Dimethylamino Research Articles

Sulfur-Free Radical RAFT Polymerization of Methacrylates in Homogeneous Solution: Design of exo-Olefin Chain-Transfer Agents (R-CH2 C(=CH2 )Z).

In this work, the development of exo-olefin compounds (R-CH2 C(=CH2 )Z) as chain-transfer agents for the sulfur-free reversible addition-fragmentation chain transfer (RAFT) radical polymerization of methacrylates in homogeneous solution is described. A series of exo-olefin compounds with a methyl methacrylate (MMA) dimer structure as the R group and a substituted α-methylstyrene unit as the -CH2 C(=CH2 )Z (Z: Ph-Y) group were synthesized and used for the radical polymerization of MMA in toluene and PhC(CF3 )2 OH. These compounds underwent transfer of the CH2 C(=CH2 )Z group via addition-fragmentation of the propagating methacryloyl radical. More electron-donating (Y) substituents, such as methoxy and dimethylamino groups, produced polymers with narrower molecular weight distributions. A continuous monomer addition method further improved molecular weight control and enabled the synthesis of colorless, sulfur-free, multiblock copolymers of methacrylates in homogeneous solutions.

Sulfur‐Free Radical RAFT Polymerization of Methacrylates in Homogeneous Solution: Design of exo‐Olefin Chain‐Transfer Agents (R−CH2C(=CH2)Z)

AbstractIn this work, the development of exo‐olefin compounds (R−CH2C(=CH2)Z) as chain‐transfer agents for the sulfur‐free reversible addition‐fragmentation chain transfer (RAFT) radical polymerization of methacrylates in homogeneous solution is described. A series of exo‐olefin compounds with a methyl methacrylate (MMA) dimer structure as the R group and a substituted α‐methylstyrene unit as the −CH2C(=CH2)Z (Z: Ph−Y) group were synthesized and used for the radical polymerization of MMA in toluene and PhC(CF3)2OH. These compounds underwent transfer of the CH2C(=CH2)Z group via addition‐fragmentation of the propagating methacryloyl radical. More electron‐donating (Y) substituents, such as methoxy and dimethylamino groups, produced polymers with narrower molecular weight distributions. A continuous monomer addition method further improved molecular weight control and enabled the synthesis of colorless, sulfur‐free, multiblock copolymers of methacrylates in homogeneous solutions.

Reaction mechanism of atomic layer deposition of zirconium oxide using zirconium precursors bearing amino ligands and water.

As a unique nanofabrication technology, atomic layer deposition (ALD) has been widely used for the preparation of various materials in the fields of microelectronics, energy and catalysis. As a high-κ gate dielectric to replace SiO2, zirconium oxide (ZrO2) has been prepared through the ALD method for microelectronic devices. In this work, through density functional theory calculations, the possible reaction pathways of ZrO2 ALD using tetrakis(dimethylamino)zirconium (TDMAZ) and water as the precursors were explored. The whole ZrO2 ALD reaction could be divided into two sequential reactions, TDMAZ and H2O reactions. In the TDMAZ reaction on the hydroxylated surface, the dimethylamino group of TDMAZ could be directly eliminated by substitution and ligand exchange reactions with the hydroxyl group on the surface to form dimethylamine (HN(CH3)2). In the H2O reaction with the aminated surface, the reaction process is much more complex than the TDMAZ reaction. These reactions mainly include ligand exchange reactions between the dimethylamino group of TDMAZ and H2O and coupling reactions for the formation of the bridged products and the by-product of H2O or HN(CH3)2. These insights into surface reaction mechanism of ZrO2 ALD can provide theoretical guidance for the precursor design and improving ALD preparation of other oxides and zirconium compounds, which are based ALD reaction mechanism.

