Coordination-Driven Salamo-Salen-Salamo-Type Multinuclear Transition Metal(II) Complexes: Synthesis, Structure, Luminescence, Transformation of Configuration, and Nuclearity Induced by the Acetylacetone Anion

A flexible polydentate Salamo-Salen-Salamohybrid ligandH(4)L containing rich pockets (salamo and salen pockets)was first designed and synthesized under the mediation of the counteranionsthat combine with transition metal(II) ions to obtain four novel complexes,[Ni-4(L)(mu(1)-OAc)(2)(mu(1,3)-Oac)(2)(H2O)(0.5)(CH3CH2OH)(3.5)]center dot 4CH(3)CH(2)OH (1), [Zn-3(L)(mu(1)-Oac)(2)]center dot 2CH(3)CH(2)OH (2), [Cu-2(H2L)(2)]center dot 2CH(3)CN (3), and [Ni(H2L)]center dot 1.5CH(3)COCH(3) (4), which have been synthesized and characterizedstructurally. The fluorescent properties of the four complexes werestudied with zebrafish, which are expected to be a potential light-emittingmaterial. Ultimately, IRI valuations, Hirshfeld surface analyses,DFT & TD-DFT, ESP, and simulations were carried out to furtherdemonstrate the weak interactions and electronic properties of H4L and its four metal(II) complexes. A flexiblepolydentate Salamo-Salen-Salamo hybrid ligand H4L was designedand synthesized, which has rich pockets (salamoand salen pockets) so that it may have fascinating coordination patternswith transition metal(II) ions. Four multinuclear transition metal(II)complexes, novel butterfly-shaped homotetranuclear [Ni-4(L)(mu(1)-OAc)(2)(mu(1,3)-OAc)(2)(H2O)(0.5)(CH3CH2OH)(3.5)]center dot 4CH(3)CH(2)OH (1), helical homotrinuclear [Zn-3(L)(mu(1)-OAc)(2)]center dot 2CH(3)CH(2)OH (2), double-helicalhomotrinuclear [Cu-2(H2L)(2)]center dot 2CH(3)CN (3), and mononuclear [Ni(H2L)]center dot 1.5CH(3)COCH(3) (4), have been synthesized andcharacterized by single-crystal X-ray diffraction. The effects ofdifferent anions [OAc- and (O2C5H7)(2-)] on the complexation behaviorof H4L with transition metal(II) ions were studied by UV-visspectrophotometry. The fluorescent properties of the four complexeswere studied with zebrafish, which are expected to be a potentiallight-emitting material. Ultimately, interaction region indicator(IRI) valuations, Hirshfeld surface analyses, density functional theory(DFT & TD-DFT), electrostatic potential analyses (ESP), and simulationswere carried out to further demonstrate the weak interactions andelectronic properties of the free ligand and its four complexes.

Automated summary

A flexible polydentate Salamo-Salen-Salamohybrid ligand H(4)L containing rich pockets was designed and synthesized to obtain four novel complexes with transition metal(II) ions. The fluorescent properties of these complexes were studied with zebrafish, suggesting their potential as light-emitting materials.