Synthesis, Structure And Properties Of Amino Acid Hydroxamic Acid Metal Crown Ether

Owing to strong coordination ability and multiform coordination, hydroxamic acid ligands can form different types of complexes when they reacted with different metal salts, most of which are M-N-O metallacrowns. The research proved that these complexes display special magnetic properties, recognition of anion and cation, catalytic activing, and biological activities. So these metallacrowns have potential application prospect and research value in magnetic materials, ion recognition reagent, catalyst, and many other fields. In addition, metallacrowns can be used as a “second construction unit” with bridge ligands constructing multi-dimensional coordination polymers, which have a variety of functions. In our work, seventeen metallacrowns were synthesized by two hydroxamic acid ligands functioning with different metal salts, and they were characterized by X-ray single crystal diffraction, IR spectra and elemental analysis. DNA binding and magnetic properties of some complexes were researched. The main contents are listed as follows:1. Seven metallacrowns: {La(OAc)(H2O)2[15-MCCu(N)glyha-5](H2O)4}·2NO3·5H2O(1), {Gd(OAc)(H2O)[15-MCCu(N)glyha-5](H2O)3}·2NO3·5H2O(2), {Tb(OAc)(H2O) [15-MCCu(N)glyha-5](H2O)4}·2NO3·4H2O(3), {Dy(OAc)(H2O)[15-MCCu N(glyha)-5](H2O)4}·2NO3·3H2O(4), {Pr(NO3)(H2O)2[15-MCCu(N)glyha-5](H2O)}·2NO3·8H2O(5), {Nd(NO3)(H2O)2[15-MCCu(N)glyha-5](H2O)2}·2NO3·7H2O(6) and {Sm(NO3)(H2O)2 [15-MCCu(N)glyha-5](H2O)2}·2NO3·6H2O(7) were obtained by the reactions of glycine hydroxamic acid(H2glyha) the ligand with different metal salts Seven metallacrowns have similar framework. Five Cu atoms and five glycine hydroxamic acid ligands formed 15-MC-5 via Cu-N-O bridging effects, the repeating unit was Cu-N-O and in the cavity of metallacrowns inlaid with a rare earth ions. There are two coordination models of copper ion, coordinate numbers ere four or five; rare earth ions also have two coordination models, coordinate numbers were eight or nine. Molecules were connected into two-dimensional network via O-H···O or N-H···O hydrogen bonds. Studies of the magnetic properties indicate the presence of dominant ferromagnetic in complex 2 at low temperatures(below 42 K) and dominant antiferromagnetic in complexes 1 and 3-7 in the range of 2-300 K. The DNA binding properties of complexes 1-7 with calf thymus DNA(CT-DNA) have also been investigated by Uv-vis spectra, fluorescent spectra and CD spectra and the result indicate that strong intercalation interactions exist between complexes 1-7 and CT-DNA.2. Eight metallacrown polymers: {[La Cu5(glyha)5(Fe(CN)5NO)(H2O)4]·NO3·8H2O}2(8), {[Pr Cu5(glyha)5(Fe(CN)5NO)(H2O)4]·NO3·8H2O}2(9), [Nd Cu5(glyha)5(Fe(CN)5NO)(H2O)4]·NO3·8H2O}2(10), {[Na Sm Cu5(glyha)5(Fe(CN)5NO)2(H2O)5]·5H2O}n(11), {[Na Gd Cu5(glyha)5(Fe(CN)5NO)2(H2O)5]·H2O}n(12), {[Na Tb Cu5(glyha)5(Fe(CN)5NO)2(H2O)5]·5H2O}n(13), {[Na Dy Cu5(glyha)5(Fe(CN)5NO)2(H2O)5]·5H2O}n(14) and {[Na Ho Cu5(glyha)5(Fe(CN)5NO)2(H2O)5]·4H2O}n(15) were obtained by the reactions of glycine hydroxamic acid metallacrowns with sodium nitroprussiate. Complexes 8-10 have similar framework. The molecules of complexes 8-10 consist of two [Ln Cu5(glyha)5(H2O)3]3+ cation, two [Fe(CN)5NO]2- anions and two nitrate anions. Complexes 11-15 were 3D coordination polymers and they have similar framework. The asymmetric unit of complexes 11-15 consist of one [Ln Cu5(glyha)5(H2O)3]3+ cation, two [Fe(CN)5NO]2- anions and one Na(H2O)2+ cation. Studies of the magnetic properties indicate dominant antiferromagnetic in complexes 8-11 and 15 in the range of 2-300 K. Studies of the magnetic properties indicate the presence of dominant ferromagnetic in complex 12(below 40 K), complex 13(below 9 K) and complex 14(below 14 K). Further studies of the magnetic properties found complexe 14 exhibits single-molecular magnets(SMM) behavior.3. Two metallacrowns: {Dy(NO3)(H2O)[15-MCCu N(L-pheha)-5]}·2NO3·2H2O(16) and {Ho(NO3)(H2O)[15-MCCu N(L-pheha)-5]}·2NO3(17) were obtained by the reactions of L-phenylalanine hydroxamic acid(H2pheha) the ligand with different metal salts. Two complexes have similar framework. The DNA binding properties of complexes 16-17 with calf thymus DNA(CT-DNA) have also been investigated by Uv-vis spectra and fluorescent spectra, the result indicate that intercalation interactions exist between complexes 16-17 and CT-DNA.