The Impact of Polymer Architecture on Polyion Complex (PIC) Micelles: When Topology Matters (and When It Doesn't)

AbstractThe influence of homopolymer architecture on the properties of polyion complex micelles is reported. Using a combination of dynamic and static light scattering, the authors show how the architecture is only relevant in kinetically trapped states of micelles formed by the electrostatic assembly of poly(N‐isopropyl acrylamide‐block‐styrene sulfonate) (p(NIPAM‐b‐SS) and linear, 4‐arm, 8‐arm star quaternized poly(dimethyl amino ethyl acrylate) (PDMAEA) homopolymers or poly(amidoamine) (PAMAM) dendrimers. Interestingly, the micellar size and the aggregation number in these kinetically arrested states follow a clear trend with the number of arms but differ in the case of dendrimers possibly due to the distinct chemical nature of the monomers. The authors show that if the micelles are prepared in a weak polyelectrolyte pairing regime (i.e., high ionic strength), they all converge into similar structures. The presented findings represent a new way of controlling the properties of polyion complex micelles through kinetically trapped states.

Nicotinonitrile-derived apoptotic inducers: Design, synthesis, X-ray crystal structure and Pim kinase inhibition

Although a plethora of targeted anticancer small molecule drugs became available, the low response rate and drug resistance imply the continuous need for expanding the anticancer chemical space. In this study, a novel series of nicotinonitrile derivatives was designed, synthesized and evaluated for cytotoxic activities in HepG2 and MCF-7 cells. All derivatives showed high to moderate cytotoxic activity against both cell lines, with cell-type and chemotype-dependent cytotoxic potential. The normal HEK-293 T cells were ca. 50-fold less susceptible to the cytotoxic effect of the inhibitors. The in vitro enzyme inhibitory activity of selected active cytotoxic derivatives 8c, 8e, 9a, 9e and 12 showed that they have sub- to one digit micromolar 50 % inhibitory concentration (IC50) against the three Pim kinase isoforms, with 8e being the most potent (IC50 ≤ 0.28 μM against three Pim kinases), comparable to the pan kinase inhibitor, Staurosporine. In HepG2, 8e induced cell cycle arrest at the G2/M phase. Apoptotic mechanistic studies with 8c and 8e in HepG2 cells, indicated a significant upregulation in both P53 and caspase-3 relative gene expression, as well as increased Bax/Bcl-2 protein expression level. Further, docking studies combined with molecular dynamic simulation showed a stable complex with high binding affinity of 8e to Pim-1 kinase; exploiting a negative electrostatic potential surface interaction with the added dimethyl amino group in the new compounds. Moreover, in silico ADME profile prediction indicated that all compounds are orally bioavailable and most of them can penetrate the blood–brain barrier. This study presents novel nicotinonitrile derivatives as auspicious hits for further optimization as antiproliferative agents against liver cancer cells and promising pan Pim kinase inhibitors at submicromolar concentrations.

