Multidentate Anchors for Surface Functionalization

Li, Zhongqiu; Tang, Jian‐Hong; Zhong, Yu‐Wu

doi:10.1002/asia.201900989

Cited by 21 publications

(26 citation statements)

References 97 publications

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“…[11][12][13][14][15][16][17][18][19][20][21] Multipods allow generally a reasonable control of molecular orientation. 11,12,17,[22][23][24][25][26][27] The perpendicular orientation of the terminal head group or functional moiety relative to the surface is dictated by the binding mode to a rigid scaffold, which, in turn is either covalently linked to the substrate via multipodal anchoring groups 28 or physisorption, either on metals 17,18,25,26,[29][30][31][32][33][34][35] or on other surface types. 28,36,37 Common multipods exhibit three anchoring groups and one head group, usually linked by a central, sp 3 -hybridized carbon or silicon atom ( Figure 1a).…”

Section: Introductionmentioning

confidence: 99%

Tetrapodal Diazatriptycene Enforces Orthogonal Orientation in Self-Assembled Monolayers

Benneckendorf

Rohnacher

Sauter

et al. 2019

ACS Appl. Mater. Interfaces

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Conformationally rigid multipodal molecules should control the orientation and packing density of functional head groups upon self-assembly on solid supports. Common tripods frequently fail in this regard, because of inhomogeneous bonding configuration and stochastic orientation. These issues are circumvented by a suitable tetrapodal diazatriptycene moiety, bearing four thiol-anchoring groups, as demonstrated in the present study. Such molecules form well defined self-assembled monolayers (SAMs) on Au(111) substrates, whereby the tetrapodal scaffold enforces a nearly upright orientation of the terminal head group with respect to the substrate even in case of 75% covalent attachment to the surface. Functionalization by condensation chemistry allows a large variety of functional head groups to be introduced to the tetrapod, paving the path towards advanced surface engineering and sensor fabrication.

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Section: Introductionmentioning

confidence: 99%

Tetrapodal Diazatriptycene Enforces Orthogonal Orientation in Self-Assembled Monolayers

Benneckendorf

Rohnacher

Sauter

et al. 2019

ACS Appl. Mater. Interfaces

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“…[24] Such a multidentate structure enhances the stability and the organization of the monolayer, similar to what was described in the literature with other multidentate anchoring systems. [25] Importantly, we demonstrate that gold nanoparticles functionalized with calix [4] arene-tetradiazonium salts have exceptional colloidal robustness toward halides or extreme pH. [26] Such a property is potentially very appealing for applications in electrocatalysis, notably for oxygen reduction reaction (ORR) since the experimental conditions are demanding.…”

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Functionalizing Gold Nanoparticles with Calix[4]arenes Monolayers for Enhancing Selectivity and Stability in ORR Electrocatalysis

Lenne

Mattiuzzi²,

Jabin

et al. 2020

Adv Materials Inter

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blocking an important proportion of their active sites and deactivating the catalysts. The removal of ligands from the nanoparticles surface without altering the specific structure that rules their catalytic function, is a major challenge. [5-7] Interestingly, organic ligands are commonly designed and employed in homogeneous catalysis to steer the activity and selectivity of metal centers. [8,9] The presence of organic ligands allows better control of selectivity. In line with this concept, the chemical surface modification of metallic nanostructures has just emerged as a promising strategy to increase their catalytic performances as recently reviewed. [10] Recent reports have highlighted that organic functionalization of metallic nanoparticles can boost their electrocatalytic properties through local interfacial steric or electronic effects. [11,12] Far from having a detrimental impact, the ligands are found to have a beneficial role. The nature of the ligands, [13] and/or the interfacial bonding, [14] promote high electrocatalytic activity, selectivity, and durability. [10] The immobilization of organic molecules to metallic surfaces includes the chemisorption of monomers, polymers or surfactants, the self-assembly, the covalent grafting or the electrostatic adsorption of charged molecules (e.g., citrates, polyelectrolytes). The strength of interaction between surface and ligands depends on the employed procedures. Whereas thiol molecules are known for decades to efficiently bind gold nanoparticles (AuNPs) via AuS bonds, [15,16] more recently, AuC (carbene), [17] AuCC (acetylide), [18] or AuC (through aryl diazonium salts reduction), [19] provide robust interfacial bonds with strong metal-ligands interactions. The aryldiazonium reduction leads to strong interaction between the metallic surfaces and the aryl moieties, with adsorption energies over 200 kJ mol −1. [20] In contrast, electrostatic adsorption, involved for instance in citrate-stabilized gold nanoparticles corresponds to a weaker interaction with binding energy lower than 85 kJ mol −1. [21] We have recently developed a unique strategy to prepare dense and compact monolayers on a wide range of materials including nanomaterials thanks to the reductive grafting of calix[4]arene-tetradiazonium salts. [22,23] The calix[4]arene-tetradiazonium cation exhibits a cone-constrained structure made up of four aromatic units linked by methylene bridges, allowing The deliberate surface modification of nanocatalysts with organic ligands has recently emerged as a promising strategy to boost their efficiency, durability, and/or selectivity in key electrocatalytic processes. The interface between the metallic interface and the immobilized ligands promotes high electrocatalytic activity. Herein, the oxygen reduction reaction activity of gold nanoparticles functionalized with a covalently bound monolayer of calix[4]arenes is compared with commercially available gold nanoparticles, classically stabilized through electrostatic adsorption of citrates onto the gold surfa...

