NH Moiety Research Articles

Trapping Acrolein by Theophylline/Caffeine and Their Metabolites from Green Tea and Coffee in Mice and Humans.

Acrolein (ACR) is found exogenously as a widespread environmental pollutant and endogenously, where it is thought to be involved as a pathogenic factor in the progression of many pathological conditions. Eliminating ACR by dietary-active substances has been found to be one potential strategy to prevent ACR-associated chronic diseases. This study first compared the scavenging ACR efficacy of four purine alkaloids, theophylline (TP), paraxanthine (PXT), theobromine (TB), and caffeine (CAF), and then, TP, CAF, and their metabolites were investigated for their ability to trap ACR in vivo. Our results indicated that TP, which possesses an -NH moiety at the N-7 position, exhibits the best ACR-trapping capacity in vitro, while CAF has a slight ability to trap ACR due to the substitutions by -CH3 at the N-1, N-3, and N-7 positions. After oral administration of TP or CAF, the ACR adducts of TP and the metabolites of TP or CAF (e.g., mono- and di-ACR-TP, mono-ACR-1,3-DMU, and mono-ACR-1-MU) were detected in urinary samples obtained from both TP- and CAF-treated mouse groups by using ultra-performance liquid chromatography-tandem mass spectrometry. The quantification studies demonstrated that TP and its metabolites significantly trapped ACR in a dose-dependent manner in vivo. Furthermore, we also detected those ACR adducts of TP and TP/CAF's metabolites in human urine after four cups of green tea (2 g tea leaf/cup) or two cups of coffee (4 g coffee/cup) were consumed per day. Those results indicated that dietary TP or CAF has the potential capacity to scavenge ACR in vivo.

Simple methods of modification of daunorubicin on the daunosamine nitrogen atom

Modification of daunorubicin on its NH2 moiety is a well-established synthetic approach to obtain novel derivatives of this compound. Moreover, the daunosamine moiety of this antibiotic is considered to be the most sensitive part of a molecule in terms of biological response to chemical transformations. Using simple and effective synthetic techniques, namely, alkylation under phase-transfer catalysis and an amine addition across an activated multiple bond, a series of daunorubicin derivatives retaining the amine functionality have been obtained, which could also be used as potential precursors for further transformations.

Systematic measurements of charge transfer complexes caused from 1-phenyl-1,2,3,4-tetrahydroisoquinoline and 4-aminoacetanilide with series of π-acceptors (BQ, DDQ, TCNQ).

Molecular charge-transfer interaction of a series of electron π-acceptors of 1,4-benzoquinone (BQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and Tetracyanoquinodimethane (TCNQ) with selected donors of 1-phenyl-1,2,3,4-tetrahydroisoquinoline (PTHIQ) and 4-aminoacetanilide (ACE) have been studied in methanol at room temperature. The stoichiometry of the complexes was determined by photometric titration method and was found to be 1:1, in all the cases. Spectro-kinetic interaction studies along with rate constants and observed formation constants (K) indicated that the strength of the complex formations is PTHIQ-BQ<PTHIQ-DDQ<PTHIQ-TCNQ. Also, Similar observations happened in ACE-BQ and<ACE-DDQ<ACE-TCNQ systems. FT-IR results indicated that the point of interaction was identifying in NH moiety of PTHIQ and NH2 moiety of ACE with series of π-acceptor complexes. The experimental results were compared with Ab initio DFT calculations at the B3LYP/6-31+G(d) level of theory. The increasing order of the experimentally measured formation constant of CT-complexes (PTHIQ and ACE with series of acceptors) was well supported by theoretical HOMO-LUMO energy gap and drastically changes in Mulliken charges of NH moiety of PTHIQ, NH2 moiety of ACE with complexation with acceptors.

