Zinc MOFs

Sometimes, LMCT or MLCT luminescence may compete with ligands-based luminescence, resulting in two emission bands. For example, excitation of the zinc MOF Zn2(ATA)3(ATA)2/2 at 320 nm at room temperature produces a blue luminescence with a weak emission peak centered at 485 nm that may be assigned to the... 

Many of the covalent PSM reactions in Table 1 were first carried out on zinc MOFs such as IRMOF-3, but recently, there has been a growing interest in the use of MOFs that are less moisture-sensitive, as these are likely to be easier to exploit for applications. This has also allowed the development of PSM reactions that are not feasible for zinc MOFs as the reaction conditions would lead to decomposition of the framework. For example. Stock and coworkers showed that MIL-101 (Cr) is sufficiently stable to acid that the aromatic rings can be nitrated with a mixture of concentrated sulfuric and nitric acids at 0°C, the reaction going to completion within 5 h. The resultant nitro groups were reduced to amines using tin(II) chloride in ethanol (equation 7). ... 

PSM protocols can be used to prepare ligands that cannot be synthesized using conventional methods. For example, 2-vinyl-l/f-benzo[J imidazole-carboxylic acid had not previously been reported before its synthesis within a MOF by alcohol dehydration on the zinc MOF [Zn3(L )2(OH)2] (equation 13). Subsequent attempts to prepare the acid without the use of the MOF as a protecting group were hindered by competing polymerization reactions. ... 

Telfer and coworkers showed that the same nitrobenzyl groups could be incorporated into bpdc linkers and that the resultant zinc MOF [Zn40(bpdc-0CH2CgH4N02-2)3] has an IRMOF structure. Photolysis of powdered samples of this 2-nitrobenzyl ether with... 

Figure 4.1 Representation of the structure of MOF-5 (a) six carboxylic acid groups from terephthalic acid are connected to four Zn" cations to form a metal-organic elementary zinc carboxylate cluster (only...

By considering the results of previous experiment, they synthesized cobalt-, nickel-, copper-, and zinc-based, new pillared MOFs of similar topologies which exhibited good water stability [233]. The grafted methyl group on the benzene dicarboxlate (BDC) ligand introduced steric factors around the metal centers consequently, water stability of MOF drastically improved. 

The composites described in this chapter present superior quality which is demonstrated by their surface properties and performance in comparison with the parent components, GO and MOF or other inorganic phases. The important aspect of these composite formations is taking advantage of the promising properties of both phases and the creation of the hybrid, which exhibits the surface features of both phases and, as a bonus, new unique properties created on the interface. Moreover, the specific behavior of the individual components when placed together can open the door for new applications, not foreseen in this concise chapter. One should see that the detailed characterization of these materials as adsorbents is only one example of their application, which we could explore in detail. Nevertheless, the zinc (hydr)oxide story, where the enhanced photoactivity and water splitting reactions were noticed while investigating the adsorption phenomena, is one more example of the open book of the usefulness of such new materials. 

Akhtar, A. and Becker, P.B. (2001) The histone H4 acetyltransferase MOF uses a C2HC zinc finger for substrate recognition. EMBO Rep. 2, 113-118. 

Figure 9.42 Secondary Building Units (SBU) using carboxylates with rigid coordination geometries that replace metal ions as vertices in MOFs. (a) Paddlewheel or lantern structure as in 9.17, (b) octahedral basic zinc acetate SBU used in MOF-5 and (c) a trigonal prismatic oxo-centred trimer. The poly-hedra use carboxylate carbon atoms as their vertices and the MOFs propagate via the linkers attached to these carbon atoms. The metal atoms are bound to only terminal ligands in addition to those shown.

Fig. 8 MOF-5,21 a porous cubic zinc terephthalate which is topologically analogous to Re03. Gray spheres denote carbon, red oxygen, and white hydrogen, with Zn04 tetrahedra in blue. Reproduced with permission. Copyright 1999, Macmillan Publishers Ltd.

Additionally the partial and total densities of states (PDOS, DOS) for the free linkers and the free connector in comparison with IRMOF crystals have been studied. The results show that the contributions of the carbon atoms of a free linker and the MOF system to the DOS do not significantly differ. On the other hand, the PDOS of the oxygen atoms change in both cases, since in a MOF we have only one type of 01 atoms, whereas in the free linker there are the two different oxygen atoms of the carboxyl group. Considering the free connector, the zinc PDOS is very similar to that in the MOF systems or bulk ZnO. 

The extinction coefficient of triplet benzophenone has been remeasured as 7220 320 dm moF cm at 530 nm and this has been used to measure the triplet yield for zinc tetraphenylporphine. The sensitization of naphthalene by benzophenone has been examined in different hydrocarbon or ethanol-ether glasses.Internal heavy-atom effects on the T, states of monochloro-... 

Fig. 18.8. The zinc terephthlate hybrid polymer MOF-5. Zn04 tetrahedra are shown in gray and carbon and hydrogen atoms are drawn as gray spheres. Solvent molecules are omitted for...

Separation of gold from copper, platinum, palladium, nickel, zinc, cadmium and mercury using triphenylarsine oxide as an extractant has been described [1]. The reaction of NN-dimethyl-p-phenylenediamine with Au in the presence of potassium persulfate made a basis of sensitive method for the determination of Au (e= 1.9 10 1 mof cm ) [2]. 

The rotational barrier associated with zinc was 1.67 kJ mol and with BDC 1 kJ mol, higher than single-walled carbon nanotubes (0.105 kJ mof ). The width of the rotational band (4 cm ) was much less than for carbon (20 cm ) showing a lower dihydrogen mobility and hence stronger binding in [Zii4(BDC)30] than carbon. 

The checkers conducted the procedure using zinc nitrate hexahydrate and at 1/5 scale (3.15 g Zn (N03)2-6H20 and 0.612 g terephthalic acid in 70 mL DEF). After exchanging solvents and evacuating at 120°C, 0.76g of pure highly crystalline MOF-5 was obtained. 

---