Modulation of Nuclearity by Zn(II) and Cd(II) in Their Complexes with a Polytopic Mannich Base Ligand: A Turn-On Luminescence Sensor for Zn(II) and Detection of Nitroaromatic Explosives by Zn(II) Complexes

Reactions of Zn(II) ion with the ligand H2L (H2L = N,N′-dimethyl-N,N′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)ethylenediamine) in the presence of bridging coligands, chloride, thiocyanate/acetate, or azide/acetate yielded three new dinuclear complexes, [Zn2LCl2(H2O)] (1), [Zn2L(SCN)2(H2O)]·H2O (2), and [Zn2L(N3)(CH3CO2)] (3), whereas Cd(II) ion formed three new tetranuclear complexes, [Cd4L2Cl4]·H2O (4), [Cd4L2(SCN)2(CH3CO2)2]·2H2O (5), and [Cd4L2(N3)2(CH3CO2)2]·3H2O (6) with the same ligand and coligands. The Zn(II) ions are penta-coordinated in all of its complexes 1–3 except one zinc center in complex 3, which is distorted tetrahedral. All four Cd(II) centers in each of its complexes 4 and 5 possess hexa-coordinated distorted octahedral geometry. In complex 6, two Cd(II) centers are hexa-coordinated, and the other two are hepta-coordinated. The deprotonated ligand (L2–) is hexa-/hepta-dentate in the Zn(II) complexes, 1–3 but octa-dentate in the CdII complexes 4–6. The differences in nuclearity and in th...