Investigating discrepancies between experimental solid-state NMR and GIPAW calculation: N[dbnd]C–N 13C and OH⋯O 1H chemical shifts in pyridinium fumarates and their cocrystals

An NMR crystallography analysis is presented for four solid-state structures of pyridine fumarates and their cocrystals, using crystal structures deposited in the Cambridge Crystallographic Data Centre, CCDC. Experimental one-dimensional one-pulse 1H and 13C cross-polarisation (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and two-dimensional 14N–1H heteronuclear multiple-quantum coherence MAS NMR spectra are compared with gauge-including projector augmented wave (GIPAW) calculations of the 1H and 13C chemical shifts and the 14N shifts that additionally depend on the quadrupolar interaction. Considering the high ppm (>10 ​ppm) 1H resonances, while there is good agreement (within 0.4 ​ppm) between experiment and GIPAW calculation for the hydrogen-bonded NH moieties, the hydrogen-bonded fumaric acid OH resonances are 1.2–1.9 ​ppm higher in GIPAW calculation as compared to experiment. For the cocrystals of a salt and a salt formed by 2-amino-5-methylpyridinium and 2-amino-6-methylpyridinium ions, a large discrepancy of 4.2 and 5.9 ​ppm between experiment and GIPAW calculation is observed for the quaternary ring carbon 13C resonance that is directly bonded to two nitrogens (in the ring and in the amino group). By comparison, there is excellent agreement (within 0.2 ​ppm) for the quaternary ring carbon 13C resonance directly bonded to the ring nitrogen for the salt and cocrystal of a salt formed by 2,6-lutidinium and 2,5-lutidinium, respectively.

Iridium catalysts featuring amine-containing ligands for the dehydrogenation of formic acid

The use of protic ligands to generate metal-ligand bifunctional catalysts has proved an excellent strategy to enhance the catalytic activity in formic acid dehydrogenation. We present here synthetic routes for complexes of general formula [Ir(H)2(IPr)(PR3)(CH3CN)2]BF4 (1a-c), [Ir (8-AQ)(H)2(IPr)(PR3)]BF4 (2a-c and 3), and [Ir(IPr)(C-N)(8-AQ)H]BF4 (5a-c) (8-AQ = 8-aminoquinoline; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; C-N = 1-phenylpiridine-1H, 1-phenylpirazol-1H or 2-(p-tolyl-1H)pyridine-1H). Complexes 2a-c, 3, 5a and c were evaluated as catalysts for the dehydrogenation of formic acid in water. The nature of the phosphane in complexes 2a-c and 3 affects drastically the catalytic activity, with more basic and less encumbered phosphanes bringing about better performances. DFT calculations suggest that the coordinated NH2 moiety of the 8-AQ ligand plays a crucial role throughout the catalytic cycle. Two key steps are the protonation of the hydride ligand directed by the NH2 moiety (H2 formation), and the hydride abstraction to regenerate the dihydride active species (CO2 formation). Complexes 5a and 5c do not improve the results obtained with 2a-c and 3, probably due to the fact that a preactivation step is required. This may be attributable to an isomerization step that places the NH2, initially trans to the hydride ligand, in cis position.

Tandem Detection of Sub-Nano Molar Level CN- and Hg2+ in Aqueous Medium by a Suitable Molecular Sensor: A Viable Solution for Detection of CN- and Development of the RGB-Based Sensory Device.

An inimitable urea-based multichannel chemosensor, DTPH [1,5-bis-(2,6-dichloro-4-(trifluoromethyl)phenyl)carbonohydrazide], was examined to be highly proficient to recognize CN– based on the H-bonding interaction between sensor −NH moiety and CN– in aqueous medium with explicit selectivity. In the absorption spectral titration of DTPH, a new peak at higher wavelength was emerged in titrimetric analytical studies of CN– with the zero-order reaction kinetics affirming the substantial sensor–analyte interaction. The isothermal titration calorimetry (ITC) experiment further affirmed that the sensing process was highly spontaneous with the Gibbs free energy of −26 × 104 cal/mol. The binding approach between DTPH and CN– was also validated by more than a few experimental studies by means of several spectroscopic tools along with the theoretical calculations. A very low detection limit of the chemosensor toward CN– (0.15 ppm) further instigated to design an RGB-based sensory device based on the colorimetric upshots of the chemosensor in order to develop a distinct perception regarding the presence of innocuous or precarious level of the CN– in a contaminated solution. Moreover, the reversibility of the sensor in the presence of CN– and Hg2+ originated a logic gate mimic ensemble. Additionally, the real-field along with the in vitro CN– detection efficiency of the photostable DTPH was also accomplished by using various biological specimens.

