Para Position Of Benzene Ring Research Articles

Network topology diversification of porous organic salts.

Hydrogen-bonded organic frameworks (HOFs) are porous organic materials constructed via hydrogen bonds. HOFs have solubility in specific high-polar organic solvents. Therefore, HOFs can be returned to their components and can be reconstructed, which indicates their high recyclability. Network topologies, which are the frameworks of porous structures, control the pore sizes and shapes of HOFs. Therefore, they strongly affect the functions of porous materials. However, hydrogen bonds are usually weak interactions, and the design of the intended network topology in HOFs from their components has been challenging. Porous organic salts (POSs) are an important class of HOFs, are hierarchically constructed via strong charge-assisted hydrogen bonds between sulfonic acids and amines, and therefore are expected to have high designability of the porous structure. However, the network topology of POSs has been limited to only dia-topology. Here, we combined tetrasulfonic acid with the adamantane core (4,4',4'',4'''-(adamantane-1,3,5,7-tetrayl)tetrabenzenesulfonic acid; AdPS) and triphenylmethylamines with modified substituents in para-positions of benzene rings (TPMA-X, X = F, methyl (Me), Cl, Br, I). We changed the steric hindrance between the adamantane and substituents (X) in TPMA-X and obtained not only the common dia-topology for POSs but also rare sod-topology, and lon- and uni-topologies that are formed for the first time in HOFs. Changing template molecules under preparation helped in successfully isolating the porous structures of AdPS/TPMA-Me with dia-, lon-, and sod-topologies which exhibited different gas adsorption properties. Therefore, for the first time, we demonstrated that the steric design of HOF components facilitated the formation, diversification, and control of the network topologies and functions of HOFs.

Preferential Crystallization of tert-Butyl-calix[6]arene Chlorobenzene Solvate from a Solvent Mixture

Calixarenes can be functionalized with relative ease on their upper and lower rims, i.e., the para positions of benzene rings and OH groups, respectively. Chemical structure adjustment allows for changes in the size and properties of the calixarene cavity; however, it is difficult to predict the separation product because both kinetic and thermodynamic factors are important in crystal formation. To explore the preferential crystallization of calixarene solvates, tert-butyl-calix[6]arene (TBC6) was crystallized from a solvent mixture [benzene, pyridine, dichloromethane, cyclohexane, toluene, methyl acetate, tetrahydrofuran, chlorobenzene (PhCl), anisole, n-heptane, acetonitrile, and ethyl acetate]. TBC6 was selectively crystallized as the PhCl solvate. The PhCl molecule was disordered over two positions with a chlorine atom rotated by ∼120°, suggesting that dichlorobenzene (PhCl2) would fit into the binding pocket of calixarenes. Due to their different sizes (oPhCl2 < mPhCl2 < pPhCl2), the dichlorobenzene derivatives affected the formation of TBC6 dimers and thereby the crystal packing. Therefore, the solvent size is the most important factor for determining crystal packing, and solvent preference for the TBC6 macrocycle follows the order of PhCl > oPhCl2 ≈ mPhCl2 ≈ pPhCl2. These results suggest that TBC6 can be used to recover chlorobenzene from a solvent mixture via selective crystallization.

Cage-Like Sodalite-Type Porous Organic Salts Enabling Luminescent Molecule's Incorporation and Room-temperature Phosphorescence Induction in Air.

Expression of room-temperature phosphorescence (RTP) in organic materials requires complicated molecular design and specific intermolecular interactions, and therefore types of RTP materials are restricted. This work presents cage-like sodalite-type porous organic salts (s-POSs) as host materials for luminescent molecules to induce RTP, using tetrasulfonic acid with an adamantane core and triphenylmethylamines that are modified with substituents in the para-positions of benzene rings (TPMA-X). By adding a representative luminescent molecule (pyrene) to a reaction solution during construction of s-POSs, the molecule is incorporated in a facile manner. s-POSs with a heavy halogen atom (X: Iodine) on the pore surface give heavy atom effects, suppression of thermal vibration, and protection from oxygen, for the incorporated molecule, which induce its RTP even in air. This strategy can be applied to various luminescent molecules, which may lead to the achievement of RTP of various colors.

