Fluorescence thermochromism of pyridine copper iodides and copper iodide

Abstract

Copper(I)iodide reacts with pyridine to form (Cu py)I, and further to form (Cu py2)I. A tripyridino compound, although existing in contact with pyridine, is not obtainable at room temperature and normal pressure. The three solvates are different in structure and in their fluorescence colour in ultraviolet light. (Cu py3)I crystals are not fluorescent at room temperature but show yellow fluorescence at −180°C. (Cu py2)I is fluorescent with a green colour at room temperature as well as at very low temperatures. (Cu py)I shows yellow fluorescence at room temperature which reversibly changes to orange, then to red and finally to violet by cooling in liquid nitrogen („fluorescence thermochromism”︁). The last named compound is spontaneously decomposed by benzene to form highly dispersed copper iodide, which fluoresces red at room temperature, but not at all in liquid nitrogen.

Luminescent Coordination Polymers Built Upon Cu4X4 (X=Br,I) Clusters and Mono‐ and Dithioethers

“…After cooling the reaction, formation of colorless crystals was observed. Surprisingly, the single-crystal X-ray analysis performed at 115 K revealed that instead of observing the expected 1D polymer [(Me 2 S) 3 {Cu(m-I) 2 }] n , the 2D-polymer [(Me 2 S) 3 {Cu 4 (m-I) 4 }] n was formed (Scheme 16).…”

“…In the early 1990s, both van Koten and coworkers and Mälger et al reported a similar series of reactions with SMe 2 and were able to determine structures by X-ray diffraction studies of CuBr Á Me 2 S and CuIÁMe 2 S adducts. [34,35] The data revealed formation of a coordination polymer consisting of a layered polymeric 2D network with composition [(mMe 2 S) 2 {Cu 2 (m 2 -Br) 2 }] n for the former (polymer 1). For the latter, the cubane cluster encountered in [(Et 2 S) 3 {Cu 4 (m 3 -I) 4 }] n was replaced by the rhombic Cu 2 I 2 unit with close Cu-Cu distance of only 2.684(1) Å (Scheme 3, polymer 2).…”

“…The discovery of the luminescence properties of this type of cluster originated from the work of Hardt et al intending to study a phenomenon called ''luminescence thermochromism.'' [1][2][3][4][5] In these studies, solids exhibiting various stoichiometries Cu x X y L z , showed different emissions, but the exact structures of these species was yet to be known. In 1974, Volker Schramm reported the X-ray structure of a compound formulated as [CuI(morpholine)] n , where n ¼ 4.…”

“…[43] Reaction of 2-(cyclohexylmethylthio)-1-thiomorpholinoethanone L7 with copper(I) iodide afforded a luminescent 1D channel-type coordination polymer [Cu 4 2 ] n polymers versus their luminescence thermochromism as a function of temperature was observed. Table 1 presents the X-ray CuÁÁÁCu distances of these two polymers, which were recorded at four different temperatures.…”

Synthesis, Characterization, Spectroscopic and Photophysical Properties of New [Cu(NCS){(L‐N)2 or (L′‐NN)}(PPh3)] Complexes (L‐N, L′‐NN = Aromatic Nitrogen Base)

“…For example, a variety of trinuclear Cu pyrazolates [12] exhibiting fascinating optical phenomena and photolumines-cent mixed-ligand copper polymers have been recently reported. [13,14] Copper phosphino and/or pyridine derivatives, [15][16][17][18][19] emissive at room or at low temperature, have been described but attempts to describe the associated spectroscopic properties in terms of known structures of the complexes remain limited. Despite the considerable attention paid to cyclic trinuclear d 10 complexes, a fundamental issue that remains outstanding concerns, for example, the role played by the transition metal in determining the molecular structure, photophysics and spectroscopic properties in mononuclear species.…”