Phenyl Ester Groups Research Articles

Synthesis of 9-(substituted phenoxycarbonyl)-10-methylacridinium trifluoromethanesulfonates: Effects of the leaving group on chemiluminescent properties.

Various 9-(substituted phenoxycarbonyl)-10-methylacridinium trifluoromethanesulfonates possessing electron-withdrawing substituents have been synthesized. The effect of substituents on the stability of the acridinium esters (AEs) at various temperatures in different buffers and the chemiluminescent properties have been examined. There was little correlation between the chemiluminescent properties of AEs and the pKa values of their associated phenols, but the steric effects of the ortho-substituents in the phenoxy group, as well as their electron-withdrawing natures, seem to play an important role in determining the properties. In general, when two identical substituents are present in the 2- and 6-positions, the compound is significantly more stable than when only a single substituent is present, presumably because of greater steric hindrance from the second group. The exception is the 2,6-difluorophenyl ester, which is less stable than the 2-fluorophenyl ester, presumably because the fluoro group is small. Addition of a third electron-withdrawing substituent at the 4-position, where it has no steric influence, typically increases susceptibility to decomposition. The presence of a nitro group has a significant destabilizing effect on AEs. Of the AEs studied, the 4-chlorophenyl ester showed the greatest chemiluminescent yield, while the 2-iodo-6-(trifluoromethyl)phenyl ester group showed the greatest stability in low pH buffers.

The Influence of Long Carbon Chains on the Antioxidant and Anticancer Properties of N-Substituted Benzisoselenazolones and Corresponding Diselenides.

Organoselenium compounds are well-known for their numerous biocapacities, which result from the uniqueness of the selenium atom and the possibility of constructing heterorganic molecules that can mimic the activity of selenoenzymes, crucial for a multitude of important physiological processes. In this paper, we have synthesized a series of N-substituted benzisoselenazolones and corresponding diphenyl diselenides possessing lipophilic long carbon chains, solely or with additional polar insets: phenyl linkers and ester groups. Evaluation of their antioxidant and cytotoxic activity revealed an increased H2O2-reduction potential of diphenyl diselenides bearing N-octyl, ethyl N-(12-dodecanoate)- and N-(8-octanoate) groups, elevated radical scavenging activity of 2,2'-diselenobis(N-dodecylbenzamide) and a promising cytotoxic potential of N-(4-dodecyl)phenylbenzisoselenazol-3(2H)-one.

Thermally Induced Cross-Linking of Polymers via C,H Insertion Cross-Linking (CHic) under Mild Conditions.

The focus of studies performed so far on the formation of surface-attached polymer networks by C,H insertion cross-linking (CHic) reaction has been largely on photochemical activation. This study describes the thermal activation of the formation of (surface-attached) polymer networks under comparably mild conditions. A novel cross-linker, based on a diazo phenyl ester group, is incorporated into various copolymers, which are subsequently deposited on solid substrates. Upon activation, the cross-linker moieties generate carbene intermediates, which lead to rapid, complete cross-linking of the whole film and simultaneous surface attachment to various organic materials via CHic. Although this system requires only comparably mild conditions (i.e., below 100 °C) to become activated, a long shelf life at room temperature is observed. The presented system might be useful in a wide range of applications, from coatings to rather complex geometries. We demonstrate the covalent binding of protein-repellent thin films to the inner surface of (rubber) tubes and the generation of patterned structures by a "branding iron" approach. For this a hot structure is pressed onto a diazo polymer coated surface, leading in the contact zone to fast cross-linking while in all other areas the polymer remains soluble and is washed off during subsequent extraction.

Structural and energetic properties of P3HT and PCBM layers on the Ag(1 1 1) surface

The structural and energetic properties of poly(3-hexyl-thiophene) (P3HT) and 6,6-phenyl C61 butyric acid methyl ester (PCBM) monolayers and multilayers on the Ag(111) surface are investigated using classical force fields and molecular dynamics simulations. The results demonstrate that P3HT has a stronger interaction with the substrate, while PCBM exhibits larger monolayer formation energy due to stronger intermolecular interactions. In addition, PCBM prefers a “tail-up” conformation by orienting the phenyl and butyric acid methyl ester groups away from the surface, thus favoring a denser packing, while relaxation of intermolecular order in P3HT is found to initiate above 450 K. For the simulations a new parameterization of the General Amber Force Field involving dihedral angles and interactions with the Ag(111) substrate was developed. The new parameters were validated successfully against available crystal structures and ab initio data.

