2つのホモトープ結合部位を持つ受容体への金属イオン調整に対する反直感的静電学
Vidar Aspelin1, Anna Lidskog2, Carlos Solano Arribas2
1Division of Theoretical Chemistry, Department of Chemistry, Lund University, Lund SE 221 00, Sweden.
Journal of the American Chemical Society
|February 10, 2022
まとめ
この研究は,第2のカリウムイオンがトローガーの bis ((18-crown-6) アナログに第1のイオンより好意的に結合することを明らかにした.
科学分野:
- 超分子化学
- 物理化学
- コンピュータ化学
背景:
- トローガーの塩基 (BCETB) のBis(18-crown-6) アナログは,イオンを結合できる宿主分子である.
- 連続イオン結合の理解は,選択的分子受容体の設計に不可欠である.
- 以前の研究では,このようなシステムにおける連続的なイオン複合化の熱力学的な原動力を完全に解明できませんでした.
研究 の 目的:
- 水溶液中のBCETBへの連続したカリウムイオン結合の熱力学を調査する.
- 観察された結合行動を支配する構造的およびエネルギー的な貢献を探求する.
- 理論的・計算的モデルで実験結果を検証する.
主な方法:
- 結合エンタルピーとアフィニティを測定するために,同熱定位カロミトリー (ITC) が使用された.
- 相互作用をモデル化するために連続体静電理論が使用されました.
- 複製交換分子動力学 (REMD) シミュレーションにより,形状と相互作用に関する原子規模の洞察が得られました.
主要な成果:
- 逆の熱力学的プロファイルが観察された:第2のカリウムイオン結合は,第1よりもエンタルピー的に有利である (ΔHbind,2° < ΔHbind,1°).
- 分子ダイナミクスシミュレーションは実験的傾向を確認し,エンタルピックK + - K + 引き寄せとイオン結合時に崩壊したBCETB構成の確率を増加させた.
- 観察された傾向は,チオシアネートの弱い水分化がエンタルピー差の大きさに影響するにもかかわらず,カウンターイオンとは大きく独立している.
結論:
- 第二のカリウムイオンの強化された結合は,BCETBの崩壊した形状によって促進された有利な分子内相互作用に起因する.
- 結合したカリウムイオン間のエンタルピック吸引は,観測された熱力学的好意性に寄与する.
- この研究は,構造的,静電的,および溶解効果の連続的な宿主-ゲスト複合性の複雑な相互作用に関する基本的な洞察を提供します.
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