Biphenyl Derivatives Research Articles

Dark and photo-induced charge transport across molecular spacers

Dithiol self-assembled molecular layers (SAMs) are exploited as controllable spacers between CdSe light absorbers and a gold collector. Using two sets of molecules, alkanes with different chain lengths and biphenyl derivatives with varied conjugation, the charge transport across corresponding SAMs is investigated by chemically resolved electrical measurements and photoluminescence (PL). Complementarity is found between the photovoltage and the PL intensity as a function of spacer thickness. However, it is not obeyed for varied conjugation, a feature shown to arise from reduced charge selectivity in the transport efficiencies. Interplay between dark and photo-induced mechanisms are revealed, where the emergence of charge traps by itself becomes spacer dependent via a remote effect of the substrate on surface chemical activity.

Discovery of novel selective GPR120 agonists with potent anti-diabetic activity by hybrid design

GPR120 is an attractive target for the treatment of type 2 diabetes. In this study, a series of biphenyl derivatives were designed, synthesized by hybrid design. The selected compound 6a exhibited potent GPR120 agonist activity (EC50 = 93 nM) and high selectivity over GPR40. The results of oral glucose tolerance test (OGTT) demonstrated that 6a exhibited significant glucose-lowering effect in glucose-loaded ICR male mice. Analysis of the structure–activity relationship is also presented. Compound 6a deserves further biological evaluation and structural modifications.

Ultrasonic accelerated coupling reaction using magnetically recyclable bis (propyl molononitril) Ni complex nanocatalyst: A novel, green and efficient synthesis of biphenyl derivatives

A novel, green and rapid sonochemical research to preparation of the biphenyls was carried out through the coupling reaction between various aryl halides and phenylboronic acid by using bis(propyl malononitrile) Ni (0) complex (NiFe2O4@SiO2-BPMN-Ni) as an efficient nano catalyst. The catalyst can be recycled via an external magnet and reused several times without considerable loss of its catalytic activity. Compare to the previous works, this procedure has advantages such as easy workup, high yields of products, environmentally benign and short reaction times. The novel nickel catalyst prepared and characterized by FT-IR, XRD, SEM, EDX, TGA and VSM techniques.

Aerobic oxidation of alkylaromatic hydrocarbons to hydroperoxides catalysed by N-hydroxyimides in ionic liquids as solvents

This paper reports studies on the oxidation of alkylaromatic hydrocarbons to hydroperoxides with oxygen in the presence of N-hydroxyimides (N-hydroxyphthalimide, N-hydroxysuccinimide, 4-dodecyloxycarbonyl-N-hydroxyphthalimide, N,N-dihydroxypyromellitimide, N-acetoxyphthalimide) in ionic liquids as solvents. Cumene, ethylbenzene, mono- and di-isopropyl derivatives of naphthalene and biphenyl were used as starting materials. As solvents, ionic liquids composed of 1-alkyl-3-methylimidazolium cations with ethyl, butyl, hexyl or octyl substituents and anions such as [BF4], [PF6], [NTf2], [CF3SO3], [OcOSO3], and [CH3OSO3] were applied. It has been established that organic solvents could be replaced by ionic liquids, which does not accelerate hydroperoxide decomposition and is characterized by relatively high oxygen and catalyst solubility and low viscosity. Among studied ILs, these with [NTf2] and [PF6] anions meet the above requirements.

Structure-Activity Relationships of Nitro-Substituted Aroylhydrazone Iron Chelators with Antioxidant and Antiproliferative Activities.

Aroylhydrazone iron chelators such as salicylaldehyde isonicotinoyl hydrazone (SIH) protect various cells against oxidative injury and display antineoplastic activities. Previous studies have shown that a nitro-substituted hydrazone, namely, NHAPI, displayed markedly improved plasma stability, selective antitumor activity, and moderate antioxidant properties. In this study, we prepared four series of novel NHAPI derivatives and explored their iron chelation activities, anti- or pro-oxidant effects, protection against model oxidative injury in the H9c2 cell line derived from rat embryonic cardiac myoblasts, cytotoxicities to the corresponding noncancerous H9c2 cells, and antiproliferative activities against the MCF-7 human breast adenocarcinoma and HL-60 human promyelocytic leukemia cell lines. Nitro substitution had both negative and positive effects on the examined properties, and we identified new structure-activity relationships. Naphthyl and biphenyl derivatives showed selective antiproliferative action, particularly in the breast adenocarcinoma MCF-7 cell line, where they exceeded the selectivity of the parent compound NHAPI. Of particular interest is a compound prepared from 2-hydroxy-5-methyl-3-nitroacetophenone and biphenyl-4-carbohydrazide, which protected cardiomyoblasts against oxidative injury at 1.8 ± 1.2 μM with 24-fold higher selectivity than SIH. These compounds will serve as leads for further structural optimization and mechanistic studies.

