I- Coordination chains and polymers
Our group has recently designed a new family of organometallic o- and p-quinonoïd complexes of iridium and rhodium. These compounds were used as organometallic-linkers "OM-linkers" to construct a novel class of luminescent coordination assemblies and polymers. Interestingly the chalcogen atoms of the p-quinonoïd complexes (Figure) are highly nucleophilic and hence are able to bind a wide range of transition metal based chromophores such as Cu(I), Ag (I), Ru(II), Pt(II), Rh(III) and Ir(III). Moreover the related o- and p-thioquinonoid OM-linkers (E= S,) were prepared for the first time following an appropriate synthetic procedure. These highly reactive intermediates were metal-stabilized and isolated as "Cp*Ir" complexes.
Figure : Organometallic o- and p-Quinonoïd Complexes : ACIE 2008, 47, 1372.
The dithiobenzoquinone complexes (E=S) are of particular interest since they allowed the preparation of a new family of polypyridyl platinum(II) compounds exhibiting important π–π and Pt(II)•••Pt(II) interactions responsible of thermochromism and photoluminescence properties (Collaboration Prof V. W. W. Yam). These compounds are potentially of great interest as luminescent material devices.
Figure : Photoluminescence and Thermochromism behavior of 1D Pt-chain with p-thioquinonoid OM- Dalton Trans. 2007, 3526.
More recently we were able to isolate the first example of a diselenobenzoquinone (E= Se) as a metal complex. The X-ray molecular structure of this molecule was determined. Furthermore this species exhibited important antitumoral properties comparable to that of cis-platin. This work was heralded the cover of the prestigious journal Angewandte Chemie.
Figure : Molecular structure of the p-diselenobenzoquinone as a metal complex : ACIE 2010, 49, 7530.
II. Chiral octahedral assemblies
Another interesting family of chiral octahedral Ir(III), Rh(III) and Ru(II) was also designed and successfully prepared using the o-quinonoid metal-complexes. The resulting chiral bimetallic assemblies showed interesting photoluminescence properties such as panchromatic absorbers and NIR emissions. These complexes hold promise for applications in the area of optoelectronics and photovolatics.
Figure : Luminescent chiral bimetallic assemblies with o-quinonoid OM-linker (M2 = Ru, Rh, Ir). Organometallics 2009, 28, 397. Inorg. Chem. 2010, 49, 10762.
III-Anion-π interactions in quinonoid OM-linkers.
Furthermore we have recently demonstrated that this kind of quinonoid OM-linkers display important noncovalent interactions with anions despite the fact they are neutral. In fact, the weakly coordinating anion triflate undergoes an anion-π interaction with the Cp*Ir moiety of the neutral quinonoid linker in the organometallic assembly [Cp*Ir(η6-C6H2O4)-(BF2)2] et l’anion triflate (CF3SO3‾) (see Figure). The work has been published in Eur. J. Inorg. Chem. and was featured on the cover of the journal.
Figure.View of the anionic part of the organometallic assembly with atom numbering system. (b) The CF3SO3 anion is perfectly located on top of Cp*Ir and lies on the same plane of symmetry as that of [Cp*Ir(η6-C6H2O4)-(BF2)2]( c ) C---O short contacts are shown by dotted lines.. Eur. J. Inorg. Chem. 2009, 3679.
Our future objectives in this research topic are devoted to the use of the new tetradentate p-quinonoid linkers for the preparation of luminescent chiral networks.