Tetrazole peptides as copper(II) ion chelators

Chelating ability and biological activity of hesperetin Schiff base

“…The [C(5)-O --C(4)-N] coordination mode, i.e. one oxygen and one nitrogen as donor atoms, is supported by the d-d electron transition energy corresponding to λ max = 640 nm which is similar to many other Cu(II) systems [44,45]. This species coexists in low pH with aqua copper(II) ions therefore λ max registered at 3.50 pH is slightly shifted to lower energy (see Fig.…”

Heterocyclic Hypervalent Iodine(III) Compounds with Fused Benziodazole and Tetrazole Rings (I-Substituted Tetrazolo[1,5-b][1,2]Benziodazoles)

“…Thus, when 5 was refluxed in acetic anhydride for 15 min, the original heterogeneous mixture turned into a brown solution, which, upon cooling to -20 ºC, afforded an off-white microcrystalline compound, 5-acetoxy-5H-  -tetrazolo[1,5b][1,2]benziodazoles or BIAT-OAc 6, which was identified spectroscopically ( 1 H and 13 C NMR as well as ESI-HRMS), and by single-crystal X-ray crystallography (Figure 3). Tetrazoles have found significant applications in coordination chemistry, 59,76,77 photography, specialty explosives, and in drug synthesis. [78][79][80][81] The last application is due to the fact that tetrazoles are metabolically (hydrolytically) stable analogues of carboxylate esters.…”

Metallo‐Foldamers with Backbone‐Coordinative Oxime Peptides: Control of Secondary Structures

“…In the helical complexes 5 – 7 , formed from 2 or 3 , two deprotonated N‐H groups bind to the Pd II centers as the trans ligands. Coordination structures of such complexes are often controllable by addition of acid and base 9a,d. Indeed, complexation of dipeptides 2 and 3 with Pd(CH 3 CN) 4 (BF 4 ) 2 containing BF 4 − anions instead of basic AcO − anions in Pd(OAc) 2 afforded alternative mononuclear complexes as confirmed by 1 H NMR spectroscopy (see Figures S27, S43 in the Supporting Information) and ESI‐TOF mass spectrometry ( m / z 527.07 [Pd(H −1 2 )] + for 8 and 512.08 [Pd(H −1 3 )] + for 9 ).…”