Synthesis, Photophysics, and Electrochemistry of Ruthenium(II) Polypyridine Complexes with Crown Ether Pendants

A series of ruthenium(II) polypyridine complexes with a crown ether-containing ligand dipyrido[3,2-a;2′,3′-c]-phenazo-15-crown-5 (dppzc) have been synthesized and characterized and their photophysics and electrochemistry studied. The photoredox reactivities of [Ru(bpy)2(dppzc)]2+ have also been investigated by Stern-Volmer quenching experiments and nanosecond transient absorption spectroscopic studies. The cation-binding properties of these ruthenium(II) polypyridine complexes have also been studied by electronic absorption spectroscopy and cyclic voltammetry and confirmed by electrospray ionization mass spectrometry

Intramolecular rearrangements guided by adaptive coordination-driven reactions toward highly luminescent polynuclear Cu(i) assemblies

International audienceAdaptive coordination-driven supramolecular chemistry based on conformationally flexible pre-organized luminescent Cu(I) precursors paves the way to the ready formation of intricate supramolecular scaffold possessing intrinsic luminescence properties. A formal ring extension of a tetrametallic Cu(I) metallacycle bearing Thermally Activated Delayed Fluorescence (TADF) properties can thus be carried out, affording a new hexametallic Cu(I) metallacycle 1 bearing modulated solid-state TADF properties. Attempts to adapt this ring extension process to the formation of targeted heterometallic Au2Cu4 and Pt2Cu8 assemblies led to the unexpected and ready formation of the Au2Cu10 and Pt4Cu11 derivatives 2 and 3, respectively. These outcomes strengthen the scope and perspectives of adaptive coordination-driven supramolecular chemistry compared to those of conventional coordination-driven supramolecular chemistry. Indeed, it guides concerted intramolecular fragmentation and redistribution of the particular building blocks used, affording selectively supramolecular scaffolds of higher nuclearity and complexity. The study of the solid-state photophysical properties of the assemblies 2 and 3 highlights enhanced and original behaviors, in which the heavy metal spin-orbit coupling values significantly influence the relaxation processes centered on the Cu(I) metal centers

Extending metal-capped polyynediyl molecular wires by insertion of inorganic metal units

Several symmetric and asymmetric bis(metalla-diynediyl)ruthenium(II) complexes of the general formula trans-{L xRu} C≡CC≡C{Ru(dppe) 2}C≡CC≡C{RuL′ y} (L x, L′ y = (PPh 3) 2Cp, (dppe)Cp, (dppe)Cp*), containing Ru(dppe) 2 as the central linking group, have been successfully synthesized and characterized spectroscopically. DFT calculations show that their HOMO's are delocalized over the Ru-C 4-Ru-C 4-Ru chain, suggesting that there is electronic interaction between the terminal RuL x groups through the C 4 chains and the Ru(dppe) 2 center. Limited electrochemical measurements reveal that the complexes undergo a series of five stepwise reversible or quasi-reversible oxidation processes. © 2012 American Chemical Society.Michael I. Bruce, Boris Le Guennic, Nancy Scoleri, Natasha N. Zaitseva, and Jean-François Hale

Reactions of 7,7,8,8-tetracyanoquinodimethane with poly-ynyl ruthenium and iron complexes

The reaction of tetracyanoquinodimethane (TCNQ) with Ru(C≡CC≡ CH)(dppe)Cp* (5) at the outer (from Ru) C≡C triple bond gives η 1-(butadienyl)ethynyl Ru{C≡CC[CH=C(CN) 2]=C 6H 4=C(CN) 2}(dppe)Cp (8), which reacts with a second equivalent of diynyl-Ru complex to give {Ru(dppe)Cp*}{C≡CC[= C 6H 4=C(CN) 2]CH=CHC[=C(CN) 2] C≡C}{Ru(dppe)Cp*} (9). The Ph-substituted complexes M{C≡CC≡CPh}(dppe)Cp* (M = Fe 6-Fe, Ru 6-Ru) and Ru{(C≡C) 3Ph}(PPh 3) 2Cp (7) react with TCNQ to give the η 1-(butadienyl)ethynyls M{C≡CC[CPh=C(CN) 2]=C 6H 4=C(CN) 2}(dppe)Cp (10-Fe, 10-Ru) and Ru{C≡CC[C(C≡CPh)=C(CN) 2]=C 6H 4=C(CN) 2}(PPh 3) 2Cp (11), respectively. Single-crystal X-ray diffraction molecular structure determinations for 8-11 have been carried out. In the Fe series, we suggest that the initial step of the mechanism involves electron transfer to form the [TCNQ] -• salt of the diynyl-iron cation, followed by C-C bond formation to give a zwitterionic intermediate. Isolated products can be rationalized by further reaction involving [2 + 2]-cycloaddition of one of the C=C(CN) 2 groups of TCNQ to a C≡C triple bond of the metal poly-ynyl complex and a subsequent ring-opening reaction of the resulting (unobserved) cyclobutenyl intermediate. On the basis of X-ray diffraction data, redox potential determinations, and 57Fe Mössbauer and UV-vis spectroscopies, the electronic structures of the new compounds contain significant contributions from polarized mesomers involving charge transfer from the electron-rich metal-ligand fragment to the cyanocarbon ligand via the conjugated unsaturated carbon linker. © 2012 American Chemical Society.Michael I. Bruce, Alexandre Burgun, Guillaume Grelaud, Claude Lapinte, Christian R. Parker, Thierry Roisnel, Brian W. Skelton, and Natasha N. Zaitsev