Electron-withdrawing Cyano Group Research Articles

Designing a high-potential metal-free viologen-based redox polymer for effective wiring of FAD-dependent glucose dehydrogenase

Metal-free organic redox mediators, whose redox potentials can be tuned according to the intended enzyme system and application, are emerging as alternative mediators for the design of improved enzyme-based biosensors and biofuel cells. We report a novel class of metal-free redox polymer containing a polymer-tethered dicyano viologen mediator for the immobilization of FAD-dependent glucose dehydrogenase (FAD-GDH) on graphite electrodes. Incorporation of strong electron-withdrawing cyano groups to the viologen moiety ensures the formation of high potential viologen-based redox polymer with an envisaged pH-independent redox potential close to 50 mV (vs Ag /AgCl/ 3 M KCl) and a negligible impact on oxygen reduction. The bioelectrode comprising of newly designed redox polymer and FAD-GDH showed enhanced electrocatalytic activity in the presence of glucose, confirming effective wiring of FAD-GDH, if embedded within the redox polymer.

Regulating the Lithium Ions' Local Coordination Environment through Designing a COF with Single Atomic Co Site to Achieve Dendrite-Free Lithium-Metal Batteries.

The detrimental growth of lithium dendrites and unstable solid electrolyte interphase (SEI) inhibit the practical application of lithium-metal batteries. Herein, atomically dispersed cobalt coordinate conjugated bipyridine-rich covalent organic framework (sp2 c-COF) is explored as an artificial SEI on the surface of the Li-metal anode to resolve these issues. The single Co atoms confined in the structure of COF enhance the number of active sites and promote electron transfer to theCOF. The synergistic effects of the Co─N coordination and strong electron-withdrawing cyano-group can adsorb the electron from the donor (Co) at a maximum and create an electron-rich environment, hence further regulating the Li+ local coordination environment and achieving uniform Li-nucleation behavior. Furthermore, in situ technology and density functional theory calculations reveal the mechanism of the sp2 c-COF-Co inducing Li uniform deposition and promoting Li+ rapid migration. Based on these advantages, the sp2 c-COF-Co modified Li anode exhibits a low Li-nucleation barrier of 8mV, and excellent cycling stability of 6000h.

Substitution effects of cyano group on the electropolymerization, thermal stability, morphology, and supercapacitor performance of indole based polymers

Substitution effects significantly impact the electropolymerization, morphology, properties and electrochemical performance of conducting polymers. In this work, the substitution effects of the electron-withdrawing cyano group on indole polymers are studied in detail. Polyindole (PIn) and its three cyano group substituted derivatives, i.e., poly(5-cyanoindole) (P5CIn), poly(6-cyanoindole) (P6CIn), and poly(7-cyanoindole) (P7CIn), are successfully electrosynthesized in 0.1 M LiClO4/acetonitrile, while it is difficult to electrodeposit 4-cyanoindole into polymer due to the steric effects. Scanning electron microscopic images reveal that P5CIn, P6CIn, and P7CIn have nanofiber structures, while PIn has a dense and cracked structure. Furthermore, P5CIn displays the best capacitance performance with a specific capacitance of 493 F g-1 at 2.5 A g-1, and 87.1% capacitance retention after 5000 cycles charge/discharge. A detailed study of cyano-substituted PIn is provided by this work and it also presents a kind of high-performance supercapacitor material.

Synthesis, mesomorphic and fluorescent properties of stilbene-containing 1,3,4-oxadiazole compounds

ABSTRACT A new class of mesogenic 1,3,4-oxadiazole derivatives 2a-2e based on stilbene has been synthesised and characterised by means of nuclear magnetic resonance (NMR), electro spray ionisation-mass spectrometry (ESI-MS) techniques and elemental analyses. The thermal properties were investigated by means of differential scanning calorimetry (DSC), polarising optical microscopy (POM) and thermogravimetric analyses (TGA). All compounds exhibited enantiotropic liquid crystal behaviours with typical calamitic mesophases (Smectic A (SmA), Smectic C (SmC) and Nematic phases) in very wide temperature range with excellent thermal stability. The nature of the mesophase is determined greatly by the polarity of the terminal groups. The electron-withdrawing cyano (for 2a) and fluoro (for 2b) groups tended to form smectic A phase, while the electron-donating methyl (for 2c), methoxy (for 2d) and decyloxy (for 2e) groups facilitated the SmA or SmC and nematic phases. Out of expectation, no banana phases were found in these mesogens. It’s noted that the solutions of all compounds in CH2Cl2 individually displayed one absorption band with λmax values at 340–355 nm, and exhibited an intense emission with λmax values at 428–486 nm and photoluminescence quantum yields of 0.39–0.55. The relationship between the molecular structures and mesogenic properties is discussed briefly in this work.

