Group 8 metal alkynyl complexes for nonlinear optics

International audienceStudies of the nonlinear optical (NLO) properties of Group 8 metal alkynyl complexes are summarized, with particular focus on results since 2003; structure-NLO property relationships are developed, optical nonlinearities of multipolar alkynyl complexes are described, and switching of the NLO response of molecules and molecular materials derived from Group 8 metal alkynyl complexes is discussed

Synthesis, reactivity, and some photochemistry of ortho-N,N-dimethylaminomethyl substituted aryl and ferrocenyl pentamethylcyclopentadienyl dicarbonyl iron complexes

Supplementary materials: CCDC 928736, 928273, 928738, 928275, 928274 and 928737 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/data_request/cifInternational audienceOrtho-lithiated N,N-dimethylaminomethyl ferrocene and benzyldimethylamine react with Cp*Fe(CO)2I to give the new complexes ((Cp*Fe(CO)2)-2-(CH2NMe2)C5H3)Fe(Cp) and Cp*Fe(CO)2-C6H4(o-CH2NMe2). Access to a wide variety of alkoxy-substituted complexes ((Cp*Fe(CO)2)-2-(CH2OR)C5H3)Fe(Cp) can be easily achieved by tandem quaternization/alcoholysis of ((Cp*Fe(CO)2)-2-(CH2NMe2)C5H3)Fe(Cp). Preliminary results show that chelated complexes can be obtained by displacement of one of the carbonyl ligands by photolysis. Crystal structures of ((Cp*Fe(CO)2)-2-(CH2NMe2)C5H3)Fe(Cp), ((Cp*Fe(CO)2)-2-(CH2OR)C5H3)Fe(Cp) (R = Ph, Bz, CHPh2 and d-menthyl) and [Cp*Fe(CO)2-C6H4(o-CH2NMe2)][I] are reported

[Fp*Fc][PF6]: A remarkable non-symmetric dinuclear cation in a very stable mixed-valent state

We report herein dicarbonyl(pentamethylcyclopentadienyl)(ferroceniumyl)iron hexafluorophosphate, which contains a dimetallic cation with a remarkably stable mixed-valent (MV) structure and unexpected redox features. The electronic structure of this compound is discussed in the light of the existing Hush model, which suggests an unusually strong electronic coupling between the two iron centers, despite the non-symmetric environment of the metallic centers. End-to-end charge delocalization is not the main contributor to the extra-large stability of this MV complex, which originates from electronic effects other than the energetic difference between the two MV redox isomers (ΔG0). This open-shell derivative has also been briefly tested as a catalyst in the reductive etherification of aldehydes by hydrosilanes.G.G. thanks Region Bretagne for partial support of a PhD scholarship. The CNRS (PICS programs N 5676 and 7106) & ANR (2010- BLAN-7191) are acknowledged for financial support. M.G.H. thanks the ARC for financial support and an Australian Professorial Fellowship. O. Mongin (UMR 6226, Rennes) is acknowledged for experimental assistance and J.-F. Meunier (LCC, Toulouse) for recording the Mossbauer spectra

A Zinc(II) Tetraphenylporphyrin Peripherally Functionalized with Redox-Active "trans-[(η5-C5H5)Fe(η5-C5H4)C≡C](κ2- dppe)2Ru(C≡C)-" Substituents: Linear Electrochromism and Third-Order Nonlinear Optics

Dedicated to Dr. Claude Lapinte on the occasion of his retirement, in memory of the good times spent together in France and Australia.International audienceA nonametallic organometallic-coordination complex (4), assembled from redox-active ferrocenyl (Fc) and Ru(κ2-dppe)2 fragments (dppe = 1,2-bis(diphenylphosphino)ethane) as peripheral donor groups and a central Zn(II) tetraphenylporphyrin (ZnTPP) core, has been prepared and characterized. Complex 4 is obtained in one step from a pentametallic organometallic porphyrin precursor following substitution of the peripheral chloride ligands by ferrocenylalkynyl moieties (Ctriple bond; length of mdashCFc). The spectroelectrochemistry of 4, and that of previously reported porphyrins featuring related peripheral electron-rich d6-transition metal alkynyl units, has been investigated; the optical and redox properties of 4 are briefly discussed, and its potential, and that of a related pentanuclear tetraferrocenyl ZnTPP complex, to function as redox-switchable chromophores is examined. Preliminary studies of the cubic NLO properties of 4 have been undertaken by Z-scan studies at 560 nm and 630 nm, the results from which are also reported

