Orthogonal Transformations on Solid Substrates: Efficient Avenues to Surface Modification

Abstract

The performance of solid substrates is not only governed by their molecular constitution, but is also critically influenced by their surface constitution at the solid/gas or solid/liquid interface. In here, we critically review the use of orthogonal chemical transformations (so‐called click chemistry) to achieve efficient surface modifications of materials ranging from gold and silica nanoparticles, polymeric films, and microspheres to fullerenes as well as carbon nanotubes. In addition, the functionalization of surfaces via click chemistry with biomolecules is explored. Although a large host of reactions fulfilling the click‐criteria exist, pericyclic reactions are most frequently employed for efficient surface modifications. The advent of the click chemistry concept has led—as evident from the current literature—to a paradigm shift in current approaches for materials modification: Away from unspecific and nonselective reactions to highly specific true surface engineering.

On the Quantitative Click Conjugation of Molecular Weight Distributions: What Can Theoretically Be Expected?

“…Click-type reactions are employed for a range of purposes, including surface modification [6] and the generation of complex macromolecular architectures [5] . Quantitative orthogonal conjugation becomes especially attractive where polymeric building blocks are joined to yield block copolymers, [7][8][9][10][11] which are not obtainable by alternative means (i.e., sequential chain extension via living/controlled (radical) polymerization).…”

Synthesis and Structural Analysis of Substituted Tripod‐Shaped Tri‐ and Tetra(p‐phenylene)s

“…Compound 2c was isolated by column chromatography (cyclohexanes/EtOAc, 9:1) as a solid foam (71 mg, 45 %). 1 …”

“…68-70°C. 1 1, 8 mL). This mixture was degassed with argon purge for 5 min, and the reaction was initiated by the addition of 6 (0.10 g, 0.15 mmol) and placed in an oil bath at 70°C for 12 h. The catalyst was filtered off and washed with acetonitrile (50 mL).…”

“…In addition, the thin films should resist the nonspecific adsorption of proteins and should ideally be readily functionalized by using bio-orthogonal reactions, such as click or Suzuki reactions. [1][2][3] The most common method to control the average density of the functional groups on monolayer surfaces prepared by self-assembly of monodentate adsorbates is by co-deposition with inert analogous adsorbates. However, it is not possible to avoid nonrandomized mixing on the nanoscale that prevents controlling the spacing between the functional surface groups.…”

Has Click Chemistry Lead to a Paradigm Shift in Polymer Material Design?

“…Grafting from or rather onto surfaces isespecially since the advent of living/ controlled radical processes -a popular route to place low polydispersity polymers with variable characteristics onto surfaces. A recent review of surface modification via click chemistry approaches [20] has demonstrated that several types of surface have by now been modified via click chemistry. Again, we question whether this flurry of activity is merely an expression of scientific 'me-tooism' or whether a deeper conceptual driving force is at work that is based on the efficiency and modularity of the click chemistry concept.…”