Synthesis of 9-anthrylmethyl-functionalised cyclopentadienyl derivatives of rhodium(I) and iridium(I) and study of their luminescence properties

Electronic properties of new homobimetallic anthracene-bridged η5-cyclopentadienyl derivatives of iridium(I) and of the corresponding cation radicals [L2Ir{C5H4CH2(9,10-anthrylene)CH2C5H4}IrL2]+

“…The very low residual fluorescence observed (<1%) is quite probably due to traces of fluorescent impurities which may be present even after the very accurate chromatographic purification of the complexes. The UV-Vis absorption spectra of the monometallic complexes 5 and 6 (290-500 nm) are quite similar to those exhibited by 3 and 4 and are in line with previous observations [5,9]: in both cases the spectra are slightly less resolved than the spectrum of 9-methylanthracene, taken as the reference compound, and both the spectra exhibit an absorption tail. Furthermore, while 9-anthrylcyclopentadiene is an efficient light-emitting molecule when excited at 365 nm [9], 5 and 6 are very poor luminescent compounds, although the residual fluorescence observed (<5%) is slightly higher than that measured for 3 and 4.…”

“…However, this pseudo-centre represents only a local symmetry, being placed in an irrational position with respect to the screw axes, which are the only symmetry operators valid for the whole structure. The conformation is very similar to that found in the isostructural rhodium(I) derivative [9], which by chance resembles 5 also having two molecules in the asymmetric unit. Due to the very similar radii of Rh(I) and Ir(I) ions, the same mean distances M-Cp and M-Eth (Cp = cyclopentadienyl centroid; Eth = ethylene centroid) and the same mean angles, Cp-M-Eth and Eth-M-Eth, are observed.…”

“…Complex 6 has already been reported in the literature [5]. Complex 5 has now been obtained (27%, yields) by reacting 9-anthrylmethylcyclopentadienylthallium(I) [9] with [IrCl(g 2 -C 2 H 4 ) 4 ] (Eq. (1)), and characterized by elemental analysis, 1 H NMR, and Turbo-V Ionspray mass spectrometry (see Section 4), as well as by single-crystal X-ray diffractometry.…”

“…The mass spectra of complexes 3 and 5 were obtained with the Applied Biosystems/MDS Sciex API 4000 triple quadruple mass spectrometry coupled with the Perkin-Elmer Series 200 Micro Pump. Dichloromethane solution of the complex was ionized by Turbo-V Ionspary technique, a variation of ESI-MS. Ionization was performed applying the voltage of 5 kV, and the declustering process was carried out using the potential of 20 V. 9,10-Bis[(cyclopentadienylmethyl)thallium(I)]anthracene [1a], chlorodicarbonyl(pyridine)iridium(I) [6], di-lchlorotetrakis(g 2 -cyclooctene)diiridium(I) [23], (g 5 -cyclopentadienyl)dicarbonyliridium(I) [6], 9-anthrylmethylcyclopentadienylthallium(I) [9] were prepared as reported. 9-Methyl-anthracene (Aldrich), cyclopentadienylthallium(I) (Aldrich), ethylene (Matheson Gas Products), carbon monoxide (Matheson Gas Products), 1,1,1,3,3,3-hexafluoropropan-2-ol (99.8% Aldrich), thallium(III) trifluoroacetate (TTFA) (Aldrich) and [bis(trifluoroacetoxy)iodo]benzene (PIFA) (97% Aldrich) were used as received.…”

Vancomycin-Iridium (III) Interaction: An Unexplored Route for Enantioselective Imine Reduction

“…The coordination of Van to the iridium metal center was then confirmed by the bathochromic shift of the metal-to-ligand charge transfer transition (MLCT) band [35] in the UV spectra (Ɛ λ436nm = 6 × 10 3 M −1 cm −1 ) [36,37]. Interestingly, the addition of [IrCp*Cl 2 ] 2 to a Van solution caused a shift of the maximum absorbance from 417 nm for [IrCp*Cl 2 ] 2 alone to 429 nm for the [Ir(Cp*)(Van)Cl] complex [38,39] (see SI, Figure S2). Circular dichroism (CD) experiments on free vancomycin and on the Ir/Van 1:1 complex further confirmed that the complexation between the chiral macromolecule and the metal was effective.…”