Pyrene‐Based Y‐shaped Solid‐State Blue Emitters: Synthesis,Characterization, and Photoluminescence

A series of pyrene‐based Y‐shaped blue emitters, namely, 7‐tert‐butyl‐1,3‐diarylpyrenes 4 were synthesized by the Suzuki cross‐coupling reaction of 7‐tert‐butyl‐1,3‐dibromopyrene with a variety of p‐substituted phenylboronic acids in good to excellent yields. These compounds were fully characterized by X‐ray crystallography, UV/Vis absorption and fluorescence spectroscopy, DFT calculations, thermogravimetric analysis, and differential scanning calorimetry. Single‐crystal X‐ray analysis revealed that the Y‐shaped arylpyrenes exhibited a low degree of π stacking owing to the steric effect of the bulky tert‐butyl group in the pyrene ring at the 7‐position, and thus, the intermolecular π–π interactions were effectively suppressed in the solid state. Despite the significantly twisted nonplanar structures, these molecules still displayed efficient intramolecular charge‐transfer emissions with clear solvatochromic shifts on increasing solvent polarity. An intriguing fact is that all of these molecules show highly blue emissions with excellent quantum yields in the solid state. Additionally, the two compounds containing the strongest electron‐accepting groups, CN ( 4d ) and CHO ( 4f ), possess high thermal stability, which, together with their excellent solid‐state fluorescence efficiency, makes them promising potential blue emitters in organic light‐emitting device applications.     

Isolation,Structure Determination,and Synthesis of Allo‐RA‐V and Neo‐RA‐V,RA‐Series Bicyclic Peptides from Rubia cordifolia L.

Two bicyclic hexapeptides, allo‐RA‐V ( 4 ) and neo‐RA‐V ( 5 ), and one cyclic hexapeptide, O‐seco‐RA‐V ( 6 ), were isolated from the roots of Rubia cordifolia L. Their gross structures were elucidated on the basis of spectroscopic analysis and X‐ray crystallography of compound 5 . The absolute stereochemistry of compounds 4 and 5 were established by their total syntheses, and the absolute stereochemistry of compound 6 by chemical correlation with deoxybouvardin ( 3 ). Comparison of the 3D structures of highly active RA‐VII ( 1 ) with less‐active compounds 4 and 5 suggests that the orientation of the Tyr‐5 and/or Tyr‐6 phenyl rings plays a significant role in their biological activity. The isolation of peptides 4 – 6 , along with compound 3 , and the comparison of their structures seem to indicate that peptide 6 may be the common precursor to bicyclic peptides 3 – 5 in the plant.     

Impact of Polycyclic Aromatic Hydrocarbons on the Electrochemical Responses of a Ferricyanide Probe at Template‐Modified Self‐Assembled Monolayers on Gold Electrodes

The impact of polycyclic aromatic hydrocarbons (PAHs) on the electrochemical responses of a ferricyanide probe using gold electrodes coated with template‐containing self‐assembled monolayers (SAMs) was investigated using cyclic voltammetry and square‐wave voltammetry. The thiolated compounds that were used to form SAMs included 1‐hexadecanethiol, 11‐mercapto‐undecanoic acid, 11‐mercaptoundecanol, and (3‐mercaptopropyl) trimethoxysilane (MPTS). When the SAMs were formed from 1‐hexadecanethiol or 11‐mercapto‐undecanoic acid in the absence of pyrene, the SAM‐modified electrodes prohibited access of the ferricyanide probe and no impact of pyrene was observed. SAM‐modified electrodes (all except for MPTS) that were formed in the presence of pyrene then washed free of pyrene showed an increase in accessibility of the probe ferricyanide upon the addition of pyrene to the electrolyte solution. When electrodes were modified with MPTS to form stabilized SAMs in the presence of pyrene, however, a reduced redox current for the ferricyanide probe was observed with increased pyrene or naphthalene in the electrolyte solution. A degree of selectivity was noted in that this current response was not observed for addition of benzo[a]pyrene.     

Facile Synthesis of Novel 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one Derivatives as Potential Anticancer Agents

A series of 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 6a – l ) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross‐coupling reactions were successfully applied to the preparation of title compounds in good‐to‐high yields. In the synthetic sequences, 3‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)acrylaldehydes ( 2 ) were found to react with ammonium thiocyanate to yield the corresponding 3‐(isothiazol‐5‐yl)‐2H‐chromen‐2‐ones ( 3 ). These derivatives were brominated with N‐bromo succinamide to yield the corresponding regioselective 3‐(4‐bromoisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 4 ). Finally, compound 4 was treated with various phenyl/pyrazole/7H –pyrrolo[2,3‐d]pyrimidinyl boronic acids 5a – l in the presence of K₂CO₃ and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a – l . All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b , 6g , 6h , and 6l displayed moderate cytotoxic activity against the tested cell lines.     