Synthesis of pyrazole tethered oxadiazole and their analogs as potent antioxidant agents

AbstractPreparation of organic compounds in environmental favor media always a fresh tool in the synthetic research. If those prepared compounds may possess therapeutically potentiality, then it called as efficient research. Herein, we report the 12 new oxadiazole linked carboxamide pyrazole substances have been synthesized and screened for their free radical scavenging activity by using hydrogen peroxide (H2O2), nitric oxide (N2O), and diphenyl picryl hydrazide (DPPH) methods. All the compounds displayed reliable biological properties. Among them, compound 8f hold high antioxidant activity may be due to the presence of methoxy group at para position of benzene ring. From the synthetic point of view, this is the novel environment favor method for the synthesis of pyrazole linked oxadiazoles, and the biological results of these compounds may stand as a referee for further development of biologically active pyrazole tethered oxadiazoles.

Insecticidal activity of ring-fluorinated benzyl acetone analogs in Queensland fruit fly, a softer class of insecticides

Insecticides used to control fruit fly pests have been implicated in negative effects on natural enemies, human health and the environment. As potential ‘softer’ insecticides, natural compounds such as essential oils and their constituents have received increased attention as insecticide candidates. Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), is the most economically damaging fruit fly species in Australia. Cuelure and melolure are plant-based attractants of males in Q-fly and many other dacine fruit flies and are structurally similar to benzyl acetone. We hypothesized that fluorination of benzyl acetone would introduce toxicity that could be exploited for insecticidal applications. Toxicity to Q-fly of nine fluorinated analogs of benzyl acetone as well as the known attractants cuelure and melolure was investigated. LC50 and LC90 values of the compounds were obtained using a surface-film assay method. Fluorination at the meta and/or para-position of benzene ring was found to increase toxicity to both Q-fly sexes. We further examined toxicity and short-range attraction to Q-fly using traps in outdoor cages. The nine fluorinated analogs of benzyl acetone were all highly toxic to male Q-flies, whereas cuelure and melolure were not. Some analogs were attractive to male Q-flies. None of the nine analogs, cuelure or melolure had an inhibitory effect on the proliferation of BEAS-2B human bronchial epithelial cells, suggesting very low or negligible mammalian toxicity. Fluorinated analogs of benzyl acetone have potential as new toxicants for Q-fly, and likely other insects, and some may also have attractive properties for cuelure-responding fruit flies.

Effect of substituents on spectral, luminescent, and time-resolved spectral properties of 2,6-diarylidene derivatives of cyclohexanone

Spectral, luminescent, and time-resolved properties of 2,6-dibenzylidene cyclohexanone and its symmetric derivatives in the para-position of benzene ring (dimethoxy, dimethylthio, and bis-N,N-diethylamino groups) have been studied in media of different polarity (cyclohexane, acetonitrile, dimethylsulfoxide, and methanol). Introduction of electro-donating substituents to dibenzylidene cyclohexanone results in the red shift of the absorption maximum by 81–138 nm upon passing from the nonpolar to polar medium. Bis(N,N-diethylamino)dibenzylidene cyclohexanone fluoresces in polar solvents, acetonitrile, dimethylsulfoxide and methanol. The bathofluoric shift on passing from acetonitrile to methanol is 39 nm. The relative quantum yield of fluorescence in acetonitrile is seven times that in methanol. An intermediate species absorbing in the range of 400–560 nm with a maximum at 430–460 nm has been observed under the action of the laser pulse on dibenzylidene cyclohexanone solutions in acetonitrile. The intermediate species has a lifetime of 40, 20, and 7 μs for dibenzylidene cyclohexanone and its dimethylthio and dimethoxy derivatives, respectively.

Analgesic and anti-inflammatory activity of 5,7-diacyl-3-H(alkіl)-6- aryl-5H-[1,2,4]triazol[3,4-b][1,3,4]tіadiazin derivaties