Photochromic Evaluation of 3(5)-Arylazo-1H-pyrazoles.

The desire to photocontrol molecular properties ranging from materials to pharmacology using light as an external trigger with high spatiotemporal resolution led to the development of a broad range of photochromic scaffolds. Among them, azobenzenes are synthetically well accessible and show excellent fatigue resistance. Their photochromic properties vary with the substitution pattern and for different heteroarenes. However, the photochromism of 3(5)-substituted-1H-pryazoles has not yet been investigated, although this compound class offers interesting possibilities of metal ion coordination and hydrogen bond formation via its NH moiety. Herein, we present the results of an experimental and computational investigation of arylazo-3(5)-arylazo-1H-pyrazoles. To elucidate their properties, solvent and substitution effects on their light absorption, thermal half-lives, photostationary states, fatigue, and quantum yields were determined.

Enhanced CO2 capture through bulky poly(urethane-urea)-based MMMs containing hyperbranched triazine based silica nanoparticles

Two types of poly(urethane-urea)-based mixed matrix membranes containing hyperbranched structures of surface-modified silica nanoparticles were fabricated. The stepwise surface modification of nanoparticles was done based on aminopropyltriethoxysilane, cyanuric chloride, and ethylenediamine. FTIR, TGA, elemental analysis, and SEM-EDX were served to characterize the modified particles. The incorporation of the nanoparticles into poly(urethane-urea)s (PUUs) altered the phase separation degree of soft and hard segments, elevated the glass transition of soft segments and reduced the chain order. MMM containing the optimal distribution of 5 wt% modified silica showed improved mechanical and gas separation properties with 20–25% and 30–36% enhancement in CO2 permeability and CO2/N2 selectivity, respectively. The presence of long adsorbent chains with NH moieties on the particles improves the particle distribution in the matrix, thereby enhanced CO2 permeability up to 5 wt% particle content. At higher loadings, the agglomeration of the particles led to the formation of non-selective channels for gas diffusion and reduced gas separation performance and mechanical properties.

Electronic aspects of hydrogen bond patterns of P=O···H in crystal structures of phosphoramido acid derivatives: QSAR study of anti-urease activity, Hirshfeld surface analysis, and DFT calculations

New derivatives of phosphoramido acid with the formula(C6H11NCH3)(NHCOCF3)P(O)(O−)(CH3–+NH2–C6H11)(1) (amidophosphoricacid), (C6H5)2P(O)(O−)(+NH3–C6H4–NH2)(2) (phosphonicacid), (C6H5O)2P(O)(O−)(+NH3–C6H4–NH2) (3) (phosphoricacidester) were synthesized and characterized by X-ray crystallography. The asymmetric unit of compounds 1–3 consists of one molecule with the P atom in a tetrahedral environment. The X-ray structural analysis showed that the H-bond patterns depend on the kind of atoms linked to the P atom. In the crystal packing of compound 1, P(O)···H–N and C(O)···H–N hydrogen bonds in 3 and P(O)···H–N distances in compounds 2 and 3 led to a one-dimensional arrangement. The energy of P–O···H–N hydrogen bond (EHB) model and stabilizing energies (E2) were calculated. Hirshfeld surface analysis demonstrated that the C···H contact is attributed to CH···π contact in the 2 and 3 compounds and the F···H contact is referred to hydrogen bond in one O···H counterion interaction. Quantitative structure–activity relationship (QSAR) was used to comprehend the relationship between molecular structural features and the inhibitory of investigated compounds. The use of density functional theory along with the QSAR model for enzymes revealed the importance of QH parameter in describing the anti-AChE and anti-urease activities of monophosphoramidates including P(O)–NH2 moiety.

