a density functional theory calculation. The thus-formed Zn⁺ species which has the doublet spin state exhibits characteristic reaction nature at room temperature for an O₂ molecule having a triplet spin state in the ground state, forming an η¹ type of Zn²⁺–O₂^– species. These features clearly indicate the peculiar reactivity of Zn⁺ in MFI, whereas Zn⁰–(H⁺)₂MFI hardly reacts with O₂ at room temperature. The bonding nature of [Zn²⁺–O₂^–] species was also evidenced by ESR measurements and was also discussed on the basis of the results obtained through DFT calculations

Direct Information on Structure and Energetic Features of Cu⁺−Xe Species Formed in MFI-Type Zeolite at Room Temperature

The interacted species of Xe with metal ions that are stable at room temperature are not known and are a subject of interest for fundamental chemistry. We have experimentally found a new and stable Xe species, XeCu⁺, which was formed at room temperature in a copper ion-exchanged MFI-type zeolite. The presence of a prominent interaction between Cu⁺ in MFI and Xe, which has a covalent nature, was for the first time evidenced from experimental in situ synchrotron X-ray absorption fine structure and heat of adsorption measurements: the Cu⁺−Xe bond length of 2.45 Å and the bonding energy of ca. 60 kJ mol⁻¹. The bonding nature between Xe and Cu⁺ in the MFI zeolite was discussed utilizing density functional theory; the observed significant stabilization comes from the d(Cu⁺ in MFI)−p(Xe) orbital interaction. These new findings may pave a new way to developing fundamental chemistry of Xe compounds