Reprint of: Impact of the corrin framework of vitamin B12 on the electrochemical carbon-skeleton rearrangement in comparison to an imine/oxime planar ligand; tuning selectivity in 1,2-migration of a functional group by controlling electrolysis potential

Among the coenzyme B12-dependent enzymes, methylmalonyl-CoA mutase (MMCM) catalyzes the carbon-skeleton rearrangement reaction between R-methylmalonyl-CoA and succinyl-CoA. Diethyl 2-bromomethyl-2-phenylmalonate, an alkyl bromide substrate having two different migrating groups (phenyl and carboxylic ester groups) on the β-carbon, was applied to the electrolysis mediated by a hydrophobic vitamin B12 model complex, heptamethyl cobyrinate perchlorate in this study. The electrolysis of the substrate at −1.0V vs. Ag-AgCl by light irradiation afforded the simple reduced product (diethyl 2-methyl-2-phenylmalonate) and the phenyl migrated product (diethyl 2-benzyl-2-phenylmalonate), as well as the electrolysis of the substrate at −1.5V vs. Ag-AgCl in the dark. The electrolysis of the substrate at −2.0V vs. Ag-AgCl afforded the carboxylic ester migrated product (diethyl phenylsuccinate) as the major product. The selectivity for the migrating group was successfully tuned by controlling the electrolysis potential. We clarified that the cathodic chemistry of the Co(III) alkylated heptamethyl cobyrinate is critical for the selectivity of the migrating group through mechanistic investigations and comparisons to the simple vitamin B12 model complex, an imine/oxime-type cobalt complex.

Impact of the corrin framework of vitamin B12 on the electrochemical carbon-skeleton rearrangement in comparison to an imine/oxime planar ligand; tuning selectivity in 1,2-migration of a functional group by controlling electrolysis potential

Among the coenzyme B12-dependent enzymes, methylmalonyl-CoA mutase (MMCM) catalyzes the carbon-skeleton rearrangement reaction between R-methylmalonyl-CoA and succinyl-CoA. Diethyl 2-bromomethyl-2-phenylmalonate, an alkyl bromide substrate having two different migrating groups (phenyl and carboxylic ester groups) on the β-carbon, was applied to the electrolysis mediated by a hydrophobic vitamin B12 model complex, heptamethyl cobyrinate perchlorate in this study. The electrolysis of the substrate at −1.0V vs. Ag-AgCl by light irradiation afforded the simple reduced product (diethyl 2-methyl-2-phenylmalonate) and the phenyl migrated product (diethyl 2-benzyl-2-phenylmalonate), as well as the electrolysis of the substrate at −1.5V vs. Ag-AgCl in the dark. The electrolysis of the substrate at −2.0V vs. Ag-AgCl afforded the carboxylic ester migrated product (diethyl phenylsuccinate) as the major product. The selectivity for the migrating group was successfully tuned by controlling the electrolysis potential. We clarified that the cathodic chemistry of the Co(III) alkylated heptamethyl cobyrinate is critical for the selectivity of the migrating group through mechanistic investigations and comparisons to the simple vitamin B12 model complex, an imine/oxime-type cobalt complex.

P-sulfonated calix[8]arene functionalized graphene as a “turn on” fluorescent sensing platform for aconitine determination

This work reports a novel method for the determination of aconitine through the competitive host–guest interaction between p-sulfonated calix[8]arene (SCX8) and signal probe/target molecules by using SCX8 functionalized reduced graphene oxide (SCX8-RGO) as a receptor. Three dyes (ST, RhB, BRB) and aconitine were selected as the probe and target molecules, respectively. The formation of SCX8-RGO·ST, SCX8-RGO·RhB, and SCX8-RGO·BRB complexes greatly decreases the fluorescence emission of ST, RhB, and BRB. The aconitine/SCX8 complex possesses a higher binding constant than ST/SCX8, RhB/SCX8, and BRB/SCX8 complexes, thus the dye in the SCX8 cavity can be replaced by aconitine to revert the fluorescence emission of SCX8-RGO·dye, leading to a “switch–on” fluorescence response. The fluorescence intensity of SCX8-RGO·ST, SCX8-RGO·RhB, and SCX8-RGO·BRB complexes increased linearly with increasing concentration of aconitine ranging from 1.0 to 14.0μM, 2.0–16.0μM, and 1.0–16.0μM, respectively. Based on the competitive host–guest interaction, the proposed detection method for aconitine showed detection limits of 0.28μM, 0.60μM, and 0.37μM, respectively, and was successfully applied for the determination of aconitine in human serum samples with good recoveries from 95.1% to 104.8%. The proposed method showed high selectivity for aconitine beyond competitive binding analytes. In addition, the inclusion complex of the SCX8/aconitine was studied by the molecular docking and molecular dynamics simulation, which indicated that the phenyl ester group of the aconitine molecule was included into the SCX8 cavity.