Development of Orodispersible Ibuprofen Tablets Based on a Polymer-drug Complex

Introduction. Orodispersible dosage forms are a very promising direction in the development of dosage forms. Such dosage forms are designed for both systemic and local action of the active pharmaceutical ingredients that make up their composition. Active pharmaceutical ingredients from orodispersible forms enter directly into the systemic circulation, bypassing the "first pass effect".Aim. Development of orodispersible tablets based on the Eudragit® EPO/ibuprofen polymer-drug complex and evaluation of ibuprofen release from the resulting system.Materials and methods. Samples of the polymer-drug complex (PDC) were obtained with different ratios of EPO and ibuprofen, as well as with different mixing orders. Turbidimetric studies to find the stoichiometry of the resulting EPO/IB PLC were performed spectrophotometrically (Lambda 25, PerkinElmer, U.S.A.) at a wavelength of 600 nm. Thermal analysis was performed by modulation differential scanning calorimetry (mDSC) on a Discovery™ DSC instrument (TA Instruments, U.S.A.). Samples sealed in Tzero aluminum pans (TA Instruments, U.S.A.) were scanned in the temperature range from 0 to 250 °С at a speed of 2 °С/min. IR spectra were recorded on a Nicolet iS5 FT-IR spectrometer (Thermo Fisher Scientific, U.S.A.) with an ATR nozzle, in the range from 500 to 4000 cm-1. Drying of samples of complexes and dispersible tablets was carried out in a FreeZone 1L laboratory freeze dryer (Labconco, U.S.A.) for a 24 hours at a temperature of –49 °C and at a pressure of 0.350 mbar. The drug release was evaluated on a dissolution tester DT 828 (ERWEKA GmbH, Germany) in a volume of 900 ml, at 37 ± 0.5 °C and a blade rotation speed of 50 rpm.Results and discussion. Studies on the formation of PDC Eudragit® EPO/ibuprofen (EPO/IB) were carried out at various molar ratios. On samples of PDC and individual components, bands are observed that are characteristic both for EPO – at 2770 and 2820 cm-1, confirming the presence of non-ionized dimethylamino groups, and at 1725 cm-1, corresponding to the stretching vibrations of carboxyl groups. A new band is appeared at 1573 cm-1, which confirm the formation of ionic bonds between carboxylate groups of IB and ionized dimethylamino groups of EPO. The mDSC thermograms of the samples are characterized by a single glass transition temperature (Tg) at 27,3 ± 0,3 °С (for molar ratio 1 : 2) and 44,9 ± 0,4 °С. (for molar ratio 1 : 1), which confirm the formation of polymer-drug complexes. Received PDC Eudragit® EPO/ibuprofen in a molar ratio of 1 : 2 and 1 : 1 and oral dispersible tablets based on them by lyophilization. The resulting systems are characterized by immediate release of IB with maximum rates at 30 min for a 1 : 1 composition and 60 min for a 1 : 2 composition.Conclusion. Eudragit® EPO/ibuprofen polymer drug complex can be used to develop orodispersible tablets providing immediate release of IB.

One-Pot Reductive Methylation of Nitro- and Amino-Substituted (Hetero)Aromatics with DMSO/HCOOH: Concise Synthesis of Fluorescent Dimethylamino-Functionalized Bibenzothiazole Ligands with Tunable Emission Color upon Complexation.

One-pot reductive N,N-dimethylation of suitable nitro- and amino-substituted (hetero)arenes can be achieved using a DMSO/HCOOH/Et3N system acting as a low-cost but efficient reducing and methylating agent. The transformation of heteroaryl-amines can be accelerated by using dimethyl sulfoxide/oxalyl chloride or chloromethyl methyl sulfide as the source of active CH3SCH2+ species, while the exclusion of HCOOH in the initial stage of the reaction allows avoiding N-formamides as resting intermediates. The developed procedures are applicable in multigram-scale synthesis, and because of the lower electrophilicity of CH3SCH2+, they also work in pathological cases, where common methylating agents provide N,N-dimethylated products in no yield or inferior yields due to concomitant side reactions. The method is particularly useful in one-pot reductive transformation of 2-H-nitrobenzazoles to corresponding N,N-dimethylamino-substituted heteroarenes. These, upon Cu(II)-catalyzed oxidative homocoupling, afford 2,2'-bibenzazoles substituted with dimethylamino groups as charge-transfer N^N ligands with intensive absorption/emission in the visible region. The fluorescence of NMe2-functionalized bibenzothiazoles remains intensive even upon complexation with ZnCl2, while emission maxima are bathochromically shifted from the green/yellow to orange/red spectral region, making these small-molecule fluorophores, exhibiting large emission quantum yields and Stokes shifts, an attractive platform for the construction of various functional dyes and light-harvesting materials with tunable emission color upon complexation.