Raman, DRIFT and ATR-IR spectra, corrosion inhibition, DFT and solid-state calculations of 4-amino-3-choloro-2,5,6-trifluoropyridine

The Raman spectrum (3700-100 cm−1) of 4-Amino-3-choloro-2,5,6-trifluoro-pyridine (ACTFP; C5H2ClF3N2) has been recorded in the solid phase using 514.5 nm (green) and 785 nm (red) lasers to trace relative intensity changes. Moreover, the ATR-IR (4000-500 cm−1) and DRIFT (4000–400 cm−1) spectra of the solid were also recorded. Nine structures were suggested for ACTFP based on amino-imino tautomerism in addition to suggested conformers as a result of amino group internal rotation. DFT-B3LYP calculations at basis sets up to 6–311++G(d,p) favor the non-planaramino form (S-1; C1 symmetry), possessing the least energy with real vibrational frequencies. Based on X-ray single crystals and owing to the observed four stretches for NH2 moiety, the presence of two molecules per unit cell (a dimer molecule) is also investigated using both Gaussian B3LYP/at 6-31G(d) and CASTEP solid state computations. Reliable vibrational assignments were proposed herein based on estimated wavenumbers, normal coordinate analyses (NCA), potential energy distributions (PEDs) and de-convoluted spectra. Nevertheless, the NCA were found to be extensively mixed, all C–F and C–Cl fundamentals were confidently allocated herein, however were not considered in earlier published data of similar molecules. Moreover, frontier molecular orbitals (HOMO and LUMO) and atomic charge distributions (NPA and ESP) were also predicted for ACTFP to examine its efficiency as a corrosion inhibitor.

Graphene oxide-terminated hyperbranched amino polymer-carboxymethyl cellulose ternary nanocomposite for efficient removal of heavy metals from aqueous solutions

A high-efficiency graphene oxide-terminated hyperbranched amino polymer-carboxymethyl cellulose ternary nanocomposite (GO-HBP-NH2-CMC) was fabricated for adsorbing heavy metals from aqueous solutions. The adsorbent was characterized by SEM, FT-IR, Raman, and XPS analyses showing its porous architecture, rough surface, abundant N- and O-containing functional groups providing enhanced binding ability towards Pb2+ and Cu2+. Experimental adsorption data fitted well to the pseudo-second-order kinetics and Langmuir isotherm models, indicating the adsorption of GO-HBP-NH2-CMC towards Pb2+ and Cu2+ being a chemical and monolayer process. The maximum adsorption capacities of GO-HBP-NH2-CMC for Pb2+ and Cu2+ at 25 °C comprised 152.86 and 137.48 mg/g, respectively. The laboratory-scale experimental study into the Pb2+ and Cu2+ adsorption in a fixed-bed column was undertaken. Effects of flow rate, bed depth and influent metals concentration on the adsorption performance were assessed. Experimental data successfully correlated with the Adams-Bohart, Thomas and Yoon-Nelson models with the R2 exceeding 0.79. Density functional theory calculation was adopted to study interactions between functional groups at GO-HBP-NH2-CMC and heavy metals showing OH, NH2 and COOH moieties in GO-HBP-NH2-CMC being more likely to bind Pb2+ rather than Cu2+, while the binding abilities of CONH towards Pb2+ and Cu2+ were similar.

Assorted functionality-appended UiO-66-NH2 for highly efficient uranium(vi) sorption at acidic/neutral/basic pH.

