ゼオライトNaY/クロロフォームム系におけるホスト・ゲストの水素結合の直接観測は,中性子散乱によるものです
Juergen Eckert1, Caroline Mellot Draznieks, Anthony K Cheetham
1Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
Journal of the American Chemical Society
|January 10, 2002
まとめ
中性子散乱は,クロロフォームとゼオライトの枠組酸素原子の間の水素結合を明らかにします. これは,多孔性の材料におけるゲストとホストの相互作用に関する以前の研究を裏付けている.
科学分野:
- 材料科学 材料科学とは
- 化学 化学は化学です.
- 物理 物理学 物理学とは
背景:
- ゼオライトは,触媒と分離における応用を持つ多孔性材料として広く使用されています.
- ゼオライト内のゲスト-ホストの相互作用を理解することは,そのパフォーマンスを最適化するために不可欠です.
- 以前の研究では,吸収された分子とゼオライトのフレームワークの間の相互作用が示唆されていたが,直接的な証拠は限られていた.
研究 の 目的:
- アドソーブされたクロロフォームとゼオライトNaYのフレームワークの間の水素結合の直接的な実験的証拠を提供すること.
- ニュートロン散乱を用いてこれらの相互作用の性質と方向性を特徴付ける.
主な方法:
- ニュートロン散乱コントラスト測定は,ゼオライトNaYに吸収された水素およびデュテラートクロロフォームで実施されました.
- 原子間距離と相関を特定するために,微分Hペア分布関数を分析した.
主要な成果:
- クロロフォームムの水素原子とゼオライトNaYのフレームワーク酸素原子の間の水素結合の直接的な証拠が観察されました.
- ソルバートの水素原子とフレームワークSi/Al原子の間の明確なベクターが特定されました.
- ゼオライトの毛穴内のクロロフォームム分子の空間的配置が解明されました.
結論:
- この研究は,クロロフォームとゼオライトの枠組みの間の特定の水素結合相互作用の存在を確認しています.
- これらの発見は,振動スペクトロスコピーとコンピュータモデリングによる以前の結論を検証しています.
- この結果は,ゼオライトにおける分子吸収機構の理解を深める.
関連する概念動画
Hydrogen Bonds
135.6K
Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....
135.6K
Hydrogen Bonds
15.5K
A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom...
15.5K
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
1.8K
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
1.8K
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
1.3K
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
1.3K
2D NMR: Overview of Heteronuclear Correlation Techniques
838
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other...
838
¹H NMR: Long-Range Coupling
2.8K
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
2.8K


