# MIL-101(Cr): supertetrahedra and giant cages

> MIL-101 is a chromium terephthalate made hydrothermally with HF. Trimers of CrO₆ octahedra and terephthalate links form supertetrahedra, which share corners like the tetrahedra of a zeolite (MTN topology). The result is a cubic cell of about 702,000 ų with mesoporous cages about 30 and 34 Å across and a Langmuir surface area near 5,900 m² g⁻¹.

- Page: https://www.labcanvas.com/templates/metal-organic-frameworks/mil-101-cr-supertetrahedra-mesoporous-cages
- Open in the LabCanvas editor (LabCanvas account): https://www.labcanvas.com/editor.html?template=mil101-giant-pores
- Updated: 2026-10-14
- Category: Metal–organic frameworks
- Method: Hydrothermal synthesis, bottom-up
- Starting materials: Chromium(III) nitrate nonahydrate, terephthalic acid (H₂BDC) and hydrofluoric acid in water
- Product: Green MIL-101(Cr) powder, Cr₃F(H₂O)₂O(BDC)₃·nH₂O (cubic, a ≈ 89 Å)
- Key result: Cell volume ≈ 702,000 ų; Langmuir surface area ≈ 5,900 ± 300 m² g⁻¹ (N₂) (Férey et al. 2005)
- Figure: 1920 × 1080 px, 85 editable layers (13 generated objects with settings)

## Steps

1. **Hydrothermal**: Cr(NO₃)₃·9H₂O, H₂BDC, HF and water in a Teflon-lined autoclave, 220 °C for 8 h
2. **Purify**: Free terephthalic acid filtered off; washing in hot ethanol
3. **Trimers**: Three CrO₆ octahedra share one μ₃-oxygen; F⁻/OH⁻ and water complete the chromium sites
4. **Supertetrahedra**: Four trimers at the corners, six BDC along the edges
5. **Cages**: Supertetrahedra share corners (MTN zeotype net): two kinds of mesoporous cage, about 30 and 34 Å

## Strengths

- Mesoporous cages that admit large molecules
- High surface area and pore volume

## Limitations

- HF and chromium in the synthesis
- Free terephthalic acid must be removed

## Uses

- Nanomold for monodisperse nanomaterials (Keggin polyanions in the cages)
- Adsorption and catalysis
- Drug storage and release (Horcajada et al. 2006)

## References

1. Férey et al., “A Chromium Terephthalate-Based Solid with Unusually Large Pore Volumes and Surface Area”, Science 2005. https://doi.org/10.1126/science.1116275 (primary)
2. Férey et al., “A Hybrid Solid with Giant Pores Prepared by a Combination of Targeted Chemistry, Simulation, and Powder Diffraction”, Angew. Chem. Int. Ed. 2004. https://doi.org/10.1002/anie.200460592 (further reading)
3. Horcajada et al., “Metal–Organic Frameworks as Efficient Materials for Drug Delivery”, Angew. Chem. Int. Ed. 2006. https://doi.org/10.1002/anie.200601878 (further reading)

Credit: Redrawn and simplified after Férey et al., Science 2005 (doi:10.1126/science.1116275) and Férey et al., Angew. Chem. Int. Ed. 2004 (doi:10.1002/anie.200460592). Trimer and supertetrahedron built at real bond lengths; cage drawn schematically.

## Questions

**What does the “MIL-101(Cr): supertetrahedra and giant cages” template show?** MIL-101 is a chromium terephthalate made hydrothermally with HF. Trimers of CrO₆ octahedra and terephthalate links form supertetrahedra, which share corners like the tetrahedra of a zeolite (MTN topology). The result is a cubic cell of about 702,000 ų with mesoporous cages about 30 and 34 Å across and a Langmuir surface area near 5,900 m² g⁻¹.

**What are the steps shown in “MIL-101(Cr): supertetrahedra and giant cages”?** 1. Hydrothermal: Cr(NO₃)₃·9H₂O, H₂BDC, HF and water in a Teflon-lined autoclave, 220 °C for 8 h. 2. Purify: Free terephthalic acid filtered off; washing in hot ethanol. 3. Trimers: Three CrO₆ octahedra share one μ₃-oxygen; F⁻/OH⁻ and water complete the chromium sites. 4. Supertetrahedra: Four trimers at the corners, six BDC along the edges. 5. Cages: Supertetrahedra share corners (MTN zeotype net): two kinds of mesoporous cage, about 30 and 34 Å.

**What are the starting materials and the product?** Starting materials: Chromium(III) nitrate nonahydrate, terephthalic acid (H₂BDC) and hydrofluoric acid in water. Product: Green MIL-101(Cr) powder, Cr₃F(H₂O)₂O(BDC)₃·nH₂O (cubic, a ≈ 89 Å).

**Which papers is “MIL-101(Cr): supertetrahedra and giant cages” based on?** Férey et al., “A Chromium Terephthalate-Based Solid with Unusually Large Pore Volumes and Surface Area”, Science 2005 (doi:10.1126/science.1116275); Férey et al., “A Hybrid Solid with Giant Pores Prepared by a Combination of Targeted Chemistry, Simulation, and Powder Diffraction”, Angew. Chem. Int. Ed. 2004 (doi:10.1002/anie.200460592); Horcajada et al., “Metal–Organic Frameworks as Efficient Materials for Drug Delivery”, Angew. Chem. Int. Ed. 2006 (doi:10.1002/anie.200601878).

**Can I edit the “MIL-101(Cr): supertetrahedra and giant cages” template?** Yes. Open it in the LabCanvas editor: all 85 layers are editable, including 13 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

**Do I need an account to use this template?** Not to view it here. To open and edit it, sign in to LabCanvas or create a free account (the free plan keeps one design of each kind). Downloading the figure is part of LabCanvas Pro (US$19 a month or US$199 a year).