Extrinsic Heavy Metal Atom Effect on the Solid‐State Room Temperature Phosphorescence of Cyclic Triimidazole

Abstract

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.

Role of Metal–Chloride Anions in Photoluminescence Regulations for Hybrid Metal Halides

“…The bulk assembly of emissive organic cations and metal–halogen anions can form a hybrid metal halide, which can provide the rigid frame caused by hydrogen bonds and π–π interactions. Furthermore, in compounds, the flexibility of pure organic cations is decreased; thus, the tunable PL for pure organic cations is realized. − And thus, several functionalized metal halides are obtained by assembling pure organic cations with multifarious metal–halogen anions. Here, we reported three new hybrid metal halides, (EnrofloH 2 )­Pb 2 Cl 6 ·H 2 O (abbreviated as ENR-Pb), (EnrofloH 2 )­BiCl 5 ·Cl·2­(H 2 O)·H 3 O (abbreviated as ENR-Bi), and (EnrofloH 2 )­SnCl 6 ·H 2 O (abbreviated as ENR-Sn).…”

Structural Landscape of Zn(II) and Cd(II) Coordination Compounds with Two Isomeric Triimidazole Luminophores: Impact of Crystal Packing Patterns on Emission Properties

“…The observed dissimilarities in crystal structures reflect crystallization in different space groups, P1̅ for 1 and R3̅ for all three other compounds. 35 The isomorphous compounds [Zn(H S2), is situated roughly parallel to L 1 , as indicated by the dihedral angle between their mean planes, 6.09( 16)°. The nitrate anion and outer sphere water molecule perching above/below L 1 from the adjacent level (Figure 3) block any possible homomeric stacking pattern, replaced by the heteromeric water S1c).…”

“…43 On the other hand, our first attempts to obtain Zn(II) or Cd(II) coordination compounds with L 1 resulted in four inclusion compounds, where L 1 shows different aggregation stacking patterns, and the resulting compounds retain the emissive properties where the metal atom behaves as an external perturber. 35 In particular, in [Zn 3 (CH 3 COO) 6 (H 2 O) 2 ](L 1 ) 2 , the luminophore molecules associate in a way very similar to the L 1 pure phase, but the increased spin−orbit coupling (SOC) manifests in an easier singlet-to-triplet intersystem crossing (ISC) resulting in intensification of the RTUP with respect to the fluorescence and in the appearance of the S 0 -T H transition in the excitation spectrum, T H being the triplet state responsible for the phosphorescent emission. These results provided further contributions in the knowledge of RTUP from extrinsically perturbed organic materials in the solid state.…”

“…, complex [Zn(H 2 O) 6 ](NO 3 ) 2 (L 1 ) 2(1) enriches the family of recently reported inclusion compounds [M(H 2 O) 6 ](An) 2 (L 1 ) 2 (M = Zn, Cd, An = BF )35 with dissimilarities provoked by the different anions' geometries, being trigonal planar for the nitrate anion versus tetrahedral for tetrafluoroborate and perchlorate anions. In particular, L 1 molecules in 1 are placed in a slipped parallel mode in the stacking dimer (FigureS1a).…”

From 1D to 2D Cd(II) and Zn(II) Coordination Networks by Replacing Monocarboxylate with Dicarboxylates in Partnership with Azine Ligands: Synthesis, Crystal Structures, Inclusion, and Emission Properties

“…The peak at 2.08 eV (595 nm) likely is determined by the impact of double chromophore pillars being the fragments of coordination arrays in 2-7 (Figures 3a, 4a, 5a, 6a, 7a, and 8a) with the overlay of their pyridine rings with the Cg•••Cg separations ca. 3.6 Å as imitating the emitting H-aggregates [41]. The significance of the peak at 2.08 eV (595 nm) increases in a row 8→5→3→2→7→6→4 in the emission spectra.…”