Modulating Liquid-Liquid Transitions and Glass Formation in Zeolitic Imidazolate Frameworks by Decoration with Electron-Withdrawing Cyano Groups.

The liquid phase of metal-organic frameworks (MOFs) is key for the preparation of melt-quenched bulk glasses as well as the shaping of these materials for various applications; however, only very few MOFs can be melted and transformed into stable glasses. Here, the solvothermal and mechanochemical preparation of a new series of functionalized derivatives of ZIF-4 (Zn(im)2, where im- = imidazolate and ZIF = zeolitic imidazolate framework) containing the cyano-functionalized imidazolate linkers CNim- (4-cynanoimidazolate) and dCNim- (4,5-dicyanoimidazolate) is reported. The strongly electron-withdrawing nature of the CN groups facilitates low-temperature melting of the materials (below 310 °C for some derivatives) and the formation of microporous ZIF glasses with remarkably low glass-transition temperatures (down to only about 250 °C) and strong resistance against recrystallization. Besides conventional ZIF-4, the CN-functionalized ZIFs are so far the only MOFs to show an exothermic framework collapse to a low-density liquid phase and a subsequent transition to a high-density liquid phase. By systematic adjustment of the fraction of cyano-functionalized linkers in the ZIFs, we derive fundamental insights into the thermodynamics of the unique polyamorphic nature of these glass formers as well as further design rules for the porosity of the ZIF glasses and the viscosity of their corresponding liquids. The results provide new insights into the unusual phenomenon of liquid-liquid transitions as well as a guide for the chemical diversification of meltable MOFs, likely with implications beyond the archetypal ZIF glass formers.

Control of the fluorescence molecule 2-(2′-hydroxyphenyl) benzothiazole derivatives by introducing electron-donating and withdrawing substituents groups

Using density functional theory (DFT) and time-dependent density functional theory (TDDFT), we investigate the fluorescence mechanism of (E)-4-(3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylstyryl)-1-methylpyridin-1-ium (HBTMY) and the excited-state intramolecular proton transfer process (ESIPT) of hydroxyphenyl. Herein, we introduce two electron-donating (amino and methoxy) and two electron-withdrawing (hydrogen and cyano) groups into HBTMY to study their effects on the fluorescence and the ESIPT process. Structural parameters, infrared vibration frequency, vertical excitation and emission energies as well as frontier molecular orbitals show that the substituents have different impacts on intramolecular hydrogen bonding behavior. The result shows that the fluorescence wavelength of molecules with the amino group could reach the near-infrared area, which favors using this fluorescence in the living cell. As the ability of electron-absorbing groups increases, the forward energy barrier in the potential energy curves decreases sharply making the ESIPT process more familiar to take place. Thus, this work offers a guide for cell imaging and provides strategies to adjust and control fluorescence by introducing substituents.

An n-Type Polythiophene Derivative with Excellent Thermoelectric Performance.

Typical n-type conjugated polymers are based on fused-ring electron-accepting building blocks. Herein, we report a non-fused-ring strategy to design n-type conjugated polymers, i.e. introducing electron-withdrawing imide or cyano groups to each thiophene unit of a non-fused-ring polythiophene backbone. The resulting polymer, n-PT1, shows low LUMO/HOMO energy levels of -3.91 eV/-6.22 eV, high electron mobility of 0.39 cm2  V-1  s-1 and high crystallinity in thin film. After n-doping, n-PT1 exhibits excellent thermoelectric performance with an electrical conductivity of 61.2 S cm-1 and a power factor (PF) of 141.7 μW m-1  K-2 . This PF is the highest value reported so far for n-type conjugated polymers and this is the first time for polythiophene derivatives to be used in n-type organic thermoelectrics. The excellent thermoelectric performance of n-PT1 is due to its superior tolerance to doping. This work indicates that polythiophene derivatives without fused rings are low-cost and high-performance n-type conjugated polymers.

