In Situ Reduction of Copper(II) Forming an Unusually Air Stable Linear Complex of Copper(I) with a Fluorescent Tag
摘要:
A new fluorescent ligand (phi(f) = 0.8 in dioxane), 2-(4'-aminophthalimidomethyl)pyridine (L), has been synthesized. A one-pot synthesis of its copper(I) complex upon reduction of copper(II) is achieved at room temperature. This complex, which has been characterized by X-ray crystallography, shows a linear N-Cu-N geometry with Cu-N bond lengths of 1.89 Angstrom. X-ray structure reveals weak (CuO)-O-... interactions between copper and one of the imide oxygen atoms of the ligand framework. Additional weak (CuO)-O-... interactions between copper and oxygen atoms of the CIO4- counteranion are detected that lead to a zigzag polymeric chain with alternate CIO4- and copper ions. A 2-D intermolecular hydrogen bonding network is also observed. This complex is found to be highly inert toward oxidation both in the solid state and in solution.
Synthesis and structure of unusually stable linear copper(I) complexes with blue fluorescence
作者:Sandip Banthia、Anunay Samanta
DOI:10.1016/j.poly.2006.01.025
日期:2006.7
A new fluorescent ligand 2-(4-aminophthalimidoethyl)pyridine (L-2) has been synthesized. Solid state structures of L-2 and 2-(4'-aminophthalimidomethyl)pyridine (L-1) have been determined by X-ray crystallography. While L-1 crystallizes in the non-centrosymmetric orthorhombic space group Fdd2, L-2 crystallizes in the monoclinic space group C2/c. The molecular packing in both systems is dominated by intermolecular N-H center dot center dot center dot O and N-H center dot center dot center dot N hydrogen bonds and relative bending of the planes defined by the pyridine and phthalimide moieties. An unusually stable two-coordinate complex of copper(I) with L-2, Cu(L-2)(2), has been synthesized upon in situ reduction of copper(II) at room temperature. This complex, which has been characterized by X-ray crystallography, crystallizes in the centrosymmetric space group C2/c with a linear N-Cu-N geometry. The Cu-N bond distance (1.89 angstrom) in Cu(L-2)(2) is found to be similar to that in Cu(L-1)(2). Both the complexes display interesting structural feature, arising from weak Cu center dot center dot center dot O interactions (3.12 angstrom in Cu(L-1)(2) and 2.71 angstrom in Cu(L-2)(2)) between the copper and oxygen atoms of the ClO4- counteranion, leading to a linear network with alternate ClO4- and Cu+ ions. A 2-D network determined by intermolecular N-H center dot center dot center dot O hydrogen bonding is also observed. These complexes are found to be highly resistant toward oxidation both in the solid state and in solution. The new complex Cu(L-2)(2), in which the metal center is more separated from the 4-aminophthalimide moieties, exhibits lesser stability than Cu(L-1)(2). Close contact between copper and one of the imide oxygen atoms of the ligand framework was detected as 3.03 angstrom in Cu(L-1)(2) and 4.0 angstrom in Cu(L-2)(2), indicating a relatively weaker electronic interaction in the later complex. Thus, the exceptional stability of these complexes is attributed to the electronic environment provided by the 4-aminophthalimide and perchlorate moieties on the metal center. (C) 2006 Elsevier Ltd. All rights reserved.