A series of functionalized metal organic frameworks (MOFs) were synthesized by the post-synthetic modification (PSM) of Zr(iv)-containing UiO-66-NH2 MOFs using covalent grafting with various functional groups utilizing pendant –NH2 moieties. The tethering of amide (with/without pendant carboxylic acid), iminopyridine, phoshinic amide and sulphur-containing functionalities produced a library of eight different UiO-66-NH2 derivatives. The functionalized MOFs were characterized by FT-IR spectroscopy, NMR, PXRD, TGA, SEM-EDX and BET surface area analysis. Uranyl ion extraction with the functionalized MOFs was investigated in acidic/neutral/basic conditions (pH 1 to 9). This work presents a comprehensive study of different functionalized MOFs to investigate the effects of various analytical parameters, including pH, contact time, and desorption process. The MOFs as solid phase extractants (SPEs) provide a direct comparison of the sorption efficiencies of different functional groups on a common solid support. A phosphorous-functionalized material, UiO-66-PO-Ph, with enhanced thermal stability (∼500 °C) exhibits the best sorption capacity (∼96%) in an acidic medium (pH 3). The parent MOF UiO-66-NH2 (92%) and iminopyridine-functionalized UiO-66-IMP (90%) showed excellent sorption in neutral conditions (pH 7). Amide-containing MOFs UiO-66-AM1 (40%), UiO-66-AMMal (31%) and UiO-66-AMGlu (70%), sulfur-based MOFs UiO-66-SMA (65%) and UiO-66-SSA (27%), and phosphorous-functionalized UiO-66-PO-OPh (50%) displayed maximum sorption in basic conditions (pH 8). The kinetics studies revealed rapid uranium sorption in about 2 h due to the effective binding of uranyl ions with the anchored functional groups of MOFs; quantitative elution of uranyl ions from the MOF framework was carried out with 0.1/0.01 M HNO3. The MOFs also exhibit moderate recyclability for uranium sorption and can be regenerated by an acidic solution. The functionalized MOFs alter the stability in acidic/basic media; thus, UiO-66-NH2 is a versatile MOF material employed as an SPE for the extraction of radionuclides from aqueous media. This work also provides a platform for the development of new functionalized MOF materials for the efficient sorption of uranium as well as moderate recyclability for its removal, and the potential applications include the removal of uranium from aqueous waste streams.

Synthesis and characterization of N, N′-bis (isatin) diamino zirconium (IV) complexes

N, N′-bis (isatin) diamine schiff base ligands were synthesized by the condensation reaction of Isatin with various diamine (ethane-1,2-diamine, propane-1,3-diamine and hexane-1,6-diamine) in 2:1 molar ratios. These ligands were used to prepare Zr (IV) complexes. Prepared ligands and complexes were characterized by using conductance measurement, FT-IR, UV-Visible and 1HNMR spectroscopy. The presence of FT-IR band for azomethine group supports the formation of ligand. Vibrational bands for Zr←N and Zr←O in complexes signify the coordination through O and N sites of ligands. 1HNMR peak for NH moiety in ligand gets almost disappeared in complex reveals tautomerism of NH with nearby carbonyl oxygen due to the effect of complexation. The absence of peak above 500 nm in the electronic spectra indicates d0 system of zirconium in complexes. The elemental analytical data was analogous to theoretical composition of ligands and complexes. The molar conductance values obtained for the complexes represent their non-electrolytic character.&#x0D; Bangladesh J. Sci. Ind. Res.54(4), 297-306, 2019

Growth and organization of (3-Trimethoxysilylpropyl) diethylenetriamine within reactive amino-terminated self-assembled monolayer on silica

Alkane chains are the most commonly used molecules for monolayer fabrication. Long chains are used for their strong van der Waals interactions inducing good layer organization. Amine function-terminated alkyl chains are of great interest and are widely used for further surface functionalization. Since it is mandatory that such layers be organized to provide amine moieties at the surface, the present study deals with exploring amine-terminated SAM formation as an alternative to the usual aminopropylalkylsilane SAM. Additionally, using a long NH2-terminated alkyl chain allows the formation of hydrogen bonding thanks to the two NH moieties born along the chain. Furthermore, such hydrogen bonding makes possible to shorten the molecule length while preserving a well-organized monolayer. For this purpose we performed a complete study of the grafting of (3-Trimethoxy-silylpropyl) diethylenetriamine (DETAS) on native silicon oxide using various solvents, relative humidity and temperature values. Grafting kinetics was monitored by ellipsometry and goniometry, and SAM structure and organization using AFM and ATR-FTIR spectroscopy. Hydrogen bonding was evidenced within the SAM growth process and in the final complete SAM. We believe such study enables a better control of good quality DETAS SAM in order to improve their efficiency in further surface functionalization applications.

