Minimizing Side Product Formation in Alkyne Functionalization of Ruthenium Complexes by Introduction of Protecting Groups

Abstract

The synthesis of alkyne functionalized bipyridine ruthenium complexes are reported. The improved synthetic approach through application of stable protecting groups prevents formation of possible side products while facilitating purification. By applying copper‐catalysed azide‐alkyne cycloaddition reactions (CuAAC) pyrene units with flexible alkyl linkers are introduced at the periphery of the complex, opening up various applications including surface immobilization and DNA intercalation. All complexes are characterized structurally as well as photophysically, especially regarding the influence of the introduced alkyne and triazolyl substituents on their photophysical behavior.

Outpacing conventional nicotinamide hydrogenation catalysis by a strongly communicating heterodinuclear photocatalyst

“…In ace-tonitrile, MLCT absorption bands with their maxima in the range of 452 to 454 nm are observed, regardless of the substituent in 5-position of the phenanthroline. Even the further expansion of the π-system in case of complexes 1 and 2 via the alkyne bond does not cause a significant change of the MLCT absorption band which is reminiscent of similar complexes with free alkyne substituents 27 , 28 . For the alkyne-based complexes 1 and 2 , a broad absorption band at 345 nm is visible.…”

“…The two systems feature 1,10-phenanthroline (phen) coordination spheres on both the (tbbpy) 2 Ru chromophore moiety as well as the RhCp* catalyst subunit and are either linked via an alkyne (complex 2 ) or a triazole linker (complex 4 ) in the easy to modify 5-position (see Fig. 1b ) 26 – 28 . In combination with the recently reported tpphz (tetrapyridophenazine) derivative (complex 5 ) 14 , 24 , this allowed us to clearly assign for the first time photocatalytic reactivity changes in [(NN) 2 Ru-BL-Rh(Cp*)Cl] 3+ systems to the different photophysics and photochemistries in these molecules caused by altered molecular structures of the BL.…”

Gatekeeping Effect of Ancillary Ligand on Electron Transfer in Click Chemistry‐Linked Tris‐Heteroleptic Ruthenium(II) Donor–Photosensitizer–Acceptor Triads

“…The click reactions were performed under modified reaction conditions compared to previously reported ones. [ 31 ] However, since some of our complexes showed only poor solubility in dichloromethane, we changed the solvent to an acetone–water mixture and performed the reaction in an ultrasonication bath as recently reported, [ 61 ] which kept click‐typical room temperature but reduced the reaction time to only 1 h and significantly improved yields of the click reaction compared to previous attempts without ultrasonication.…”

Which bridge to cross, which mountain to climb – Supramolecular Photocatalysis Outpacing Conventional Catalysis

“…The two systems feature 1,10-phenanthroline (phen) coordination spheres on both the (tbbpy)2Ru chromophore moiety as well as the RhCp* catalyst subunit and are either linked via an alkyne or a triazole linker in the easy to modify 5-position (see Figure 1). [26][27][28] In combination with the recently reported bridging ligand, a tpphz (tetrapyridophenazine) derivative, 20,24 this allowed us to clearly assign for the first time photocatalytic reactivity changes in [(NN)2Ru-BL-Rh(Cp*)Cl] 3+ systems (bridging ligand = BL) to the different photophysics and photochemistry in these molecules caused by altered molecular structures of the intramolecular bridge.…”

“…Even the further expansion of the π-system in case of complexes 1 and 2 via the alkyne bond does not cause a significant change of the MLCT absorption band which is reminiscent of similar complexes with free alkyne substituents. 28,38 For the alkyne based complexes 1 and 2, a broad absorption band at 345 nm is visible. Due to its absence in complexes 3 and 4, we can assign this to a ligand centered π-π* transition of the delocalized alkyne bridged phenanthrolines.…”