Solvatochromic studies of a novel Cd2+–anthracene-based curcuminoid and related complexes

The present manuscript introduces a new Cd2+–curcuminoid derivative and the solvatochromic studies performed with such system. Coordination of the recently reported 9Accm (1,7-(di-9-anthracene)-1,6-heptadiene-3,5-dione) (1) with Cd(NO3)2·H2O in a 2:1 ratio allows the formation of complex 2, [Cd(9Accm)2(dmf)2]. Several spectroscopic and spectrofluorimetric techniques have been used for the characterization of the compound. lvatochromic properties of 2 together with a related complex, [Zn(9Accm)2] (3), and the free ligand 9Accm (1), have been explored by recording changes on absorption and emission spectra in 10 solvents with a wide range of polarities. Kamlet–Taft multiparametric equation has been used to analyze the solvent effect on the lowest energy emission transition, since negligible changes have been observed in the absorption. This way it has been established that the H-bond donor (or electron pair acceptor) capacity of the studied solvents plays a crucial role in the solvatochromism of all three species, 1–3. Also, metal coordination and/or environment can affect the energy of the emission bands.