Discovery of a new biphenyl derivative by epigenetic manipulation of marine-derived fungus Aspergillus versicolor

Cultivation of the marine-derived Aspergillus versicolor MCCC 3A00080 with the addition of a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), significantly enhanced the diversity of secondary metabolites. From the culture treated, a new biphenyl derivative, named versiperol A (1), along with two known compounds, 2,4-dimethoxyphenol (2) and diorcinol (3) were isolated. The structures of 1–3 were established based on spectroscopic analysis and comparison with literature data. Among the isolates, versiperol A (1) exhibited modest inhibition of Staphylococcus aureus growth with MIC value of 8 μg/mL.

Neutral Binuclear Ag(I) and Au(I) N‐Heterocyclic Carbene Complexes of Axially Chiral and Racemic Scaffolds: Synthesis and Characterization

AbstractNeutral bimetallic silver(I) and gold(I) complexes of N‐ heterocyclic carbene ligands derived from racemic biphenyl and axially chiral binapthyl frameworks have been synthesized and structurally characterized. In particular, the neutral bimetallic silver(I) complexes of the type {L(NHC)2M2} (M=Ag, Au) [L=2,2′‐dioxo‐biphenyl, NHC=1‐methyl‐3‐(‐2‐phenyl‐acetamido)‐imidazol‐2‐ylidene (1 f); L=2,2′‐dioxo‐binapthyl, NHC=1‐methyl‐3‐(‐2‐phenyl‐acetamido)‐imidazol‐2‐ylidene (2 e)] are synthesized from the corresponding imidazolium chloride salts (1‐2)d by the reaction with Ag2O in quantitative yields. The gold(I) complexes are synthesized by the transmetallation of their corresponding {L(NHC)2}Ag2 complexes. Quite interestingly, a weaker argentophilic interaction was observed in the solid state X‐ray crystalllographic structure of binapthyl derivative 2 e, as Ag⋅⋅⋅Ag contact of 3.3011 Å while in case of biphenyl derivative 1 f there is no such aurophilic interaction exhibited a significant Au⋅⋅⋅Au contact.

Thermodynamic properties of some biphenyls

Standard vaporization enthalpies of 4-nitrobiphenyl and 1, 1′- biphenyl are obtained on an isothermal heat conducting Calvet microcalorimeter with an estimated accuracy of ≤ 1 per cent for the first time. Standard formation enthalpies of some biphenyl derivatives in state of gas are determined. The calculation scheme by a method by “a double difference” of formation enthalpies of aromatic radicals and bond dissociation energies is offered. Using fundamental equations of the chemical physics, the new calculation method is offered to determine the energies of reorganization of molecules fragments into radicals. Formation enthalpies of radicals, namely biphenyl-4-yl and 3-methylfurazan-4-yl, are determined. Reorganization energies of radicals and bond chemical energies have been calculated.

Luminescence properties of carborane-containing distyrylaromatic systems

A set of distyrylbenzene, distyrylbiphenyl and distyrylanthracene end-substituted with carborane clusters is introduced herein. All these compounds have been prepared from the corresponding styrene-containing carborane derivatives via Heck coupling reaction. High regioselectivity has been achieved yielding exclusively E isomers. All compounds have been fully characterized and the crystal structure of the distyrylbiphenyl end-substituted with Methyl-o-carborane was analyzed by X-ray diffraction. The absorption properties of compounds were elucidated by TD-DFT calculations, highlighting the importance of the aromatic core and π-conjugation. It is worth noting that the luminescence properties of these systems depend on the aromatic core; in solution, benzene and biphenyl derivatives showed higher fluorescence emission than the anthracene ones and the presence of the carborane clusters does not induce any major change in fluorescence as compared to the pristine non-carborane containing partners. Nevertheless, all compounds exhibited low fluorescence quantum yields in aggregation state, which gives clear evidence of considerable intermolecular interactions between aggregates that could be the reason of the fluorescence quenching.

Role of Pyridinium Groups and Iodide Ions in Photoelectrochromism in Viologen-Based Ion-Pair Charge-Transfer Complexes: Molecular Orbital Analysis

Quantum chemistry calculations were performed to examine the fundamentals of photoinduced electron transfer (ET) in viologen (V)-based ion-pair charge-transfer complexes and the resulting photoelectrochromism with respect to photoswitching applications. For the purpose, the photoinduced ET from counter anions to viologen or biphenyl (BP) derivatives was modeled, and its relationship with their structures was analyzed. Our results showed that the electron reduction of V2+, assuming photoinduced ET, that is, V2+ → V+ → V0, changes the conformational preference from a twisted to a planar structure because of the lowest unoccupied molecular orbital (LUMO) in V2+ showing a planar tendency. A similar feature appears in the reduction of neutral BP, that is, BP0 → BP– → BP2–, leading to a twisted → planar preference change because of the LUMO in BP0. The similarity between V2+ and BP0 can be explained by their similar MO shape and their identical number of electrons. The time-dependent density functional theory (...