The search for new analgesic and anti-inflammatory drugs, exceeding by efficacy and/or safety the existing&lt;br /&gt;analogues is very important and relevant. The nitrogenous heterocycles are promising in this respect, in particular,&lt;br /&gt;the compounds containing an imidazole triazol and tіadiazin moiety. The aim of the current study was to investigate&lt;br /&gt;the antiexudative and antinociceptive activity of new derivatives of 5,7-diacyl-3-H(alkyl)-6-aryl-5H[1,2,4]triazol[3,4-b]&lt;br /&gt;[1,3,4]thiadiazine.&lt;br /&gt;The antinociceptive and antiexudative activity studies were carried out on the white nonlinear mice. The&lt;br /&gt;experimental evaluation of specific activity was carried out on the models “Hot plate”, acetic acid induced writhing&lt;br /&gt;(antinociceptive action) and carrageenan edema (antiexudative action). The substance was used in a single oral rout&lt;br /&gt;administration in a dose of 25 mg/kg. Ketorolac was used as a reference product in the dose of 25 mg/kg (models&lt;br /&gt;“Hot plate”, acetic acid induced writhing). Diclofenac was used as a reference product in the dose of 25 mg/kg on&lt;br /&gt;the model carrageenan edema. The experimental study showed the antinociceptive and antiexudative effects of the&lt;br /&gt;derivatives. The antinociceptive activity of 5,7-diacyl-3-H(alkіl)-6-aryl-5H[1,2,4]triazol[3,4-b][1,3,4]tіadiazin derivaties&lt;br /&gt;related to the modification structure in the para position of benzene ring. The antiexudative activity is associated with&lt;br /&gt;acetyl groups thiadiazine ring. The most promising compound IFT_247 showed a significant antinociceptive effect,&lt;br /&gt;which is comparable to an active comparator ketorolac: “Hot plate” +232.46 % and +112.71 %; acetic acid induced&lt;br /&gt;writhing -66.67 % and -61.02 %, respectively.

Синтез и биологическая активность гидрохлоридов 1-(4-замещенных фенил)-1-алкил(арил)-2-фенил- 3-аминопропан-1-олов

Аминометилированием 1-(4-замещенных фенил)-2-фенилэтанонов с параформальдегидом и амином в среде этанола получены α-фенил-β-амино-4-замещенные пропиофеноны. Взаимодействием последних с реактивами Гриньяра в среде эфира получены третичные аминопропан-1-олы и их гидрохлориды. Показано достаточно эффективное, но различное ингибирование аденозиндезаминазы (АДА, К.Ф.3.5.4.4), одного из ключевых ферментов пуринового обмена синтезированными соединениями. Отмечена взаимосвязь «структура — активность» для ингибирования АДА. Исследование антибактериальной активности синтезированных соединений показало ее полное отсутствие для большинства соединений, и наличие умеренной антибактериальной активности в отношении грамположительных микроорганизмов только у соединений Vа, Vг и VIг.

Influence of chlorine substituents on the aggregation behavior of chlorobenzoyl-substituted ferrocene derivates

The influence of chlorine substituents on the molecular arrangement in the solid state of chlorinated benzoyl-ferrocene derivates with restricted molecular flexibility was investigated by crystal structure determinations and theoretical calculations. Four different chlorinated benzoyl-ferrocene derivates were crystallized from a saturated CHCl3 solution and analyzed by X-ray diffraction. Under consideration of the structural restrictions, a comparable trend of rearrangement in the crystal organization with increasing number of chlorine atoms is observed, which is analogous to findings for chlorine-substituted benzenes. More important, the molecules arrange in layers (1 and 4) and columns (2 and 3) and in all cases with repulsively orientated CF3···CF3 substituents. In addition, Cl···Cl interactions are visible in 1 (type I) and 4 (type II). Furthermore, the crystal packing motifs were also analyzed based on ab initio quantum-chemical calculations of the intermolecular interaction energy, using the B97-D3/def2-TZVP method. According to the topology of intermolecular interaction, the crystal structures have either columnar or layered structure depending on the presence of Cl substituent in para-position of benzene ring. It was also found that Cl···Cl interactions play a secondary role in crystal organization, and the substituent effect is maybe due to polarization of the aromatic ring, which leads ultimately to an increase in the energy of stacking interactions between the aryl substituents. Analysis of the crystal structures of chlorine substituents on the molecular arrangement in the solid state of restricted molecular flexible chlorinated benzoyl-ferrocene derivates shows a trend of rearrangement in the crystal organization with increasing number of chlorine atoms.

Synthesis and biological evaluation of 4-nitro-substituted 1,3-diaryltriazenes as a novel class of potent antitumor agents

