Beyond Classical Coordination Chemistry: The First Case of a Triply Bridging Phosphine Ligand.

The first example of a triply bridging (µ3 -P) phosphine ligand has been discovered in the crown-shaped [Cu3 (µ2 -Hal)3 L] (Hal=Cl, Br, or I) complexes supported by tris[2-(2-pyridyl)ethyl]phosphine (L). Theoretical analysis completely confirms the observed µ3 -P-bridging pattern, revealing the interaction of the same lone pair of phosphorus with three valence 4s-orbitals of Cu atoms. The presented complexes exhibit outstanding blue phosphorescence (λem =442-465 nm) with the quantum efficiency reaching 100 %. The complex [Cu3 (µ2 -I)3 L] also exhibits remarkable thermo- and mechanochromic luminescence resulting in a sharp change in the emission colour upon external stimuli. These findings essentially contribute to coordination chemistry of the pnictine ligands.

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides.

Secondary phosphine oxides react with vinyl sulfides (both alkyl- and aryl-substituted sulfides) under aerobic and solvent-free conditions (80 °C, air, 7-30 h) to afford 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides in 70-93% yields.

Alkyl-dependent self-assembly of the first red-emitting zwitterionic {Cu4I6} clusters from [alkyl-P(2-Py)3]+ salts and CuI: when size matters.

A series of red-emissive {Cu4I6} clusters have been synthesized from alkyl-tris(2-pyridyl)phosphonium halides, [R-PPy3]Hal, and CuI. The size of the alkyl substituent (R) has a dramatic impact on the structure of the clusters assembled. [Me-PPy3]I salt reacts with CuI (1 : 2) to give the ionic [Cu(Me-PPy3)I]2Cu2I4 complex consisting of the scorpionate [Cu(N,N',N''-Me-PPy3)I]+ cation. Under similar conditions, [Pr-PPy3]I forms the zwitterionic [Cu4I6(Pr-TPP)2] complex containing an unusual stepwise [Cu4I6] cluster core. The use of [Bu-PPy3]I or [Bn-PPy3]I in this reaction leads to zwitterionic [Cu4I6(R-TPP)2] complexes, in which a linear-shaped [Cu4I6] module appears. Photophysical studies supported by TD-DFT computations have revealed that the title complexes in the solid state at 298 K exhibit a red photoluminescence (λemmax = 620-650 nm) with short lifetimes (0.04-2.10 µs), which are assigned to the thermally activated delayed fluorescence (TADF) mixed with the cluster centered (3CC) phosphorescence. The compounds synthesized are the first red-emitting representatives of the recently discovered family of zwitterionic CuI-based complexes (so-called "AIO" structures).

Bright green-to-yellow emitting Cu(i) complexes based on bis(2-pyridyl)phosphine oxides: synthesis, structure and effective thermally activated-delayed fluorescence.

A family of brightly luminescent dinuclear complexes of [Cu(µ2-X)(N^N)]2 type (X = I or SCN) has been synthesized in 76-90% yields by the reaction of bis(2-pyridyl)phosphine oxides (N^N) with the corresponding Cu(i) salts. The X-ray diffraction study reveals that the Cu2I2 core of the [Cu(µ2-I)(N^N)]2 complexes has either a butterfly- or rhomboid-shaped structure, while the eighth-membered [Cu()Cu] ring in the [Cu2(SCN)2(N^N)]2 complexes is nearly planar. In the solid state, these compounds exhibit a strong green-to-yellow emission (λ = 536-592 nm) with high PLQYs (up to 63%) and short lifetimes (1.9-10.0 µs). The combined photophysical and DFT study indicates that the ambient-temperature emission of the complexes obtained can be assigned to the thermally activated-delayed fluorescence (TADF) from the 1(M + X)LCT excited state, while at 77 K, phosphorescence from the 3(M + X)LCT state is likely observed.