An efficient synthesis of 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles

Some new target products 5‐aryl‐4,5‐dihydro‐3‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐1‐(4‐phenylthiazol‐2‐yl)pyrazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j have been synthesized by reaction of 2‐bromo‐1‐phenylethanone and compounds 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j which were prepared from the combination of thiosemicarbazide and (E)‐3‐aryl‐1‐(5‐methyl‐1‐p‐tolyl‐1H‐1,2,3‐triazol‐4‐yl)‐prop‐2‐en‐1‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j . All the structures were established by MS, IR, CHN, and ¹H NMR spectra data. Synthesis of structure diversity is applied. J. Heterocyclic Chem., (2011).     

Synthesis and Antimicrobial Evaluations of 1,3,4‐Thiadiazoline‐based Bisheterocyclics

The bisthiadiazolines ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) were synthesized from the cyclization of bisthiosemicarbazones ( 3a , 3b , 3c , 3d , 3e , 3f , 3g ) by refluxing under Ac₂O medium. The intermediates were obtained from the reactions of dibenzaldehydes ( 2a , 2b , 2c , 2d , 2e , 2f , 2g ) with thiosemicarbazide by refluxing in the presence of dry EtOH/HCl. The latter were prepared in good yields from the O‐alkylation of 3‐hydroxybenzaldehyde with suitable dibromo derivatives under the alkaline conditions. The structures of prepared compounds were determined from rigorous analysis of their spectral parameters (UV–vis, IR, ¹H NMR, ¹³C NMR and ESI‐MS). The newly prepared compounds were screened for their antimicrobial activity against seven bacterial and five fungi strains using serial tube dilution method.     

Synthesis of crown ethers bearing 2,4‐dinitrophenylhydrazone

The o‐dihydroxy‐ ( 2a‐b ), dimethoxy ( 3a‐b ), ethylendioxy‐ ( 4a‐b ) and macrocyclic polyethers ( 4c‐i ) are the initial compounds while the 2,4‐dinitrophenylhydrazone compounds ( 5a‐d, 6a‐i ) represent new derivatives. Novel hydrazone compounds were synthesized from the corresponding cyclic ketones ( 4a‐i ) and 2,4‐dinitrophenylhydrazine in H₂SO₄/EtOH/H₂O solution at room temperature for 1 h. The structures of obtained hydrazone compounds were confirmed by ¹H‐NMR, ¹³C‐NMR, EI‐MS, IR spectra and elemental analysis.     

Synthesis and In Vitro Antimicrobial Screening of New Azetidin‐2‐ones of 5‐Ethyl Pyridine‐2‐ethanol

A new series of azetidinones is described in this paper; Schiff base ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k , 4l , 4m , 4n , 4o ) were synthesized from 4‐[2‐(5‐ethylpyridin‐2‐yl)ethoxy]benzaldehyde, which was used to synthesize azetidinones ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l , 5m , 5n , 5o ), ( 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j , 6k , 6l , 6m , 6n , 6o ), and ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i , 7j , 7k , 7l , 7m , 7n , 7o ). The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, ¹H NMR, and ¹³C NMR spectral data. All the products were screened against different strains of bacteria and fungi. Most of the monosubstituted and disubstituted chloro groups are more effective to both bacterial and fungal species in comparison with the standard drugs.     

A Novel Synthesis of 1‐Aryl‐6‐bromo‐3‐(5‐ethylthio‐4‐phenyl‐4H‐1,2,4‐triazol‐3‐yl)‐1H‐pyrazolo[4,3‐b]quinolin‐9(4H)‐ones via Thermal Cyclization of 4‐Azidopyrazoles