Syntheses,Structure, Electrochemistry,and Optical Properties of 1,3‐Diethyl‐2,3‐dihydro‐1‐H‐1,3,2‐pyrido‐[4,5‐b]‐diazaboroles

Reaction of 2,5‐bis(dibromoboryl)thiophene ( 4 ) or 1,4‐bis(dibromoboryl)benzene ( 6 ) with two equivalents of N,N′‐dilithiated 2,3‐diaminopyridine ( 3 ) led to the generation of the pyridodiazaboroles 5 and 7 in which the two diazaborole rings are linked by 2,5‐thiophen‐diyl or 1,4‐phenylene units via the boron atom. The novel compounds were characterized by elemental analyses and spectroscopy (¹H‐, ¹¹B‐, ¹³C‐NMR, MS, and UV‐VIS). The molecular structure of 5 was elucidated by X‐ray diffraction. Cyclovoltammograms of 5 and 7 show two irreversible oxidation waves at 0.76 and 0.73 V, respectively vs Fc/Fc⁺. The novel compounds display intense blue luminescence with Stokes shifts of 76 and 74 nm and relative quantum yields of 39 and 43 % vs Coumarin 120 (Φ = 50 %).     

N‐substituted bis(tetrazol‐5‐yl)diazenes: Synthesis,spectra, X‐ray molecular and crystal structures,and quantum‐chemical DFT calculations

N‐Substituted bis(tetrazol‐5‐yl)diazenes (substituents are 1‐CH₃ ( 3a ), 1‐Ph ( 3b ), 2‐CH₃ ( 3c ), and 2‐^tBu ( 3d )) were synthesized by oxidative coupling of corresponding 5‐aminotetrazoles. All compounds were characterized with ¹H and ¹³C NMR, IR‐ and UV‐spectroscopy, and thermal analysis. Crystal and molecular structures of bis(1‐phenyltetra‐ zol‐5‐yl)diazene ( 3b ) and bis(2‐tert‐butyltetrazol‐5‐yl)diazene ( 3d ) were determined by single crystal X‐ray diffraction. Molecules of these compounds are trans‐isomers in solid. According to X‐Ray data, 3b molecule is S‐trans‐S‐trans conformer, however 3d is S‐cis‐S‐cis one. Quantum‐chemical investigation of geometry and relative stability of cis‐ and trans‐isomers and stable conformations of compounds 3a–d was carried out. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:24–35, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20574     

Synthesis of 5‐(6‐Pyridazinone‐3‐yl)‐2‐Glycosylamino‐1,3,4‐Oxadiazoles

N‐Glycosyl‐2‐(1,4,5,6‐tetrahydropyridazin‐6‐one‐3‐carbonyl)‐hydrazinecarbothioamides 3a‐3g and N‐glycosyl‐2‐(1,6‐dihydropyridazin‐6‐one‐3‐carbonyl)‐hydrazinecarbothioamides 5a‐5g were prepared by the reaction of glycosyl isothiocyanates with the compounds 1,4,5,6‐tetrahydro‐3‐hydrozinecarbonyl‐6‐pyridazinone ( 1 ) and 1,6‐dihydro‐3‐hydrozinecarbonyl‐6‐pyridazinone ( 2 ). The terminal heterocyclic compounds 1,3,4‐oxadiazole derivatives were obtained from cyclization of compounds ( 3a‐3g ) and ( 5a‐5g ) by mercuric acetate. Their structures were confirmed by IR, ¹H NMR, MS and elemental analyses.     

An Unexpected and Green Synthetic Protocol for Ethyl 1‐Aroyl/Aroylmethyl‐5‐methyl‐3‐methylthiopyrazole‐4‐carboxylates: High Regioselectivity in Alkylation and Acylation Reactions between N‐1 and N‐2 of a Pyrazole Ring

Two series, totaling twelve, of new compounds, ethyl 1‐aroyl/(aroylmethyl)‐5‐methyl‐3‐methylthiopyrazole‐4‐carboxylates ( 5 / 6 ), have been synthesized via highly regioselectively acylation and alkylation reactions of ethyl 3‐methyl‐5‐methylthio‐1 H‐pyrazole‐4‐carboxylate ( 2a ) with aroyl chloride ( 3 ) and eco‐friendly reagents alpha‐tosyloxysubstituted acetophenones ( 4 ), respectively, and a green protocol has been developed. The acylation reactions were carried out under ultrasound irradiation, and the alkylation reactions were under microwave irradiation and ultrasound irradiation, respectively. Conventional reaction conditions, as well as the use of alpha‐bromosubstituted acetophenone ( 4 ′) have also been applied in the synthesis of some randomly selected compounds in both series and have generated identical compounds correspondingly. Unexpected structures of compounds were unambiguously determined by X‐ray crystallographic analysis.     

