Cyclic triimidazole (C 9 H 6 N 6 , L), with C 3h molecular symmetry and three nitrogen atoms available for coordination, is here successfully employed for the first time in the synthesis of coordination compounds. In particular, by varying the reaction conditions (e.g., solvent, temperature, template), seven Cu(I)-halide coordination polymers of different dimensionality are obtained: two 1D polymers, [CuIL] n (1) and {[CuIL]•(I 2 ) 0.5 } n (2), three 2D nets, [CuXL] n (X = I, Br) (3−5), and two 3D networks, [CuClL] n (6) and {[Cu 3 L 4 ]I 3 } n (7). Single crystal X-ray diffraction analysis reveals that the structural versatility of both the ligand and the CuX moiety allows isolating 1D double-stranded stairs in which L is monodentate, 2D layers containing either Cu 2 (μ-X) 2 or Cu 2 (μ-X) moieties and bidentate L ligands, 3D frameworks built up by tridentate L linkers and either monodentate or noncoordinating halogen atoms. The 3D frameworks show nets of srs and bor topologies. The SHG efficiency of powders of 7 (the only noncentrosymmetric derivative of the series) is 10 times higher than that of sucrose. Phosphorescent emission of XLCT character is observed for 1 and 6.

Four coordination compounds [Zn3(CH3COO)6(H2O)2](TT)2 [Cd(H2O)6](ClO4)2(TT)2, [Cd(H2O)6](BF4)2(TT)2, [Zn(H2O)6](BF4)2(TT)2 (1–4) accommodating the crystallization induced emissive triimidazo[1,2‐a:1′,2′‐c:1′′,2′′‐e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H‐aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn. In 2 and 3, the heavier Cd atom is responsible for a decrease in the lifetimes of the afterglow emission, despite the presence of tightly overlapped H‐dimers in the crystal structure. Finally, for 4, isostructural with 3, the Zn atom reveals in RTUP lifetime comparable with that of 1.

The interplay of different Zn(II) and Cd(II) salts with two luminescent triimidazole ligands, triimidazo[1,2-a:1′,2′-c:1″,2″-e][1,3,5]triazine (L 1 ) and its positional isomer triimidazo[1,2-a:1′,2′-c:1″,5″-e][1,3,5]triazine (L 2 ), in solvothermal synthetic conditions resulted in mono-, bi-, and polynuclear Zn(II) and Cd(II) coordination compounds with diverse metal/ luminophore(L 1 ,L 2 )/anion/water ratios, [Zn(H 14). Herein, for the first time, the Zn and Cd coordination compounds with L 1 and L 2 luminophores as inner-sphere ligands have been obtained and structurally characterized. The structural landscape includes inclusion compound 1, supramolecular isomers 1−3, isomorphs 2 and 3, polymorphs 5 and 6, and onedimensional coordination polymer 13. In discrete complexes, both luminophores coordinate to the metals in monodentate mode; in 13, L 1 acts as a bidentate bridging ligand giving rise to the structure extension. Since the crystal packing and stacking patterns of the luminophore molecules are important factors underlying the aggregation induced emission, the finite and infinite stacking motifs registered in the crystal structures 1−14 are reported. All compounds reveal an emissive response upon irradiation under the UV−vis lamp. The best performing compounds in the series, namely, 4, 5, and 10, have been fully spectroscopically characterized.

Design of materials with ligand-centered emission from a highly emissive ligand with the use of optically inactive metal ions Zn(II) and Cd(II) allows tuning the ligands stacking and influences on the lifetime, quantum yield and stability of emitters. Generally, d 10 metal complexes show no emission originating from MLCT/LMCT excited states, since these ions are in a stable oxidation state. Otherwise, d 10 metals have flexible coordination numbers,