2‐Aryl‐hydrazononitriles 3a , 3b , 3c were prepared by coupling 3‐ethylthio‐5‐cyanomethyl‐4‐phenyl‐1,2,4‐triazole ( 1 ) with diazonium salts 2a , 2b , 2c . Reacting 3a , 3b , 3c with both ethyl bromoacetate ( 4a ) and 4‐bromobenzyl bromide ( 4b ) in DMF, in the presence of K₂CO₃, at 80 °C for 3–4 h, gave the corresponding 4‐amino‐pyrazoles 6a , 6b , 6c , 6d , 6e , 6f . Diazotization of 6a , 6b , 6c , 6d , 6e , 6f , followed by reaction with NaN₃, leads to the formation of 4‐azidopyrazoles 8a , 8b , 8c , 8d , 8e , 8f , a new heterocyclic ring system. Interestingly, fusion of 4‐azidopyrazoles 8d , 8e , 8f at temperature higher than their melting points with 5 °C for 2 min did not give the expected fused pyrazolo[4,3‐c]isoxazoles 9 but furnished instead the novel pyrazolo[4,3‐b]quinolinones 10a , 10b , 10c , in high yields.     

Pentaatomic planar tetracoordinate silicon with 14 valence electrons: A large‐scale global search of (n + m = 4; q = 0, ±1, −2; X,Y = main group elements from H to Br)

Designing and characterizing the compounds with exotic structures and bonding that seemingly contrast the traditional chemical rules are a never‐ending goal. Although the silicon chemistry is dominated by the tetrahedral picture, many examples with the planar tetracoordinate‐Si skeletons have been discovered, among which simple species usually contain the 17/18 valence electrons. In this work, we report hitherto the most extensive structural search for the pentaatomic ptSi with 14 valence electrons, that is, (n + m = 4; q = 0, ±1, ?2; X, Y = main group elements from H to Br). For 129 studied systems, 50 systems have the ptSi structure as the local minimum. Promisingly, nine systems, that is, , HSiY₃ (Y = Al/Ga), Ca₃SiAl^?, Mg₄Si^2?, C₂LiSi, Si₃Y₂ (Y = Li/Na/K), each have the global minimum ptSi. The former six systems represent the first prediction. Interestingly, in HSiY₃ (Y = Al/Ga), the H‐atom is only bonded to the ptSi‐center via a localized 2c–2e σ bond. This sharply contradicts the known pentaatomic planar‐centered systems, in which the ligands are actively involved in the ligand–ligand bonding besides being bonded to the planar center. Therefore, we proposed here that to generalize the 14e‐ptSi, two strategies can be applied as (1) introducing the alkaline/alkaline‐earth elements and (2) breaking the peripheral bonding. In light of the very limited global ptSi examples, the presently designed six systems with 14e are expected to enrich the exotic ptSi chemistry and welcome future laboratory confirmation. © 2014 Wiley Periodicals, Inc.     

Lanthanide metals in the boron cages: Computational prediction of M@Bn (M = Eu,Gd; n = 38, 40)

Endohedral metalloborofullerenes (EMBFs) are novel boron analogues of the famous endohedral metallofullerenes (EMFs). Many EMBFs have been proposed by theoretical calculations thus far. However, in sharp contrast to EMFs, which trap most of the lanthanides with f electrons inside the cages, the corresponding lanthanide‐based EMBFs have never been reported. In this work, the encapsulation of Eu and Gd in the B₃₈ and B₄₀ fullerenes was studied by means of density functional theory calculations. Our results revealed that Gd@B₃₈(⁹A), Eu@B₄₀(⁸B₂), and Gd@B₄₀(⁷A″) all favor the endohedral configuration, and the electronic structures can be described as Gd³⁺@ , Eu²⁺@ , and Gd³⁺@ with jailed f electron spins. The large binding energies and sizable HOMO–LUMO gaps suggest that they may be achieved experimentally. They feature σ and π double aromaticity, and their excellent stabilities were confirmed by the Born–Oppenheimer molecular dynamics simulations. Finally, the infrared and UV/vis spectra were simulated to assist experimental characterization.     

Synthesis and antimicrobial activities of new 4,6‐diaryl‐ 4,5‐dihydro‐3‐hydroxy‐2H‐indazoles

A series of new 4,6‐diaryl‐4,5‐dihydro‐3‐hydroxy‐2H‐indazoles 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k were synthesized by the cyclization of ethyl 2‐oxo‐4,6‐diarylcyclohex‐3‐ene carboxylates 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i , 4j , 4k . The compounds were characterized by IR, ¹H NMR, ¹³C NMR, 2D NMR, and elemental analysis. The synthesized compounds were evaluated for in vitro antibacterial and antifungal activities against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger, Aspergillus flavus, and Rhizopus sp. Most of the compounds exhibited good activity against the tested organisms. J. Heterocyclic Chem.,, (2012).     