Enhanced two-photon absorption cross-sections of zinc(II) tetraphenylporphyrins peripherally substituted with d(6)-metal alkynyl complexes

International audienceThe syntheses of new Zn(II) tetraphenylporphyrin (ZnTPP) derivatives functionalized with electron-rich d6-transition metal alkynyl complexes at their periphery are reported. Z-scan measurements reveal remarkably large effective two-photon absorption (TPA) cross-sections in the visible range for these compounds

Synthesis, characterization and third-order nonlinear optical properties of a dodecaruthenium organometallic dendrimer with a zinc(ii) tetraphenylporphyrin core

A new Zn(ii) porphyrin-based dendrimer (5(2)) containing twelve Ru(ii) alkynyl fragments, has been prepared following a convergent approach in two steps from 5,10,15,20-tetra(4-ethynylphenyl)porphyrinatozinc(ii) (6). The cubic nonlinear optical (NLO) properties of 5(2) and other derivatives of 6 have been measured by third-harmonic generation (THG) at 1907 nm and by Z-scan over the spectral range 500-1700 nm, revealing the remarkable NLO response of 5(2) in the near-IR range. These results highlight the beneficial role of the extended cross fourchee-like polymetallic structure of 5(2) on its third-order NLO properties.This research was supported by grants from the “Region Bretagne” (A. M. and G. G.) and the Australian Research Council (M. G. H.). The CNRS (PICS programs No. 5676 & 7106 and LIA Redochrom) and UEB/FEDER/RTR-Bresmat (EOPT 11MF422-02 Porphamp) are acknowledged for financial support. T. G., S. K. and J.-F. H. thank GENCI (Grand Equipment National de Calcul Intensif ) for HPC resources project GENCI A0030807367-gen7367). Drs. M. Reynolds (UMR 8537), A. Bondon and O. Mongin (UMR 6226) are acknowledged for assistance during spectroscopic characterizations

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The synthesis and characterization of a set of redox-active iron and ruthenium alkynyl complexes of general formula [[M]­Cl_{(1–<i>p</i>)}{CCC₆H_5–<i>m</i>(CCFlu)_<i>m</i>}_(1+<i>p</i>)]­[PF₆]_<i>n</i> are reported (<i>n</i> = 0–1; <i>m</i> = 1–2; [M] = [Fe­(η⁵-C₅Me₅)­(κ²-dppe)] and <i>p</i> = 1 or [M] = [<i>trans</i>-Ru­(κ²-dppe)₂] and <i>p</i> = 0–1). The linear and third-order nonlinear optical properties of these new organometallic complexes featuring phenylalkynyl ligands functionalized by 2-fluorenyl (Flu) groups were studied in their stable redox states. Their first electronic transitions are assigned with the help of DFT calculations. We show here that these compounds possess significant third-order NLO responses in the near-IR range for molecules of their size. In particular, the remarkably large 2PA activities of the new Ru­(II) compounds in the 600–800 nm range (<i>Z</i>-scan) make them attractive nonlinear chromophores. Structure–property studies emphasize the importance of para- versus meta-connection of the 2-fluorenylethynyl units on the phenylalkynyl core and reveal that upon progressing from mono- to bis-alkynyl complexes a further increase of the 2PA cross section can be obtained while maintaining linear transparency in the visible range

Linear and Third-Order Nonlinear Optical Properties of Fe(n5-C5Me5)(k2-dppe)- and trans-Ru(k2-dppe)2-Alkynyl Complexes Containing 2-Fluorenyl End Groups

