Synthesis, crystal structures and photophysical properties of two supramolecular complexes of cadmium(II)

The reaction of Cd(NO3)2 with 5-sulfoisophthalic acid monosodium salt (NaH2sip) in the presence of piperazine (pip) or ethylenediamine (en) produced three-dimensional supramolecular complexes [Cd(sip)(Hpip)(H2O)2] (1) and [Cd(sip)(H2O)3] · 0.5(H2en) · H2O (2). In both compounds, the Cd2+ atoms are linked by sip3− into a one-dimensional zig zag chain. The resultant negative ribbons are charge balanced by the coordinated protonated pip (Hpip) in 1 but by free, half occupied H2en in 2. The zigzag chains are further linked together by hydrogen bonds and π–π stacking interactions to form supramolecular open frameworks. Both 1 and 2 show violet–blue photoluminescence at room temperature.