Unique self-organized structures of metal(II)-arginine complexes through directed hydrogen bonds

The copper(II) complexes of L/D-arginine(L/D-Arg), one of the essential ami no acids, have been revealed to form various self-organized structures, suc h as right- and left-handed double helical and single helical and sheet str uctures, according to the structural requirements for hydrogen bonds with t he key counteranions. The reflectance and solid state ESR spectra for these systems reflected the coordination environments around the metal atoms and their crystal structures, respectively. The self-organization process in s olution leading to the double helical structure of [Cu(L-Arg)(2)] (isophtha late) in solid state has been followed by CD and NMR spectra by use of the corresponding [Pd(L-Arg)(2)](2+)-(isophthalate) system. The structure-deter mining factors in the self-organizing system are discussed in detail.