Lowering the dielectric mismatch for efficient inverted perovskite solar cells through incorporating cyano-functionalized fullerene additive

Fullerene derivatives especially [1,1]-phenyl-C61-butyric-acid-methyl-ester (PC61BM) have been commonly used as electron transport layers and additives of inverted (p-i-n) perovskite solar cells (PVKSCs); however the dielectric constant (the εr) of PC61BM (3.8) is much smaller than those of organolead halide hybrid perovskites (6.5 for CH3NH3PbI3 [MAPbI3]), resulting in unfavorable exciton dissociation and impeded interfacial charge transport and consequently undesirable nonradiative recombination. Herein, a novel cyanofunctionalized fullerene in which two cyano groups are incorporated via a rhodanine moiety (abbreviated C60-Rhd-CN) was synthesized and introduced into the MAPbI3 active layer to construct inverted PVKSCs via an anti-solvent method. The involvement of two electron-withdrawing cyano groups within C60-Rhd-CN obviously increases the εr value (5.1) relative to PC61BM (3.8), hence lowering the dielectric mismatch between MAPbI3 and fullerene. Besides, the cyano groups enable strong coordination interactions with the Pb2+ ions of MAP-bI3, rendering efficient defect passivation of perovskite. As a result, C60-Rhd-CN incorporation facilitates exciton dissociation and interfacial charge transport and suppresses the nonradiative recombination, affording dramatic power conversion efficiency (PCE) enhancement of inverted PVKSC devices from 18.43% to 20.81%. Furthermore, C60-Rhd-CN incorporation helps to improve the ambient and thermal stabilities of PVKSC devices. To elucidate the critical role of cyano groups in increasing the the εr value and efficiency enhancement, another analogous novel rhodanine-functionalized fullerene with the two cyano groups substituted by a sulfur atom (abbreviated C60-Rhd-S) was also synthesized, which delivered a lower PCE of 19.45% than C60-Rhd-CN-incorporated devices due mainly to its lower the εr value (4.0).

Facile Synthesis of β-Tetracyano Vanadyl Porphyrin from Its Tetrabromo Analogue and Its Excellent Catalytic Activity for Bromination and Epoxidation Reactions.

Complex 2,3,12,13-tetracyano-5,10,15,20-tetraphenylporphyrinatooxidovanadium(IV) {[VIVOTPP(CN)4], 2} has been prepared by nucleophilic substitution of β-bromo groups of the corresponding 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrinatooxidovanadium(IV) {[VIVOTPP(Br)4], 1} using CuCN in quinoline. Both complexes show biomimetic catalytic activity similar to enzyme haloperoxidases and efficiently brominate various phenol derivatives in the presence of KBr, H2O2, and HClO4 in the aqueous medium. Between these two complexes, 2 exhibits excellent catalytic activity with high turnover frequency (35.5-43.3 s-1) due to the strong electron-withdrawing nature of the cyano groups attached at β-positions and its moderate nonplanar structure as compared to 1 (TOF = 22.1-27.4 s-1). Notably, this is the highest turnover frequency value observed for any porphyrin system. The selective epoxidation of various terminal alkenes using complex 2 has also been carried out, and the results are good, specifying the importance of electron-withdrawing cyano groups. Catalysts 1 and 2 are recyclable, and the catalytic activity proceeds through the corresponding [VVO(OH)TPP(Br)4] and [VVO(OH)TPP(CN)4] intermediates, respectively.

Fluorescence Sensing of Anions by Silanediols Bearing Substituted Naphthyl Groups.

Silanediols bearing naphthyl moieties substituted at 5-position with an electron-withdrawing cyano group and an electron-donating N,N-dimethylamino group, respectively, have been prepared and characterized. The substituents on the naphthyl moieties strongly influence the reactivity, photophysical properties, and sensing abilities for anions. The silanediol bearing 1-(5-N,N-dimethylaminonaphthyl) groups exhibited large Stokes shifts based on intramolecular charge transfer and large quantum yields in organic solvents. The silanediol showed favorable ratiometric fluorescence responses of upon the addition of biologically important anions, AcO-and H2PO4- with the association constants of 4.08 ×104 and 8.76× 103mol-1dm3, respectively.

