Azonia Spiro polyaza macrocycles containing biphenyl subunits as anion and cation receptors

作者：Isabel Burguete M; Paz Clares M; Garcia Espana Enrique^*; Luis Santiago V; Querol Mane; Marti Centelles Vicente

来源：Tetrahedron, 2011, 67(25): 4655-4663.

DOI：10.1016/j.tet.2011.04.071

• Supramolecular chemistry
• Macrocycles
• Polyaza cyclophanes
• Anion recognition
• Metal complexes

The reaction of N-Boc triprotected cyclam with bis(chloromethyl)biphenyl followed by the corresponding deprotection of the nitrogen atoms allows the preparation of receptor 3 containing an azonia Spiro subunit. This receptor shows slightly increased basicity than cyclam, in particular for the formation of the appropriate triply charged species as a consequence of the reduced capacity of the structure present in 3 to stabilize the species with lower protonation degrees through the formation of intramolecular hydrogen bonds. The properties of 3 as a receptor for Cu(2+) and Zn(2+) and the anions derived from PO(4)(3-) (Pi), P(2)O(7)(4-) (PPi), P(3)O(10)(5-) (TPP) and ATP have been studied by pH-metric titrations carried out in aqueous solution. While Cu(2+) forms a CuL(2+) complex and two hydroxylated species of moderate stability, Zn(2+) forms only hydroxylated complexes. The association constants obtained for the 1:1 A:L anion complexes denote significant stability for Pi, PPi and ATP; the stability of the H(5)LA complex found in the case of TPP being lower. (1)H NMR spectra for the ATP:L carried out at pD=5.8 show features attributable to the occurrence of intermolecular pi-pi stacking between the biphenyl unit of 3 and the adenine ring of the nucleotide. OFT calculations have been carried out to rationalize some of the results found, in particular the remarkable different basicity between receptor 3 and cyclam.

• 出版日期2011-6-24