A Series of Mononuclear Complexes Constructed from Transition Metals and Amino Acid Derived Ligands: Syntheses, Structures and Photoluminescence

Eight neutral mononuclear complexes constructed from transition metals (M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II)) and ligands N-(2-pyridylmethyl)-L-phenylalanine (L-Hpmpa) and N-(2-pyridylmethyl)-L-tyrosine (L-Hpmtyr) have been. synthesized by both hydrothermal and conventional room temperature reactions. Four of them have been structurally characterized by single-crystal X-ray diffractions. They are: [Co(L-pmpa)(2)center dot 2H(2)O] 1, [Ni(L-pmpa)(2)center dot 2H(2)O] 2, [Cu(L-pmpa)(2)center dot 2H(2)O] 3 and [Cu(L-pmtyr)(2)center dot 2H(2)O] 4. Single-crystal X-ray analysis, IR and elemental analysis revealed that complexes 1, 2 and 3 are isostructural. Powder X-ray diffraction, IR and elemental analysis revealed that complexes 4, 5 (Zn[L-pmtyr](2)center dot 2H(2)O), 6 (Cd[L-pmtyr](2)center dot 2H(2)O), 7 (Co[L-pmtyr](2)center dot 2H(2)O) and 8 (Ni[L-pmtyr](2)center dot 2H(2)O) are isostructural. The photoluminescence properties of L-Hpmtyr ligand, compounds 5 and 6 were also investigated.