A perfluorocyclopentene based diarylethene bearing two terpyridine moieties – synthesis, photochemical properties and influence of transition metal ions

Falk Wehmeier,Jochen Mattay

doi:10.3762/bjoc.6.53

Abstract

The synthesis of a perfluorocyclopentene based diarylethene bearing two terpyridine units is reported. Furthermore studies of the free ligand’s photochromism and investigations regarding the influence of various transition metal ions on the photochromic reaction are presented. The photochromism of the central diarylethene unit is strongly dependent on the transition metal present, vice versa the photochromic reaction seems to influence the MLCT transition of a binuclear Ru(II) complex.

Highlights

A microreview concerning the synthesis of functionalized terpyridines has been published since the electronic properties of the ligand are influenced by the substituents present [6]. Because of this impact of terpyridine derivatives in photochemistry, we focused our attention on the synthesis and studies of photoswitchable terpyridine ligands
We report the synthesis of terpyridine functionalized diarylethenes based on perfluorocyclopentene, their photochemistry and investigations regarding the influence of transition metals
Synthetic routes to terpyridine substituted diarylethenes via the above mentioned catalytic cross coupling reactions require suitably functionalized terpyridine precursors, e.g. boronic acid derivatives for Suzuki type cross coupling reactions. 4′-(4-Bromophenyl)-2,2′:6′,2′′-terpyridine (7a) and its meta-substituted analogue 7b can be synthesized by Kröhnkecondensation of 2-acetylpyridine (5) with p-bromobenzaldehyde (6a) or m-bromobenzaldehyde (6b), respectively [15]

Summary

Introduction

Because of this impact of terpyridine derivatives in photochemistry, we focused our attention on the synthesis and studies of photoswitchable terpyridine ligands. We report the synthesis of terpyridine functionalized diarylethenes based on perfluorocyclopentene, their photochemistry and investigations regarding the influence of transition metals. The terpyridine moieties can be attached to the diarylethene unit by Suzuki type cross coupling of the diiodo switch 4 with the boronic esters 9a and 9b under conditions similar to those described for other aryl boronic acids and their derivatives to yield the target molecules 10a and 10b (Scheme 3) [14].

Results

Conclusion