Visible‐Light Photoresponsivity of a 4‐(Dimethylamino)azobenzene Unit Incorporated into Single‐Stranded DNA: Demonstration of a Large Spectral Change Accompanying Isomerization in DMSO and Detection of Rapid (Z)‐to‐(E) Isomerization in Aqueous Solution

Abstract

We demonstrate significant visible‐light photoresponsivity in a synthesized oligonucleotide containing a built‐in pseudo‐nucleotide possessing a 4‐(dimethylamino)azobenzene (4‐DMAzo) side chain. In dry DMSO as solvent, two clearly distinguishable spectra corresponding to the (E) and (Z) forms of the 4‐DMAzo moiety tethered to the oligonucleotide were recorded with a conventional spectrophotometer before and after irradiation with 420 nm wavelength light, which induced (E)‐to‐(Z) isomerization. In addition, (Z)‐to‐(E) isomerization was accelerated by irradiation with either visible (λ = 550 nm) or UV (λ = 350 nm) light, demonstrating reversible photoresponsivity of the pseudo‐oligonucleotide. In aqueous solutions the (Z)‐to‐(E) thermal isomerization of the photoresponsive pseudo‐oligonucleotide was very rapid and was only detectable by laser flash photolysis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Mechanical Motion of Chiral Azobenzene Crystals with Twisting upon Photoirradiation

“…UV‐light irradiation ( λ =365 nm) just after visible‐light irradiation more quickly recovered the peak height due to the photochemical cis ‐to‐ trans back‐isomerization. The changes of the spectra in the solutions were coincident with those of analogous azobenzene derivatives, which were reported previously . In contrast, as mentioned above, the spectral changes in the crystalline state were opposite to those in the solution; the trans ‐to‐ cis isomerization increased the absorption peak at λ =450 nm (n–π* transition) and the cis ‐to‐ trans back‐isomerization decreased the peak height (Figures and S2 in the Supporting Information).…”

Azobenzenes—synthesis and carbohydrate applications

“…The synthesis of symmetrical azobenzene derivatives was effected by: (i) oxidation reactions of aromatic primary amines; [19][20][21][22][23][24][25][26][27][28][29][30] (ii) reduction reactions of aromatic compound having nitro groups; [32][33][34][35][36] (iii) diazo-coupling via diazonium salts; [54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] and (iv) coupling reactions with arenediazonium salts. 100,101 The synthesis of dissymmetrical azobenzene derivatives was effected by: (i) oxidation reactions of aromatic primary amines; 31 (ii) coupling of primary arylamines with nitroso compounds (Mills reaction); [37][38][39][40][41][42][43][44][45][46]…”

“…[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Compound 52 was obtained starting from the nitroso compound 50 and the aniline derivative 51 in acetic acid at 60 C in quantitative yield (Scheme 20). 51 It was notable that, using the Mills reaction, different electron-withdrawing and -donating groups could be present in the ortho-, meta-, and para-positions of both the aromatic nitroso compounds and the aromatic amines.…”

Visible‐Light Photoresponsivity of a 4‐(Dimethylamino)azobenzene Unit Incorporated into Single‐Stranded DNA: Demonstration of a Large Spectral Change Accompanying Isomerization in DMSO and Detection of Rapid (Z)‐to‐(E) Isomerization in Aqueous Solution

“…In Scheme on p. 1847 of the original article, 1 the 4‐(dimethylamino) groups of compounds 2 – 5 are missing; the correct Scheme is shown here.…”