Pd-Catalyzed, Highly Selective C(sp²)-Br Bond Coupling Reactions of o-(or m-, or p-) Chloromethyl Bromobenzene with Arylboronic Acids.

Highly selective C(sp2)–C(sp2) cross-coupling of dihalogenated hydrocarbons comprising C(sp2)–Br and C(sp3)–Cl bonds with arylboronic acids is reported. This highly selective coupling reaction of the C(sp2)–Br bond is successfully achieved using Pd(OAc)2 and PCy3·HBF4 as the palladium source and ligand, respectively. A series of chloromethyl-1,1′-biphenyl compounds are obtained in moderate-to-excellent yields. Moreover, this protocol can be extended to the one-pot dual arylation of 1-bromo-4-(chloromethyl)benzene with two arylboronic acids, leading to diverse unsymmetrical 4-benzyl-1,1′-biphenyl derivatives.

Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium-Legume Symbiosis.

Legume-rhizobium symbioses have the potential to remediate soils contaminated with chlorinated organic compounds. Here, the model symbiosis between Medicago sativa and Sinorhizobium meliloti was used to explore the relationships between symbiotic nitrogen fixation and transformation of tetrachlorobiphenyl PCB 77 within this association. 45-day-old seedlings in vermiculite were pretreated with 5 mg L-1 PCB 77 for 5 days. In PCB-supplemented nodules, addition of the nitrogenase enhancer molybdate significantly stimulated dechlorination by 7.2-fold and reduced tissue accumulation of PCB 77 (roots by 96% and nodules by 93%). Conversely, dechlorination decreased in plants exposed to a nitrogenase inhibitor (nitrate) or harboring nitrogenase-deficient symbionts (nifA mutant) by 29% and 72%, respectively. A range of dechlorinated products (biphenyl, methylbiphenyls, hydroxylbiphenyls, and trichlorobiphenyl derivatives) were detected within nodules and roots under nitrogen-fixing conditions. Levels of nitrogenase-derived hydrogen and leghemoglobin expression correlated positively with nodular dechlorination rates, suggesting a more reducing environment promotes PCB dechlorination. Our findings demonstrate for the first time that symbiotic nitrogen fixation acts as a driving force for tetrachlorobiphenyl dechlorination. In turn, this opens new possibilities for using rhizobia to enhance phytoremediation of halogenated organic compounds.

Pd‐Catalyzed C‐H/N‐H Arylation: One‐Pot Synthesis of Indolo[1, 2‐f]phenanthridines

AbstractA novel Pd‐catalyzed method for the synthesis of indolo[1, 2‐f]phenanthridines from 2‐bromo‐2′‐iodo‐1,1′‐biphenyl and indole derivatives has been reported. The reaction involves direct N−H and C2‐H arylation of indole. This Pd‐catalyzed double arylation provides a useful route to synthesize indolo[1, 2‐f]phenanthridine derivatives from simple and readily accessible starting materials.

Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent Bonding, Control of Selectivity, and Chirality Sensing with a Single System.

Axial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central-to-axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling.

Dynamic Covalent Chemistry within Biphenyl Scaffolds: Reversible Covalent Bonding, Control of Selectivity, and Chirality Sensing with a Single System

AbstractAxial chirality is a prevalent and important phenomenon in chemistry. Herein we report a combination of dynamic covalent chemistry and axial chirality for the development of a versatile platform for the binding and chirality sensing of multiple classes of mononucleophiles. An equilibrium between an open aldehyde and its cyclic hemiaminal within biphenyl derivatives enabled the dynamic incorporation of a broad range of alcohols, thiols, primary amines, and secondary amines with high efficiency. Selectivity toward different classes of nucleophiles was also achieved by regulating the distinct reactivity of the system with external stimuli. Through induced helicity as a result of central‐to‐axial chirality transfer, the handedness and ee values of chiral monoalcohol and monoamine analytes were reported by circular dichroism. The strategies introduced herein should find application in many contexts, including assembly, sensing, and labeling.