Mesomorphic, micro-Raman and DFT studies of new calamitic liquid crystals; methyl 4-[4-(4-alkoxy benzoyloxy)benzylideneamino]benzoates

The mesomorphic properties of newly synthesized homologous series of calamitic liquid crystals; methyl 4-[4-(4-alkoxy benzoyloxy)benzylideneamino]benzoates, H2n+1CnOC6H4COOC6H4C(H)N C6H4COOCH3; n=6, 8, 10, 12, 14, 16 (MABBAB-n) containing ester and Schiff base groups as linker have been studied by temperature dependent micro-Raman study, differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). All members of this series exhibit enantiotropic smectic A (SmA) mesophase with oily streak and focal conic textures. Analyses of Raman marker bands of phenyl rings, Schiff base and ester groups of MABBAB-10 confirm the phase transitions. The Raman study also gives an evidence of breaking of weak intermolecular hydrogen bonds associated with ester groups and formation of new hydrogen bonds through CN bond at Cr→SmA phase transition. The monomer and dimer were optimized and vibrational assignment of MABBAB-10 was also done with density functional theoretical (DFT) technique to understand the experimental results.

Surface Wettability Controllable Polyimides Bearing Long-chain Alkyl Groups via Phenyl Ester and Benzophenone Groups by UV Light Irradiation

Surface Wettability Controllable Polyimides Bearing Long-chain Alkyl Groups via Phenyl Ester and Benzophenone Groups by UV Light Irradiation

Wavelength selective refractive index modulation in a ROMP derived polymer bearing phenyl- and ortho-nitrobenzyl ester groups

Patterning and tuning of the refractive index in polymers by means of UV-light is of great interest for optical applications such as polymeric waveguides or optical data storage devices. In this contribution, we report on the synthesis of a polynorbornene based copolymer bearing ortho-nitrobenzyl and phenyl ester groups capable of undergoing the photo-induced cleavage reaction and in a subsequent step optionally the photo-Fries rearrangement upon irradiation with UV-light. The photoreaction of these aromatic ester groups was investigated by means of FTIR, UV-VIS and spectroscopic ellipsometry. Due to the difference in UV absorption of the photoreactive units, the o-nitrobenzyl ester can be selectively excited by UV-light above 300 nm, while a subsequent illumination with 254 nm induces the photo-Fries rearrangement of the remaining phenyl ester groups. The structural changes in the chemical composition upon UV illumination lead to significant changes in the refractive index of the polymeric materials. Whilst the photo-Fries rearrangement of the phenyl ester groups causes a remarkable increase in the refractive index, it was found that the photo-induced cleavage reaction of ortho-nitrobenzyl ester moieties causes a decrease of the refractive index. This fact enables a selective tailoring of the refractive index by the choice of the applied wavelength. In addition, a two-step irradiation procedure using a sequence of different wavelengths provides the possibility of erasing and even inverting the index contrast.

Kinetic model of transesterification of diphenyl carbonate and 1,4-butyldiol

The transesterification of diphenyl carbonate (DPC) with 1,4-butyldiol (BD) was kinetically investigated in the presence of lithium acetate catalyst at 465 K. The reaction was followed by the measurement of the quantity of phenol which was distilled from the reactor. The experiments supported the assumption that the phenyl ester groups in DPC and phenyl hdroxybutyl carbonate (PHBH) had the same reactivity, and the transesterification obeyed first-order kinetics with respect to DPC and BD, and a rate equation was derived. The reaction rate was found to be first order with respect to the catalyst concentration as well. When those data were incorporated in the rate equation, excellent agreement between calculated values and the observed ones was recognized over a wide range.

Synthesis of 1,4-Benzo- and Pyrido-oxazepinones via a Domino Process

Reported is a new regioselective domino ring-opening/carboxamidation reaction of N-tosylaziridines 1 and 2-halophenols/pyridinols 2 under phase-transfer catalysis to afford 1,4-benzo- and pyrido-oxazepinones 3. During optimization studies, it was demonstrated that the presence of the phase-transfer catalyst, TEBA, improved the yield of products (D. Albanese, D. Landini, M. Penso Tetrahedron 1997, 53, 4787). The scope of this reaction was examined by treating 2-iodophenols bearing EDGs and EWGs with cyclic (five-, six-, and seven-membered ring) and acyclic N-tosylaziridines. The 2-iodophenols bearing phenyl and methyl ester groups provide higher yield of the corresponding product 3. However, with 2-bromophenol, harsher conditions are required for the conversion of this into 1,4-benzoxazepinone 3 (18-crown-6 and PTC at 400 psi CO).