We describe the synthesis and biological activity of a new class of 1,3-diaryltriazenes, namely 4-nitro-substituted 1,3-diaryltriazenes. Structure–activity relationship analysis reveals that 1,3-diaryltriazenes can be modified from inactive to highly cytotoxic compounds by the introduction of two nitro groups at the para positions of benzene rings and two additional electron-withdrawing groups (bromo, chloro, trifluoromethyl or fluoro substituents) at their ortho position. In order to increase the solubility of the modified compounds, we introduced various acyl groups to their triazene nitrogen. The results of LC-MS/MS analysis showed that N-acyltriazenes can be considered as prodrugs of non-acylated triazenes. Selected 3-acetyl-1,3- bis(2-chloro-4-nitrophenyl)-1-triazene ( 8b) is highly cytotoxic against different tumor cell lines, including cisplatin-resistant laryngeal carcinoma cells. Notably, its antiproliferative activity is significantly higher against tumor cells than against normal cells. DNA binding analysis suggests that neither 8b nor its non-acylated derivative 8a bind into the minor groove of DNA. Instead, 8b induces reactive oxygen species that could provoke endoplasmic reticulum (ER a ) stress finally leading to apoptosis. Our data suggest that 4-nitro-substituted 1,3-diaryltriazenes are a new class of anticancer molecules which preferentially target malignant cells and may serve as potential antitumor agents.

Substituent-induced delocalization effects on hydrogen-bonding interaction in poly( N-phenyl methacrylamide) derivatives

Within small molecules, the hydrogen-bonding behaviors affected by delocalization have been studied thoroughly, but rare publication in macromolecules. Therefore, three poly( N-phenyl methacrylamide)s, poly( N-phenyl methacrylamide) (PNPAA), poly( N-4-methoxyphenyl methacrylamide) (PMPMA) and poly( N-4-bromophenyl methacrylamide) (PBPMA), with different inductive substitution at para position of benzene ring are prepared to investigate the substituent-induced delocalization effects on the hydrogen-bonding interaction behaviors. In this study, the variable-temperature FTIR spectrum is used as tool to study the self- and inter-association hydrogen-bonding interaction. FTIR analyses could provide evidences that there is relatively stronger inter-associative hydrogen bonding in poly( N-4-bromophenyl methacrylamide)/P4VP blends. High resolution 13C CP/MAS solid-state NMR analyses indicate that the spin-lattice relaxation time ( T 1 ρ H ) in all PBPMA blends are homogeneous on the scale at which spin-diffusion occurs within the time T 1 ρ H , also due to the enhancement by substituent inductive delocalization.

Synthesis, substituent effects and solvatochromic properties of some disperse azo dyes derived from N-phenyl-2, 2′-iminodiethanol

A series of monoazo disperse dyes based on N-phenyl-2, 2′-iminodiethanol were synthesized using p-substituted anilines as diazo components. The prepared dyes were characterized by UV–vis, FT-IR and 1H NMR spectroscopic techniques. The effect of varying pH and the evaluation of solvatochromic properties of synthesized dyes with donor–acceptor p-substituted groups are described. The absorption maxima of these dyes changed very significantly by the introduction of various substituents on the para-position of benzene ring.

Dynamic NMR studies of N-benzoyl pyrrolidine and N-benzoyl piperidine derivatives

Variable-temperature 1H and 13C NMR spectroscopy are used to investigate barrier of C–N rotation in series of amides, such as N-benzoyl pyrrolidine, N-(4-chlorobenzoyl) pyrrolidine, N-(4-methoxybenzoyl) pyrrolidine, N-(4-chlorobenzoyl) piperidine, and N-(4-methoxybenzoyl) piperidine. Δ G 298 ≠ of 65.2, 60.6, 58.8, 60.1, and 57.1 kJ mol −1are found for the above compounds, respectively. Theoretical studies were done for these compounds and the results showed good agreement with the experimental results. Theoretical and experimental results showed that substituted methoxy group on the para position of benzene ring decreases the rotational barrier. Increasing steric effect and therefore unstabilizing the ground state (GS) in piperidine compare to pyrrolidine ring also decreases the rotational barrier. It was found out that the rotational barrier in the polar solvent is higher than non-polar solvent.

Synthesis and structures of aryl-substituted tetramethylcyclopentadienyl dinuclear metal carbonyl complexes

A series of 14 aryl-substituted tetramethylcyclopentadienyl dinuclear metal carbonyl complexes have been synthesized by treating the corresponding ligands (C 5Me 4C 6H 4X-4) (X = H, Me, Cl, OMe) with Ru 3(CO) 12, Fe(CO) 5, or Mo(CO) 3(MeCN) 3, respectively in refluxing xylene. It showed that the electronic effects of the substituents had influence on the molecular structures and reactions of the complexes, especially for the ruthenium and molybdenum complexes. In the reactions of aryl-substituted tetramethylcyclopentadiene with Mo(CO) 3(MeCN) 3, the electron-withdrawing effect of the substituent in the para position of benzene ring is favorable to produce the Mo–Mo triple bonded complexes, but the electron-donor effect of the substituent in the para position of benzene ring is favorable to produce the Mo–Mo single bonded complexes. In a given condition, the Mo–Mo single bonded complex could be transformed into the corresponding Mo–Mo triple bonded complex. The structures of nine complexes were determined by single crystal X-ray diffraction.

