The structure and chemio-physical properties of the Metal Organic Frameworks (MOFs) are strongly affected by the nature of metal clusters and organic linkers, which are fundamental to the formation of coordination polymers with multidimensional networks. Given the geometry and chemical properties of multivalent, aromatic carboxylic acids, the materials have proven to be key to the production of high surface area and porous materials.
The advantages of carboxylic ligands include commercial availability and low cost, however their major drawback is the thermal resistivity. Stability of the framework can be controlled by using metal clusters. A good example is 08-0175, [1,1'-biphenyl]-4,4'-dicarboxylic acid, (BPDC). BPDC based MOFs generally display ultra high porosity1 and high thermal resistivity [UiO-67, isoreticular MOF of UiO-66 (catalog # 40-1105)]2. BPDC based materials can be used as adsorbents and for catalytic applications.
08-1220, Hydroxyl group enriched 2,5-Dihydroxyterephthalic acid (H4DOBDC) based MOFs, with open metal sites (M = Mg, Ni, Co, Mn, Fe, Zn), exhibit desirable adsorption and selectivity features.3 Another modification of a terephthalic acid based ligand is 15-7170, 2-(Diphenylphosphino)terephthalic acid, which contains a metal coordinating diphenylphosphine group. Product 07-1942, 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) contains four carboxylic groups and four nitrogen atoms for coordination.
08-1165, 1,4-Phenylenediacetic acid (H2PDA) has fluorescent properties and could be used for the preparation of photoluminescent MOFs. In addition, the H2PDA ligand has carboxylic groups in the 1,4 position, which allows the molecule to adopt various conformations and accommodate various geometric requirements.4
Other useful products include 08-0195, 1,3,5-Tricarboxybenzene (Trimesic acid, BTC), and 08-0635, 1,3,5-Tris(4-carboxyphenyl)benzene, (H3BTB or simply BTB=benzenetribenzoate). BTC reacts with many metal salts. Given the extended benzene ring structure, BTB based MOFs generally have very high surface areas [e.g. MOF-177 (5250 m2/g].5
References:
1. H. Furukawa et al. Ultrahigh Porosity in Metal-Organic Frameworks; Science, 2010, 329, 424.
2. K. P. Lillerud et al. A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability. J. Am. Chem. Soc., 2008, 130, 13850.
3. X. Kong et al. CO2 Dynamics in a Metal−Organic Framework with Open Metal Sites;
J. Am. Chem. Soc., 2012, 134, 14341.
4. G.P. Yang. A series of Zn(II) coordination complexes derived from isomeric phenylenediacetic acid and dipyridyl ligands: syntheses, crystal structures, and characterizations.
CrystEngComm, 2010, 12, 1509.
5. H. Furukawa et al, Independent verification of the saturation hydrogen uptake in MOF-177 and establishment of a benchmark for hydrogen adsorption in metal–organic frameworks.
J. Mater. Chem., 2007, 17, 3197.
Products mentioned in this blog and related products:
08-0175: [1,1'-Biphenyl]-4,4'-dicarboxylic acid, min. 98%, CAS # 787-70-2
08-1220: 2,5-Dihydroxyterephthalic acid, 98% H4DOBDC, CAS # 610-92-4
08-1165: 1,4-Phenylenediacetic acid, 97%, CAS # 7325-46-4
08-0195: 1,3,5-Tricarboxybenzene, min. 95% (Trimesic acid) BTC, CAS # 554-95-0
08-0635: 1,3,5-Tris(4-carboxyphenyl)benzene, min. 98% BTB, CAS # 50446-44-1
15-7170: 2-(Diphenylphosphino)terephthalic acid, 98%, CAS # 1537175-69-1
40-1105: Zirconium 1,4-dicarboxybenzene MOF (UiO-66), CAS # 1072413-80-9
07-1942: 1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid, min. 98% DOTA, CAS # 60239-18-1
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