Uranyl salophen complex

By using derivatives of cellulose 3,5-dimethylphenyl carbamate (Chiracel OD) as the chiral phase Bergman measured the enantiopurity of complexes of molybdenum (2.45) and iridium (2.46) (Figure 2.67). With the same type of stationary phase, Gladysz measured the ee of rhenium complexes ReCp(NO)P(C6H5)2Br (2.13), and uranyl-salophen complexes of uranium were analysed with a Chiracel ODH column. 

Asfari, Z. Thuery, P. Nierlich, M. Vicens. J. Unsym-metrical calix[4]- /5-crowns-6 with unequivalent crown loops. Tetrahedron Lett. 1999. 40. 499-502. van Axel Castelli. V. Cort, A.D. Mandoliai. L. Rein-houdt, D.N. Schiaffino. L. Catalysis of the addition of benzenethiol to 2-cyclohexen-I-ones by uranyl-salophen complexes A catalytic metallocleft with high substrate specificity. Chem. Eur. J. 2000, 6. 1193-1198. Albrecht, M. Hovestad, N.J. Boersma, J. van Koten. G. Multiple use of soluble rnetallodendritic materials as catalysts and dyes. Chem. Eur. J. 2001, 7. 1289-1294. Haino. T. Araki. H. Yamanaka. Y. Fukazawa, Y. Fullerene receptor based on calix[5]arene through metal-assisted self-assembly. Tetrahedron Lett. 2001. 42, 3203-3206. 

Early contributions in this area came from Reinhoudt s group and refer to cases in which the ion-pair-binding mechanism is of the host-separated type (Figure 19c) (for original references see reviews ). They first exploited cone calix[4]arene tetraesters or 1,3-alternate calix[4] crowns as binding units for alkali metal ions and uranyl-salophen complexes as anion-binding sites. 

Inherent chirality Chirality that does not originate from a stereogenic element, but from the presence of a curvature in the structure. Originally coined for calixarenes, this term is also used for jullerenes and uranyl-salophen complexes. 

The majority of the devices mentioned thus far rely on the Hofmeister series for anion selectivity. However, for anions that deviate from this series, organometallic receptors can be utilised. The type of ligand or metal centre will influence the sensor selectivity due to the characteristics of the electron acceptance of the complex. An interesting development that is being explored here is the use of calixarenes. These have previously found use as cation-selective species, but with suitable substitution are now being incorporated within anion-selective devices. Compounds suitable as receptors for halides [61],benzoate [61] and acetate [62] have been developed. Reinhoudt and his co-workers have reported the production of a POj-selective CHEMFET based on a uranyl cation immobilised within a salophene ligand (Fig. 5), which shows selectivity over more lipophilic anions such as Br" and NOj [63]. 

The structured binding sites of metalloclefts mean that they are often highly selective hosts. An example is the salophen-uranyl-based metallocleft 3, which complexes neutral molecules, provided that the two phenyl groups of the host are parallel to one another. The salophen-uranyl unit may be employed as a catalyst for Michael additions, and the high steric requirements of the metallocleft of 3 result in it acting as a highly selective supramolecular catalyst. Metalloclefts of Type 4 selectively bind SO2 molecules and may be incorporated into dendritic materials that show catalytic activity. ... 

For the complexation of anions we have studied first the simple uranyl containing salophenes 22. Red single crystals of the complex of 22a with tetraethylammonium chloride were grown from a dichloromethane solution. The uranyl cation is coordinated to two oxygen atoms and two nitrogens of the salophene unit and to the chloride anion (U...C1 distance 2.76 A) which clearly shows the anion complexation (Figure 4). 

In receptors 23a-e, and 24 the uranyl center contains only one "vacant" position. We have also synthesized so-called "naked salophenes" 25a-c which have two vacant positions for complexation with guests [ref 28]. "Naked" U02-salophenes 25a-c have been prepared by reaction of the corresponding aldehydes, o-aminophenol and U02(0Ac)2 2H20 in refluxing MeOH in yields of 91-98%.Oi ange single crystals of the complex of "naked" ligand 25a with... 

The X-ray structure of U02(L1747)4H20 shows that the uranyl cation is com-plexed in the salophen moiety. The cavity is filled with four water molecules, one of which is coordinated at the fifth position of the complexed uranyl cation [113]. X-Ray crystallography of mononuclear barium complexes of H2LI739 and H2LI74O showed that the macrocyclic ligand used all oxygens to coordinate to the central atom. 

For the design of new receptor molecules with unique complexation properties calix[4]arenes have been combined with several other building blocks making use of the methods for their selective functionalization that were developed. In this paragraph the combination of calix[4]arenes with glycol chains (8), a terphenyl (9), and a uranyl containing salophen moiety (10) will be discussed. 

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