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“…Calix[4]arenes are macrocycles built from the linkage of four aromatic subunits through methylene bridges. With adequate groups at the small rim, they offer a rigid cone-constrained structure, being smart building blocks for the construction of highly robust monolayers with diazonium chemistry ( Figure 2 ): (i) the methylene bridges prevent side reactions from the aryl radical and thus the formation of multilayers (ii) appending arms at the small rim allow the introduction of various functional molecules or objects with a fine spatial control imposed by the small rim geometry and (iii) several diazonium functions at the large rim provide multiple anchoring points, which is expected to enhance the stability of the monolayers as already highlighted in self-assembled monolayers (Li et al, 2019 ). We have thus functionalized the large rim of calix[4]arenes with diazonium functions, and densely-packed monolayers were obtained through the reduction of these calix[4]arene-based diazonium cations as revealed by AFM and ellipsometry measurements (Mattiuzzi et al, 2012 ; Troian-Gautier et al, 2020 ).…”

Section: Calix[4]arene-diazonium Saltsmentioning

confidence: 99%

Strategies for the Formation of Monolayers From Diazonium Salts: Unconventional Grafting Media, Unconventional Building Blocks

Mattiuzzi¹,

Lenne

Padilha

et al. 2020

Front. Chem.

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Pioneered by J. Pinson and coll. in 1990s, the reductive grafting of aryldiazonium salts has become a powerful method for surface functionalization. Highly robust interfaces result from this surface attachment, resistant to heat, chemical degradation and ultrasonication. Importantly, this approach can be applied to many materials, ranging from conducting, semi-conducting, oxides to insulating substrates. In addition, either massive, flat surfaces or nanomaterials can be functionalized. The method is easy to process and fast. The grafting process involves the formation of highly reactive aryl radicals able to attack the substrate. However, the generated radicals can also react with already-grafted aryl species, leading to the formation of loosely-packed polyaryl multilayer films, typically of 10-15 nm thick. It is thus highly challenging to control the vertical extension of the deposited layer and to form well-ordered monolayers from aryldiazonium salts. In this mini review, we briefly describe the different strategies that have been developed to prepare well-ordered monolayers. We especially focus on two strategies successfully used in our laboratories, namely the use of unconventional solvents, i.e., room temperature ionic liquids (RTILs), as grafting media and the use of calixarene macrocycles by taking benefit of their pre-organized structure. These strategies give large possibilities for the structuring of interfaces with the widest choice of materials and highlight the potential of aryldiazonium grafting as a competitive alternative to self-assembled monolayers (SAMs) of alkyl thiols.

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Multidentate Anchors for Surface Functionalization

Cited by 21 publications

References 97 publications

Tetrapodal Diazatriptycene Enforces Orthogonal Orientation in Self-Assembled Monolayers

Tetrapodal Diazatriptycene Enforces Orthogonal Orientation in Self-Assembled Monolayers

Functionalizing Gold Nanoparticles with Calix[4]arenes Monolayers for Enhancing Selectivity and Stability in ORR Electrocatalysis

Strategies for the Formation of Monolayers From Diazonium Salts: Unconventional Grafting Media, Unconventional Building Blocks

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