Naphthalene Groups Research Articles

2,3-Dihydro-1H-cyclopenta[b]naphthalen-1-ol

In the title compound, C13H12O, the cyclo­pentene ring fused with the naphthalene group adopts an envelope conformation. The cyclo­pentene torsion angle, with the fusion bond at the centre, has a magnitude of 1.16 (16)°. In the crystal, neigh­bouring mol­ecules are connected through O—H⋯O hydrogen bonds into an R 4 4(8) ring motif. The crystal packing also features weak π–π stacking inter­actions [centroid–centroid distance = 3.8981 (8) Å] and C—H⋯π inter­actions.

Abstract 2324: Translational Stroke Research: Identification Of A Novel Family Of Natural Product Derived Flavonoid-Based Polyphenols With Potent Pleiotropic Neuroprotective Activity.

Multiple plant (fruits, vegetables) and spice (turmeric)-derived natural products, which have pleiotropic activities (anti-inflammatory, antioxidant, anti-apoptotic, neurogenic) are also neuroprotective in vitro against numerous chemical insults and promote behavioral recovery in vivo following embolic strokes. We have focused on 2 types of natural products: 1) curcumin-based compounds such as CNB-001 and 2) flavone-based compounds such as fisetin and baicalein. We have synthesized a new library of flavonoid molecules to improve their pharmacological characteristics and have selected candidates using a battery of vitro screening assays with stringent criteria: 1) HT22 hippocampal cell survival (in vitro ischemia model using 20µM iodoacetic acid); 2) primary mouse cortical neurons cell survival (in vitro excitotoxicity assay using 10µM glutamate); 3) HT22 hippocampal cell survival assay (oxytosis using 5 mM glutamate to induce non-NMDA mediated cell death due to the absence of NMDA receptors on HT22 cells). EC50 ≤ 100 nM and survival ≥80% in the IAA assay, ≥35% survival in the cortical neuron assay and EC 50 ≤ 300 nM and ≥50% survival in the oxytosis assay. All compounds were screened in triplicate using concentrations up to 10 µM. We chemically modified fisetin to improve its potency, increase blood brain barrier penetration (CLogP, an indicator of blood brain barrier penetration) and reduce tPSA (topographical polar surface area). We have developed a structure activity relationship (SAR) indicating that the absence of a hydroxyl group on the A ring of fisetin enhances its potency. Two compounds PM-001 and PM-004) are 6 fold more potent than fisetin. Altering a hydroxyl group at the 3-position of the B ring has no impact on activity. The addition of multiple hydrophobic groups to various positions on the A ring, such as the addition of methyl groups at the 6 and/or 7 position improved potency ∼10-100 fold over fisetin (e.g. compound PM-010) while the addition of a more hydrophobic naphthalene group (PM-002) and (PM-003) improved the potency ∼40 fold over fisetin and increased the ClogP and reduced the tPSA. SAR studies on the C ring suggested that hydrogen bond accepting groups such as a methoxy at the 4' position and a hydrogen bond donating group such as a hydroxyl at the 3' position further enhanced potency. For example compound CMS-064, CMS-069 and CMS-092 are some of the most potent compounds, with EC 50 s below 40 nM. These compounds also have CLogPs and tPSAs consistent with enhanced brain penetration. In conclusion, we have used a rational medicinal chemistry approach in combination with in vitro screening analysis to identify new flavonoid molecules to optimally promote neuroprotection. The molecules which will be discussed in detail are being further characterized and de-risked to treat stroke.

Computational Study on the Palladium-Catalyzed Allenylative Dearomatization Reaction

The detailed mechanism of the Pd-catalyzed coupling of naphthalene allyl chloride with allenyltributylstannane, resulting in the dearomatization of the naphthalene group, has been studied using density functional theory (DFT) calculations at the B3LYP level. The catalyst cycle can be divided into three main stages involving oxidative addition, transmetalation, and reductive elimination, none of which contains significantly large barriers. It is found that the oxidative addition takes place through a monophosphine pathway. The transmetalation step is responsible for the formation of the propargylic dearomatized product, due to the orientation of the metal-coordinated allenyl ligand. Reductive elimination of the dearomatized product from the intermediate (η3-allylnaphthalene)(η1-allenyl)PdPH3 occurs by coupling of the terminal carbon of the η1-allenyl ligand with the ortho carbon of the η3-naphthalene ligand. Furthermore, it is shown that dichloromethane as solvent does not change the mechanistic picture significantly.