Polycyclic polyprenylated acylphloroglucinols and biphenyl derivatives from the roots of Garcinia nuntasaenii Ngerns. & Suddee

Seven previously undescribed compounds, including three polycyclic polyprenylated acylphloroglucinols (garcinuntins A–C), three biphenyl derivatives (garcinuntabiphenyls A–C) and a lanostane triterpene (garcinuntine), along with thirteen known compounds were isolated from the root of Garcinia nuntasaenii Ngerns. & Suddee. Their structures were elucidated on the basis of spectroscopic techniques. For garcinuntins A–C, the absolute configurations were confirmed by the combination of single X-ray crystallography and ECD calculations. Anti-HIV activity using anti-HIV-1 reverse transcriptase and syncytium inhibition assays, and cytotoxic activity against a panel of cultured mammalian cancer cell lines of isolated compounds were investigated.

Are beryllium-containing biphenyl derivatives efficient anion sponges?

The structures and stabilities of 2,2'-diBeX-1,1'-biphenyl (X = H, F, Cl, CN) derivatives and their affinities for F-, Cl-, and CN- were theoretically investigated using a B3LYP/6-311 + G(3df,2p)//B3LYP/6-31 + G(d,p) model. The results obtained show that the 2,2'-diBeX-1,1'-biphenyl derivatives (X = H, F, Cl, CN) exhibit very high F-, Cl-, and CN- affinities, albeit lower than those reported before for their 1,8-diBeX-naphthalene analogs, in spite of the fact that the biphenyl derivatives are more flexible than their naphthalene counterparts. Nevertheless, some of the biphenyl derivatives investigated are predicted to have anion affinities larger than those measured for SbF5, which is considered one of the strongest anion capturers. Therefore, although weaker than their naphthalene analogs, the 2,2'-diBeX-1,1'-biphenyl derivatives can still be considered powerful anion sponges. This study supports the idea that compounds containing -BeX groups in chelating positions behave as anion sponges due to the electron-deficient nature and consequently high intrinsic Lewis acidity of these groups. Graphical Abstract Compounds containing -BeX groups in chelating positions, such as 2,2'-diBeX-1,1'-biphenyl (X = H, F, Cl, CN) derivatives, behave as anion sponges due to the electron-deficient nature of these groups.

Ethyl 7-hydroxycoumarin-3-carboxylate derivatives: Synthesis, characterization and effect of liquid crystal properties

Two sets of new ethyl 7-hydroxycoumarin-3-carboxylate derivatives were synthesized and characterized to study the liquid crystalline properties. Chemical structures were confirmed by IR, NMR, CHN analysis techniques. Mesomarphic properties were accomplished by DSC, POM and X-ray studies. Density functional theory calculations and photophysical studies also performed. In the first set, smaller homologues of alkoxybenzoic acid derivatives exhibit monotropic smectic A (SmA) and higher homologous exhibit enantiotropic smectic A mesophase. The second set alkyl biphenyl derivatives exhibit stable SmA and nematic (N) mesophases. The well defined focal conic texture for SmA and threaded texture for nematic mesophases have been observed.

Tris(perfluoroalkyl)germylethynyl derivatives of biphenyl containing ferrocenyl donor group: Structure, spectra, and photoinduced intramolecular electron transfer

Ferrocenyl derivatives with perfluorinated organometallic fragments are prospective sensitizers for photovoltaic devices which can provide higher stability and resistance to oxidation in comparison with the known analogs. For the development of the photovoltaic devices based on such molecules, the estimates of probabilities of photoinduced electron transfer both inside the molecule and from the molecule to the internal semiconductor electrode are required. In this work, the structural, electronic, spectral and radiative parameters of trialkylgermyl (alkyl = Me, n-C3H7, CF3, n-C3F7) derivatives of 4,4′-diethynylbiphenyl containing ferrocenyl donor group are considered. The spectral and radiative parameters of these compounds were calculated using the TD-DFT theory with the B3LYP, PBE0, BHandHLYP и CAM-B3LYP functionals. For all the molecules, the probabilities of photoinduced electron transfer to the outer molecular fragments inside the sensitizer are estimated on the basis of direct analysis of charge redistributions in the excited states.

Suzuki‐Miyaura Cross‐Coupling Reaction Catalyzed by Palladium Complexes of Hydroxynaphthalene‐2‐Oxazolines

AbstractA new palladium catalyst system, generated in situ from palladium(II) chloride and hydroxynaphthalene‐2‐oxazolines as ligands, has been developed and used in Suzuki‐Miyaura cross‐coupling reactions with potassium heteroaryl‐ and aryltrifluoroborate salts to synthesize biphenyl derivatives in good to high yields. It was observed that the catalyst works only when generated in situ. When isolated the formation of a solid occurs which when subjected to x‐ray diffraction shows that the palladium atom is bound to two oxazolines. The presence of electron donor or electron withdrawals groups does not significantly affect reaction performance. This allows easy preparation for use without the inconvenience of catalyst decomposition and need for storage care. A plausible mechanism reaction was suggested based on HRMS studies.