Studies on the halogen substituted β-amino acids and their Cu(II) coordination complexes in crystallography

Abstract

Halogen substituted β-amino acids, D,L-3-amino-3-(4-fluoro)phenylpropionic acid(D,L-HL1, 1) and D,L-3-amino-3-(4-bromo)phenylpropionic acid(D,L-HL2, 2), as well as their Cu(II) coordination complexes [Cu(L1)2(CH3OH)2]·2CH3OH(3) and [Cu(L2)2(CH3OH)2]·2CH3OH(4) were investigated and their single crystal structures were discussed in details. Supramolecular helical chains were found in β-amino acids 1 and 2 while there was no helix in their coordination complexes 3 and 4. The formation of supramolecular helixes could be due to the hydrogen bonds between terminal ―NH 3 + and adjacent ―COO– in β-amino acids 1 and 2. While, this kind of hydrogen bonds could not be observed in their Cu(II) coordination complexes 3 and 4, in which central-symmetrical dimers could be formed via coplanar coordinated bonds(N―Cu―O) between ―NH2 and ―COO–.