Tripodal Pseudopeptides with Three Histidine or Cysteine Donors:  Synthesis and Zinc Complexation

Abstract

Peptide coupling of benzene-1,3,5-carboxylic acid with 3 equiv of histidine ethyl ester or cysteine ethyl ester has yielded the tripodal pseudopeptide ligands THB and H(3)TCB. Likewise, the combination of tris(carboxyethyl)nitromethane with 3 equiv of cysteine ethyl ester gave the tripod H(3)TCM. With zinc salts, the pseudopeptides form the insoluble compounds (THB)(2)Zn(5)Cl(10), Zn(3)(TCB)(2), and Zn(3)(TCM)(2) which are likely to be coordination polymers. Solution studies of THB with potentiometric methods have identified the complex species [(THB)(2)Zn](2+), [(THB)Zn-OH(2)](2+), and [(THB)Zn-OH](+). The pK(a) of the zinc-bound water molecule is 6.2, making the (THB)Zn complex a viable model of carbonic anhydrase.

Tuning the coordination properties of multi-histidine peptides by using a tripodal scaffold: solution chemical study and catechol oxidase mimicking

“…Several tripodal peptides with different platforms have been designed as receptors of either organic molecules 16 or metal ions. [17][18][19][20][21][22][23][24][25][26][27][28][29] These ligands have several advantages in addition to the pre-organized structure and enhanced chelate effect. Using different amino acids, it is relatively easy to fine-tune the metal ion binding ability.…”

“…Only a few reports are available in the literature describing metal ion interactions with tripodal peptides, [17][18][19][20][21][22][23][24][25][26][27][28] most of them are related to sulphur-containing ligands. [17][18][19][20][21] A series of tricarboxylic acids have been used 22 …”

Columnar self-assembly of N,N′,N′′-trihexylbenzene-1,3,5-tricarboxamides investigated by means of NMR spectroscopy and computational methods in solution and the solid state

“…[8] Detailed studies of their aggregation process have highlighted the cooperative nature of these self-assemblies. [9,10] Derivatives of BTA have been investigated as MRI contrast agents, [11] metal complexation agents [12] and utilized in drug-delivery systems. [13] Investigations of BTA-based self-assemblies have focused on the effects of the aliphatic chains, [14,15] introduction of elements of chirality [16] and substitutions on the central aromatic moiety.…”

A Series of Tripodal Cysteine Derivatives as Water‐Soluble Chelators that are Highly Selective for Copper(I)

“…Therefore, three cysteine moieties can be attached with peptide bonds to nonbiological scaffolds to get pseudopeptide ligands. [20] Indeed, chemical scaffolds can serve as platforms for the design of podands that have all their binding arms oriented in the same direction to coordinate metal ions. [21] We have used such a strategy to obtain polydentate metal complexing molecules by appending several chelating functions in the same chemical architecture.…”