Prediction of decomposition temperature of azole-based energetic compounds in order to assess of their thermal stability

This investigation exhibits a novel reliable correlation for the prediction of thermal decomposition temperature (Td) of azole-based energetic compounds by their structural parameters. It is shown that the decomposition temperature of these compounds can be declared as a function of optimum elemental composition, n–NH–NO2, nC=NH, nN3 and several structural moieties by multiple linear regression approach. The obtained results have shown that the number of azido groups has the decreasing role on the Td of the azole-based energetic compound as well as NH–NO2 group. Meanwhile, the number of C=NH groups can cause an increase in Td. The correlation coefficient of the suggested model is R2 = 0.936. The model has the root-mean-square deviation and the average absolute deviation of 16.23 and 13.27 °C, respectively, for 115 azole-based energetic compounds with different molecular structures as training set. The predictive capability of the correlation is checked using internal and external validation. The coefficient of leave-many-out cross-validation test is $$Q_{\text{LMO}}^{2} = 0.937$$ . Also, this equation gives good anticipation for further 30 azole-based energetic compounds as test set. The coefficient of external validation is $$Q_{\text{Ext}}^{2} = 0.925$$ . The suggested model can also be used for designing new green energetic compounds with good thermal stability. For this purpose, it is necessary to consider the role of effective descriptors which are introduced by the model.

Homogeneous cobalt-catalyzed reductive amination for synthesis of functionalized primary amines

The development of earth abundant 3d metal-based catalysts continues to be an important goal of chemical research. In particular, the design of base metal complexes for reductive amination to produce primary amines remains as challenging. Here, we report the combination of cobalt and linear-triphos (bis(2-diphenylphosphinoethyl)phenylphosphine) as the molecularly-defined non-noble metal catalyst for the synthesis of linear and branched benzylic, heterocyclic and aliphatic primary amines from carbonyl compounds, gaseous ammonia and hydrogen in good to excellent yields. Noteworthy, this cobalt catalyst exhibits high selectivity and as a result the -NH2 moiety is introduced in functionalized and structurally diverse molecules. An inner-sphere mechanism on the basis of the mono-cationic [triphos-CoH]+ complex as active catalyst is proposed and supported with density functional theory computation on the doublet state potential free energy surface and H2 metathesis is found as the rate-determining step.

Low-Temperature Atomic Layer Deposition of Highly Conformal Tin Nitride Thin Films for Energy Storage Devices.

We present an atomic layer deposition (ALD) process for the synthesis of tin nitride (SnNx) thin films using tetrakis(dimethylamino) tin (TDMASn, Sn(NMe2)4) and ammonia (NH3) as the precursors at low deposition temperatures (70-200 °C). This newly developed ALD scheme exhibits ideal ALD features such as self-limited film growth at 150 °C. The growth per cycle (GPC) was found to be ∼0.21 nm/cycle at 70 °C, which decreased with increasing deposition temperature. Interestingly, when the deposition temperature was between 125 and 180 °C, the GPC remained almost constant at ∼0.10 nm/cycle, which suggests an ALD temperature window, whereas upon further increasing the temperature to 200 °C, the GPC considerably decreased to ∼0.04 nm/cycle. Thermodynamic analysis via density functional theory calculations showed that the self-saturation of TDMASn would occur on an NH2-terminated surface. Moreover, it also suggests that the condensation of a molecular precursor and the desorption of surface *NH2 moieties would occur at lower and higher temperatures outside the ALD window, respectively. Thanks to the characteristics of ALD, this process could be used to conformally and uniformly deposit SnNx onto an ultranarrow dual-trench Si structure (minimum width: 15 nm; aspect ratio: ∼6.3) with ∼100% step coverage. Several analysis tools such as transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and secondary-ion mass spectrometry were used to characterize the film properties under different deposition conditions. XRD showed that a hexagonal SnN phase was obtained at a relatively low deposition temperature (100-150 °C), whereas cubic Sn3N4 was formed at a higher deposition temperature (175-200 °C). The stoichiometry of these thermally grown ALD-SnNx films (Sn-to-N ratio) deposited at 150 °C was determined to be ∼1:0.93 with negligible impurities. The optoelectronic properties of the SnNx films, such as the band gap, wavelength-dependent refractive index, extinction coefficient, carrier concentration, and mobility, were further evaluated via spectroscopic ellipsometry analysis. Finally, ALD-SnNx-coated Ni-foam (NF) and hollow carbon nanofibers were successfully used as free-standing electrodes in electrochemical supercapacitors and in Li-ion batteries, which showed a higher charge-storage time (about eight times greater than that of the uncoated NF) and a specific capacity of ∼520 mAh/g after 100 cycles at 0.1 A/g, respectively. This enhanced performance might be due to the uniform coverage of these substrates by ALD-SnNx, which ensures good electric contact and mechanical stability during electrochemical reactions.