Selenium Supplementation Can Slow the Development of Naphthalene Cataract

Purpose: To evaluate the effect of selenium supplementation on the progress of naphthalene cataract.Materials and Methods: Sprague-Dawley rats were randomly divided into five groups as follows: normal control, naphthalene control and selenium-supplemented groups (Selenium I, II and III, which were orally administrated with selenium at doses of 0.0104 mg/kg, 0.0208 mg/kg and 0.0416 mg/kg, respectively). All the intervention groups were orally administered with 10% naphthalene solution for 5 weeks. The lens density of each group was determined by photography. Moreover, glutathione peroxidase (GPx) activity in the lens, erythrocyte and plasma was investigated. In addition, lens glutathione (GSH), malondialdehyde (MDA) and hydroxyl radical levels were evaluated. Selenium level in aqueous humor was determined using atomic absorption spectrometry.Results: The maximum, mean and minimum densities of lens opacities were lower in Selenium group II and III than those in naphthalene group. The maximum density of the lens increased more slowly in Selenium group I than that in naphthalene controls. In selenium-supplemented groups, blood and lens GPx activities as well as aqueous humor selenium level increased significantly. Selenium supplementation also significantly ameliorated the decrease in GSH level and increase in MDA and hydroxyl radical levels in the lens of naphthalene-treated rats.Conclusions: Selenium supplementation could slow the development of naphthalene cataract possibly by attenuating the oxidative stress in the lens.

A new Hg2+ fluorescent sensors based on 1,3-alternate thiacalix[4]arene (L) and the complex of [L+Hg2+] as turn-on sensor for cysteine

A new thiacalix[4]arene derivative in a 1,3-alternate conformation bearing four naphthalene groups through crown-3 chains has been synthesized, which exhibits high selectivity toward Hg2+ by forming a 1:2 complex, among other metal ions ( Na+, K+, Mg2+, Ba2+, Ca2+, Sr2+, Cs+, Mn2+, Fe2+, Cd2+, Co2+, Ni2+, Cu2+, Li+, and Zn2+) with a low detection limit (3.30×10−7 M). The metal ion-binding properties were studied by fluorescence, AFM, and 1H NMR spectroscopy. The in situ prepared [Hg2++L] complex shows well recognition ability for cysteine with a low detection limit (2.23×10−7 M) through fluorescence turning on. The mechanism of fluorescence turning on is the host L releasing from [L+Hg2+] for [Cys+Hg2+] complex formed. Thus the paper reports secondary-sensor design: Hg2+ as a first sensor for [L+Hg2+] form, cysteine as a second sensor for Hg2+ releasing from the [L+Hg2+] complex after cysteine adding in.

A new Schiff base system bearing two naphthalene groups as fluorescent chemodosimeter for Zn 2+ ion and its logic gate behavior

1-((E)-(2-((2-nitrobenzyl)(2-((E)-(2-hydroxynaphthalen-1-yl)methyleneamino)ethyl)amino)ethylimino)methyl)naphthalen-2-ol (H 2L), The new compound featuring two naphthalene units was synthesized and characterized. We find that H 2L has high selectivity and sensitivity to detect Zn 2+ ion over other metal ions such as Na +, Ag +, Cd 2+, Co 2+, Cr 3+, Cu 2+, Hg 2+, Mn 2+, Ni 2+, Fe 3+, and the sensitivity is about 10 −7 M. The fluorescent changes of H 2L upon the addition of cations Zn 2+ and triethylamine is utilized as an AND logic gate at the molecular level, using Zn 2+ and triethylamine as chemical inputs and the fluorescence intensity signal as output.