Introducing N-Heterocyclic Iminophosphoranes (NHIPs): Synthesis by [3 + 2] Cycloaddition of Azophosphines with Alkynes and Reactivity Studies

Azophosphines (Ar-N═N-PR2) were prepared from N-aryl-N'-(trimethylsilyl)diazenes (Ar-N═N-SiMe3) and R2PCl by Me3SiCl elimination or oxidation of phosphinohydrazines (Ar-NH-NH-PR2) by 2,5-dialkyl-1,4-benzoquinones. Azophosphines underwent 1,3-dipolar cycloaddition with cyclooctyne and dimethylacetylene dicarboxylate to give N-heterocyclic iminophosphoranes (NHIPs), which are structurally similar to cyclic (alkyl)(amino)carbenes. The cycloaddition reaction is compatible with various phosphorus atom substituents including phenyl (NHIP-1,4,6), isopropyl (NHIP-2), cyclohexyl (NHIP-3), and dimethylamino (NHIP-5) groups. The pKBH+ values of the NHIPs in acetonitrile range from 13.13 to 23.14. On the basis of the Huynh electronic parameter, NHIP-1 and NHIP-2 have σ-donor strengths comparable with that of 1,8-diazabicyclo[5.4.0]undec-7-ene. NHIP-1 underwent facile 1,2-addition with pentafluoropyridine to form a rare fluorophosphorane. The treatment of NHIP-1 with triphenylsilane resulted in P-N bond cleavage, accompanied by the reduction of phosphorus(V) to phosphorus(III). A homoleptic, cationic CuI-NHIP-1 complex was also prepared. The potential utility of π-donating NHIPs was demonstrated by the stabilization of a reactive iminoborane (Cl-B≡N-SiMe3). The facile scalable synthesis, tunability of steric demands, and basicity of NHIPs suggest that this new heterocycle class may find a wide range of applications in synthetic chemistry.

Asymmetric Core-Expanded BOPYOs: Facile Synthesis and Optical Properties.

N,O-bidentate BF2 complexes with five- and six-membered core rings have been thoroughly investigated. However, the development of seven-membered N,O-boron complexes is still an area to be explored. We have developed BF3 ⋅ OEt2 -induced self-condensation and coordination reactions based on a single starting material, which had been elucidated by experiment and calculation. This parent asymmetric core-expanded borondifluoride-(Z)-1,3-di(1H-pyrrol-2-yl)but-2-en-1-one (BOPYO) showed reactivity with a wide range of aldehydes, thus providing a series of conjugation BOPYOs. Moreover, a BOPYO derivative with a dimethylamino group was developed as a new NIR dye that responds to acid with favorable photophysical properties based on intramolecular charge transfer effect.

Controlling the Site Selectivity in Acylations of Amphiphilic Diols: Directing the Reaction toward the Apolar Domain in a Model Diol and the Midecamycin A1 Macrolide Antibiotic.

Seeking to improve the site selectivity of acylation of amphiphilic diols, which is induced by imidazole-based nucleophilic catalysts and directs the reaction toward apolar sites, as we recently reported, we examined a new improved catalytic design and an alteration of the acylating agent. The new catalysts performed slightly better selectivity-wise in the model reaction, compared to the previous set, but notably could be prepared in a much more synthetically economic way. The change of the acylating agent from anhydride to acyl chloride, particularly in combination with the new catalysts, accelerated the reaction and increased the selectivity in favor of the apolar site. The new selectivity-inducing techniques were applied to midecamycin, a natural amphiphilic antibiotic possessing a secondary alcohol moiety in each of its two domains, polar as well as apolar. In the case of the anhydride, a basic dimethylamino group, decorating this substrate, overrides the catalyst’s selectivity preference and forces selective acylation of the alcohol in the polar domain with a more than 91:1 ratio of the monoacylated products. To counteract the internal base influence, an acid additive was used or the acylating agent was changed to acyl chloride. The latter adjustment leads, in combination with our best catalyst, to the reversal of the ratio between the products to 1:11.