Bandgap engineering in graphitic carbon nitride: Effect of precursors

Bandgap engineering plays a vital role in the optoelectronic application of semiconducting material. In this work, Graphitic carbon nitride (g-C3N4) nanoparticles are synthesized by pyrolyzing different precursors and the role of precursor on the reduction bandgap is analyzed. X-ray diffraction pattern confirms the presence of tri-s-triazine units. Fourier transform infrared spectroscopy result reveals the presence of carbon nitride heterocycle. Urea with glycine derived g-C3N4 (UG) shows a layered structure. The absorption band edge of 620 nm and reduction in bandgap of 2.35 eV is observed for UG sample. The addition of glycine in urea significantly reduces the optical band gap and thus wider the light absorption range. Photoluminescence measurement reveals the presence of n- π* transition and defect induced luminescence. The quenching of photoluminescence intensity is observed for UG sample and the glycine produces additional NH moieties, which create disorder in the g-C3N4 structure. Reduction in bandgap with lower recombination rate significantly improves light harvesting ability and photocatalytic performance of g-C3N4 material.

Control strategy of displacement processes to sense biothiols via fluorescent changes

Two different bis-pyrene derivatives BP-1 and BP-2 were synthesized, which showed efficient fluorescent quenching by Cu2+. The addition of biothiols, such as GSH, Cys, and Hcy, restored their fluorescent emissions. Differences in the affinities of BP-1 and BP-2 for Cu2+ were successfully applied to the different detection limits and the linear detection range of biothiols. An NH moiety and a sulfur atom in the linker were the only differences between BP-1 and BP-2. Since BP-1 bound Cu2+ more tightly than BP-2, BP-1-Cu2+ required more GSH, Cys, and Hcy equivalents to restore the fluorescent emission. In contrast, only two equivalents of biothiols restored the original emission of BP-2-Cu2+. As a proof-of-concept, we demonstrated that molecular recognition chemistry and host-gest chemistry, more specifically the modulation of metal ion recognition, can be successfully applied to biothiol detection, especially over different concentration ranges. BP-1 showed a fluorescent quenching effect in living cells upon the addition of Cu2+ and BP-1-Cu2+ was also successfully applied to imaging biothiols in living cells.

Design, Synthesis and Antiplasmodial Evaluation of Sulfoximine-triazole Hybrids as Potential Antimalarial Prototypes.

Malaria, caused by the deadly Plasmodium falciparum strain, claims the lives of millions of people annually. The emergence of drug-resistant strains of P. falciparum to the artemisinin-based combination therapy (ACT), the last line of defense against malaria, is worrisome and urges for the development of new chemo-types with a new mode of action. In the search of new antimalarial agents, hybrids of triazoles and other known antimalarial drugs have been reported to possess better activity than either of the parent compounds administered individually. Despite their better activity, no hybrid antimalarial drugs have been developed so far. In the hope of developing new antimalarial prototypes, we propose the design, synthesis and antimalarial evaluation of novel sulfoximine-triazole hybrids owing to their interesting biological and physiological properties. The sulfoximine part of the hybrid will be synthesized via imidation of the corresponding sulfoxide. Propargylation of the NH moiety of the sulfoximine followed by copper-catalyzed click chemistry with benzyl azide was envisaged to provide the target sulfoximine-triazole hybrids. Five novel sulfoximine-triazole hybrids possessing various substituents on the sulfoximine moiety have been successfully synthesized and evaluated for their antiplasmodial and cytotoxicity activities. The results revealed that the co-presence of the sulfoximine and triazole moieties along with a lipophilic alkyl substituent on the sulfur atom impart significant activity. Sulfoximine-triazole hybrids could be used as a prototype for the synthesis of new derivatives with better antiplasmodial activities.