Syntheses,Characterization, and Antibacterial Activities of Four New Schiff Base Compounds Derived from 1‐Phenyl‐3‐methyl‐4‐benzoyl‐2‐pyrazolin‐5‐one

Four new Schiff bases were designed and synthesized. 5‐Methyl‐4‐(4‐aminophenylamino‐phenyl‐methylene)‐2‐phenyl‐2,4‐dihydro‐pyrazol‐3‐one (compound 1 ) and 5‐methyl‐4‐(2‐aminophenylamino‐phenyl‐methylene)‐2‐phenyl‐2,4‐dihydro‐pyrazol‐3‐one (compound 2 ) were synthesized by interaction of 1‐phenyl‐3‐methyl‐4‐benzoyl‐2‐pyrazolin‐5‐one (PMBP) with o‐ and p‐phenylenediamine, respectively; 4,4′‐(1,2‐phenylenebis(azanediyl)bis(phenylmethanylylidene))bis(3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one) (compound 3 ) and 5‐methyl‐4‐(phenyl(2‐((3‐phenylallylidene)amino)phenylamino)methylene)‐2‐phenyl‐2,4‐dihydro‐pyrazol‐3‐one (compound 4 ) were synthesized by interaction of compound 2 with PMBP and cinnamaldehyde in an ethanolic medium, respectively. The molecular structures of the title compounds were first characterized by single‐crystal X‐ray diffraction, mass spectrometry, and elemental analysis. The title compounds were tested for antibacterial activity (Escherichia coli, Staphylococcus aureus, and Bacillus subtilis) by disk diffusion method.     

Synthesis of New (Pyrazol‐3‐yl)‐1,3,4‐oxadiazole Derivatives by Unexpected Aromatization During Oxidative Cyclization of 4,5‐Dihydro‐1H‐pyrazole‐3‐carbohydrazones and Their Biological Activities

A series of novel 2‐(4‐(4‐chlorophenyl)‐1H‐pyrazol‐3‐yl)‐5‐(Aryl)‐1,3,4‐oxadiazoles were synthesized by unexpected aromatization during oxidative cyclization of 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazones using chloramine‐T as an oxidant. The hydrazones were derived from 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1H‐pyrazole‐3‐carbohydrazide and various substituted aldehydes. The structure of the synthesized compounds was confirmed by FTIR, ¹H NMR, ¹³C NMR, and mass spectral data. The synthesized compounds were evaluated for their antitubercular and antioxidant activities. All the compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h and 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h showed good antitubercular activity against Mycobacterium tuberculosis (minimum inhibitory concentration = 25 µg/mL for 4f and 4g , 50–100 µg/mL for the rest). However, all the compounds exhibited poor antioxidant activity against 1,1‐diphenyl‐2‐picryl‐hydrazil free radical.     

1,2,3‐Triazole derivatives of 3‐ferrocenylidene‐2‐oxindole: Synthesis,characterization, electrochemical and antimicrobial evaluation

A series of bioactive, triazole‐linked benzyl, aryl, sugar and aliphatic conjugates of 3‐ferrocenylidene‐oxindole have been synthesized. A facile 1,3‐dipolar‐Huisgen coupling reaction of the respective azides with the 3‐ferrocenylidene‐oxindole N‐propargyl moiety ( 3 ) gave the corresponding conjugates ( 5a–n ). All the newly synthesized compounds ( 5a–n ) were characterized by ¹H‐NMR, ¹³C‐NMR, HRMS, Fourier transform‐infrared spectroscopy and elemental analysis. The UV–Vis and electrochemical studies of these compounds were performed in dimethylsulfoxide solutions. The structure of compound ( 3 ) was determined by single crystal X‐ray diffraction study. These compounds exhibited moderate to good antimicrobial activity against Gram‐positive and Gram‐negative strains.     

