- Azobenzene-derived tris-β-diketonate lanthanide complexes: Reversible: trans -to- cis photoisomerization in solution and solid state
-
Novel azobenzene-derived β-diketonates (4,4,5,5,6,6,6-heptafluoro-1-azobenzene-1,3-hexanedione (LA), 4,4,5,5,6,6,6-heptafluoro-1-(4-dimethylamino)azobenzene-1,3-hexanedione (LB)) were designed and their complexes with lanthanide cations (La3+,
- Lin, Li-Rong,Wang, Xuan,Wei, Gao-Ning,Tang, Hui-Hui,Zhang, Hui,Ma, Li-Hua
-
-
Read Online
- Flavylium-based hypoxia-responsive probe for cancer cell imaging
-
A hypoxia-responsive probe based on a flavylium dye containing an azo group (AZOFlav) was synthesized to detect hypoxic conditions via a reductase-catalyzed reaction in cancer cells. In in vitro enzymatic investigation, the azo group of AZO-Flav was reduc
- Chansaenpak, Kantapat,Duangkamol, Chuthamat,Kamkaew, Anyanee,Lai, Rung-Yi,Ngivprom, Utumporn,Noisa, Parinya,Pewklang, Thitima,Sukwattanasinitt, Mongkol,Wangngae, Sirilak,Wet-Osot, Sirawit
-
supporting information
(2021/08/25)
-
- Hole Catalysis as a General Mechanism for Efficient and Wavelength-Independent Z → E Azobenzene Isomerization
-
Whereas the reversible reduction of azobenzenes has been known for decades, their oxidation is destructive and as a result has been notoriously overlooked. Here, we show that a chain reaction leading to quantitative Z → E isomerization can be initiated before reaching the destructive anodic peak potential. This hole-catalyzed pathway is accessible to all azobenzenes, without exception, and offers tremendous advantages over the recently reported reductive, radical-anionic pathway because it allows for convenient chemical initiation without the need for electrochemical setups and in the presence of air. In addition, catalytic amounts of metal-free sensitizers, such as methylene blue, can be used as excited-state electron acceptors, enabling a shift of the excitation wavelength to the far red of the azobenzene absorption (up to 660 nm) and providing quantum yields exceeding unity (up to 200%). Our approach will boost the efficiency and sensitivity of optically dense liquid-crystalline and solid photoswitchable materials. Video Abstract: [Figure presented] Molecular switches are a key ingredient in stimulus-responsive and adaptive materials and devices. Light is among the most attractive stimuli, yet photoswitches often require intense irradiation with high-energy UV light and suffer from inefficient switching as well as fatigue. Thus, the design of robust and efficient photoswitches constitutes an important challenge to boost the sensitivity and energy efficiency of the respective materials and devices. Here, we describe that the isomerization of azobenzene switches from their less stable Z isomer back to the more stable E isomer can be triggered by tiny, i.e., catalytic, amounts of holes caused by chemical, electrochemical, or photochemical oxidation. Our method is generally applicable to the entire family of azobenzene switches, does not require expensive equipment, and allows the reliable and efficient operation of these photoswitches by using red light with quantum efficiencies up to 200%. An efficient and generally applicable method is developed for operating azobenzene molecular switches by using catalytic amounts of holes (via an oxidant) or photons (via a photosensitizer). The pathway allows for indirect Z → E photoisomerization using lower-energy light than required for direct azobenzene excitation and with high quantum yields exceeding unity. The method should help to enhance the sensitivity of photoresponsive materials and devices with high optical density.
- Goulet-Hanssens, Alexis,Rietze, Clemens,Titov, Evgenii,Abdullahu, Leonora,Grubert, Lutz,Saalfrank, Peter,Hecht, Stefan
-
supporting information
p. 1740 - 1755
(2018/06/29)
-
- Convenient and rapid diazotization and diazo coupling reaction via aryl diazonium nanomagnetic sulfate under solvent-free conditions at room temperature
-
For the first time, nanomagnetic-supported sulfonic acid is used for conversion of several types of aromatic amine, containing electron-withdrawing groups as well as electron-donating groups to the corresponding azo dyes in excellent yield. The synthesis of these compounds is described by the sequential diazotization-diazo coupling of various aromatic amines with sodium nitrite, nanomagnetic supported sulfonic acid and coupling agents under solvent-free conditions at room temperature. This new method offers several advantages including short reaction time, mild reaction conditions, avoidance of harmful acids, and simple work-up procedure. More importantly, aryldiazonium salts supported on magnetic nanoparticles (aryl diazonium nanomagnetic sulfate) were sufficiently stable to be kept at room temperature in the dry state.
- Koukabi, Nadiya,Otokesh, Somayeh,Kolvari, Eskandar,Amoozadeh, Ali
-
-
- Fluorescence quenchers for hydrazone and oxime orthogonal bioconjugation
-
We describe the synthesis and properties of new fluorescence quenchers containing aldehyde, hydrazine, and aminooxy groups, allowing convenient bioconjugation as oximes or hydrazones. Conjugation to oligonucleotides proceeded in high yield with aniline as catalyst. Kinetics studies of conjugation show that, under optimal conditions, a hydrazine or aminooxy quencher can react with aldehyde-modified DNA to form a stable hydrazone or oxime adduct in as little as five minutes. The resulting quencher-containing DNAs were assessed for their ability to quench the emission of fluorescein in labeled complements and compared to the commercially available dabcyl and Black Hole Quencher 2 (BHQ2), which were conjugated as phosphoramidites. Results show that the new quenchers possess slightly different absorbance properties compared to dabcyl and are as efficient as the commercial quenchers in quenching fluorescein emission. Hydrazone-based quenchers were further successfully incorporated into molecular beacons and shown to give high signal to background ratios in single nucleotide polymorphism detection in vitro. Finally, aminooxy and hydrazine quenchers were applied to quenching of an aldehyde-containing fluorophore associated with living cells, demonstrating cellular quenching within one hour.
- Crisalli, Pete,Hernández, Armando R.,Kool, Eric T.
-
p. 1969 - 1980
(2012/11/13)
-
- Synthesis of new spin probes based on aminoaryl-substituted imidazoline nitroxides
-
A series of new spin probes, azides and isothiocyanates, were synthesized starting from aminoaryl-substituted nitroxides which are derivatives of 3-imidazoline and 3-imidazoline-3-oxide.The new compounds were transformed to complexones, derivatives of iminodiacetic acid. - Key words: nitroxyl radical; azides; isothiocyanates; spin probes; diazonium salts.
- Reznikov, V. A.,Berezina, T. A.,Kirilyuk, I. A.,Volodarskii, L. B.
-
p. 424 - 427
(2007/10/02)
-
- Steric Effects in 4-Dimethylaminoazobenzenes and Their Protonated Species
-
The effects of steric crowding in the amino-substituted ring of the 4-dimethylaminoazobenzene system have been examined by electronic absorption spectroscopy, using methyl substituents to induce loss of planarity.The most significant effects are produced by methyl groups ortho to the amino group.No evidence for electronic buttressing could be found in the case of dyes with electron withdrawing groups in the second benzene ring.The effects of steric crowding in the protonated forms of the dyes have also been examined.
- Griffiths, John,Roospeikar, Ehizan,Thomasson, Jeffrey
-
p. 3722 - 3739
(2007/10/02)
-