Copper(I) complexes with remotely functionalized phosphine ligands: Synthesis, structural variety, photophysics and effect onto the optical properties

Abstract

The synthesis, chemical and photophysical investigation of a series of eight novel copperhalide derivatives with different nuclearity is herein presented. One mononuclear copper(I) complex with formula [CuI(pyridine)(P)2], where P is a functionalized phosphine, six dinuclear derivatives bearing the rhombic {Cu2I2} subunits and with general formula [Cu(µ -I)(P)(N)]2 (N = pyridine, quinoline and 4-cyanopyridine) as well as one tetranuclear copperiodide clusters of general formula [Cu(µ -I)P]4 consisting of a cubane-like {Cu4X4} motif were straightforwardly prepared, also by means of mechano-chemical synthetic procedure.The phosphine ligands were prepared in excellent yield by using simple hydrophosphination reactions. For five of the investigated cuprous iodide derivatives their atom connectivity and solid-state crystalline packing was unambiguously confirmed by solving their single-crystal X-ray structure. All the investigated complexes resulted into photo-and thermally-stable luminescent species. In the solid state as microcrystalline powder samples, the complexes display intense photoluminescence ranging from the sky-blue to orange-red portion of the spectrum with PLQY values of 0.28-0.50 and 0.34-0.97 at room and low (77 K) temperature, respectively, depending on the nature of both the coordinated N-heteroaromatic ring and phosphine ligands. In spite of the remote location of the functionalization of the phosphine, profound effects are observed onto the solid-state emission properties highlighting the importance of microenvironment for the emitters in the aggregated phase.

A Stable and Photoreactive Copper‐Iodide Cubane Suitable for Direct Post‐Functionalization

“…Although exceptionally stable, we anticipated that the P−H functions could be activated to allow a direct hydrophosphination reaction onto alkene substrates. Hydrophosphination of methyl vinyl ketone was examined first (Scheme 2) to generate the functionalized cubane 2 , a complex that we recently synthesized starting from CuI and the corresponding tertiary phosphine [13] . Interestingly, traces of cubane 2 were observed when dissolving compound 1 in methyl vinyl ketone at room temperature for 12 hours, demonstrating its reactivity (entry 1).…”

“…This emission is attributable to a radiative process from a triplet excited state with admixed cluster-centered ( 3 CC) and halogen-to-ligand charge transfer ( 3 XLCT) nature, in comparison with related copper-iodine cubane clusters of {Cu(μ 3 -I)(phosphane)} 4 general structure. [6,9,13] An irreversible and slow photodegradation of the sample was observed upon cycling photoluminescence spectra, which hampered deeper investigation by means of time-resolved techniques. Nevertheless, observation of photoluminescence in solution is surprising and unprecedented for copper-iodide cubane, to the Scheme 3.…”

“…Hydrophosphination of methyl vinyl ketone was examined first (Scheme 2) to generate the functionalized cubane 2, a complex that we recently synthesized starting from CuI and the corresponding tertiary phosphine. [13] Interestingly, traces of cubane 2 were observed when dissolving compound 1 in methyl vinyl ketone at room temperature for 12 hours, demonstrating its reactivity (entry 1). The conversion could be improved by heating and 18 % of conversion were observed after 12 h in refluxing acetonitrile (entry 2).…”

Recent Progress in Luminescent Cu(I) Halide Complexes: A Mini-Review

“…The Cu…Cu bond distance in 15 with a cubane appearance was recorded at 2.77Å, being the shortest among all other complexes. The broad but varying solid-state emissions from the complexes were interdependent on the nature of the ligands with a corresponding mechanism such as 3 (M + X)LCT and 1 (M + X)LCT (( Supplementary Figure S6 ) ( Egly et al, 2021 ).…”

Novel Copper Complexes as Visible Light Photoinitiators for the Synthesis of Interpenetrating Polymer Networks (IPNs)

“…On the other hand, organometallic compounds are not really used in industry; in other words, manufacturers avoid incorporating metallic compounds in their synthetic formulations due to their potential toxicity and price [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. With their photochemical properties, such as high-absorption properties in the near-UV and visible range [ 65 , 66 , 67 , 68 ], long-lived excited states [ 69 , 70 , 71 , 72 , 73 , 74 ], suitable redox potentials [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ], copper complexes can be used as photoinitiators (PIs)/photoredox catalysts able to produce active species, according to a catalytic cycle [ 90 , 91 ]. Therefore, it is very important to develop new metal-free photoinitiators or low-cost organometallic-based complexes [ 92 , 93 , 94 , 95 ].…”