- Viscosity sensitive near-infrared fluorescent probes based on functionalized single-walled carbon nanotubes
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A viscosity-sensitive fluorescent probe is demonstrated by grafting a rotatable 4-N,N′-dimethylaniline group on (6,5) single-walled carbon nanotubes. The rotation of the grafted group is constricted by solution viscosity, causing changes in the photoluminescence behaviors of the nanotubes. This enables a highly sensitive fluorescent probe for determining solution ratiometric viscosity in the biologically transparent second near-infrared region. This journal is
- Chen, Yuan,Li, Wei,Liu, Fei,Sui, Xiao,Wang, Chaojun,Xu, Meiying,Yuan, Ziwen
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- Diazonium salts for surface-confined visible light radical photopolymerization
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The surface chemistry of aryl diazonium salts has progressed at a remarkable pace in the last two decades, and opened many avenues in materials science. These compounds are excellent coupling agents for polymers to surfaces via several surface-confined polymerization methods. For the first time, we demonstrate that diazonium salts are efficient for surface initiating radical photopolymerization in the visible light of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) taken as model monomers. To do so, 4-(dimethylamino)benzenediazonium salt was electroreduced on gold plates or flexible ITO sheets to provide 4-(dimethylamino)phenyl (DMA) hydrogen donor layers; while excited state camphorquinone acted as the free hydrogen abstractor. In the same way, we co-polymerized HEMA and MMA with ethylene glycol dimethacrylate in order to obtain crosslinked polymer grafts. We demonstrate by XPS that gold was efficiently screened by the polymer layers and that the wettability of the surfaces accounts for the hydrophilic or hydrophobic characters of the tethered polymers. Homo- and crosslinked PMMA grafts were found to resist removal by the paint stripper methyl ethyl ketone. The grafted DMA/camphorquinone system operating in the visible light holds great promises in terms of adhesion of in situ designed continuous or patterned polymer coatings on various substrates.
- Bakas, Idriss,Yilmaz, Gorkem,Ait-Touchente, Zouhair,Lamouri, Aazdine,Lang, Philippe,Battaglini, Nicolas,Carbonnier, Benjamin,Chehimi, Mohamed M.,Yagci, Yusuf
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- Near-Infrared Boron Difluoride Formazanate Dyes
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Near-infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light-mediated therapies. Since long-wavelength photoluminescence typically involves extensive π-conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3-cyanoformazans affords efficient production of relatively simple NIR-active BF2 formazanate dyes (λabs=691–760 nm, λPL=834–904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF2 formazanate moieties. Density-functional calculations indicate that the NIR electronic transitions in BF2 formazanates are of π→π*-type, but do not always involve strong charge transfer.
- Buguis, Francis L.,Maar, Ryan R.,Staroverov, Viktor N.,Gilroy, Joe B.
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p. 2854 - 2860
(2021/01/20)
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- Aryl Diazonium Salts: Powerful Arylating Agents for Catellani-Typeortho-Arylation
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The Catellani reaction provides an efficient synthetic approach to polyfunctionalized arenes. However, the selectiveortho-arylating reagents employed in these reactions have been strictly limited to activated bromoarenes. As demonstrated in this work, aryl diazonium salts bearing both electron-donating and electron-withdrawing substituents, after in situ transformations with KI into the corresponding iodoarenes, were efficient arylating reagents for Catellani typeortho-arylation approaches.
- Fu, Ying,Guo, Liang-Liang,Zhang, Yu-Xia
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supporting information
p. 17437 - 17444
(2021/12/02)
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- Aryldiazonium Salts as Nitrogen-Based Lewis Acids: Facile Synthesis of Tuneable Azophosphonium Salts
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Inspired by the commercially available azoimidazolium dyes (e.g., Basic Red 51) that can be obtained from aryldiazonium salts and N-heterocyclic carbenes, we developed the synthesis of a unique set of arylazophosphonium salts. A range of colours were obtained by applying readily tuneable phosphine donor ligands and para-substituted aryldiazonium salts as nitrogen-based Lewis acids. With cyclic voltammetry, a general procedure was designed to establish whether the reaction between a Lewis acid and a Lewis base occurs by single-electron transfer or electron-pair transfer.
- Habraken, Evi R. M.,van Leest, Nicolaas P.,Hooijschuur, Pim,de Bruin, Bas,Ehlers, Andreas W.,Lutz, Martin,Slootweg, J. Chris
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supporting information
p. 11929 - 11933
(2018/09/11)
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- Practical Reagents and Methods for Nucleophilic and Electrophilic Phosphorothiolations
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New late-stage phosphorothiolation methods are disclosed that allow the efficient transfer of SP(O)(OR)2 groups to diversely functionalized substrates using nucleophilic and electrophilic reagents. The nucleophilic reagent, tetramethylammonium O,O-dimethyl phosphorothioate, was synthesized in near-quantitative yield from Me3SiP(O)(OMe)2, elemental sulfur and Me4NF. Its umpolung with N-bromophthalimide provided the electrophilic reagent, O,O-dimethyl-S-(N-phthalimido)phosphorothioate. Complementary methods based on these reagents enable the phosphorothiolation of diversely functionalized alkyl halides, arenediazonium salts, arylboronic acids and electron-rich arenes in good yields under mild conditions. (Figure presented.).
- Kovács, Szabolcs,Bayarmagnai, Bilguun,Aillerie, Alexandre,Goo?en, Lukas J.
