Lanthanide nitrato complexes bridged by the bis-tridentate ligand 2,3,5,6-tetra(2-pyridyl)pyrazine: Syntheses, crystal structures, Hirshfeld surface analyses, luminescence properties, DFT calculations, and magnetic behavior

Syntheses, Crystal Structures, and Luminescence of Hexafluoroacetylacetone Dinuclear Lanthanide Complexes Bridged by “Back-to-Back” Bisterpyridine

“…The solid-state luminescence characteristics of 1,4-bteb and 1−13 were recorded at RT or 77 K. In our previous work, UV irradiation of 1,4-bteb at RT yields one broad fluorescence band centered at 380 nm, which originates from the 1 ππ* ligand-centered (LC) singlet excited state energy level. 39 As shown in Table S12, as compared with those of tppz 16 and 4′-phenyl-2,2′:6′,2″-terpyridine (ptpy), 40 one might note that the fluorescent emissions are red-shifted in the sequence from 365 nm (ptpy) to 380 nm (1,4-bteb), and then to 385 nm (tppz), which might be contributed from the enhanced π-conjugation of the terpyridine-based ligands. As shown in Figure S10, at 77 K, the steady-state emission spectrum of 1,4-bteb shows one broad emission band at 547 nm.…”

Nickel Complexes of 2,3,5,6‐tetra‐(2‐pyridyl)pyrazine Containing [Ln(NO3)5]2− [Ln(III)=Nd, Eu, Gd, Tb, Dy, Er] as Counterions‐Syntheses, Structures and Luminescent Properties

“…This conformation of tppz is different from the 3XNNX configuration in the mononuclear iron complex [Fe(tppz) 2 ](PF 6 ) 2 • H 2 O reported by Hadadzadeh [8] and the 5XXXX configuration in the dinuclear complex [Eu-(NO 3 ) 3 (H 2 O)] 2 (μ-tppz) reported by our group. [3] The dihedral angles between the ring planes are listed in Table 1. The central pyrazine ring shows torsion angles N5-C19-C7-N11 of 14.77°a nd N5-C13-C6-N11 of 15.17°, which are greater than the torsion angles of 10.8°in [Ni(tppz) 2 ][NO 3 ] 2 complex.…”

“…CrystalExplorer was used to analyze the intermolecular interactions within the crystal structures of complex 1-6. [3,13] The 3D Hirshfeld surface and the associated two-dimensional (2D) fingerprint plots of 2 (as an example since the six compounds showed similar patterns) are plotted in Figure 5. In the d norm Hirshfeld surface, the regions of shortest intermolecular contacts are visualized by red circle areas.…”

“…[2] One of our current research interests has focused on the construction of luminescent polynuclear 4f and 3d-4f complexes by using the π-conjugated N-heterocyclic ligand 2,3,5,6-tetra(2-pyridyl) pyrazine (tppz). [3] Tppz is a remarkably versatile electron donor that displays a wide variety of binding modes. [4] In addition, tppz possesses two transterpyridine coordination sites to coordinate towards transition metal ions and lanthanide(III) ions, [3,5] which might be an idea ligand to construct heterometallic 3d-4f coordination complexes.…”

“…[3] Tppz is a remarkably versatile electron donor that displays a wide variety of binding modes. [4] In addition, tppz possesses two transterpyridine coordination sites to coordinate towards transition metal ions and lanthanide(III) ions, [3,5] which might be an idea ligand to construct heterometallic 3d-4f coordination complexes. Therefore, [Ni(tppz) 2 ](NO 3 ) 2 was used as the building block to react with Ln(NO 3 ) 3 • 6H 2 O under solvothermal condition to construct heterometallic 3d-4f coordination complexes.…”