The synthesis and characterization of a set of redox-active iron and ruthenium alkynyl complexes of general formula [[M]Cl(1–p){C≡CC6H5–m(C≡CFlu)m}(1+p)][PF6]n are reported (n = 0–1; m = 1–2; [M] = [Fe(η5-C5Me5)(κ2-dppe)] and p = 1 or [M] = [trans-Ru(κ2-dppe)2] and p = 0–1). The linear and third-order nonlinear optical properties of these new organometallic complexes featuring phenylalkynyl ligands functionalized by 2-fluorenyl (Flu) groups were studied in their stable redox states. Their first electronic transitions are assigned with the help of DFT calculations. We show here that these compounds possess significant third-order NLO responses in the near-IR range for molecules of their size. In particular, the remarkably large 2PA activities of the new Ru(II) compounds in the 600–800 nm range (Z-scan) make them attractive nonlinear chromophores. Structure–property studies emphasize the importance of para- versus meta-connection of the 2-fluorenylethynyl units on the phenylalkynyl core and reveal that upon progressing from mono- to bis-alkynyl complexes a further increase of the 2PA cross section can be obtained while maintaining linear transparency in the visible range

New electrochromic organometallic materials for light modulation

Group 8 metal alkynyl complexes are particularly attractive as building blocks for nonlinear optical materials for two reasons: the high efficiency of the resulting materials, especially for large complexes such as dendrimers, and the possibility of switching the nonlinear activity using various stimuli. The work reported in this thesis focuses on the second aspect, using an already existing complex as starting point and optimizing its properties by various structural modifications. In the Introduction, the theory of nonlinear optics, its various effects, and experimental methods for measuring NLO responses are presented. The effect of structural variations on the NLO activities of group 8 metal alkynyl complexes is reviewed to contextualize the present work. A new type of heterobimetallic complex is studied as potential redox end-group in the first chapter, with a special focus on its properties in the mixed-valent state. In a second part of this chapter, the possibility of using a more extended analogue of the ferrocenyl end{u00AD}group is explored, with a report on the third-order NLO activity of a model complex bearing this extended end-group. The second and third chapter share the same topic, concerned with the use of triphenylpnictogen as connecting cores for octupolar complexes. The use of triphenylamine is covered in the second chapter, the aim being to increase the number of redox states obtainable within a given octupolar complex as a result of the unique properties of triphenylamine-type compounds. In the third chapter, triphenylphosphine and its P(V) derivatives are investigated. This study, which led to the use of extended triphenylphosphine oxide is detailed in the first part of this third chapter. In a second part, the synthesis and characterization of the physicochemical properties of complexes bearing this extended triphenylphosphine core is discussed. Lastly, in the fourth chapter, the search for new types of redox-switchable end-group is pursued. After judicious structural modification of a simple starting complex, two new and different types of functionalities have been developed. In the first part of this last chapter, functionalization of the model complex with a pendant alkyne group is demonstrated to allow for the grafting of this complex on silicon surfaces, giving the opportunity of obtaining a redox-switchable material out of these air-stable ferrocenyl ruthenium alkynyl complexes via a simple modification. The synthesis of potentially Si-graftable precursors related to these complexes is also presented. In the second part, the possibility of using ferrocenyl allenylidene as redox-switchable groups is presented. It is demonstrated that these complexes might lead to systems possessing a dual type of redox switching, namely using either oxidation or reduction, leading to new possibilities in the design of NLO-active multi{u00AD}redox-stable molecules

Synthesis of new triphenylphosphines with pending ethynyl substituents

International audienceThe straightforward isolation and characterization of new triphenylphosphines possessing a pendent ethynyl substituent on one or several peripheral aryl ring(s) are reported. The synthesis of this family of compounds is achieved by retro-Favorsky reactions from the corresponding propargylic alcohol derivatives, themselves obtained following a classic Sonogashira-type coupling between the ad hoc bromophenyl phosphines and 2-methylbut-3-yn-2-ol