An Interesting Small Molecule Fluorescent Probe for A Narrow Range (12.5~13) pH and DMSO Detection

Aims: The development of a sensitive and visual analytical method for detecting and monitoring the change of pH has always attracted great interest because it plays a significant role in chemical reactions, environmental monitoring, and biological systems. Methods: In this paper, a simple condensation reaction from readily available substrates 2-hydroxy-1- naphthylaldehyde and malononitrile has been carried out to produce probe L with good aggregationinduced luminescence, and its chemical structure was confirmed by 1H NMR, 13C NMR and ESI-MS. Objective: There is a conjugated system containing two electron-withdrawing cyano groups and an electron- donating hydroxyl group in probe L's molecular structure, exhibiting obvious fluorescence intensity and visible color change through intramolecular charge transfer (ICT) under different pH conditions. Results: Probe L assumes excellent fluorescence intensity in a DMF/H2O (1:9, v:v) mixed solvent system, and exhibits good reversibility in a very narrow range of pH values (pH = 12.5~13). In addition, probe L can also selectively identify solvent DMSO by the induction of fluorescence quenching. Conclusion: Probe L can be used for the analysis and visual detection to pH change in DMF/H2O system, and it may also be used as the indicator for the detection and monitoring of trace amounts of DMSO.

Theoretical design and prediction of novel fluorene-based non-fullerene acceptors for environmentally friendly organic solar cell

Organic solar cells (OSCs) with electron-withdrawing cyano-group (−CN) have created massive interest by exhibiting higher efficiencies. Nevertheless, introducing the − CN group through malononitrile during their synthesis is highly toxic and harmful to the environment. Therefore, the development of environmentally friendly OSCs (EFOSCs) is of utmost importance. Taking inspiration from the recent reports, this manuscript looks to suggest more efficient novel fluorene-based EFOSCs based on DTC-T-F type molecule containing fluorene as central core and thiophene as the linker. The − CN of 2-(6-oxo-5,6-dihydro-4H-cyclopenta[c]thiophen-4-ylidene) malononitrile (TC) present as an end-capped acceptor in DTC-T-F is replaced with non-toxic electron-pulling units -CF3, -SO3H, –NO2 and a novel series developed through quantum chemical calculation of fluorene-based photovoltaic materials (C1- C9). Frontier molecular orbital, density of state, heat maps of TDM, and finally, the charge shift process is observed by blending the C3 acceptor with donor polymer PTB7-Th (HOMOPTB7-Th-LUMOC3). The designed molecules gave comparable and better results from reference C. The minimum energy gap is observed in C3, C6 and C9 molecules with 2.29 eV, 2.28 eV and 2.27 eV energy gap values respectively. The proposed C9 compound exhibits a prominent redshift in solvent (681.82 nm) and gas phase (618.88 nm). Open circuit voltage (Voc) is the key parameter while assessing the OSC efficiency. The highest Voc is possessed by C5 (2.05 V). Exciton binding energy (Eb) is computed, and C7 has the lowest value of Eb = 0.38 eV. Finally, the reorganization energy values shown by proposed molecules indicate that fluorene-based series are effective candidates for manufacturing EFOSCs. All of the data showed that the designed molecules not only have superior optoelectronic properties to those of the synthetic compound, but also possess environmentally benign properties. This theoretical understanding will provide a CNfree strategy for developing next-generation EFOSCs and novel fluorene-based environmentally friendly materials for OSCs applications.

Structural Insights into Binding of Remdesivir Triphosphate within the Replication-Transcription Complex of SARS-CoV-2.

Remdesivir is an adenosine analogue that has a cyano substitution in the C1′ position of the ribosyl moiety and a modified base structure to stabilize the linkage of the base to the C1′ atom with its strong electron-withdrawing cyano group. Within the replication–transcription complex (RTC) of SARS-CoV-2, the RNA-dependent RNA polymerase nsp12 selects remdesivir monophosphate (RMP) over adenosine monophosphate (AMP) for nucleotide incorporation but noticeably slows primer extension after the added RMP of the RNA duplex product is translocated by three base pairs. Cryo-EM structures have been determined for the RTC with RMP at the nucleotide-insertion (i) site or at the i + 1, i + 2, or i + 3 sites after product translocation to provide a structural basis for a delayed-inhibition mechanism by remdesivir. In this study, we applied molecular dynamics (MD) simulations to extend the resolution of structures to the measurable maximum that is intrinsically limited by MD properties of these complexes. Our MD simulations provide (i) a structural basis for nucleotide selectivity of the incoming substrates of remdesivir triphosphate over adenosine triphosphate and of ribonucleotide over deoxyribonucleotide, (ii) new detailed information on hydrogen atoms involved in H-bonding interactions between the enzyme and remdesivir, and (iii) direct information on the catalytically active complex that is not easily captured by experimental methods. Our improved resolution of interatomic interactions at the nucleotide-binding pocket between remedesivir and the polymerase could help to design a new class of anti-SARS-CoV-2 inhibitors.

