Metal Complexes with a New N₄O₃Amine Pendant-Armed Macrocyclic Ligand:  Synthesis, Characterization, Crystal Structures, and Fluorescence Studies

Abstract

The synthesis of a new oxaaza macrocyclic ligand, L, derived from O(1),O(7)-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren containing an amine terminal pendant arm, and its metal complexation with alkaline earth (M = Ca(2+), Sr(2+), Ba(2+)), transition (M = Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+)), post-transition (M = Pb(2+)), and Y(3+) and lanthanide (M = La(3+), Er(3+)) metal ions are reported. Crystal structures of [H(2)L](ClO(4))(2).3H(2)O, [PbL](ClO(4))(2), and [ZnLCl](ClO(4)).H(2)O are also reported. In the [PbL] complex, the metal ion is located inside the macrocyclic cavity coordinated by all N(4)O(3) donor atoms while, in the [ZnLCl] complex, the metal ion is encapsulated only by the nitrogen atoms present in the ligand. pi-pi interactions in the [H(2)L](ClO(4))(2).3H(2)O and [PbL](ClO(4))(2) structures are observed. Protonation and Zn(2+), Cd(2+), and Cu(2+) complexation were studied by means of potentiometric, UV-vis, and fluorescent emission measurements. The 10-fold fluorescence emission increase observed in the pH range 7-9 in the presence of Zn(2+) leads to L as a good sensor for this biological metal in water solution.

Copper complexes with new oxaaza-pendant-armed macrocyclic ligands: X-ray crystal structure of a macrocyclic copper(II) complex

“…The distance of the Cu atom to the N 3 coordination plane (N1N3N4) is 0.0993 (0.0120) Å , indicating that the metal is barely out of the plane but the distance is 0.2776(0.0106) to the N1N3N4 0 plane. The crystal structure is similar to that of [Zn(1)Cl](ClO 4 ) AE H 2 O previously reported [14] and in that case the fifth coordination position around Zn(II) is occupied by a chloride ion. The macrocycle is folded and the dihedral angle between the aromatic rings is 64.82 (0.37)°.…”

“…As for macrocycle 1 [14], the spectra show that the two halves of the macrocyclic ring are chemically equivalent; i.e., there is a C 2 -axis that crosses the middle ether oxygen and the tertiary nitrogen atom as shown by the 13 C spectra that exhibit only 11 resonances for the carbons of the macrocyclic backbone and 9 for carbons of the pendant arm. In the proton NMR spectrum of 4 the -NCH 2 CH 2 N-chains give rise to well resolved signals, however, the -OCH 2 CH 2 O-chains give rise to multiplets, indicating that this part of the macrocycle is less rigid.…”

“…Recently, we have reported synthesis and characterization of the functionalized pendant-armed macrocyclic ligand 1 [14]. This saturated ligand, which is more stable against hydrolysis than the corresponding diiminic ligand, has been obtained by in situ reduc- tion of L with NaBH 4 in the absence of any metal anion.…”

Synthesis and Biophysical Studies of Bis‐Macrocyclic Cobalt/Copper(II) Complexes Having a Pyridine Spacer with CT DNA and 5′‐GMP

“…The , corresponding to n(CÀN), confirm the macrocyclic structure of the complexes. Additionally, broad bands at 3200 -3300 cm À 1 were ascribed to the stretching vibration of n(NÀH) of the NHÀCH 2 ÀCH 2 ÀNH linkage [30]. Other diagnostic bands of medium intensity at 2769 -2781 and 1300 -1400 cm À 1 were assigned to CÀH stretching and bending vibrational modes, respectively [31].…”

Synthesis and Characterization of a New Macrocyclic Copper(II) Complex with an N‐Glycosidic Pendant Arm: in vitro Cytotoxicity and Binding Studies with Calf‐Thymus DNA

“…Additionally, a single band at ca. 3251 cm À1 was observed in the IR spectra of 1a,b, which was attributed to n(NÀH) of the coordinated secondary amino functions of the macrocycle [26], and the signals at 1398 and 1284 cm À1 were ascribed to n(CÀN) and t(CÀH) vibrations. The far-IR spectra of the complexes exhibited a further absorption at ca.…”