Grafting of lanthanide complexes on silica surfaces dehydroxylated at 200 °C: a theoretical investigation

Abstract

Cluster models of SiO 2 -200 are proposed and compared with spectroscopic (IR and NMR) experimental data. Five models describing the variety of surface silanols (isolated, vicinal and germinal) at the SiO 2 -200 surface have then been derived and used to study the grafting reaction of homoleptic silylamide lanthanum(III) complexes. Three different grafting modes have been obtained (mono-, bi-and tri-grafted) in line with the experimental knowledge. In terms of energetic stability as well as spectroscopic properties of coordinated OPPh3 (as a probe), all modes could coexist at the surface. The analysis of the δ( 31 P) chemical shifts for the coordinated OPPh3 indicates some possible important differences in Lewis acidity of the lanthanide centre, that may impact the catalysis.

Grafting of Lanthanum Complexes on a Functionalized Graphene Surface: Theoretical Investigation on Ethylene and 1,3‐Butadiene Homo‐ and Co‐Polymerization

“…As in the experimental approaches, some of us have recently described, from ac omputationalp oint of view,t he reactiono fO PPh 3 with different silica-grafted lanthanide species, showingt hat the OPPh 3 coordination strength can be affected by the coordination sphere of the grafted complex. [46,48] To probe the influence of the graphene surface, we have now investigated the OPPh 3 interaction with the graphene grafted hexamethyldisilylamido lanthanum complexesa bove described. The coordination of O= PPh 3 on both the Figure 4b)s pecies through an exothermic process (À28.9 and À24.7 kcal mol À1 ,r espectively).…”

“…[43][44][45] Combined experimental and theoretical studies on the grafting of lanthanide com-plexes on silica have been recently reported. [46][47][48][49] They show that the formation of ac ovalent SiOÀLn bond requires the presence of hydroxyl groups on the surface, [46] the graftingr eaction of [Ln(N(SiMe 3 ) 2 ) 3 ]( Ln = La Nd, Sm) occurringt hrough a protonolysiso ft he LnÀNb ondb yt he surface silanols. As some of us have previously described, the graftingo famolecular complex on silica surfaces provides as ignificant modification of its catalytic properties.…”

“…As some of us have previously described, the graftingo famolecular complex on silica surfaces provides as ignificant modification of its catalytic properties. [11,46,48] The polymerization of methyl methacrylate by as ilica-supported neodymium catalyst, indeed, leads to the formationo famoderately isotactic polymer while the homogenous precursor generates am oderately syndiotactic polymer. [50,51] To the best of our knowledge,n oe xample describing the influence of the graftingo falanthanide complex on other oxide supports or carbon nanotubes has ever been described in the literature.…”

Self-Assembled Monolayers of Redox-Active 4d–4f Heterobimetallic Complexes

“…Lanthanides complexes have been grafted onto Si or silica surfaces. [6][7][8][9] Langmuir-Blodgett layers or molecular printboards using -cyclodextrins have been also employed to immobilize lanthanides complexes. 10,11 Immobilization procedure involving anchoring thiols groups have been described onto gold planar surfaces, [12][13][14][15] but also onto gold nanoparticles.…”

Desenvolvimento de diferentes métodos LC-MS/MS para a determinação de fármacos e endocanabinóides em amostras de plasma

“…Portanto, esta atividade depende da quantidade de grupos silánóis disponíveis e do seu caráter ácido, assim, a faixa de pH da fase móvel influencia na ionização. Além disso, a atividade silanol também está relacionada ao tipo de silánóis residuais, podendo ser isolado, germinal ou vicinal (Figura 23) (Lesellier e West, 2007;Del Rosal et al, 2015).…”