Synthesis of New 2,4‐Diaryl‐6‐methyl‐5‐nitropyrimidines as Antibacterial and Antioxidant Agents

A new series of 2,4‐diaryl‐6‐methyl‐5‐nitropyrimidines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i ) were synthesized in good yields by Suzuki–Miyaura coupling of 2,4‐dichloro‐6‐methyl‐5‐nitropyrimidine ( 3 ) with various aryl boronic esters ( 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i ) in the presence of 1,1′‐ bis(diphenylphosphino)ferrocene dichloropalladium(II) (Pd(dppf)₂Cl₂). Further, antibacterial and antioxidant properties were screened for the title compounds 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i . Most of the compounds possessed significant activity against Gram‐positive bacteria Staphylococcus aureus and Bacillus subtilis and Gram‐negative bacteria Escherichia coli and Klebsiella pneumoniae. The antioxidant activity of the title compounds showed significant antioxidant activity when compared with vitamin C.     

Synthesis and Antimicrobial Studies of New Bis[4,5‐dihydro‐1‐phenyl‐5‐thienyl‐3‐(phenyl‐4‐alkoxy)‐1H‐pyrazole] Derivatives

Syntheses and antimicrobial behavior of the alkyl linked new bispyrazolines 4a , 4b , 4c , 4d , 4e , 4f , 4g have been investigated. These compounds exhibited better antimicrobial activities as compared with their corresponding bischalcones. The structures of the prepared compounds ( 3a , 3b , 3c , 3d , 3e , 3f , 3g and 4a , 4b , 4c , 4d , 4e , 4f , 4g ) were determined from the rigorous analysis of their IR, ¹H NMR, ¹³C NMR, and mass spectral parameters.     

Synthesis of 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4′′‐hydroxyphenyl)‐thiazoles and their O‐glucosides

In continuation of our work, we synthesized 2‐(sulfamoylphenyl)‐4′‐amino‐4‐(4″‐hydroxyphenyl)‐thiazole ( 3a ), which were reacted with various (aryl/hetroaryl) aldehyde to form 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐hydroxyphenyl)‐thiazoles ( 4a , 4b , 4c , 4d , 4e , 4f ). Glucosylation of compounds ( 4a , 4b , 4c , 4d , 4e , 4f ) have been done by using acetobromoglucose as a glucosyl donor to afford 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(2,3,4,6‐tetra‐O‐acetyl‐4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 5a , 5b , 5c , 5d , 5e , 5f ), further on deacetylation to produce 2‐(sulfamoylphenyl)‐4′‐(iminoaryl/hetroaryl)‐4‐(4″‐O‐β‐D ‐glucosidoxyphenyl)‐thiazoles ( 6a , 6b , 6c , 6d , 6e , 6f ). The compounds are confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR, and ES‐Mass spectral analysis. J. Heterocyclic Chem., (2011).     

Synthesis and Antimicrobial Activities of Novel Series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one Derivatives

In the present investigation, a novel series of 3‐(4‐(2‐substituted thiazol‐4‐yl)phenyl)‐2‐(4‐methyl‐2‐substituted thiazol‐5‐yl)thiazolidin‐4‐one derivatives were synthesized by condensation of 2‐substituted‐4‐methylthiazole‐5‐carbaldehyde with 4‐(2‐substituted thiazol‐4‐yl)benzenamine followed by cyclo‐condensation with thioglycolic acid in toluene. All the newly synthesized compounds were characterized by spectral (IR, ¹H NMR, ¹³C NMR, and Mass) methods. The title compounds were screened for quantitative antibacterial activity (minimal inhibitory concentration). All compounds 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h and 8a , 8b , 8c , 8d , 8e , 8f , 8g , 8h show moderate to good antimicrobial activity, whereas compounds ( 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h ) also show moderate antifungal activity.     

