【公開日：2023.08.03】【最終更新日：2023.11.09】

課題データ / Project Data

課題番号 / Project Issue Number

22NR0036

利用課題名 / Title

導電性 metal-organic framework ナノシートの気液界面合成：溶媒種がナノシート形成に与える影響

利用した実施機関 / Support Institute

奈良先端科学技術大学院大学 / NAIST

機関外・機関内の利用 / External or Internal Use

外部利用/External Use

技術領域 / Technology Area

【横断技術領域 / Cross-Technology Area】（主 / Main）計測・分析/Advanced Characterization（副 / Sub）-

【重要技術領域 / Important Technology Area】（主 / Main）マルチマテリアル化技術・次世代高分子マテリアル/Multi-material technologies / Next-generation high-molecular materials（副 / Sub）-

キーワード / Keywords

電子顕微鏡/Electron microscopy,X線回折/X-ray diffraction,電子分光

利用者と利用形態 / User and Support Type

利用者名（課題申請者）/ User Name (Project Applicant)

牧浦 理恵

所属名 / Affiliation

大阪公立大学大学院工学研究科物質化学生命系専攻

共同利用者氏名 / Names of Collaborators in Other Institutes Than Hub and Spoke Institutes

大畑考司,田知本和顕

ARIM実施機関支援担当者 / Names of Collaborators in The Hub and Spoke Institutes

河合　壯,淺野間文夫,片尾昇平,藤原正裕,石原綾子,大野智子,河合由子,上久保順子

利用形態 / Support Type

（主 / Main）共同研究/Joint Research（副 / Sub）-

利用した主な設備 / Equipment Used in This Project

NR-401：多機能走査型X線光電子分光分析装置
NR-301：X線構造解析装置

報告書データ / Report

概要（目的・用途・実施内容）/ Abstract (Aim, Use Applications and Contents)

   Nanosheets of metal–organic frameworks (MOFs)—porous crystalline materials consisting of metal ions and organic ligands—are actively studied for their intrinsic chemical/physical properties attributed to the reduced dimensionality and for their potential to function as ideal components of nanodevices, especially when electrical conduction is present. Air/liquid interfacial synthesis is a promising technique to obtain highly oriented MOF nanosheets. However, rational control of size and shape combined with the aimed functionality remains an important issue to address making it necessary to research the critical factors governing nanosheet characteristics in the interfacial synthesis. Here, we investigate the influence of the solvent—methanol (MeOH) versus N,N-dimethylformamide (DMF)—used to prepare the ligand spread solution on the assembly of MOF nanosheets composed of Ni²⁺ and 2,3,6,7,10,11-hexaiminotriphenylene (HITP) (HITP-Ni-NS).
    Under ARIM project, we investigate electronic states and atomic ratios of HITP-Ni-NS by X-ray photoelectron spectroscopy.

実験 / Experimental

    The synthetic procedure of HITP-Ni-NS at the air/liquid interface was initiated by spreading a ligand HATP solution using MeOH or DMF as solvent onto an aqueous solution of Ni(OAc)₂·4H₂O in the Langmuir trough (Figure 1a). The HATP solution and the aqueous solution of Ni(OAc)₂·4H₂O are referred to as the spread solution and the subphase, respectively. By spreading the HATP solution onto the subphase, nanosheets were assembled via coordination bonds between Ni²⁺ and HITP (deprotonated HATP) at the air/liquid interface. We denote the nanosheets prepared with the spread solutions of MeOH and DMF as HITP-Ni-NS_MeOH and HITP-Ni-NS_DMF, respectively. After the completion of the spreading process, the interface was left standing without any treatment for up to 60 min standing time (Figure 1b). Then, the surface compression with Teflon-coated barriers was applied to the air/liquid interface and HITP-Ni-NS was gathered (Figure 1c).    X-ray photoelectron spectroscopy (XPS) measurements of HITP-Ni-NS on Si substrates were conducted using a ULVAC-PHI PHI 5000 VersaProbeII installed at the Nara Institute of Science and Technology. The measurements were performed under ultra-high vacuum at room temperature. A monochromatic Al K_α X-ray (1486.6 eV) was employed.

結果と考察 / Results and Discussion

Elemental analysis of HITP-Ni-NS_MeOH and HITP-Ni-NS_DMF transferred on Si substrates by XPS (Figures 2a–c). The whole-region spectra display the peaks contributing to the expected atomic components, C, N, and Ni for both HITP-Ni-NS_MeOH and HITP-Ni-NS_DMF (Figures 2a). The peaks in the Ni 2p_3/2 region for HITP-Ni-NS_MeOH consist of a main peak with a peak center at 855 eV and a satellite peak with a center at 864 eV (Figures 2b). The peak configuration suggests that the oxidation state of the nickel ion is +2, retaining its value in Ni(OAc)₂·4H₂O. The same configuration was also observed for HITP-Ni-NS_DMF (Figures 2b). Higher statistics fine scans in the N 1s region of HITP-Ni-NS_MeOH and HITP-Ni-NS_DMF display single component peaks attributed to HITP (Figures 2c). By calculating the peak areas in the Ni 2p_3/2 and N 1s regions, the atomic ratios of N to Ni for HITP-Ni-NS_MeOH and HITP-Ni-NS_DMF were evaluated as 4.0 and 4.7, respectively. The value in HITP-Ni-NS_MeOH matches the value of 4 as expected from the stoichiometry—four N atoms coordinate to one Ni atom while for HITP-Ni-NS_DMF the content of N is higher than 4, suggesting that unreacted amino groups not coordinating to nickel ions are included in HITP-Ni-NS_DMF.

図・表・数式 / Figures, Tables and Equations

Fig. 1   Overview of the assembly of HITP-Ni-NS at the air/liquid interface.

Fig. 2   XPS spectra of HITP-Ni-NS_MeOH (top) and HITP-Ni-NS_DMF (bottom) transferred on Si substrates at π = 20 mN m^-1 in the whole (a), in Ni 2p_3/2 (b) and in N 1s regions (c). For all spectra, binding energies were calibrated based on the C 1s peak of triphenylene (284.3 eV).

その他・特記事項（参考文献・謝辞等） / Remarks(References and Acknowledgements)

成果発表・成果利用 / Publication and Patents

論文・プロシーディング（DOIのあるもの） / DOI (Publication and Proceedings)

1. Takashi Ohata, Influence of the Solvent on the Assembly of Ni3(hexaiminotriphenylene)2 Metal–Organic Framework Nanosheets at the Air/Liquid Interface, Bulletin of the Chemical Society of Japan, 96, 274-282(2023).
   DOI: https://doi.org/10.1246/bcsj.20220283
   
2. Kazuaki Tachimoto, Assembling Triphenylene-Based Metal–Organic Framework Nanosheets at the Air/Liquid Interface: Modification by Tuning the Spread Solution Concentration, Langmuir, 39, 8952-8962(2023).
   DOI: https://doi.org/10.1021/acs.langmuir.2c02685
   
3. Takashi Ohata, Air/liquid interfacial formation process of conductive metal–organic framework nanosheets, Journal of Colloid and Interface Science, 651, 769-784(2023).
   DOI: https://doi.org/10.1016/j.jcis.2023.05.151
   

口頭発表、ポスター発表および、その他の論文 / Oral Presentations etc.

特許 / Patents

特許出願件数 / Number of Patent Applications：0件
特許登録件数 / Number of Registered Patents：0件