Functionalizing a protein-binding aptamer with an acylation catalyst leads to site-selective modification of the target protein in proximity to the aptamer–protein interface. This protein modification can be switched ON or OFF by an external trigger.
The application of hexa[(dimethylamino)-methyl]-functionalized triphenylphosphine (1) and its benzylammonium salt, Bn-Dendriphos (2), in the Suzuki-Miyaura cross-coupling of aryl bromides with arylboronic acids is described. The 3,5-bis[(benzyldimethylammonio)methyl] substitution pattern in 2 leads to a rate enhancement compared to both the non-ionic parent compound 1 and triphenylphospine (PPh 3 ) itself. At the same time, the resulting catalytic species are stable towards palladium black formation, even at a phosphine/palladium ratio of 1. These observations are attributed to the presence of a total of six ammonium groups in the backbone of the phosphine ligand, which presumably leads to an unsaturated phosphine-palladium complex.
The synthesis of the first series of 4-mono and 3,5-bis(dimethylamino)methyl-functionalized triarylphosphanes of the general formula PPh 3 À n Ar n (Ar = 1-C 6 H 3 (CH 2 NMe 2 ) 2 -3,5 (NC(H)N), n = 1 (ligand 2) or n = 3 (ligand 4); Ar = 1-C 6 H 4 (CH 2 NMe 2 )-4 (NC(H)), n = 3 (ligand 7)) is described. These phosphanes were used for the construction of complexes of the form [AuCl(P)] and [PtCl 2 (P) 2 ]. In these complexes selective coordination of phosphorus to the metal ion is observed. The 31 P NMR data show the formation of cis-Pt complexes, even in the case of triarylphosphane 4, which features a tris{3,5-bis(dimethylamino)methyl} substitution pattern. The structure of the gold complex of mono-3,5-functionalized triarylphosphane 2 in the solid state shows a striking resemblance to the structure of the corresponding complex [AuCl(PPh 3 )]. The solid-state structure of the AuCl complex of tris-4-functionalized ligand 7 differs from that of [AuCl(PPh 3 )] in the sign of the torsion angles. The amine functionalities in this class of gold compounds could be reacted selectively with either acid (HCl, H 3 PO 4 ) to generate ammonium salts or with an alkylating agent (benzyl bromide) to afford benzyl ammonium salts, without the violation of the Au-P bond.
Rapid and quantitative click functionalization of surfaces remains an interesting challenge in surface chemistry. In this regard, inverse electron demand Diels–Alder (IEDDA) reactions represent a promising metal‐free candidate. Herein, we reveal quantitative surface functionalization within 15 min. Furthermore, we report the comprehensive effects of substrate stereochemistry, surrounding microenvironment and substrate order on the reaction kinetics as obtained by surface‐bound mass spectrometry (DART‐HRMS).
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