Photodegradation of commercial dye, CI Reactive Blue 160 using ZnO nanopowder: Degradation pathway and identification of intermediates by GC/MS

The ZnO-mediated photocatalysis process has been successfully applied to degradation of commercial dye, CI Reactive Blue 160 (RB 160). Eleven reaction intermediates were separated, identified and characterized by the GC–MS techniques, giving insight into mechanistic details of the ZnO-mediated catalysis process under UV irradiation and the pathways of degradation process. The degradation process take place through competitive reactions such as destruction of chromophoric group, hydroxylation of the aromatic ring, substitution on aromatic ring, desulphonation, decarboxylation and further ring opening to give aliphatic compounds. Smaller aliphatic compounds formed during the process were identified by IC, while the triazine group and naphthalene group containing compounds remains intact even after decolorization for a prolonged time due to high resistance to oxidation. The probable degradation pathways were proposed and discussed.

Thermodynamic and fluorescence emission properties of the Zn(II), Cd(II) and Pb(II) complexes with a fluorescent chelator bearing phenanthroline and naphthalene subunits

The new ligand L consisting of a 1,10-phenanthroline unit bearing in 2,9 positions two triamine branches with terminal naphthalene groups was synthesized and used for protonation and metal ion (Zn(II), Cd(II), Pb(II)) coordination studies. Protonation and metal ion coordination were analyzed by means of potentiometric measurements, affording speciation of the systems and determination of the relevant equilibrium constants, and by means of 1H NMR, UV–Vis and fluorescence emission spectroscopy. L forms stable complexes with the three metal ions showing very high selectivity for the binding of Zn(II) over Pb(II) (selectivity coefficient of 42,000 around pH 8.3), high selectivity for the binding of Cd(II) over Pb(II) (selectivity coefficient of 710 around pH 7.7) and modest selectivity for the bind of Zn(II) over Cd(II) (selectivity coefficient of about 70 around pH 9).Exciplex emission in the visible region due to the interaction of the coordinated phenanthroline unit with a naphthalene group is observed for the Zn(II) and Cd(II) complexes, while the Pb(II) complex is completely quenched. Such thermodynamic and photochemical properties define the conditions for selective sensing of Zn(II) and Cd(II) in the presence of Pb(II).

1H NMR Chemical Shift Calculations as a Probe of Supramolecular Host–Guest Geometry

The self-assembled supramolecular host [Ga(4)L(6)](12-) (1; L = 1,5-bis[2,3-dihydroxybenzamido]naphthalene) can encapsulate cationic guest molecules within its hydrophobic cavity and catalyze the chemical transformations of bound guests. The cavity of host 1 is lined with aromatic naphthalene groups, which create a magnetically shielded interior environment, resulting in upfield shifted (1-3 ppm) NMR resonances for encapsulated guest molecules. Using gauge independent atomic orbital (GIAO) DFT computations, we show that (1)H NMR chemical shifts for guests encapsulated in 1 can be efficiently and accurately calculated and that valuable structural information is obtained by comparing calculated and experimental chemical shifts. The (1)H NMR chemical shift calculations are used to map the magnetic environment of the interior of 1, discriminate between different host-guest geometries, and explain the unexpected downfield chemical shift observed for a particular guest molecule interacting with host 1.

Maleic acid–2-vinylnaphthalene copolymer in aqueous solution: investigation of the dissociation and fluorescence quenching

The alternating maleic acid–2-vinylnaphthalene copolymer was synthetized and characterized. The amphiphilic polyelectrolyte adopts a pseudomicellar conformation in aqueous solution. The hydrophobic microdomains are formed by the naphthalene groups and the water solubility is conferred by the hydrophilic maleic acid groups. The two-step dissociation of polyelectrolyte was studied by potentiometric titrations and the conformational transition was investigated by viscometry and fluorescence techniques. By increasing the neutralization degree over an αN ~ 0.2, an expansion of the polymer coil takes place from a compact to a loose or extended form, but the hydrophobic microdomains formed by the naphthalene groups are present on the whole neutralization range. The investigation of the naphthalene fluorescence quenching by different transition metal ions shows an extremely high quenching efficiency by Cu2+ ions. The ionic strength influences the polyelectrolyte conformation and the fluorescence quenching process. The maleic acid–2-vinylnaphthalene copolymer can be used for the solubilization of polynuclear aromatic compounds or other sparingly water-soluble organic compounds or for the design of fluorescent sensors.