Design,Synthesis, and Herbicidal Activities of 3‐Aryl‐4‐substituted‐5‐[3‐(trifluoromethyl)phenoxy]‐1,2,4‐triazoles

In order to find novel bleaching herbicide lead compounds, a series of novel 3‐aryl‐4‐substituted‐5‐[3‐(trifluoromethyl)phenoxy]‐1,2,4‐triazoles were designed and synthesized by the multi‐step reactions. N‐(Arylformamido)phenylthioureas undergo ring closure in the presence of sodium hydroxide to generate 3‐aryl‐4‐substituted‐4H‐[1,2,4]triazol‐5‐thiols 1 , which reacted with methyl sulfate in the presence of K₂CO₃ to give 3‐aryl‐5‐methylsulfanyl‐4‐substituted‐4H‐[1,2,4]triazoles 2 . The target compounds 4 were synthesized by the oxidation of 2 in the presence of H₂O₂ and Na₂WO₄, followed by the substitution with 3‐(trifluoromethyl)phenol in moderate to good yields. Their structures were confirmed by IR, ¹H NMR, EI–MS, and elemental analyses. The preliminary bioassay indicated that some of them displayed moderate to good selective herbicidal activity against Brassica campestris L at the concentration of 100 µg/mL. Compounds 4c and 4i possessed 75.0% and 82.6% inhibition against Brassica campestris L at the concentration of 100 µg/mL. However, the target compounds 4 showed weak herbicidal activity against Echinochloa crus‐galli at the concentration of 100 and 10 µg/mL.     

Copper‐catalyzed C(sp2)–C(sp) Sonogashira‐type cross‐coupling reactions accelerated by polycyclic aromatic hydrocarbons

Copper‐catalyzed Sonogashira‐type reactions were dramatically accelerated by introducing a catalytic amount of polycyclic aromatic hydrocarbon additive. This novel catalytic system features low copper loading (0.5 mol% < Cu < 5 mol%), broad reaction scope and remarkable substrate tolerance. Both aromatic and aliphatic terminal alkynes as well as diverse aryl iodides were employed in this transformation, affording respectable yields of the desired products. The novel Cu(OTf)₂/pyrene system was subsequently employed to synthesize phenylacetylene‐based fluorescent compounds. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Characterization of New Thebaine Derivatives as Potential Opioid Agonists and Antagonists: 2‐[N‐(1H‐Tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazoles

In this study, we report the synthesis a series of novel 2‐[N‐(1H‐tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazole derivatives ( 7a – e ) which have potential opioid antagonist and agonist. The substitution reaction of 6,14‐endo‐ethenotetrahydrothebaine‐7α‐carbohydrazide with corresponding benzoyl chlorides gave diacylhydrazine compounds 4a – e in good yields. The treatment of compounds 4a – e with POCl₃ caused the conversion of side‐chain of compounds 5a – e into 1,3,4‐oxadiazole ring at C(7) position; thus, compounds 5a – e were obtained. Subsequently, cyanamides ( 6a – e ) were prepared from compounds 5a – e and then compounds 7a – e were synthesized by the azidation of 6a – e with NaN₃. The structures of the compounds were established on the basis of their IR, ¹H NMR, ¹³C APT, 2D‐NMR (COSY, NOESY, HMQC, HMBC) and high‐resolution mass spectral data.     

Synthesis and Herbicidal Activity of 2‐Alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines

To find novel bleaching herbicide lead compounds, a series of novel 2‐alkyl(aryl)‐4‐amino‐3‐[alkyl(alkoxy)carbonyl]‐5‐cyano‐6‐[(3‐trifluoromethyl)phenoxy]‐pyridines was designed and synthesized by the multistep reactions. N,S‐acetal 1 reacted with 2 to obtain multisubstituted pyridines 3 in the presence of zinc nitrate as the catalyst. The target compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l were formed by the oxidation of 3 , followed by the substitution with 3‐(trifluoromethyl)phenol in the presence of potassium carbonate. Their structures were confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses. The preliminary bioassays indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L at the concentration of 100 mg/L.     

Competition between Arene–Perfluoroarene and Charge‐Transfer Interactions in Organic Light‐Harvesting Systems

Two typical types of luminescent organic cocrystals comprising pyrene–octafluoronaphthalene (pyrene–OFN) and pyrene–1,2,4,5‐tetracyanobezene (pyrene–TCNB) were developed by a simple supramolecular assembly strategy. The cocrystals exhibit distinct optical properties because of their different intermolecular interaction modes; that is, arene–perfluoroarene (AP) and charge‐transfer (CT) interactions. Unexpectedly, a pyrene–TCNB system with strong CT interactions was incorporated into a pyrene–OFN host as a robust guest to generate white‐light emission (WLE). In the supramolecular cocrystal system, an efficient energy‐transfer process from pyrene–OFN to pyrene–TCNB occurred because of the well‐matched spectra of the constituents and a desirable energy donor/acceptor (D/A) distance. The present competitive intermolecular interaction strategy could be applied to the fabrication of more complicated organic light‐harvesting systems.     

