A Luminescent Ruthenium Azide Complex as a Substrate for Copper‐Catalyzed Click Reactions

Abstract

A new ligand and its luminescent polypyridyl–RuII complex were synthesized and characterized. Both provide two azide functionalities in their periphery, which are electronically separated from the π‐system of the 2,2′‐bipyridine ligands by a methylene group. This azide‐functionalized ruthenium complex provides access to the formerly inaccessible substrate spectrum of alkynyl‐functionalized coupling substrates by using the copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC). Test CuAAC reactions were performed on the ligand and directly on the RuII complex by using phenylacetylene as a model substrate, and relatively high yields of the products were obtained under mild conditions. Transformation of the azide into the triazole had only minor influences on the photophysical properties of the polypyridyl–ruthenium core.

Functional Dimming of Pincer‐Shaped Bibenzimidazole‐Ruthenium(II) Complexes with Improved Anion‐Sensitive Luminescence

“…[13,14] On the other hand, the vast synthetic variability of the general tris(diimine) framework allows the adjustment of a chromophore for a distinct application. [15][16][17] For example, 2,2′-bibenzimidazole ligands provide an elegant direct connection between a cisdiimine function for coordination to a ruthenium center with and XRD studies. The emission intensities of these complexes are dimmed compared with that of K0, whereas titration experiments with tetrabutylammonium (TBA) salts of fluoride, chloride, bromide, and iodide show strongly enhanced sensitivity to hydrogen bonding with chloride and bromide ions, which increases the emission intensity to ca.…”

Modular Synthesis of Elongated Phosphonate Bipyridines

“…[42] 4,4Ј-Bis(ethynyl)-2,2Ј-bipyridine (4) was prepared according to literature methods. [44] L2 was characterized by 1 H, 13 C and 31 P NMR, and HRMS [m/z (MALDI) = 743.26195.]. [44] L2 was characterized by 1 H, 13 C and 31 P NMR, and HRMS [m/z (MALDI) = 743.26195.].…”

“…The solid-state structure of 7 was derived from X-ray suitable single crystals ( Figure S1 in the Supporting Information). [44] The complexation of Cu I with bipyridine might be one reason for the modest yield. [42] L3 was obtained by the click reaction of azide 8 and bisalkyne 4 in 30 % yield, by using the same conditions as for the synthesis of L2.…”

“…[42] 4,4Ј-Bis(ethynyl)-2,2Ј-bipyridine (4): This compound was prepared according to literature. [44] Compound 3 (0.63 g, 2.34 mmol) was added to a solution of 4 (134 mg, 0.66 mmol) in CH 2 Cl 2 (25 mL), which was followed by the addition of a mixture of copper sulfate pentahydrate (60 mg, 0.24 mmol) and (+)-sodium l-ascorbate (NaAsc; 117 mg, 0.59 mmol) in H 2 O (25 mL). [44] Compound 3 (0.63 g, 2.34 mmol) was added to a solution of 4 (134 mg, 0.66 mmol) in CH 2 Cl 2 (25 mL), which was followed by the addition of a mixture of copper sulfate pentahydrate (60 mg, 0.24 mmol) and (+)-sodium l-ascorbate (NaAsc; 117 mg, 0.59 mmol) in H 2 O (25 mL).…”

Towards Ruthenium‐Based Building Blocks for CuAAC Click Reactions: Challenges in Generating Ruthenium(II) Poly­pyridine Alkynes

“…The stability of the azide group is then ensured by the introduced methylene spacer. [6] The alternative substrate, an alkyne bearing bipyridine appears to be a simple reagent for the synthesis of the corresponding ruthenium(II) polypyridine complexes. And so, complexation of an alkyne-substituted bipyridine onto a ruthenium(II) polypyridine is of great interest.…”