Design of a conductive metal–organic framework based on a TTF-inspired Ligand
Notice bibliographique
Résumé
This thesis presents the design of novel sulphur-metal linked conductive metal-organic frameworks (c-MOFs) based on a tetrathiafulvalene (TTF)-inspired ligand, 2,4,6-tris(4,5-disulfanyl-1,3-dithiol-2-ylidene)-1,3,5-cyclohexanetrione (TDCT). TDCT was chosen due to its planar π-conjugated structure, reversible redox activity, narrow electrochemical bandgap (1.27 eV), non-integer oxidation state, and the precedence of high conductivity in related TTF and dithiolene systems. The combination of conductivity and porosity in c-MOF enables various applications, such as electrocatalysis, energy storage and sensing.To verify the feasibility of the synthesis of c-MOF based on TDCT ligands, we first synthesized molecular complexes modelling the structure of the target c-MOFs, [Ni(4Bu-TDCT)₂]2-(Bu4N+)2 and [Zn(4Bu-TDCT)₂]2–(Bu4N+)2. Cyanoethyl protecting groups were introduced onto the ligand molecules to obtain air-stable derivatives. Following in-situ deprotection and coordination with metal ions, the resulting complexes were obtained as dark orange and dark green solids. Their structures were established via NMR spectroscopy and mass spectrometry. The ¹³C NMR spectrum of the Ni complex showed no signals for carbon atoms located in proximity (within eight bonds) of the metal center. This is attributed to paramagnetic broadening owed to the presence of the oxidized radical anion species [Ni(4Bu-TDCT)₂]•-. Integration of the S–CH₂ and N–CH₂ proton signals confirmed the presence of a mixed-valence state in the nickel complex, showing its non-stoichiometric nature as [Ni(4Bu-TDCT)₂]1.37–(Bu4N+)1.37. In contrast, the Zn complex revealed the expected stoichiometric ratio [Zn(4Bu-TDCT)₂]2–(Bu4N+)2 and did not show any paramagnetic broadening in its NMR.The Ni complex in CDCl3 solution also exhibited a strong Electron Paramagnetic Resonance (EPR) signal, while the Zn complex was EPR silent. Cyclic voltammetry (CV) revealed a highly electron-rich nature of [Ni(4Bu-TDCT)₂], which undergoes a reversible oxidation at a very low potential E1/2 = –0.69 V vs. Fc/Fc⁺, suggesting facile oxidation by oxygen in the air. In contrast, the oxidation potential of Zn complex was higher (E1/2 = -0.21 V vs. Fc/Fc⁺), explaining its greater air stability.Both complexes also showed reversible two-electron reduction waves (one electron per ligand). The electrochemically determined HOMO-LUMO gaps (1.27 eV and 1.76eV) are very close to their optical gaps, Eg =1.28 eV for Ni and 1.76 eV for Zn. Guided by these results, we explored the synthesis of a two-dimensional c-MOF, Ni₃(TDCT)₂, via a similar deprotection strategy from hexa(2-cyanoethyl)-TDCT precursor. The reaction is limited by the oxidative instability of the hexaanionic TDCT intermediate, and we explored several strategies to minimize the oxidative side reactions. We have the preliminary investigations showing partial crystallinity observed in the WAXS of the c-MOF. The electrical conductivity of 10-3 S/cm was measured in compressed pellets by a two-probe technique. This work establishes a new TTF-derived platform of ligand for conductive framework development and underscores the importance as well as the challenges of redox-active linkers in the design of c-MOFs
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».