2-(Naphthalen-1-yl)-4-(thiophen-2-ylmethylidene)-1,3-oxazol-5(4H)-one

The asymmetric unit of the title compound, C18H11NO2S, contains two crystallographically independent mol­ecules. In one mol­ecule, the oxazole and thio­phene rings are oriented at dihedral angles of 17.40 (9) and 18.18 (7)° with respect to the naphthalene ring system, while the oxazole and thio­phene rings are oriented to each other at a dihedral angle of 0.86 (9)°. In the other mol­ecule, the corresponding angles are 3.05 (8), 9.62 (6) and 7.02 (8)°, respectively. In each mol­ecule, a weak intra­molecular C—H⋯N hydrogen bond links the oxazole N atom to the naphthalene group. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure. π–π stacking between the oxazole and thio­phene rings, between the thio­phene and naphthalene rings, and between the oxaozole and naphthalene rings, [centroid–centroid distances = 3.811 (2), 3.889 (2), 3.697 (2) and 3.525 (2) Å] may further stabilize the crystal structure.

Sulfonated Block Poly(arylene ether sulfone) Membranes for Fuel Cell Applications via Oligomeric Sulfonation

Poly(arylene ether sulfone) multiblock copoly. were synthesized via oligomeric sulfonation. The successful oligomeric sulfonation enabled multiblock copolymer membranes with different hydrophobic block moiety (biphenyl and naphthalene units). High local concentration of sulfonic acid groups within the hydrophilic blocks enhanced the phase separation between hydrophilic and hydrophobic moiety. Rigid, nonpolar, and planar hydrophobic moiety such as naphthalene groups were effective in increasing proton conductivity and decreasing gas permeability. The multiblock copolymers with naphthalene hydrophobic units with IEC = 2.01 mequiv/g showed comparable proton conductivity to Nafion NRE 212 membrane (0.91 mequiv/g) at >40% RH. The longer blocks were found to increase a characteristic factor (ratio of the proton conductivity to the water volume fraction) as well as phase separation. The membrane showed relatively low oxidative stability under Fenton’s test conditions due to higher water uptake and swelling. However, low gas permeability could compensate this drawback for fuel cell applications.

Preparation and photopatterning of Langmuir-Blodgett (LB) films of a novel copolymer containing swallow-tailed double naphthalene groups

A new series of copolymer poly(N-hexadecylmethacrylamide-co-dinaphthalen-2-yl 2-allylmalonate) poly(HDMA-co-DNAM)s containing swallow-tailed double naphthyl groups and long alkyl group were designed and synthesized. The behavior of copolymer molecular arranging on water surface, patterning properties of copolymer LB films, and photochemical reactions in ultrathin film were investigated. The poly(HDMA-co-DNAM)s could form a stable, well-defined molecular orientation Langmuir monolayer at air/water interface. The polymer main chain was lying flat on water surface and the side chains attached to the main chain stretching out at the angle of about 50°. The results obtained showed that a well-ordered layer-by-layer structure was successfully controlled in LB films, in which most of naphthyl groups in poly(HDMA-co-DNAM)s LB films were in dimer and the copolymer LB films were decomposed hardly upon irradiation of deep UV light. We found that the exposed and unexposed regions of the poly(HDMA-co-DNAM)s copolymer LB films had solubility differentiation in gold etchant, which is a mixed solution of I2/NH4I/C2H5OH/H2O. Therefore, we could obtain gold photopattern with the maximal resolution of the employed mask without any development process. Copyright © 2011 John Wiley & Sons, Ltd.