Study of effects in polyethylene terephthalate films induced by high energy Ar ion irradiation

Semicrystalline polyethylene terephthalate (PET) foil stacks were irradiated with 1.373 GeV Ar ions to different fluences ranging from 1.0×10 10 to 5.0×10 12 ions/cm 2. The induced effects were investigated by means of the Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible absorption spectroscopy (UV/VIS) and electron spin resonance spectroscopy (ESR). FTIR measurements show that bond breaking processes are mainly observed at the ethylene glycol residue of trans configuration and at the para position of benzene rings above a critical dose of about 4.0 MGy. Damage cross-section has been extracted for the band at 973 cm −1 from the dependence of the absorbance on fluence and it shows a linear dependence on the mean electronic energy loss. UV/VIS measurements show a strong increase in absorbance in the ultraviolet and visible regions. It is found that for the same absorbed dose, more increase in absorbance is induced at higher electronic energy loss. ESR measurements indicate the creation of free radicals. The radical concentration is found to increase rapidly with the increasing absorbed dose above 4.0 MGy.

Inherently Chiral Phosphoruscontaining Calix[4]Arenes

Inherently chiral phosphoruscontaining calix[4]arenes with asymmetrical placement of substituents at the macrocyclic lower rim (phenolic oxygen atoms) as well as with asymmetrical superposition of substituents at the upper rim (para-positions of benzene rings) and at the lower rim have been synthesized. The key steps of the synthesis are O,O-phosphorotropic rearrangements of 1,3-distally disubstituted calix[4]arenes into 1,2-proximal isomers induced by strong bases.

Inherently Chiral Phosphoruscontaining Calix[4]Arenes

Inherently chiral phosphoruscontaining calix[4]arenes with asymmetrical placement of substituents at the macrocyclic lower rim (phenolic oxygen atoms) as well as with asymmetrical superposition of substituents at the upper rim (para-positions of benzene rings) and at the lower rim have been synthesized. The key steps of the synthesis are O,O-phosphorotropic rearrangements of 1,3-distally disubstituted calix[4]arenes into 1,2-proximal isomers induced by strong bases.

Second-Order Hyperpolarizabilities of Stilbazolium Cations Studied by Semiempirical Calculation

Second-order hyperpolarizabilities (β), electron distribution, dipole moment, and excitation energy together with oscillator strength of stilbazolium cations have been investigated by a semiempirical calculation with PM3 parametrization of the MNDO Hamiltonian. Since stilbazoliums were found to generally have several times larger β value than nitrostilbene derivatives with similar experimental absorption maximum wavelength, such ionic species are concluded to be advantageous to create new second-order nonlinear optical materials having large β and short cutoff. Among the stilbazolium derivatives investigated, the β values increase with increasing electron-donating ability of the substituent at the para position of benzene ring, and exceptionally chlorinated one was found to have comparatively large β value withstanding its short absorption maximum wavelength. The main reason for the large β values of stilbazolium cations is the strong acceptor property of the pyridinium ring resulting in large difference in dipole moment between the ground and excited states, which could be shown using the two-level model. The tendency of calculated β values of stilbazolium cations shows good agreement with that obtained from the hyper Rayleigh scattering (HRS) measurement.

Effect of benzamide derivatives on rat brain monoamine oxidase activityin vitro

The ability of moclobamide and other benzamide derivatives to inhibit the activity of monoamine oxidase in the rat brain was studied. Distinct effects of these compounds on the deamination of serotonin and norepinephrine (MAO-A substrates); 2-phenylethylamine (selective MAO-B substrate); tyramine and dopamine (MAO-A and MAO-B substrates) are shown. It was demonstrated that among all the compounds studied moclobamide appeared to be the most active and selective inhibitor of MAO-A: at a concentration of 100 microM it caused a 100% inhibition of serotonin and norepinephrine deamination, which might be explained by the presence of C1 atom in the para-position of benzene ring in moclobamide molecule. Other benzamide derivatives were less active in inhibiting MAO-A and had but a negligible effect on dopamine- and 2-phenylethylamine deamination.