Dihydrogen phosphates, interactions

FIGURE 5. (A) Interaction of atovaquone with the Fe-S center (on left) in the cytochrome bc complex via H-bonding with the coordinated His (Plate VIII). (B) The active center of a class 2 dihydroorotate dehydrogenase (PDB ID 1UUM) with a hound inhibitor atovaquone (top baU-and-stick stmcture), orotic acid (green) and riboflavin 5 -(dihydrogen phosphate) (FMN, pink) (Plate IX)... 

We recently incorporated the ruthenium(II) bipyridyl moiety into acyclic, macrocyclic, and lower rim caUx[4Jarene structural frameworks to produce a new class of anion receptor capable of optical and electrochemical sensing (226, 253. 254). Stability constant determinations in DMSO using H NMR titration techniques demonstrated that these acyclic receptors (131 and 132) form strong complexes with chloride and dihydrogen phosphate anions (stronger than with analogous monopositive cobaltocenium based receptors). The ruthenium ion is dipositive and hence the electrostatic interactions are particularly favorable. The 4,4 -substituted ruthenium bipyridyls were observed to bind anions more... 

Thus, at this point, it makes it clear that a supramolecular host/receptor is meant to display an ability to make use of the possible covalent and noncovalent interactions to achieve the enhancement of binding strength and/or of selectivity. Dihydrogen phosphate was found in 13 in polar organic solvents with stability constants as high as 10 ... 

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