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supporting information
p. 1913 - 1918
(2018/03/30)
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- Design and synthesis of photodissociable ligands based on azoimidazoles for light-driven coordination-induced spin state switching in homogeneous solution
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Light-switchable azoimidazoles were rationally designed and synthesized, and their performance was investigated as photodissociable ligands (PDL) and for spin state switching of Ni porphyrins. The rationally designed ligands exhibit a high photochemical conversion rate (trans a? cis > 98%) and no measurable fatigue over a large number of switching cycles at room temperature under air. As compared to the known phenylazopyridines, the phenylazoimidazoles exhibit a much stronger affinity as axial ligands to Ni porphyrin in the binding trans configuration and a low affinity in their cis form. This affinity switching was used to control the coordination number of Ni2+. Concomitant with the change in coordination number is the change of the spin state from triplet (high spin) to singlet state (low spin). We report on phenylazoimidazole-based PDLs that switch the paramagnetic ratio of the investigated nickel species by up to 70%. Consequently, azoimidazoles exhibit considerably higher switching efficiencies than previously described pyridine-based PDLs.
- Schütt, Christian,Heitmann, Gernot,Wendler, Thore,Krahwinkel, Bahne,Herges, Rainer
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supporting information
p. 1206 - 1215
(2016/02/18)
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- Trifluoromethylselenolation of Aryldiazonium Salts: A Mild and Convenient Copper-Catalyzed Procedure for the Introduction of the SeCF3 Group
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The straightforward introduction of the trifluoromethylseleno group into aromatic and heteroaromatic compounds is accomplished by the utilization of readily available aryldiazonium tetrafluoroborates, potassium selenocyanate, and Ruppert-Prakash reagent. The reaction tolerates a wide range of aromatic and heteroaromatic diazonium salts and is also amenable to the synthesis of pentafluoroethyl selenoethers. Furthermore, the methodology can be applied directly starting from anilines.
- Nikolaienko, Pavlo,Rueping, Magnus
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supporting information
p. 2620 - 2623
(2016/02/27)
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- Synthesis of difluoromethyl thioethers from difluoromethyl trimethylsilane and organothiocyanates generated in situ
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A copper-CF2H complex generated in situ from copper thiocyanate and TMS-CF2H smoothly converts organothiocyanates into valuable difluoromethyl thioethers. This reaction step can be combined with several thiocyanation methods to one-pot protocols, allowing late-stage difluoromethylthiolations of widely available alkyl halides and arenediazonium salts. This strategy enables the introduction of difluoromethylthio groups - a largely unexplored substituent with highly promising properties - into drug-like molecules. A copper-CF2H complex generated in situ from copper thiocyanate and TMS-CF2H smoothly converts organothiocyanates into valuable difluoromethyl thioethers. This reaction step can be combined with several thiocyanation methods to one-pot protocols, allowing late-stage difluoromethylthiolations of widely available alkyl halides and arenediazonium salts.
- Bayarmagnai, Bilguun,Matheis, Christian,Jouvin, Kvin,Goossen, Lukas J.
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supporting information
p. 5753 - 5756
(2015/06/10)
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- Sandmeyer trifluoromethylation of arenediazonium tetrafluoroborates
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Copper capabilities: Diazonium salts are converted into the corresponding trifluoromethyl derivatives in the presence of a trifluoromethyl-copper complex generated in situ from CuSCN and the inexpensive, easy-to-use trifluoromethylating reagent Me3Si-CF3 (see scheme). This Sandmeyer-type reaction allows the straightforward synthesis of trifluoromethylated arenes and heteroarenes from the corresponding amines. Copyright
- Danoun, Grégory,Bayarmagnai, Bilguun,Grünberg, Matthias F.,Goo?en, Lukas J.
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supporting information
p. 7972 - 7975
(2013/08/23)
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- Comparative studies on the redox reaction of Fe(CN)6 4-/3- at modified glassy carbon electrodes Via diazonium salts electroreduction
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In this paper, the electrochemical properties of glassy carbon (GC) electrodes modified with different functional groups have been investigated. A diazonium salt coupling procedure was used to covalently bind the various p-substituted aryl groups to GC surface. In order to establish suitable grafting conditions enforceable to all kinds of diazonium derivatives, the selection of the molecules to be grafted was done for the contrasted electronegativity of the substituents. We obtained that grafting density could be controlled by varying the concentration of the diazonium, the duration and the value of the applied potential. The surface modification was checked by the blocking action of GC modified electrodes for Fe(CN)63-/4- redox probe in cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements.
- Raicopol, Matei,Branzoi, Viorel,Necula, Luiza,Ionita, Mariana,Pilan, Luisa
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p. 807 - 814
(2013/05/09)
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- Influence of Steric and Electronic Effects on the Binding of Arenediazonium Cations to 18-Crown-6 in Methanol at 25 deg C
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Log K, ΔH, and TΔS values for the interaction of several arenediazonium salts with 18-crown-6 were determined in methanol at 25 deg C by the calorimetric titration technique.The complex of benzenediazonium cation with 18-crown-6 is enthalpy stabilized with log K = 2.50.Substitution of a methyl group onto the ortho position(s) of benzenediazonium cation results in a total loss of complex stability.Substitution of various groups onto the para position results in changes in complex stability according to the electronic effect exerted in the diazonium moiety.A linear Hammett relationship (ρ = 0.65) was found between log K and ?+p values associated with the para substituent.
- Izatt, R. M.,Lamb, J. D.,Swain, C. S.,Christensen, J. J.,Haymore, Barry L.
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p. 3032 - 3034
(2007/10/02)
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