Synthesis and Antifungal Screening of 2‐(2‐Aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole Derivatives

A new series of synthesis and biological screening of 2‐(2‐aryl‐4‐methyl‐thiazol‐5‐yl)‐5‐((2‐aryl/benzylthiazol‐4‐yl)methyl)‐1,3,4‐oxadiazole derivatives 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i was achieved by condensation of 2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 2a , 2b , 2c with 4‐methyl‐2‐arylthiazole‐5‐carbaldehyde 3a , 3b , 3c followed by oxidative cyclization of N'‐((4‐methyl‐2‐arylthiazol‐5‐yl)methylene)‐2‐(2‐aryl/benzylthiazol‐4‐yl)acetohydrazide 4a , 4b , 4c , 4d , 4e , 4f , 4g , 4h , 4i using iodobenzene diacetate as oxidizing agent. All the synthesized compounds were screened for their in vitro antifungal activity against Candida albicans, Candida tropicalis, Aspergillus niger, and Aspergillus flavus. Some of the synthesized compounds showed good antifungal activity.     

Kinetic Analysis of A2 + AB2 Polymerization Approach

The kinetic model of the co‐polycondensation with A₂ and AB₂ type monomers is developed and the analytical expressions of the various molecular parameters of the products are derived rigorously. The monomer feed ratio (α) of A₂ to AB₂ significantly affects the molecular parameters and the critical condition of gelation. Gelation can be avoided if α is > . At the critical state, the degree of branching decreases firstly and reaches its minimum value at about α≈0.22. Then, it increases with increasing α‐value. In comparison with experimental results, non‐equal reactivity of the active groups should be considered.

     

D∞h B2(BS)2−/2− and Td B(BS)4−: Boron sulfide clusters containing BB multiple bonds and B− tetrahedral centers

A density functional theory investigation on the geometrical and electronic properties of B₄S (B₂(BS)) and B₅S (B(BS)) clusters has been performed in this work. Both the doublet B₂(BS) ([S?B? BB? B?S]^?) (D_∞h, ²Π_u) and the singlet B₂(BS) ([S?B? B?B? B?S]^2?) (D_∞h, ¹Σ) proved to have perfect linear ground‐state structures containing a multiply bonded BB core (BB or B?B) terminated with two BS groups, while T_d B(BS) turned out to possess a perfect B^? tetrahedral center directly corrected to four BS groups, similar to the corresponding boron hydride molecules of D_∞h B₂H, D_∞h B₂H, and T_d BH, respectively. B₄S₂ and B₅S₄ neutrals, however, appeared to be much different: they favor a planar fan‐shaped C_2v B₄S₂ (a di‐S‐bridged B₄ rhombus) and a planar kite‐like C_2v B₅S₄ (a di‐S‐bridged B₃ triangle bonded to two BS groups), respectively. One‐electron detachment energies and symmetrical stretching vibrational frequencies are calculated for D_∞h B₂(BS) and T_d B(BS) monoanions to facilitate their future characterizations. Neutral salts of B₂(BS)₂Li₂ with an elusive B?B triple bond and B(BS)₄Li containing a tetrahedral B^? center are predicted possible to be targeted in experiments. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Untersuchungen an elektronenleitenden Oxidsystemen. XXI. Stabile spinelle ZnzNiMn2−zO4 und Vergleich mit Spinellen MgzNiMn2−zO4

Investigations on Electronically Conducting Oxide Systems. XXI [1] Stable Spinels Zn_zNiMn_2?zO₄ and Comparison with Spinels Mg_zNiMn_2?zO₄ Stable spinels are obtained in the result of substitution of Zn^II for manganese in the series Zn Ni^IIMnMnO₄ (O ? z ≤1). Different from spinels Mg Ni^IIMnMnO₄ (O ? z ?1)they don't be submitted to decomposition in air during slow cooling at medium temperatures. ZnNiMnO₄ (z=1) could not be prepared in a mono-phase state which is indicated by the composition of ZnNiMnO_3.96 deduced from analysis by oxidimetric titration. The comparably small variation of the specific electrical conductivity and of the activation energy observed in the range O ? z ? 2/3 for Zn_zNiMn_2?z is discussed in relation to larger alterations in the series Mg_zNiMn_2?zO₄. Structural interpretation is proposed based on the comparison of the molar volume of spinels M Mn₂O₄ (M: Mn, Fe, Co, Ni, Cu, Zn, Mg).     

