アミン基本性 (pKb) は,単一壁の炭素ナノチューブ電子センサー配列の分析剤結合エネルギーを制御する
Chang Young Lee1, Michael S Strano
1Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|January 15, 2008
まとめ
研究者らは,アミン機能化を使用して,単一壁の炭素ナノチューブ (SWNT) センサー配列に可逆吸収部位を作成しました. このブレークスルーにより,再生なしに, parts-per-trillion レベルでの分析物の非常に敏感で,可逆的な検出が可能になりました.
科学分野:
- マテリアルサイエンス 材料科学
- ナノテクノロジー ナノテクノロジー
- 化学センサー 化学センサー
背景:
- 単一壁の炭素ナノチューブ (SWNT) ネットワークは,電子センサーとトランジスタで広く使用されています.
- SWNT表面での不可逆的な分析剤吸収は,その検出アプリケーションを制限する.
- この不可逆的吸収の根本的なメカニズムは,まだ十分に理解されていない.
研究 の 目的:
- SWNTのアナリート吸附機構を理解し,制御する.
- リバーシブルな分析剤結合のためのSWNT表面を設計する.
- 高感度で再利用可能なSWNTベースのセンサーを開発する.
主な方法:
- SWNT配列の非共性機能化は,アミン末端分子によるものです.
- チオニルクロライドをモデルアドソルベートとして使って,アドソルプションを研究する.
- X線光電子スペクトロスコーピー (XPS) と分子ポテンシャル計算を用いた特徴化.
- ポリエチレンアミン (PEI) のような様々なアミンを含む分子とポリマーアミンのテスト.
主要な成果:
- SWNT配列では,アミン機能化 (pKa <8.8) を通じて,可逆的吸収部位が成功裏に作成されました.
- 分析物質の吸収は,表面アミン群の塩基性 (pKb) によって著しく影響を受けます.
- 結合エネルギーを減らす媒介性吸附機構がXPSと計算によって特定され,支持されました.
- 活性再生なしのポリエチレニミン (PEI) 機能化を使用して parts-per-trillion レベルの可逆検出を達成しました.
結論:
- 特定のアミン分子による表面機能化は,SWNTの可逆的な分析剤吸収を可能にします.
- この媒介性吸附機構は,様々なSWNTベースのセンサー設計に適用できる一般的な現象です.
- 開発された方法は,痕跡分析物質の検出のためのSWNTセンサーの再利用性と感度を大幅に高めています.
関連する概念動画
Basicity of Aliphatic Amines
Amines can behave as Brønsted–Lowry bases by accepting a proton from the acid to form corresponding conjugate acids. Due to a lone pair of nonbonding electrons, aliphatic amines can also act as Lewis bases by forming a covalent bond with an electrophile.
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates higher...
Basicity of Heterocyclic Aromatic Amines
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
Basicity of Aromatic Amines
The basicity of aromatic amines is much weaker than that of aliphatic amines due to the involvement of the lone pair of electrons over the N atom in resonance with the aryl rings. Generally, the electron-donating ability of any substituents on the aryl ring of aromatic amines increases the basicity of the amine by increasing electron density, and hence the availability of lone pair on the nitrogen. On the other hand, electron-withdrawing functional groups on the aryl ring of amines decrease the...
Acid and Bases: Ka, pKa, and Relative Strengths
This lesson delves into a critical aspect of the relative strengths of acids and bases. The strength of an acid is evaluated by the acid dissociation into its conjugate base and a hydronium ion in water. The complete dissociation of a strong acid is confirmed with a very high concentration of hydronium ions. As a result, an incomplete dissociation process affirms a weak acid. Therefore, the equilibrium is in the forward direction for strong acids and backward for weak acids in these reactions.
Potentiometry: Membrane Electrodes
Membrane electrodes, also known as p-ion electrodes, use membranes that selectively interact with free analyte ions, generating a potential difference across the membrane. The resulting membrane potential, known as the asymmetry potential, is not zero even when analyte concentrations on both sides of the membrane are equal. The membrane's response is typically not selective to a single analyte but proportional to the concentration of all ions in the sample solution capable of interacting at the...