A saccharide-based supramolecular hydrogel for cell culture

It is well known that the saccharides forming the intricate sugar coat that surrounds the cells play important biological roles in intercellular communication and cell differentiation. Therefore, it is worthwhile developing saccharide-based hydrogels for cell culture study. In this study, three novel saccharide-based compounds were designed and synthesized. It was found that one of them could form hydrogels efficiently, while the other two precipitated from water. The stability of the resulting hydrogel was tested, and the supramolecular nanofiber with fiber diameters in the range of 80–300 nm was characterized as the structural element by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fluorescence microscopy revealed that extensive hydrogen bonds between sugar rings assisted the formation of efficient π–π stacking between aromatic naphthalene groups, thus resulting in the formation of a stable hydrogel in aqueous solution. When the gel was applied for mouse embryonic fibroblast (NIH 3T3), human hepatocellular carcinoma (HepG2), AD293 and HeLa cells culture in two dimensional environments, all of them showed a very good adhesion and good proliferation rate on the top of the hydrogel. These results indicates that the biocompatible hydrogel reported here has a potential to be developed into useful materials for in vitro cell culture, drug delivery, and tissue engineering.

Combined 3D-QSAR, molecular docking and molecular dynamics study on derivatives of peptide epoxyketone and tyropeptin-boronic acid as inhibitors against the β5 subunit of human 20S proteasome.

An abnormal ubiquitin-proteasome is found in many human diseases, especially in cancer, and has received extensive attention as a promising therapeutic target in recent years. In this work, several in silico models have been built with two classes of proteasome inhibitors (PIs) by using 3D-QSAR, homology modeling, molecular docking and molecular dynamics (MD) simulations. The study resulted in two types of satisfactory 3D-QSAR models, i.e., the CoMFA model (Q2 = 0.462, R2pred = 0.820) for epoxyketone inhibitors (EPK) and the CoMSIA model (Q2 = 0.622, R2pred = 0.821) for tyropeptin-boronic acid derivatives (TBA). From the contour maps, some key structural factors responsible for the activity of these two series of PIs are revealed. For EPK inhibitors, the N-cap part should have higher electropositivity; a large substituent such as a benzene ring is favored at the C6-position. In terms of TBA inhibitors, hydrophobic substituents with a larger size anisole group are preferential at the C8-position; higher electropositive substituents like a naphthalene group at the C3-position can enhance the activity of the drug by providing hydrogen bond interaction with the protein target. Molecular docking disclosed that residues Thr60, Thr80, Gly106 and Ser189 play a pivotal role in maintaining the drug-target interactions, which are consistent with the contour maps. MD simulations further indicated that the binding modes of each conformation derived from docking is stable and in accord with the corresponding structure extracted from MD simulation overall. These results can offer useful theoretical references for designing more potent PIs.

Complexation between Pentiptycene Derived Bis(crown ether)s and CBPQT4+ Salt: Ion-Controlled Switchable Processes and Changeable Role of the CBPQT4+ in Host−Guest Systems

The pentiptycene derived bis(crown ether)s with two 24-crown-8 moieties in the cis position could include the CBPQT(4+) ring inside their cavities to form 1:1 complexes, and the naphthalene groups connected in the crown ether moieties showed less effective complexation ability toward the CBPQT(4+) ring than the host containing two terminal benzene rings. This result was probably due to the stereohindrance effect of the naphthalene groups, and it was obviously different from that of the pentiptycene derived mono(crown ether)s. For the pentiptycene derived bis(crown ether) with two 24-crown-8 moieties in the trans position, it formed a 1:2 stable complex with the CBPQT(4+) salt in solution and in the solid state, in which the pentiptycene moiety played an important role in stabilizing the complex. Moreover, binding and release of the CBPQT(4+) ring in the complexes based on the pentiptycene-derived crown ethers could be chemically controlled by adding and removing potassium ions, in which the complexation modes played the key role. Interestingly, it was further found that switching the role of the CBPQT(4+) ring in host and guest systems based on the pentiptycene derived bis(crown ether)s was easily achieved, which represents a new kind of supramolecular system.

