Turning “On” and “Off” a Pyridoxal 5′‐Phosphate Mimic Using Light

Abstract

Licht wird verwendet, um ein photoresponsives Mimetikum des Cofactors Pyridoxalphosphat zwischen zwei Isomeren zu schalten, von denen nur eines die Racemisierung einer Aminosäure katalysieren kann. Die Funktion beruht auf dem Herstellen und Unterbrechen der elektronischen Kommunikation zwischen den beiden Katalysatorkomponenten, einem Aldehyd und einem Pyridiniumkation.

Light‐Controlled Release and Uptake of Zinc Ions in Solution by a Photochromic Terthiazole‐Based Ligand

“…However,aprecise determination of the cyclizationq uantum yield of Zn 2 -(1a-2H) 2 is extremely complicated because it is not as imple At oB photoreaction:i na ddition to Zn 2 -(1a-2 H) 2 ,Z n 2 -(1a-2 H)(1b-2H)a nd Zn 2 -(1b-2 H) may be transient photoproducts before falling apart to give 1b and also some 1a (see below) Nevertheless, consideringo nly the spectral evolutiono fZ n 2 -(1a-2 H) 2 at the very beginning of the UV irradiation,w here one can reasonably neglect the contribution of different photoproducts to the absorption spectra, the determination of the slope at the origin allows us to approximate the cyclization quantum yield. Thus, aquantum yield of approximately 2% was found for Zn 2 -(1a-2 H) 2 and approximately 5% for 1a.T he value of the latter is compatible with that (4 %) determined previously by fitting the whole spectral changes of 1a upon UV irradiation. [27] The quantum yield of the back reaction( cycloreversion) is not significantly affected by the presence of zinc ions as, at the end, only 1b absorbs in the visible region.…”

“…Upon irradiation at 600 nm, the blue solutiont urned yellow, with restorationo falarge parto ft he initial spectrum. After the end of irradiation at 600 nm, the spectrum evolvedi nt he dark within hours,w ith af inal spectrum almosti dentical to that of Zn 2 -(1a-2 H) 2 .…”

“…To evaluate the photo-reactivity of the complexes, the electronic transitions of Zn 2 -(1a-2 H) 2 and Zn 2 -(1a-2 H)(1b-2 H) have been computed by time-dependent DFT (TD-DFT). All the details of these calculations are providedi nF igures S9-S10 in the SupportingI nformation.…”

“…A methanol solution of zinc acetate dihydrate (13 mg in 1mLo f methanol) was added to this solution and then the solution was heated at reflux for approximately 3h,t hen cooled down to room temperature. The yellow precipitate was filtered and washed with methanol and dried under vacuum to give Zn 2 -(1a-2H) 2 Single crystals suitable for structure determination were grown by slow evaporation of aZ n 2 -(1a-2 H) 2 solution of am ixture of dichloromethane and methanol at room temperature.…”

“…Owing to their good photochromic features, especially in terms of thermal stability and fatigue-resistance, diarylethenes have emerged over the last few decades as av ery popular class of opticalm olecular switches fort he design of various photo-responsive systems. [1][2][3][4][5][6][7][8][9][10][11][12][13] In principle, it is possible to photo-modulate any structure-dependent property of as ystem by exploiting the reversible structural changes of an appropriate diarylethene-baseds witch. In this regard, associationo f photochromic diarylethenes with metal ions is appealing as it providesaconvenient way to photo-switch properties and functions, which are not always readilya ccessible within pure organic systems.…”