Metal-organic frameworks (MOFs) have emerged as versatile materials with applications in gas separation,

catalysis, and energy storage due to their high porosity and tunable structures. However, traditional synthesis

methods often involve toxic solvents and high energy inputs, limiting scalability and environmental

sustainability. This review explores green synthesis strategies for robust MOFs, focusing on water-based

hydrothermal and ambient temperature approaches that enhance stability and performance. Key examples

Metal-organic frameworks are crystalline materials composed of metal ions or clusters that are coordinated to

organic linkers, forming porous structures with vast surface areas. Robust MOFs, particularly those with

tetravalent metals like zirconium or aluminum, exhibit enhanced chemical and thermal stability, making them

suitable for real-world applications. Green synthesis emphasizes the use of eco-friendly solvents, such as

water, and mild conditions to minimize environmental impact. This approach addresses challenges in

scalability and toxicity associated with conventional methods using organic solvents or high temperatures.

Recent advances in ambient and hydrothermal green syntheses have enabled the production of MOFs with

tailored properties for energy-efficient processes.

Ambient synthesis occurs at room temperature, reducing energy consumption. Approaches include stepwise

assembly or direct mixing of precursors. For robust tetravalent MOFs, such as those based on zirconium, water

or minimal solvents are used to form stable frameworks. A notable example is the “bottle-around-ship” strategy

for incorporating metal nanoparticles into MOFs, creating composites at ambient conditions.

Aqueous synthesis at mild conditions yields robust MOFs like ZU-901, a zirconium-based framework, with

99% yield. This method involves pore engineering to optimize adsorption properties, using water as the sole

solvent for eco-friendly production. Other strategies incorporate waste materials, such as polyethylene

terephthalate (PET) for linkers, further enhancing sustainability.

isotherm with a working capacity of 0.31 mL H₂O mL⁻¹. This behavior is attributed to strong hydrogen bonding

interactions between water molecules and hydroxyl groups within the framework’s helical aluminum chains,

enhancing its suitability for water adsorption applications. The material maintains structural stability under

repeated adsorption-desorption cycles, with no significant loss of crystallinity after exposure to humid

conditions.

ZU-901, a zirconium-based MOF produced through aqueous-phase synthesis, showcases ultra-microporous

channels and remarkable stability across a wide range of chemical environments, including acidic (pH 2), basic

(pH 12), and aqueous conditions. Its high yield (99%) and robust framework are achieved through pore

engineering, optimizing the pore size distribution for selective gas adsorption. The stability of ZU-901 is

further confirmed by its consistent performance over multiple regeneration cycles, making it a promising

the nanoparticles from aggregation while facilitating substrate access.

CAU-10pydc demonstrates exceptional performance in water adsorption-driven heat allocation, achieving

coefficients of performance (COP) of 0.79 for cooling and 1.72 for heating, with a heat storage capacity of

273.5 kWh m⁻³. These metrics highlight its potential for solar-driven cooling and heating systems, particularly

in low-temperature environments. The S-shaped isotherm enables efficient water uptake and release at

moderate relative pressures, reducing energy requirements for regeneration compared to traditional adsorbents

like silica gels. This makes CAU-10pydc a sustainable alternative for energy-efficient thermal management

systems, with scalability enhanced by its water-based synthesis.

as a transformative material for industrial gas purification processes.

MNPs@MOF composites, synthesized under ambient conditions, exhibit synergistic effects between the

MOF’s porous structure and the catalytic activity of embedded nanoparticles. For example, these composites

demonstrate enhanced efficiency in peptide hydrolysis and CO₂ reduction, with turnover frequencies

significantly higher than those of standalone nanoparticles. The MOF matrix stabilizes the nanoparticles,

preventing leaching and enabling recyclability. Beyond catalysis, green-synthesized MOFs show promise in

environmental applications, such as wastewater remediation, where their high surface area and tunable pore

chemistry enable efficient removal of organic pollutants. Additionally, their integration into biosensors

leverages their structural precision for selective detection of biomolecules, opening avenues for medical

diagnostics.

The success of green synthesis methods lies in their ability to produce MOFs with tailored structural and

functional properties while minimizing environmental impact. The high yields and stability of frameworks

like ZU-901 underscore the scalability of aqueous-phase synthesis, addressing a key barrier to industrial

adoption. The use of water as a solvent eliminates the need for toxic organic solvents, aligning with green

chemistry principles. Moreover, the versatility of these MOFs across applications—from energy storage to

catalysis—demonstrates their potential to address global challenges such as energy efficiency and

environmental remediation. However, challenges remain, including optimizing synthesis conditions for even

lower energy inputs and exploring the integration of renewable feedstocks for linker production.

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