N,N'-{1,3-Phenylenebis[methyleneoxy-2,1-phenylene(Z)methylylidene]}bis[1-(1-naphthyl)methanamine

A new fluorescent di-imine compound containing two naphthalene groups has been synthesized by classical Schiff-base reaction between 2,2’-[1,3-phenylene­bis­(methyleneoxy)]dibenzaldehyde and 1-naphthylmethylamine. The new bischromophoric compound has been characterised by IR, NMR and MALDI-TOF MS spectroscopy. The photophysical characterization was carried out by UV-vis and fluorescence emission spectroscopy, using chloroform. The monomer and excimer bands, typical for the naphthalene in solution, are present in the emission spectra for the compound.

Enforced Effects of Side Group Substitution Position on Luminescence Properties; Synthesis of Bis(dipyrrinato)zinc Complex Derivatives

New yellow-green emitting materials using bis(dipyrrinato)zinc complex moiety were synthesized by substituting phenyl group and 1- or 2-positioned naphthalene group. Bis[5-(1-naphthalenyl)-dipyrrinato]zinc complex (Zn(1-NaPN)2) substituted at position 1 of naphthalene group showed about 10 times stronger photoluminescence (PL) property and sharper PL spectrum compared to bis[5-(phenyl)-dipyrrinato]zinc complex (Zn(PPN)2) and bis[5-(2-naphthalenyl)-dipyrrinato]zinc complex (Zn(2-NaPN)2). Optical properties in film state were almost identical to the result of non-doped organic light emitting diodes (OLEDs) device. Luminance efficiency (cd/A) of Zn(1-NaPN)2 was 0.33 cd/A, which was about 4∼8 times higher than Zn(PPN)2, 0.04 cd/A and Zn(2-NaPN)2, 0.08 cd/A. Quantum efficiency was also about 2∼3 times higher.

Detailed analysis of diesel vehicle exhaust emissions: Nitrogen oxides, hydrocarbons and particulate size distributions

Exhaust emissions from a diesel vehicle were studied using FTIR, SMCA-REMPI, and SMPS. With these techniques, quantitative emission properties of NO, NO 2, N 2O, NH 3, CO, CH 4, C 2H 4, C 3H 6, HCHO, toluene, toluene + CH 2, toluene + 2CH 2, β-methylstyrene, naphthalene, 2-methylnaphthalene, phenanthrene, and o-cresol, as well as particle size distributions, were obtained in constant-speed operation at 0–80 km/h, which corresponds to a brake mean effective pressure (BMEP) of 0–293 kPa. NO emission increased as the in-cylinder temperature increased, corresponding to increased engine load. NO 2 and N 2O had a strong correlation to equivalence ratio. The emission characteristics of non-aromatic hydrocarbons depended on engine load. At low load, the emissions were high because low in-cylinder temperature and Exhaust Gas Recycling (EGR) prevented complete fuel oxidation. Equivalence ratio had a slight influence on the non-aromatic hydrocarbon emissions. The profiles of aromatic hydrocarbon exhibited two shapes. One was a toluene group and another was a styrene and naphthalene group. The shapes of the toluene group were similar to those of non-aromatic hydrocarbons. On the other hand, the styrene and naphthalene group emissions at idling were low, suggesting that they were not formed at low load. These features concerning the two groups of aromatic hydrocarbons were also observed in a transient driving cycle. Emission of accumulation mode particles was correlated with equivalence ratio. Higher emissions were observed when the equivalence ratio was higher, and the particle diameters also increased. Emission of nucleation mode particles increased as the engine load increased, because the amount of injected fuel per cycle increased.

1-Phenyl-1H-naphtho[1,2-e][1,3]oxazin-3(2H)-one

In the title compound, C18H13NO2, the naphthalene (r.m.s. deviation = 0.025 Å) and benzaldehyde (r.m.s. deviation = 0.006 Å) groups are oriented at a dihedral angle of 89.48 (4)°. The oxazine group is oriented at dihedral angles of 13.36 (4) and 85.08 (5)°, respectively, with respect to the naphthalene and benzaldehyde fragments. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R 2 2(8) loops. The dimers are linked into [010] chains via N—H⋯O hydrogen bonds. Weak C—H⋯π links and aromatic π–π stacking between the centroids of the naphthalene phenyl rings [centroid–centroid separation = 3.5977 (8) Å] help to consolidate the packing.