Divergent Approach for Tris-Heteroleptic Cyclometalated Iridium Complexes Using Triisopropylsilylethynyl-Substituted Synthons.

Bis-heteroleptic cyclometalated iridium complexes of the form Ir(La)2(acac), where La is a substituted 2-phenylpyridine derivative and acac is an acetylacetonato ligand, are a useful class of luminescent organometallic complexes for a range of applications. Related tris-heteroleptic complexes of the form Ir(La)(Lb)(acac) offer the potential advantage of greater functionality through the use of two different cyclometalated ligands but are, in general, more difficult to obtain. We report the synthesis of divergent bis- and tris-heteroleptic triisopropylsilylethynyl-substituted intermediate complexes that can be diversified using a “chemistry-on-the-complex” approach. We demonstrate the methodology through one-pot deprotection and Sonogashira cross-coupling of the intermediate complexes with para-R-aryliodides (R = H, SMe, and CN). The photophysical and electrochemical behaviors of the resultant bis- and tris-heteroleptic complexes are compared, and it is shown that the tris-heteroleptic complexes exhibit subtly different emission and redox properties to the bis-heteroleptic complexes, such as further red-shifted emission maxima and lower extinction coefficients, which can be attributed to the reduced symmetry. It is demonstrated, supported by DFT and time-dependent DFT calculations, that the charge-transfer character of the emission can be altered via variation of the terminal substituent; the introduction of an electron-withdrawing cyano group in the terminal position leads to a significant red shift, while the introduction of an SMe group can substantially increase the emission quantum yield. Most notably, this convenient synthetic approach reduces the need to perform the often challenging isolation of tris-heteroleptic complexes to a single divergent intermediate, which will simplify access to families of complexes of the form Ir(La)(Lb)(acac).

Cyano Substituent on the Olefin Linkage: Promoting Rather than Inhibiting the Performance of Covalent Organic Frameworks

It is generally believed that the electron-withdrawing cyano group in the olefin linkage would inhibit the stability and π-conjugation of covalent organic frameworks (COFs), which raises concerns about their optoelectronic properties. However, the structure–activity relationship between the structure of olefin linkages and properties of COFs is still inconclusive. In this work, imine-, vinylene-, and acrylonitrile-linked COFs with identical triphenyltriazine building blocks were designed and synthesized. Our work demonstrated that construction of acrylonitrile linkages not only enhanced the chemical stability and photostability but also led to remarkable optoelectronic properties with a record fluorescence quantum yield of 35.37% in the solid state. Further, the acrylonitrile linkage endows TTAN-COF/Pt NPs with superior and durable photocatalytic activity in both the hydrogen evolution reaction (11.94 mmol g–1 h–1; BET surface area, 739.28 m2 g–1) and aerobic oxidation reaction. This work demonstrates that the acrylonitrile linkage can significantly enhance the optoelectronic properties and photocatalytic activities of COFs compared with the highly π-conjugated vinylene linkage, providing a valuable reference for the design of optoelectronic functional materials.

A conjugated polymer with Electron-withdrawing cyano group enables for flexible asymmetric electrochromic supercapacitors

Flexible electrochromic supercapacitors (ECSCs) consisting of conjugated polymer electrodes are promising for integrating optical modulation with sustainable energy storage. However, there remain formidable challenges to achieving long-term cycling stability while maximizing high device output voltage. Here, we design a new twisted conjugated polymer bearing dual-redox centers (thiophene and triphenylamine) and an electron-withdrawing cyano group. The as-prepared conjugated polymer showcases elevated discharge potential and highly efficient charge transport synchronously, attributed to the lowered energy of the lowest unoccupied molecular (LUMO) orbitals and twisted alignment of the polymer chain. Coupled with the transparent vanadium pentoxide (V2O5) nanowires ion-storage material, the flexible ECSC affords a high optical contrast of 67 %, wide voltage window of 2 V, large capacitance of 32.9 mF/cm2, and outstanding cycling durability (86 % capacitance and 96 % optical modulation retention after 7000 cycles at 0.2 mA/cm2). This molecular engineering strategy and insight illustrated by density functional theory (DFT) calculation together with electrochemical kinetics analysis provide another way along the route toward the synergetic improvement of electrochromic and energy storage performance.