(Digital Presentation) Wavelength Controllable Multi-Color Firefly Luciferin Analogues

I will show you the multi-color luciferin analogues, and in particular the usefulness of near-infrared(NIR) luciferin analogues.Firefly bioluminescent reaction requires luciferin, luciferase, Mg2+, ATP and O2, and emits light at 560 nm (green-yellow light). As the light emission efficiency of the firefly bioluminescence system is extremely high(ΦBL=41%), this system is attracting widespread attention as a bioimaging tool.We have studied the relationship between structure modification and the firefly luminescence wavelength, where the luciferase of Photinus pyralis (Ppy) was used. As a result, we are able to control the wavelength of the luciferin analogues to some extent. An analog having the thiazoline ring connected directly to p-(dimethylamino)phenyl group exhibited blue shifted luminescence maximum. Furthermore, replacement of the dimethylamino group into a hydroxyl group caused blue shift of luminescence wavelength. On the other hand, Introduction of a double bond between the thiazoline ring and the benzene ring caused large red shift of luminescence wavelength.Based on these structure-activity relationships, we have synthesized a number of luciferin analogs. The shortest emission wavelength of luciferin analogs is 430 nm, and the longest is 760 nm by using Ppy luciferase. Among them, near-infrared(NIR) light is expected to be applied to in vivo imaging because of its high living body permeability.Therefore, Thus, AkaLumine, a luciferin analogue that produces light at 675 nm wavelength, was developed. This compound was shown to yield useful results when applied to the in vivo imaging of mice. We have improved the characteristics of AkaLumine to optimize this compound for use in in vivo imaging, thus obtaining the compounds dubbed TokeOni and seMpai. In this way, bioluminescence imaging technology is undergoing constant innovation, and we continue to develop NIR luciferin analogues that can be used as imaging tools.In this conference, I will present the characteristics of recently developed multi-color luciferin analogues, include NIR luciferin analogues. Figure 1

Synthesis and biological activity of acetylene compounds derivatives of benzoin

Paper involves and some acetylene compounds from benzoin 4,4-dimethyl benzoin, 4-methyl benzoin, 4,4-dichloro benzoin, 4,4-dibromo benzoin and 4-dimethyl amino benzoin treated with 3-bromo propyne yielded series of new acetylene compounds were characterized by FTIR, 1HNMR and C-H-N. The compounds good activity of antibacterial.

Redox-Switchable Behavior of Transition-Metal Complexes Supported by Amino-Decorated N-Heterocyclic Carbenes.

The coordination chemistry of the N-heterocyclic carbene ligand IMes(NMe2)2, derived from the well-known IMes ligand by substitution of the carbenic heterocycle with two dimethylamino groups, was investigated with d6 [Mn(I), Fe(II)], d8 [Rh(I)], and d10 [Cu(I)] transition-metal centers. The redox behavior of the resulting organometallic complexes was studied through a combined experimental/theoretical study, involving electrochemistry, EPR spectroscopy, and DFT calculations. While the complexes [CuCl(IMes(NMe2)2)], [RhCl(COD)(IMes(NMe2)2)], and [FeCp(CO)2 (IMes(NMe2)2)](BF4) exhibit two oxidation waves, the first oxidation wave is fully reversible but only for the first complex the second oxidation wave is reversible. The mono-oxidation event for these complexes occurs on the NHC ligand, with a spin density mainly located on the diaminoethylene NHC-backbone, and has a dramatic effect on the donating properties of the NHC ligand. Conversely, as the Mn(I) center in the complex [MnCp(CO)2 ((IMes(NMe2)2)] is easily oxidizable, the latter complex is first oxidized on the metal center to form the corresponding cationic Mn(II) complex, and the NHC ligand is oxidized in a second reversible oxidation wave.

Novel examples of electrophilic rearrangement of substituted pyrimidin-4-ones under Vilsmeier-Haack reaction condition

The critical influence of the size of aliphatic annulated cycles in 2,2-disubstituted pyrimidin-4-ones on the conditions of rearrangement under the action of Vilsmeier-Haack reagent was established. Compounds with a 5-membered ring cycle to pyrimidin-4-one require heating at 1100C for 2 h due to the coplanar arrangement of dimethyliminium and chloriminium groups in intermediates, which leads to placement of a positive charge on the nitrogen atom of the dimethylamino group, which is unfavorable for the reaction. In the case of 6- and 7-membered annulated cycles, there is interatomic repulsion in the intermediates from the hydrogen atoms of methyl and methylene groups, as well as hydrogen atoms of CH and NH, which contributes to placement of a positive charge on the endocyclic atom of nitrogen and chloriminium salt and easier rearrangement. The size of aliphatic annealed and spirocycles to the pyrimidine framework affects not only the reaction conditions but also the formation of products.

