Aromatic carboxylate-controlled self-organization of copper(II)-L-arginine complexes

Self-organization of [Cu(L-Arg)(2)](2+) complex ions (Arg = arginine) in the presence of aromatic carboxylates has been studied by spectroscopic and X-ray diffraction methods. [Cu(L-Arg)(2)]Cl-2 dissolved in aqueous solutions containing benzene-1,4-dicarboxylate (terephthalate, p-pa(2-)) and -1,2,4,5-tetracarboxylate (pyromellitate, pma(4-)) gave crystals of [Cu(L-Arg)(2)](p-pa) . 2H(2)O (1) and [Cu(L-Arg)(2)](2)(pma) . 4H(2)O (2), respectively. Both complexes have a square-planar structure with two L-Arg molecules in the trans configuration. The [Cu(L-Arg)(2)](2+) units in the crystal structure are bound by hydrogen bonds to form one-dimensional (1D) infinite tapes {[Cu(L-Arg)(2)](2+)}(n), which are connected by p-pa(2-) or pma(4-) to form a 2D sheet through guanidinium-carboxylate hydrogen bonds (N ... O = 2.72(1)-3.10(1) Angstrom). The electro-spray ionization mass spectrum of 1 in dimethylsulfoxide indicated the formation of 2:1 and 3:2 [Cu(L-Arg)(2)](2+) -p-pa(2-) aggregates. (C) 1999 Elsevier Science S.A. All rights reserved.