Polymorph and isomer conversion of complexes based on CuI and PPh₃easily observed via luminescence

Abstract

Reactions between copper(I) iodide and triphenylphosphine have been explored in solution and in the solid state and six luminescent coordination complexes have been obtained and characterized by X-ray diffraction and UV-vis spectroscopy and photophysics. Solid-state reactions of CuI with PPh(3) in different conditions (kneading, vapour digestion) and stoichiometries resulted in the formation of high ratio ligand:metal compounds while tetrameric structures could be obtained only by solution reactions. Crystal structures were determined by single crystal X-ray diffraction while purity of the bulk product was checked by powder diffraction (XRPD). Three different tetrameric structures with 1:1 stoichiometry have been synthesized: two closed cubane-type polymorphs [CuI(PPh(3))](4) (form 1a) and [CuI(PPh(3))](4) (form 1b) and an open step-like isomer [CuI(PPh(3))](4) (form 2). The conversions between the polymorphs and isomers have been studied and characterized by XRPD. The most stable form [CuI(PPh(3))](4) (form 1b) can convert into the open step-like isomer [CuI(PPh(3))](4) (form 2) in a slurry experiment with EtOH or CH(2)Cl(2) or AcCN and converts back into [CuI(PPh(3))](4)1b when exposed to vapors of toluene. At room temperature all the tetrameric compounds exhibit luminescence in the solid state and, notably, the two polymorphs show a dissimilar dual emission at low temperature. The luminescence features in the solid state seem to be peculiarly related to the presence of the aromatic phosphine ligand and depend on the Cu-Cu distance in the cluster.

Cu(I) hybrid inorganic–organic materials with intriguing stimuli responsive and optoelectronic properties

“…At 77 K, isomer 96 displayed a bathochromic shift of 10 nm, while the more pronounced red-shift (22 nm) observed for 97 was explained with significantly reduced intermetallic distances on lowering the temperature. Later, the same group, isolated six different coordination compounds from the solution and solid state reaction between CuI and PPh 3 [87]. In particular, three different already known tetrameric structures with CuI : PPh 3 1 : 1 stoichiometry were prepared, namely the two closed cubane-type polymorphs [CuI(PPh 3 )] 4 (39) and [CuI(PPh 3 )] 4 (42) and an open step-like isomer [CuI(PPh 3 )] 4 (98) (Figure 18).…”

Geometry Flexibility of Copper Iodide Clusters: Variability in Luminescence Thermochromism

“…All compounds were obtained as colorless crystals (Experimental Section), and the crystal structures were determined by single-crystal XRD analysis at 150 K. In all the structures, solvent molecules are included, and the formulas are [Cu 6 I 6 (PPh 2 (CH 2 ) 3 PPh 2 ) 3 ]·2 CH 2 Cl 2 (1·2 Note that the synthesis of 2 has been already reported in the literature by refluxing CuI and PPh 3 in chloroform 22 or by mechanosynthesis method. 27 In the former case, a crystal structure of 2 has been determined but without solvent included. Two polymorphs of the cubane cluster [Cu 4 I 4 (PPh 3 ) 4 ] are known, which crystallize in the monoclinic P2 1 /c (3P) 16 and cubic I-43d space groups.…”

X-ray absorption spectroscopy: towards more reliable models in material sciences

“…In fact, even after isolation and in the solid state, some Cu(I) complexes undergo dissociation and rearrangement reactions, as it has been investigated for various examples of cationic complexes. [28,[32][33][34][35][36][37][38][39] This is why the possibility of deviations from models based on single crystal X-ray diffraction in real, amorphous samples needs to be taken into account. X-ray absorption spectroscopy offers the possibility to do this, as will be demonstrated in the next sections.…”