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Visible-light photolytic synthesis of multinuclear and dendritic iron-nitrile cationic complexes

Publication . Ornelas, Cátia; Ruiz, Jaime; Rodrigues, João; Astruc, Didier

Multinuclear and dendritic iron-nitrile piano-stool cationic complexes were synthesized in quantitative yield by a single-step synthesis involving visible-light photolysis of the complex [CpFe(eta(6)-toluene)][PF6]. This synthetic strategy was applied to mono-, bis- and tris-nitrile ligands and to new nitrile-terminated dendrimers containing 9, 27, and 81 tethers. All the synthesized products are deep red solids or red waxy products, highly stable to air and moisture. They were characterized by (1)H, (13)C, and (31)P NMR, elemental analysis, UV-vis spectroscopy, and cyclic voltammetry (single reversible oxidation wave to Fe(III)). Only the para-disubstituted arene dinitrile diiron complex shows two separated reversible waves indicating some electronic communication between the iron centers through the nitrile ligands.

2008-05-19Journal article

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Poly(alkylidenamines) dendrimers as scaffolds for the preparation of low-generation ruthenium based metallodendrimers

Publication . Rodrigues, João; Jardim, Manuel G.; Figueira, João; Gouveia, Marisol; Tomás, Helena; Rissanen, Kari

The aim of this article is to highlight the use of nitrile-functionalized poly(alkylidenamines) dendrimers as building blocks for the preparation of low-generation ruthenium based cationic metallodendrimers having in view potential biomedical applications. Air-stable poly(alkylidenamines) nitrile dendrimers, peripherally functionalized with the ruthenium moieties [Ru(Z5-C5H5)(PPh3)2]+ or [RuCl(dppe)2]+, have been prepared, characterized and are being studied for their anticancer activity. The followed strategy is based on the biological advantages associated with low-generation dendrimers, the known activity of ruthenium compounds as anticancer drugs and the stability of these dendrimers at the physiological temperature.

2011Journal article

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Divergent route to the preparation of hybrid Pt–Fe 2,4,6-Tris(4-ethynyl)phenyl-1,3,5-triazine metallodendrimers for nonlinear optics

Publication . Maiti, Swarup K.; Jardim, Manuel G.; Rodrigues, João; Rissanen, Kari; Campo, Jochen; Wenseleers, Wim

The synthesis strategy for the preparation of novel platinum acetylide homometallic and heterobimetallic dendrimers (containing Fe as the other metal fragment) based on a 2,4,6-tris(4-ethynyl)phenyl-1,3,5-triazine core (3) is reported. All the dendrimer generations (G0−G2) were synthesized under copper-free conditions following a divergent route. The G0-Pt dendrimer (4) was synthesized using the 1,3,5-triazine core (3) and cis[Pt(PEt3)2Cl2] with a molar ratio of 1/4. The advantage of the current method is that diﬀerent dendrimers can be prepared by following the same procedure with only changes in the molar ratios of the reactants involved. For instance, when 3 reacts with 4 in a 4/1 molar ratio, the G1 dendrimer 7 is aﬀorded without the peripheral Pt moiety, but the G1 dendrimer with the peripheral Pt moiety (8) is formed when 3 reacts with 4 in a 1/3 molar ratio. On the other hand, the G2 dendrimer with a peripheral Pt moiety (9) is synthesized when 7 reacts with 4 in a 1/6 molar ratio. The heterobimetallic dendrimers were synthesized up to generation 1 by capping the corresponding Pt dendrimers with the ethynylferrocenyl group (EFC). The respective G0 (6)- and G1-capped (10) dendrimers were synthesized when EFC reacted with 4 and 8 in molar ratios of 9/1 and 18/1, respectively. Nonlinear optical (NLO) polarizabilities measured by hyper-Rayleigh scattering (HRS) have been evaluated for the core 3, for the G0 dendrimer 4, and for the G0 dendrimer capped with EFC (6). In spite of the fact that the stability of the higher generations in chloroform is too low to allow HRS measurements, the reported NLO results show a remarkable enhancement (plus 50%) upon capping the zero dendrimer generation (6), reﬂecting the importance of the introduction of electron donor organometallic capping groups in the hyperpolarizabilities of the resulting dendrimers.

2013Journal article

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A convenient route for the preparation of the monohydride catalyst trans-[RuCl(H)(dppe)2] (dppe=Ph2PCH2CH2PPh2): improved synthesis and crystal structure

Publication . Figueira, João; Jardim, Manuel G.; Rodrigues, João; Valkonen, Arto; Rissanen, Kari

A novel and improved room temperature synthesis of the monohydride catalyst trans-[RuCl(H)(dppe)2] complex (1, dppe (1,2-bis(diphenylphosphino)ethane) = Ph2PCH2CH2PPh2) proceeds through oxidation of methanol (the solvent) by the pentacoordinated cis-[RuCl(dppe)2][PF6] complex and t-BuOK as the base is described. Compound 1 was fully characterized by NMR (1H, 13C, 31P), ESI-MS(TOF +), FTIR and elemental analysis. The X-ray structure of 1 was reported for the first time and unambiguously confirms the trans-configuration of the complex.

2013Journal article

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Preparation and characterization of novel poly(alkylidenamine) nitrile ruthenium metallodendrimers

Publication . Jardim, Manuel G.; Rissanen, Kari; Rodrigues, João

Complete functionalization of N,N,N ,N -[tetrakis(cyanoethyl)hexamethylenediamine] [N C(CH2)2]2N(CH2)6N[(CH2)2C N]2 (4) and N,N,N ,N -[tetrakis(cyanoethoxypropyl)hexamethylenediamine] [N C(CH2)2O(CH2)3]2N(CH2)6N[(CH2)3O(CH2)2C N]2 (7) with the organometallic moiety [Ru(η5C5H5)(PPh3)2Cl] and the five-coordinate cis-[RuCl(dppe)2][PF6] [dppe = 1,2-bis(diphenylphosphanyl)ethane] was attained with good yield, respectively, by treating the metallofragment with the core in methanol (at room temperature and in presence of TlPF6 as a chloride abstractor) and in 1,2 dichloroethane (under reflux). These novel nitrile-functionalized poly(alkylidenamine) dendrimers peripherally functionalized with the ruthenium moieties [Ru(η5-C5H5)(PPh3)2]+ and [RuCl(dppe)2]+ (8–11) were fully characterized by NMR (1H, 13C, 31P), TOF-MS and FTIR. The present results represent a step forward in the knowledge of the most adequate synthetic strategy for total coordination of poly(alkylidenamine) nitrile core derivatives to the different ruthenium complex moieties and confirm the versatility of these systems as building blocks in metallodendrimer chemistry.

2010Journal article

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