Refractive index modulation in polymers bearing photoreactive phenyl and naphthyl ester units using different UV wavelengths

Tuning and patterning of the refractive index in polymeric films is of importance for modern optical applications such as wave guiding and optical data storage. In this contribution, we report on the synthesis of new photoreactive polymers bearing aryl esters which undergo the photo-Fries rearrangement to give aromatic hydroxyketones. Poly(norbornene)-based polymers bearing naphthyl ester groups (poly-2) and copolymers bearing both phenyl and naphthyl ester groups (poly(1-co-2)) were prepared by ring opening metathesis polymerization (ROMP). The photochemistry of these polymers under irradiation with UV light of either 254 nm or 313 nm was investigated. The photoreaction causes an increase of the refractive index in poly-2 between Δn589 = +0.022 and +0.048 depending on the irradiation wavelength. The copolymer poly(1-co-2) offers the possibilities of selectively exciting either the naphthyl ester with UV light of 313 nm causing an increase in the refractive index of Δn589 = 0.010, or both the naphthyl and phenyl chromophores with UV light of 254 nm (Δn589 = 0.036). When thin films of poly(1-co-2) already irradiated with 313 nm light are subjected to a second illumination step with 254 nm light, a significant decrease of the refractive index (Δn589 = −0.043) is observed. The reason for this behaviour seems to arise from the formation of different photoproducts depending on the irradiation sequence. Thus the final refractive index can be adjusted to values between n589 = 1.564 to n589 = 1.633. The two step illumination procedure provides the possibility of erasing and even inverting the index contrast generated during the first illumination step.

DFT Study on Methanofullerene Derivative [6,6]-Phenyl-C 61 Butyric Acid Methyl Ester

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) with hybrid functional B3LYP were used to investigate several physical and chemical properties of [6,6]-phenyl-C 61 butyric acid methyl ester (PCBM), including the geometry, electron structure, charge population, bond properties, as well as IR, Raman and electronic absorption spectra. The analysis of the natural bond orbital (NBO) suggested that there were about 0.11 electrons transferred from moiety phenyl and butyric acid methyl ester group of PCBM to fullerene cage. The strongest IR and Raman peaks came from different modes with the frequencies of 1773 and 1492 cm −1, respectively. The calculated isotropic polarizability, polarizability anisotropy invariant, and hyperpolarizability were 577.7, 96.9, and −22.8 a.u., respectively. Based on TDDFT, the electronic absorption spectra of PCBM were calculated and analyzed. The calculated absorption band near 349 nm agreed well with the experimental measurement.

Preparation of polyimide/nylon 6 graft copolymers from polyimides containing ester moieties: Synthesis and characterization

AbstractPolyimide‐g‐nylon 6 copolymers were prepared by the polymerization of phenyl 3,5‐diaminobenzoate with several diamines and dianhydrides with a one‐step method. The polyimides containing pendant ester moieties were then used as activators for the anionic polymerization of molten ϵ‐caprolactam. In the graft copolymer syntheses, the phenyl ester groups reacted quickly with caprolactam anions at 120°C to generate N‐acyllactam moieties, which activated the anionic polymerization. The thermal stability and chemical resistance were dramatically increased by the incorporation of only 5 wt % polyimide in the graft copolymers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 309–318, 2006

Structure and properties of polyimide‐g‐nylon 6 and nylon 6‐b‐polyimide‐b‐nylon 6 copolymers

