Substrate-Mediated C–C and C–H Coupling after Dehalogenation

Abstract

Intermolecular C-C coupling after cleavage of C-X (mostly, X = Br or I) bonds has been extensively studied for facilitating the synthesis of polymeric nanostructures. However, the accidental appearance of C-H coupling at the terminal carbon atoms would limit the successive extension of covalent polymers. To our knowledge, the selective C-H coupling after dehalogenation has not so far been reported, which may illuminate another interesting field of chemical synthesis on surfaces besides in situ fabrication of polymers, i.e., synthesis of novel organic molecules. By combining STM imaging, XPS analysis, and DFT calculations, we have achieved predominant C-C coupling on Au(111) and more interestingly selective C-H coupling on Ag(111), which in turn leads to selective synthesis of polymeric chains or new organic molecules.

A review on special wettability textiles: theoretical models, fabrication technologies and multifunctional applications

“…Atom transfer radical polymerization (ATRP) is a controlled radical polymerization technology that has been proven useful for synthesis of functional macromolecules with controlled architectures [84][85][86][87][88] and the method has also been used for the modi-cation of various substances. [89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104] In order to convert the hydrophilic cotton cellulose bre into a superhydrophobic and self-cleaning surface, Nyström 74 achieved it via surface in situ polymerization of glycidyl methacrylate using an ATRP method combined with a post-modication reaction. Based on the environmental concerns over uorine-containing compounds and their high cost, the work has demonstrated a versatile route to fabricate superhydrophobic and self-cleaning surfaces using low amounts or even no uorinated materials.…”

Two‐Sidedness of Surface Reaction Mediation

“…Compared with Au(111), Ag(111) can suppress side reactions like hydroalkynylations and hence outperforms. Similarly, using (R)‐(−)‐6,6′‐dibromo‐1,1′‐bi‐2‐naphthol (DN) as the precursor, the intermolecular CC coupling reaction involving the CBr bond cleavage has been explored on Au(111) and Ag(111) . The experimental results demonstrate that the CC coupling reaction dominates on Au(111), while selective CH coupling occurs on Ag(111).…”

On the “True” Structure of Push–Pull‐Type Low‐Bandgap Polymers for Organic Electronics

“…For metal-catalyzed cross-coupling polycondensations employed to prepare push-pull copolymers, it is often assumed that the halogen and organometallic functional groups are still present at the end of the polymer chains after the reaction. However, for this type of reactions it is known from research on small organic molecules that different side reactions can occur, such as protodeborylation, [46][47][48] dehalogenation, [49][50][51] ligand exchange [52][53][54][55][56] and hydroxylation, [57,58] which terminate the growing polymer chains. Although identification of the end groups can hence be very insightful, only very limited efforts have been devoted to studies that go beyond the mere preparation of the desired materials.…”

“…Moreover, also cyclic derivatives were formed. Careful analysis of the MALDI-TOF spectra allowed to identify the different end groups, originating from ligand scrambling, [52][53][54][55][56] protodeborylation [46][47][48] and hydroxylation [57,58] (Figure 10). Although the MALDI-TOF spectra provided evidence that all of these side reactions were occurring, ligand scrambling appeared to be the main side reaction limiting the formation of high molar mass species.…”