Metal-Organic Frameworks With Node Defects

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Solution Overview

Problem

Current methods for controlling missing-cluster defects in metal-organic frameworks (MOFs) lack sophistication and often require excessive modulator concentrations or environmentally undesirable substances, limiting the formation of well-defined and tunable structures with high surface area and porosity.

Innovation Solution

The synthesis of metal-organic frameworks comprising tetravalent cations and terephthalate linkers in a primitive cubic lattice, using a process involving specific divalent cations and monocarboxylic acids to induce node defects, resulting in materials with controlled surface area, porosity, and relative intensity, while minimizing the use of environmentally harmful modulators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional methods are used to control missing-cluster defects in MOFs, then defect formation can be achieved, but the control mechanisms lack sophistication and require excessive modulator concentrations or environmentally undesirable substances

Engineering Contradiction:

Improvedefect formation controlVSAvoidmodulator concentration requirements

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the chemical parameters of the modulator by using fluorinated carboxylic acids with specific fluorine substitution patterns. This modifies the modulator's interaction with metal nodes, enabling effective node defect formation at lower concentrations and with environmentally favorable substances

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fluorinated carboxylic acid modulators act as intermediaries that selectively bind to under-coordinated metal ions at defect sites. This intermediary mechanism enables precise control of node defect formation while avoiding the need for excessive concentrations or environmentally harmful substances

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If fluorinated carboxylic acids are used as modulators to promote node defects, then defect control is improved, but environmental desirability deteriorates

Engineering Contradiction:

Improvenode defect controlVSAvoidenvironmental impact

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by introducing fluorine atoms at specific positions on the carboxylic acid molecule. This localized modification enhances the modulator's ability to control node defects while using environmentally benign base structures, thereby improving environmental profile without sacrificing defect control

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If MOFs are made more stable by incorporating trivalent or tetravalent metals, then structural stability is improved, but the formation of well-defined defect structures becomes more difficult to control

Engineering Contradiction:

ImproveMOF stabilityVSAvoiddefect structure control

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent substitutes chemical mechanisms for physical/structural constraints by using fluorinated carboxylic acid modulators that chemically interact with metal nodes. This chemical approach enables precise defect control in stable MOFs containing trivalent or tetravalent metals, overcoming the difficulty of controlling defect formation in these robust structures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively generates metal-organic frameworks with enhanced surface area, porosity, and controlled defect structures, improving their adsorption and catalytic properties without relying on excessive modulator concentrations or environmentally undesirable substances.

Implementation Method 1

control mechanisms generating missing-cluster defects (node defects)

Methodology Applied

Scientific EffectDefect formation:

Implementation Method 2

certain modulators have been shown effective in adjusting missing-linker defects

Methodology Applied

Scientific EffectModulation of defect formation:

Implementation Method 3

Metal-organic frameworks have organic linkers that bridge metal nodes through coordination bonds to form a coordination network

Methodology Applied

Scientific EffectCoordination bonding: Chemical Bonding

Implementation Method 4

heating the reaction solution to provide a reaction mixture

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS20240278208A1Metal Organic Frameworks Having Node Defects And Methods Of Making The Same

Publication Date: 2024.08.22 EXXONMOBIL TECHNOLOGY & ENGINEERING CO

AI summary

Provided are metal-organic frameworks made by the process of comprising the steps of reacting a first metal source that can generate a tetravalent metal cation in solution, a linear dicarboxylic acid, a second metal source that can generate a divalent cation in solution, and one or more monocarboxylic acid modulators in a solvent to provide a reaction solution. The reaction solution is heated to provide a metal-organic framework having between about 0 wt. % to 10 wt. % of divalent cation, surface area between about 1100 m2/g and 2700 m2/g, a porosity of between about 0.45 cc/g and 1.1 cc/g, and a relative intensity equal to or greater than 0.35 and a peak width ratio of less than 3.0.