A Facile Supramolecular Approach towards Strategic Fluorescence Switching and Recognition‐Controlled Photoreduction
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Abstract A supramolecular system design strategy to control photoreduction is reported. 1,4,5,8‐naphthalenediimide (NDI) was used as the core unit to synthesize two different sets of ionic aromatic amphiphiles (AA), one incorporating the NDI with an aliphatic chain (denoted NDI) and the other with a phenoxy‐based chain (denoted NDI‐Phe). These systems form self‐assembled structures which are different to those in their monomeric states and which can selectively be photoreduced to generate the radical anion (NDI‐Phe .− ) and dianion (NDI 2− ) in the presence of dicarboxylic acids as the counter anion (CA). Interestingly, fluorescence (FL) switching was detected in the different redox states. The reduction mechanisms and the kinetics were found to be different for these two sets of AAs and the reduction kinetics were further controlled by the structurally different CAs. This unexpected observation reveals molecular recognition in the controlled‐assembly systems. The changes in spectroscopic output upon an electronic input have been described as a simple “off/on” FL switch. The appealing “bottom‐up” approach toward molecular device fabrication is possible only in molecular assembly systems such as these.Keywords:
Molecular switch
Tetrafluoroborate
Imide
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Stable multilayer films were fabricated on the basis of the alternating layer-by-layer assembly of a two-component bolaform supramolecular amphiphile and diazoresins, followed by photochemical cross-linking of the structure. UV-visible spectroscopy and atomic force microscopy revealed a uniform deposition process. Moreover, one component of the supramolecular amphiphile can be removed from the multilayer films after cross-linking between the second component and the diazoresin. The release and uptake of the imprinted supramolecular amphiphile component are shown to be reversible. Furthermore, uptake experiments of different molecules show the selectivity of the imprinted sites for the template molecule. Thus, surface-imprinted films can be formed by employing dissociable two-component supramolecular amphiphiles. This research reveals that supramolecular amphiphiles can be used as a novel concept for the construction of multilayer films, and it also provides a new method of generating surface-imprinted multilayers.
Amphiphilic molecule
Supramolecular chirality
Component (thermodynamics)
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Supramolecular assembly
Molecular Recognition
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3-Methyl-1-(propyloxycarbonylmethyl)imidazolium octylsulfate 1a and 3-methyl-1-(pentyloxycarbonylmethyl)imidazolium octylsulfate 2a are ionic liquids that have previously been shown to be readily biodegradable in the CO2 headspace test (ISO 14593). In the present study, these ionic liquids were evaluated as reaction media for Diels–Alder and hydrogenation reactions. The comparison of the performance of these two designer solvents in these reactions with those conducted in other, non-biodegradable ionic liquids has demonstrated that they are comparable and viable solvents.
Biocatalysis
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Abstract The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono‐ and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π‐surface areas were used, namely [bmim][NTf 2 ], [Bzmim][NTf 2 ], [Bzbim][NTf 2 ], [ p ‐Xyl‐(bim) 2 ][NTf 2 ] 2 , and [ m ‐Xyl‐(bim) 2 ][NTf 2 ] 2 [bmim = 1‐butyl‐3‐methylimidazolium, Bzmim = 1‐benzyl‐3‐methylimidazolium, Bzbim = 1‐benzyl‐3‐butylimidazolium, NTf 2 = bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could help to rationalize the effects of the solvent media on a given reaction, the thermally induced mononuclear rearrangement of heterocycles was studied. Variation of the cation structure has significant repercussions on the 3D structure of the ILs and on the effect they can exert on a given reaction.
Imide
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A CO2-enhanced bola-type supramolecular amphiphile was constructed from a water-soluble pillar[5]arene and a CO2-responsive bola-amphiphile. The gas-responsive self-assembly behavior of this supramolecular amphiphile and its application in controlled release were investigated.
Pillar
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Abstract Indoles react smoothly with carbonyl compounds in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF 4 ) or 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim]PF 6 ) ionic liquids under mild reaction conditions to afford the corresponding bis‐indolylmethanes in excellent yields. These ionic liquids can be recovered and recycled in subsequent reactions without any apparent loss of activity.
Hexafluorophosphate
Tetrafluoroborate
Environmentally Friendly
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Ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [bmIm][BF4] and 1-butyl-3-methylimidazolium hexafluorophosphate [bmIm][PF6] were evaluated as reaction media for allylic and benzylic oxidation reactions using manganese dioxide. The use of ionic liquids as an extractant in the reaction work-up was also investigated. Procedures for recycling of the [bmIm][PF6] ionic liquids used in these MnO2 oxidation reactions were also developed.
Hexafluorophosphate
Tetrafluoroborate
Biocatalysis
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Abstract Supramolecular assemblies of gold complex‐based amphiphiles in aqueous media are highly structural sensitive to external environments, providing an attractive prospect for its application in soft functional materials. Notably, the development of a supramolecular assembly transformation of gold (III) amphiphiles directly controlled by counterion exchange is of fundamental importance for exerting the full potential of dynamic supramolecular assembly by external stimuli. Here we present a reversible supramolecular assembly of gold (III) amphiphiles controlled by counterions in aqueous media and their co‐assembly with gold nanoparticles.
Aqueous medium
Supramolecular assembly
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In this paper,a series of imidazolium ionic liquids with different anions and cations were prepared and the performance of these reaction medium for the synthesis of β-enaminones was investigated.The results showed that anion and cation had obvious effect on the performance of the ionic liquids.When anion was BF4-,the activity order of ionic liquids with different cations was [Hmim]+ [bmim]+,[emim]+ [bmmim]+.Among these reaction medium,[Hmim]BF4 exhibited the highest activity and had a yield of 96% after 10 min reaction.When cation was[Hmim]+,ionic liquids with a anion of BF4-,Tsa-,Br-and NO3-exhibited high activity and had a yield higher than 93% after 15 min reaction,while ionic liquid with HSO4-had a yield of 60% after 30 min.When cation was[bmim]+,the activity order was[bmim]Br [bmim]PF6 [bmim]BF4 and these three solvent/catalysts had a yield over 85%,while [bmim]HSO4 and [bmim]H2 PO4 ionic liquids presented a bad performance and had a yield below 70%.The [Hmim]BF4 was reused five times without considerable loss of activity and had a yield of 89% after 10 min.
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