Synthesis and antimicrobial activity of some 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones

The title compounds, 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been synthesized by reacting various 4‐hydroxy coumarins 1a , 1b , 1c with 2‐arylidene‐1‐tetralones 2a , 2b , 2c , 2d in the presence of ammonium acetate and acetic acid under Krohnke's reaction condition. The structures of all the synthesized compounds were supported by analytical, IR, ¹H‐NMR, and ¹³C‐NMR data. All the synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been screened for their antibacterial activities against Escherichia coli (Gram ?ve bacteria), Bacillus subtilis (Gram +ve bacteria), and antifungal activity against Candida albicans (Fungi). J. Heterocyclic Chem., (2011).     

A theoretical study on the stability difference of the borane and carborane C2Bn−2Hn (5 ≤ n ≤ 7) clusters

In order to study the electronic structure and structural stability of borane and carborane C₂B_n?2H_n (5 ≤ n ≤ 7) clusters, especially the stability difference between the borane and carborane C₂B₃H₅. The frontier orbital energy levels of the borane and carborane C₂B_n?2H_n (5 ≤ n ≤ 7) clusters are calculated at CCSD(T)/aug‐cc‐pVXZ//B3LYP/def2‐TZVPP level. The results are further analyzed by qualitative frontier orbital method based on the cap–ring interaction. The results reveal that: (1) the larger E_gap(HOMO‐LUMO energy gap) of carborane C₂B_n?2H_n (5 ≤ n ≤ 7) clusters than borane (5 ≤ n ≤ 7) clusters originates from the more effective cap–ring orbital overlap of carborane C₂B_n?2H_n (5 ≤ n ≤ 7) clusters than that of borane (5 ≤ n ≤ 7) clusters; (2) the smallest E_gap of the borane results from the highest energy level of the ring symmetry‐adapted linear combination orbital of cluster; and (3) the largest E_gap of the carborane C₂B₃H₅ is induced by the most effective cap–ring orbital interaction of C₂B₃H₅ cluster. © 2014 Wiley Periodicals, Inc.     

Efficient Synthesis of Novel 3‐Phenyl‐5‐thioxo‐3,4,5,6‐tetrahydroimidazo[4,5‐c]pyrazole‐2(1H)‐carbothioamide Derivatives Using a CeO2–MgO Catalyst and Evaluation of Antimicrobial Activity

Imidazo[4,5‐c ]pyrazole derivatives ( 3a–f , 4a–f , and 5a–f ) were efficiently synthesized by one‐pot three‐component reactions using CeO₂–MgO as the catalyst. The synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectroscopic analyses. The in vitro antimicrobial activity of the synthesized compounds against various bacterial and fungal strains was screened. Compound 3b was highly active [minimum inhibitory concentration (MIC): 0.5 μg/mL] against Gram‐positive Staphylococcus aureus , and compounds 3b , 3f , 4d , and 4e were highly active (MIC: 0.5, 2, 2, and 0.5 μg/mL, respectively) against Gram‐negative Pseudomonas aeruginosa and Klebsiella pneumoniae , relative to standard ciprofloxacin in the antibacterial activity screening. Compounds 3b and 4f were highly active (MIC: 4 and 0.5 μg/mL, respectively) against Aspergillus fumigatus and Microsporum audouinii in the antifungal activity screening compared with the clotrimazole standard.     

Synthesis of 2‐Arylquinazolin‐4(3H)‐ones by N‐Aryl Benzamidines with Aromatic Carbonates

The reaction of N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n with diphenyl carbonate 2a or ethyl phenyl carbonate 2b synthesized 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n in simple and safe process with good yields (71–90%). It was suggested that different electron‐donating substituent in N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n afforded similar effect to the yields of 2‐arylquinazolin‐4(3H)‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n . In these reactions, N‐aryl benzamidines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m , 1n built up intermediate compounds by nucleophilic addition to carbonates 2 to give annulation products 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , following to cyclization involving the elimination of ethanol/phenol.