Computational investigation of substituent effects on the fluorescence wavelengths of oxyluciferin analogs

Oxyluciferin, which is the light emitter for firefly bioluminescence, has been subjected to extensive chemical modifications to tune its emission wavelength and quantum yield. However, the exact mechanisms for various electron-donating and withdrawing groups to perturb the photophysical properties of oxyluciferin analogs are still not fully understood. To elucidate the substituent effects on the fluorescence wavelength of oxyluciferin analogs, we applied the absolutely localized molecular orbitals (ALMO)-based frontier orbital analysis to assess various types of interactions (i.e. permanent electrostatics/exchange repulsion, polarization, occupied–occupied orbital mixing, virtual–virtual orbital mixing, and charge-transfer) between the oxyluciferin and substituent orbitals. We suggested two distinct mechanisms that can lead to red-shifted oxyluciferin emission wavelength, a design objective that can help increase the tissue penetration of bioluminescence emission. Within the first mechanism, an electron-donating group (such as an amino or dimethylamino group) can contribute its highest occupied molecular orbital (HOMO) to an out-of-phase combination with oxyluciferin’s HOMO, thus raising the HOMO energy of the substituted analog and narrowing its HOMO-LUMO gap. Alternatively, an electron-withdrawing group (such as a nitro or cyano group) can participate in an in-phase virtual–virtual orbital mixing of fragment LUMOs, thus lowering the LUMO energy of the substituted analog. Such an ALMO-based frontier orbital analysis is expected to lead to intuitive principles for designing analogs of not only the oxyluciferin molecule, but also many other functional dyes.

Compositionally Anisotropic Colloidal Surfactant Decorated with Dual Metallic Nanoparticles as a Pickering Emulsion Stabilizer and Their Application in Catalysis.

We aim to introduce compositionally anisotropic Janus particles, hemispheres of which was modified by hydrophilic poly(2-dimethyl amino ethyl methacrylate) [poly(DMAEMA)] brushes to display amphiphilic surfactant-type characteristics. Acquired by the electrohydrodynamic co-jetting technique, these colloidal surfactants were employed to stabilize octanol/water-based Pickering emulsion, which shows prolonged stability for more than 4 months. To explore their potential as the interfacial catalyst, iron(0) nanoparticles were incorporated in one hemisphere during electrojetting, whereas gold nanoparticles (GNPs) were patched onto the surface of the other hemisphere, which was previously modified by the poly(DMAEMA) brush. Ultimately, simultaneous rapid reduction (100% conversion in 1 min) of p-nitrophenol or methyl orange (MO) by GNPs in the aqueous phase and dechlorination of trichloroethylene (a hazardous chlorinated solvent waste) present in the octanol phase were accomplished at the organic-water interface stabilized by the Janus particles decorated by dual metallic nanoparticles. In addition, facile recovery and recyclability of the catalyst were also achieved. The novel colloidal surfactant demonstrated in this study may open up a new avenue to accomplish catalysis of several organic reactions occurring at the water-oil interface.

Spectrophotometric methods for estimation of amlodipine besylate in pure form and in it’s pharmaceutical formulations