AbstractPolyimide‐g‐nylon 6 copolymers were prepared by the polymerization of phenyl 3,5‐diaminobenzoate with several diamines and dianhydrides with a one‐step method. The polyimides containing pendant ester moieties were then used as activators for the anionic polymerization of molten ε‐caprolactam. Nylon 6‐b‐polyimide‐b‐nylon 6 copolymers were prepared by the use of phenyl 4‐aminobenzoate as an end‐capping agent in the preparation of a series of imide oligomers. The oligomers were then used to activate the anionic polymerization of ε‐caprolactam. In both the graft and copolymer syntheses, the phenyl ester groups reacted quickly with caprolactam anions at 120°C to generate N‐acyllactam moieties, which activated the anionic polymerization. All the block copolymers had higher moduli and tensile strengths than those of nylon 6. However, their elongations at break were much lower. The graft copolymers based on 2,2′‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride and 2,2′‐bis[4‐(4‐aminophenoxy)phenyl]propane displayed elongations comparable to that of nylon 6 and the highest moduli and tensile strengths of all the copolymers. The thermal stability, moisture resistance, and impact strength were dramatically increased by the incorporation of only 5 wt % polyimide into both the graft and block copolymers. The graft and block copolymers also exhibited improved melt processability. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 300–308, 2006

Nonnucleoside HIV-1 Reverse Transcriptase Inhibitors, Part 4[1]. Synthesis and Anti-HIV Activity of N-1-β-Carbonyl-6-naphthyl-methyl Analogues of HEPT

A series of 6-naphthylmethyl substituted HEPT analogues bearing a β-carbonyl and a terminal phenyl ring or ester groups on the N-1 side chain of uracil were synthesized, and the in vitro anti-HIV activity was evaluated. Most of these HEPTs were considerably less potent and selective or inactive, only a few compounds showed moderate or high activity against HIV-1. The results demonstrated that the anti-HIV-1 activity of 6-naphthylmethyl substituted HEPT analogues was diminished or eliminated when the β-oxygen of N-1 side chain was replaced by a carbonyl group.

Fluorescence quenching of dyes by tryptophan: interactions at atomic detail from combination of experiment and computer simulation.

Fluorescence spectroscopy and molecular dynamics (MD) simulation are combined to characterize the interaction of two organic fluorescent dyes, rhodamine 6G (R6G) and an oxazine derivative (MR121), with the amino acid tryptophan in aqueous solution. Steady-state and time-resolved fluorescence quenching experiments reveal the formation of essentially nonfluorescent ground-state dye/Trp complexes. The MD simulations are used to elucidate the molecular interaction geometries involved. The MD-derived probability distribution of the distance r between the centers of geometry of the dye and quencher ring systems, P(r), extends to higher distances for R6G than for MR121 due to population in the R6G/Trp system of fluorescent interaction geometries between Trp and the phenyl ring and ester group of the dye. The consequence of this is the experimental finding that under the conditions used in the simulations about 25% of the R6G dye is fluorescent in comparison with 10% of the MR121. Combining the above findings allows determination of the "quenching distance", r, above which no quenching occurs. r is found to be very similar (approximately 5.5 A) for both dye/Trp systems, corresponding to close to van der Waals contact. Both experimental dynamic Stern-Volmer analysis and the MD trajectories demonstrate that the main determinant of the fluorescence intensity is static quenching. The approach presented is likely to be useful in the structural interpretation of data obtained from fluorescent conjugates commonly used for monitoring the binding and dynamics of biomolecular systems.

Columnar liquid crystals from wedge-shaped tetrahedral copper(i) complexes

Very stable copper(I) complexes were engineered from pyridine ligands bearing on one side an iminophenyl fragment and on the other a pivotal methyl group. The phenyl group was substituted in the para position either by a methoxy group or by a phenyl ester group grafted with three paraffin chains (n = 8, 12, 16). The methoxy complex in the crystalline state was characterized by X-ray diffraction. Its molecular structure was found to correspond to a distorted tetrahedral arrangement round the copper(I) metal centre. The long-chain complexes near room temperature were found to produce columnar liquid crystals of hexagonal symmetry. The columns were found to result from the aggregation of the wedge-shaped molecules round the columnar axis with the metal-containing iminopicoline ligands crowded together in the centre and the alkyl chains pointing outwards with a disordered conformation. The degree of molecular aggregation, around 7, was found to decrease significantly on heating.

2-Methylphenyl 2-methoxyacridine-9-carboxylate.

The title compound, C(22)H(17)NO(3), crystallizes in the monoclinic space group P2(1)/c with four molecules per unit cell. The molecules are arranged in centrosymmetric pairs, joined via the C and attached H atoms in the meta position relative to the methoxy group. These pairs are bonded in the crystalline phase as a result of non-specific dispersive interactions, and through a network of C-H...O interactions involving the non-bonded O atom of the carboxy group and, to some extent, the O atom of the methoxy group. The methoxy substituent lies in the plane of the almost planar acridine moiety and is directed towards the phenyl ester group. The phenyl ester group itself is twisted by 35.9 (5) degrees relative to the mean plane of the acridine moiety.