Methods for Electrochemically Induced Cathodic Deposition of Crystalline Metal-Organic Frameworks

• US 20120297982A1
• Filed: 04/04/2012
• Published: 11/29/2012
• Est. Priority Date: 04/04/2011
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Dinca, Mircea, Li, Minyuan
• Granted Patent: US 8,764,887 B2
• Time in Patent Office: Days
• US Class Current: 96/4
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 71/02 Inorganic material
• CPC Class Codes: B01D 71/0213 Silicon
• CPC Class Codes: B01D 71/028 Molecular sieves carbon B01D71/021
• CPC Class Codes: B01J 20/226 Coordination polymers, e.g. metal-organic frameworks [MOF], zeolitic imidazolate frameworks [ZIF] preparation of metal complexes containing carboxylic acid moieties C07C51/418; MOF's per se C07F
• CPC Class Codes: B01J 20/28033 Membrane, sheet, cloth, pad, lamellar or mat
• CPC Class Codes: B01J 20/30 Processes for preparing, regenerating, or reactivating
• CPC Class Codes: C07C 51/418 Preparation of metal complexes containing carboxylic acid moieties
• CPC Class Codes: C07C 63/28 Salts thereof
• CPC Class Codes: C07F 3/003 without C-Metal linkages
• CPC Class Codes: C25D 17/002 Cell separation, e.g. membranes, diaphragms
• CPC Class Codes: C25D 9/08 by cathodic processes
• CPC Class Codes: Y10T 428/12674 Ge- or Si-base component

Abstract

Embodiments of the invention relate to a method for preparing crystalline metal-organic frameworks (MOFs). The method includes the steps of providing an electrolyte solution in contact with a conductive surface, and applying a current or potential to the conductive surface in contact with the electrolyte solution. The electrolyte solution includes a protonated organic ligand, a metal ion, and a probase. Application of the reductive current or potential to the conductive surface produces the crystalline metal-organic framework (MOF) deposited on the conductive surface. The MOFs produced by the method may be incorporated into a gas separation membrane, a purification filter, and/or a sensor.

Claims

1. A method for preparing a crystalline metal-organic framework (MOF), the method comprising the steps of:

providing an electrolyte solution in contact with a conductive surface, the electrolyte solution comprising a protonated organic ligand, a metal ion, and a probase; and

applying a current or potential to the conductive surface in contact with the electrolyte solution, thereby producing the crystalline metal-organic framework (MOF) deposited on the conductive surface.

2. The method of claim 1, wherein the protonated organic ligand contains a proton with an acidity constant (pK_a in water and at 25°

C.) having a value from 0 to 15 such that the proton can be removed in situ by an electrochemically produced base species.

3. The method of claim 2, wherein the electrochemically produced base species is a hydroxide anion.

4. The method of claim 2, wherein the electrochemically produced base species is an amine.

5. The method of claim 1, wherein the organic ligand comprises one or more members selected from the group consisting of a carboxylic acid, a tetrazole, a 1,2,3-triazole, a 1,2,4-triazole, a pyrazole, a sulfonic acid, a phosphonic acid, a sulfinic acid, a phosphinic acid, and an imidazole.

6. The method of claim 1, wherein the metal ion comprises a member selected from the group consisting of Zn²⁺, Cu²⁺, Cu⁺, Co²⁺, Co³⁺, Ni²⁺, Mn²⁺, Mn³⁺, Mn⁴⁺, Fe²⁺, Fe³⁺, V²⁺, V³⁺, Cr²⁺, Mo²⁺, W²⁺, Ru²⁺, Os²⁺, Cd²⁺, Be²⁺, Mg²⁺, Ca²⁺, Ba²⁺, Sr²⁺, and Ln³⁺ where Ln is any of the lanthanide ions.

8. The method of claim 1, wherein the conductive surface catalyzes the reduction of the probase to generate a base species.

9. The method of claim 1, wherein the conductive surface is transparent or semi-transparent.

10. The method of claim 1, wherein the deposition of the crystalline metal-organic framework on the conductive surface is cathodic electrodeposition rather than anodic electrodeposition, such that the conductive surface does not undergo corrosion during the deposition.

11. The method of claim 1, wherein the current or potential is applied to the conductive surface in contact with the electrolyte solution such that the probase is reduced at or near the conductive surface, thereby generating a base species, wherein the protonated organic ligand is deprotonated in situ by reaction with the base species, and wherein the deprotonated organic ligand reacts with the metal ion, thereby producing the crystalline metal-organic framework deposited on the conductive surface.

12. The method of claim 1, wherein the probase comprises an oxoanion.

13. The method of claim 12, wherein the oxoanion comprises a member selected from the group consisting of nitrate (NO₃⁻

), perchlorate (ClO₄⁻

), and sulfate (SO₄²⁻

).

14. The method of claim 1, wherein the probase comprises a member selected from the group consisting of water, molecular oxygen (O₂), triethylammonium, benzoquinone, a benzoquinone derivative, or the protonated organic ligand itself.

15. The method of claim 1, wherein the probase comprises an ammonium cation.

16. The method of claim 1, wherein the deposition of the crystalline metal-organic framework on the conductive surface is performed in a single step.

17. The method of claim 1, wherein the deposition of the crystalline metal-organic framework on the conductive surface is performed at room temperature.

18. A gas separation membrane comprising the crystalline metal-organic framework prepared by the method of claim 1.

19. A purification filter comprising the crystalline metal-organic framework prepared by the method of claim 1.

20. A luminescent sensor comprising the crystalline metal-organic framework prepared by the method of claim 1.

21. A sensing device comprising the crystalline metal-organic framework (MOF) prepared by the method of claim 1, wherein the conductive surface comprises silicon and/or a transparent conductive material, and wherein the MOF and the conductive surface are integrated into an electronic circuit.

22. A luminescent small molecule sensor comprising a crystalline metal-organic framework deposited on a transparent or semi-transparent substrate using the method of claim 1, wherein the metal-organic framework is intercalated with luminescent guest molecules that interact with the metal-organic framework in the presence of a specific small molecule, thereby producing a detectable luminescence that is characteristic of the presence of the specific small molecule.

23. A crystalline metal-organic framework deposited on a transparent or semi-transparent substrate using the method of claim 1.

24. A sensing device comprising a crystalline metal-organic framework (MOF) deposited on a conductive surface using the method of claim 1, the conductive surface comprising silicon and/or a transparent conductive material, wherein the MOF and the conductive surface are integrated into an electronic circuit.

7. The method of laim 1, wherein the conductive surface comprises one or more members selected from the group consisting of fluorine doped tin oxide (FTO), indium tin oxide (ITO), silicon, carbon, graphite, zinc, cobalt, nickel, copper, titanium, iron, and steel.