Metalloporphyrin receptors

Metalloporphyrin receptors (e.g., 73) based solely on a single metal ion-anion coordinative interaction have seen considerable application as receptor species for incorporation in electrode systems (176-180). The main goal in... 

Beer. P.D. Drew. M.G.B. Jagessar. R. Selective anion recognition by novel 5,10,15,20-tetrakis(o-ferrocenylcar-bonylaminophenyl-substituted) zinc metalloporphyrin receptors. J. Chem. Soc. Dalton Trans. 1997, 5, 881. 

Finally, examples of the third type of ditopic receptor 30, containing two electron deficient metalloporphyrin receptor sites, can be synthesised by the route outlined in Scheme 4 [34]. The properties of these face-to-face porphyrins 39 as selective hosts have not yet been investigated although rather different face-to-face porphyrins have been investigated by Collmann and coworkers in a different context [35]. The diaryIpophyrin system of 39 was selected to provide a well defined structural unit and it is hoped that this approach to a largely pre-or-ganised cavity will prove to be effective. 

Figure 3. Quinone-receptor porphyrin left) and metalloporphyrin right).

Figure 24. AH-TAS plot for complexation by quinone-receptor porphyrins ( ) and ligation to metalloporphyrins (o).

The self-assembling principle has begun to be exploited by chemists in the design of synthetic molecular receptors. Hunter and co-workers [61] describe the use of metalloporphyrin coordination chemistry to build up the self-association of a very stable cyclic porphyrin dimer 45 which recognizes derivatives of terephthalic acid (46, 47) through hydrogen-bonding interactions (Scheme 15). 

Konishi K., Yahara K. A novel anion-binding chiral receptor based on a metalloporphyrin with molecular asymmetry. Highly enantioselective recognition of amino acid derivatives. J Am Chem Soc 1994 116 1337-44. 

Receptor 33 also incorporates a secondary Lewis acid anion binding site. This molecule is the zinc metallated ansdogue of 17 with the cobal-tocenium reporter groups replaced with ferrocenes [27]. The freebase precursor to 33 in dichloromethane solution shows no significant anion induced shifts in the H NMR signals of the amide protons, whereas the metalloporphyrin binds bromide (JC = 6200M ), nitrate (K = 2300M i)... 

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