Two unexpensive, sensitive, reproducible UV- spectrophotometric methods were developed for the determination of Amlodipine Besylate (ADB) in pure form and in pharmaceutical dosage forms. The first method was using Crystal violet dye (CV) as reagent (Tris (4-dimethyl amino) phenyl) methylium chloride). This method relied on oxidizing (ADB) in acidic medium in presence of an oxidizing agent of potassium bromide: potassium bromate (KBr:KBrO3) to form a blue colored product of absorbance at λmax 592 nm, It obeys the Beer's law in a concentrations range of (5-92.5) µg/ml with a molar absorptivity (2.13×105) L/mole.cm and the limit of detection is (0.01) µg/ml. The second method includes the reduction reagent p-nitroaniline using a nitrogenous agent (NaNO2) in an acidic medium followed coupling reaction between (ADB) and p-nitroaniline to form yallow product has absorbance at λmax 368 nm, It obeys the Beer's law in a concentrations range of (10-200) µg/ml with a molar absorptivity (3.42×105) L/mole.cm and the limit of quantification is found to be (0.01) µg/ml. The tow proposed methods are successfully applied for measuring the quantity of (ADB) in pure form and in tablets formulations.

Dimethylamino group modified polydopamine nanoparticles with positive charges to scavenge cell-free DNA for rheumatoid arthritis therapy.

Excessive cell-free DNA (cfDNA) released by damaged or apoptotic cells can cause inflammation, impacting the progression of rheumatoid arthritis (RA). cfDNA scavengers, such as cationic nanoparticles (NPs), have been demonstrated as an efficient strategy for treating RA. However, most scavengers are limited by unfavorable biocompatibility and poor scavenging efficacy. Herein, by exploiting the favorable biocompatibility, biodegradability and bioadhesion of polydopamine (P), we modified P with dimethylamino groups to form altered charged DPs to bind negatively charged cfDNA for RA therapy. Results showed that DPs endowed with superior binding affinity of cfDNA and little cytotoxicity, which effectively inhibited lipopolysaccharide (LPS) stimulated inflammation in vitro, resulting in the relief of joint swelling, synovial hyperplasia and cartilage destruction in RA rats. Significantly, DPs with higher DS of bis dimethylamino group exhibited higher positive charge density and stronger cfDNA binding affinity, leading to excellent RA therapeutic effect among all of the treated groups, which was even close to normal rats. These finding provides a novel strategy for the treatment of cfDNA-associated diseases.

A Rotation-Inversion Dual-Motion Molecular Switch: Race for NMR Signaling.

The interplay between the thermal helical inversion (THI) of the stiff-stilbene moiety and the rotation of the dimethylamino (DMA) group in 1 results in a dependence of the DMA NMR signals on the THI kinetics in (E)-1 but the rotation kinetics in (Z)-1, because the faster motion mode is responsible. Consequently, the photochemical switching from (E)-1 to (Z)-1 illustrates the phenomenon of "switchable motion detection" by the same set of NMR signals in a dual-motion molecular system.

Bioremoval of toxic malachite green from water through simultaneous decolorization and degradation using laccase immobilized biochar

In this study, decolorization and degradation of malachite green dye was studied using the laccase immobilized pine needle biochar. Successful immobilization of biochar was achieved by adsorption and confirmed through scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX), Fourier transform infrared spectroscopy (FTIR). High laccase binding of 64.4 U/g and high immobilization yield of 78.1% was achieved using 4U of enzyme at pH3 and temperature 30 °C. The immobilized laccase retained >50% relative activity in the pH range 2–7, >45% relative activity at 65 °C and >55% relative activity at 4 °C for 4 weeks. The re-usability of immobilized enzyme was checked with 2, 2′-azino-bis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) substrate and enzyme retained 53% of its activity after 6 cycles. Immobilized laccase was used for the degradation and decolorization of azo dye malachite green in aqueous solution. More than 85% removal of malachite green dye (50 mg/L) was observed within 5 h. FTIR and high performance liquid chromatography (HPLC) analysis clearly indicated the breakdown of dye and presence of metabolites (leuco malachite green, methanone, [4-(dimethyl amino)pheny]phenyl and 3-dimethyl-phenyl amine) in gas chromatography–mass spectrometry (GC-MS) analysis confirmed the dye degradation. Phytotoxicity analysis indicated that the enzymatic degradation resulted in lesser toxic metabolites than the original dye. Thus, laccase immobilized biochar can be used as an efficient biocatalytic agent to remove dye from water.