Partial in Situ Reduction of Copper(II) Resulting in One-Pot Formation of 2D Neutral and 3D Cationic Copper(I) Iodide-Pyrazine Coordination Polymers: Structure and Emissive Properties.

Author(s) Malaestean, I.L.; Kravtsov, V.Ch; Lipkowski, J.; Cariati, E.; Righetto, S.; Marinotto, D.; Forni, A.; Fonari, M.S.
Journal Inorg Chem
Date Published 2017 May 01

On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO3)2·3H2O in the presence of pyz, successive precipitation of known yellow [(Cu(I)I)2(pyz)]n, new orange [Cu(I)I(pyz)]n, and new dark blue {[Cu(I)(pyz)2]·I5}n polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(Cu(I)I)2(bpy)]n and new brown {[Cu(II)(NO3)(bpy)2]·I3·(dmf·H2O)}n coordination polymers. By using either Cu(CH3COO)2·H2O or Cu(BF4)2 as starting materials, both known forms, yellow [(Cu(I)I)2(bpy)]n and orange [Cu(I)I(bpy)]n, precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [Cu(I)I(pyz)]n represents the missing member in the row of two-dimensional coordination networks with general formula [Cu(I)X(pyz)]n (X = Cl, Br, I). Its steady state and time-resolved characterization together with DFT and TDDFT calculations revealed that the emission at room temperature is mainly delayed fluorescence originating from mixed singlet metal-to-ligand charge transfer and halide-to-ligand charge transfer states, while that at 77 K is phosphorescence, associated with the small singlet-triplet energy differences (ΔE = 70 meV).

DOI 10.1021/acs.inorgchem.7b00290
ISSN 1520-510X
Citation Inorg Chem. 2017;56(9):51415151.

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