Synthesis,Characterization, and Anti‐inflammatory Activity of Novel Isoxazolyl‐4‐(2‐oxo‐2,3‐dihydro‐1H‐3‐indolyl)pyrrole‐3‐carboxylates

A series of novel isoxazolyl‐4‐(2‐oxo‐2,3‐dihydro‐1H‐3‐indolyl)pyrrole‐3‐carboxylates ( 17a – i) were synthesized by a three‐component reaction of 4‐amino‐3‐methyl‐5‐styrylisoxazole 14 , β‐keto ester 15 , and 3‐phenacylideneoxindole 16 , in the presence of CAN catalyst in ethanol. The structures of the synthesized compounds have been established on the basis of spectral and analytical data. The title compounds 17a – i were evaluated for their anti‐inflammatory activity. Compounds 17b and 17c exhibited potent anti‐inflammatory activity as that of standard drug.     

Synthesis of 3,4‐Dialkyl‐5‐(1‐oxo‐ethyl)‐3H‐thiazole‐2‐thiones Derivatives and Their Pesticidal Activity

By interaction of N‐methyl(ethyl)‐dithiocarbamate sodium salt with 3‐chloro‐pentane‐2,4‐dion the 1‐(3‐alkyl‐4‐methyl‐2‐thioxo‐2,3‐dihydro‐thiazol‐5‐yl)‐ethanones 1 , 2 and corresponding oximes 7 , 8 were synthesized. On the basis of the mentioned compounds hydrazono ( 3 , 4 ), ureayl and thioureayl ( 5 , 6 ) derivatives, substituted oximes ( 9 , 10 ) and azinyl oximes ( 11 , 12 ) were obtained. The structures of synthesized compounds were confirmed by proton nuclear magnetic resonance spectroscopy and elemental analysis. The pesticidal activities of synthesized compounds were studied. Some of the synthesized compounds simultaneously have shown growth stimulant and fungicidal activity.     

Synthesis and Herbicidal Activity of 5‐Alkyl(aryl)‐3‐[(3‐trifluoromethyl)anilino]‐4,5‐dihydro‐1H‐pyrazolo[4,3‐d]pyrimidin‐4‐imines

A series of novel 5‐alkyl(aryl)‐3‐[(3‐trifluoromethyl)anilino]‐4,5‐dihydro‐1H‐pyrazolo[4,3‐d]pyrimidin‐4‐imines were designed and synthesized by the multistep reactions. 1 reacted with 3‐(trifluoromethyl)aniline to obtain N,S‐acetals 2 in the presence of 10 mol% DBU. 2 reacted with hydrazine to form 5‐amino‐3‐[(3‐trifluoromethyl)anilino]‐1H‐pyrazol‐4‐ nitrile 3 , the target compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m were obtained by the reaction of 3 with triethyl orthoformate followed by the cyclization of 4 with various amines. Their structures were confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses. The preliminary bioassay indicated that some of them displayed moderate herbicidal activity against dicotyledonous weed Brassica campestris L at the concentration of 100 mg/L. For example, compounds 5f , 5g , 5h , and 5j possessed 60.1%, 63.4%, 67.1%, and 61.3% inhibition against Brassica campestris L at the concentration of 100 mg/L.     

Green approach for the synthesis of 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol 3‐yl)methylene)‐1H‐pyrazole‐5(4H)‐ones and their DNA Cleavage,antioxidant, and antimicrobial activities

3‐Methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones (5a‐i) was prepared by the condensation reaction of different 3‐formyl‐2‐phenylindole derivatives (2a‐i) and 3‐methyl‐1‐phenyl‐2‐pyrazoline‐5‐one in quantitative yield by applying various green synthetic methods as grinding, microwave irradiation using different catalysts under solvent‐free mild reaction conditions with high product yields. The structures of the synthesized compounds were characterized on the basis of elemental analysis, infrared, ¹HNMR, ¹³C NMR, and mass spectral data. The synthesized compounds were screened for free radical scavenging, antimicrobial, and DNA cleavage activities. Most of the tested compounds belonging to the 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones series exhibited promising activities.