A red-emissive benzothiazole-based luminophore with ESIPT and AIE natures and its application for detecting and imaging hypochlorous acid

A new “ESIPT + AIE” based dye of benzothiazole with red emission and a large Stokes shift was constructed by combining 2-(2′-hydroxyphenyl)benzothiazole as the ESIPT unit and α-cyanostilbene as the AIE unit. The compound BACN was found to be a ideal HClO chemosensor, and presented palpable fluorescence and colorimetric responses toward HClO via the HClO-trigged oxidation cleavage of the ethylene bridge activated by the electron withdrawing cyano group. BACN was capable of recognizing HClO rapidly (12 s) and sensitively under physiological conditions, with good selectivity over other biologically pertinent substances. Thanks to strong red emission (λem = 606 nm) and large Stokes shift (213 nm) resulted from the combination of ESIPT and AIE effects, it was successfully utilized for the recognition of exogenous and endogenous HClO in living HeLa cells.

Selective imaging of hydrogen peroxide over peroxynitrite by a boronate-based fluorescent probe engineered via a doubly activated electrophilicity-increasing strategy

Boronate-based fluorescent probes are widely used for the imaging of hydrogen peroxide (H2O2). However, their selectivity might be subjected to the interference of other reactive oxygen species, especially peroxynitrite (ONOO-), due to the reaction of boronates with ONOO- being several orders of magnitude faster than with H2O2. This work highlights a doubly activated electrophilicity-increasing strategy to develop a boronate-based fluorescent probe THMP for selective imaging of H2O2 over ONOO-, where a boronate-modified pyridiniumylacrylonitrile is grafted on the 2-(2′-hydroxy-3′-methoxyphenyl) benzothiazole scaffold. Specifically, the boronate oxidation of THMP by H2O2 leads to the release of the free fluorophore THMP-N, triggering a ratiometric fluorescence response from red to green. The presence of a doubly activated electrophilic site on the carbon-carbon double bond of THMP, by both the strong electron-withdrawing cyano group and the pyridinium moiety, allows selective oxidative cleavage of the double bond by ONOO- to an aldehyde HMBT-CHO, thereby excluding the interference of ONOO- in monitoring H2O2. With the aid of the probe, we successfully visualized increased levels of H2O2 during ferroptosis of HepG2 cells, and burst of H2O2 in brains of live mice during cerebral ischemia reperfusion injury.

A DFT/TD-DFT Study on the ESIPT-Type Flavonoid Derivatives with High Emission Intensity.

To reveal the influence of different substituents on the excited-state intramolecular proton transfer (ESIPT) process and photophysical properties of 4′-N, N-dimethylamino-3-hydroxyflavone (DMA3HF), two novel molecules (DMA3HF-CN and DMA3HF-NH2) were designed by introducing the classical electron-withdrawing group cyano (-CN) and electron-donating group amino (-NH2). The three molecules in the acetonitrile phase were systematically researched by applying the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The excited-state hydrogen bond enhancement mechanism was confirmed, and the hydrogen bond intensity followed the decreasing order of DMA3HF-NH2 > DMA3HF > DMA3HF-CN, which can be explained at the electronic level by natural bond orbital, fuzzy bond order, and frontier molecular orbital analyses. Moreover, we found from the electronic spectra that the fluorescence intensity of the three molecules in keto form is relatively strong. Moreover, the calculated absorption properties indicated that introducing the electron-withdrawing group -CN could significantly improve the absorption of DMA3HF in the ultraviolet band. In summary, the introduction of an electron-donating group -NH2 can promote the ESIPT reaction of DMA3HF, without changing the photophysical properties, while introducing the electron-withdrawing group -CN can greatly improve the absorption of DMA3HF in the ultraviolet band, but hinders the occurrence of the ESIPT reaction.

Dehydrative amination of benzhydrols with electron-withdrawing group-substituted 2-aminopyridines utilizing Au(III)/TPPMS catalyst system in water.

We report a method for gold(III)/sodium diphenylphosphinobenzene-3-sulfonate (TPPMS)-catalyzed direct amination of benzhydrols using 2-aminopyridines with poor nucleophilic character in water. Various functional groups such as electron-withdrawing nitro, cyano and halogen groups were tolerated well to form the desired N-benzylated 2-aminopyridine compounds. On the basis of mechanistic studies including kinetic profiles, Hammett study and isotope effects, we propose a pathway in which a Lewis acidic gold cation species activates the sp3 C-O bond of the alcohol in the rate-determining step.