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Molecules, Volume 14, Issue 6 (June 2009), Pages 1966-2305

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Open AccessReview Ionic Liquids in Tribology
Molecules 2009, 14(6), 2286-2305; https://doi.org/10.3390/molecules14062286
Received: 24 May 2009 / Revised: 20 June 2009 / Accepted: 23 June 2009 / Published: 24 June 2009
Cited by 363 | PDF Full-text (605 KB)
Abstract
Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research
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Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided. Full article
(This article belongs to the collection Ionic Liquids)
Open AccessArticle Synthesis of Symmetrical and Non-symmetrical Diimines from Dimedone
Molecules 2009, 14(6), 2278-2285; https://doi.org/10.3390/molecules14062278
Received: 7 May 2009 / Revised: 21 May 2009 / Accepted: 9 June 2009 / Published: 24 June 2009
Cited by 2 | PDF Full-text (979 KB)
Abstract
Symmetrical and non-symmetrical diimines derived from dimedone were synthesized by the reaction of their corresponding enaminothiones with primary amines. The synthesized compounds were characterized using micro analytical data and NMR spectroscopy. Theoretical calculations by B3LYP/6-31G(d,p) level of theory show that the enolic form
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Symmetrical and non-symmetrical diimines derived from dimedone were synthesized by the reaction of their corresponding enaminothiones with primary amines. The synthesized compounds were characterized using micro analytical data and NMR spectroscopy. Theoretical calculations by B3LYP/6-31G(d,p) level of theory show that the enolic form is the most stable within the possible tautomeric forms of the compounds. Full article
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Open AccessArticle A New Cadinane Sesquiterpene from the Marine Brown Alga Dictyopteris divaricata
Molecules 2009, 14(6), 2273-2277; https://doi.org/10.3390/molecules14062273
Received: 25 May 2009 / Revised: 11 June 2009 / Accepted: 23 June 2009 / Published: 24 June 2009
Cited by 9 | PDF Full-text (149 KB)
Abstract
A sample of the marine brown alga D. divaricata collected off the coast of Yantai (P.R. China) was dried, powdered, and extracted with the mixture of CHCl3 and MeOH (1:1, v/v). By a combination of silica gel and Sephadex LH-20 column chromatography
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A sample of the marine brown alga D. divaricata collected off the coast of Yantai (P.R. China) was dried, powdered, and extracted with the mixture of CHCl3 and MeOH (1:1, v/v). By a combination of silica gel and Sephadex LH-20 column chromatography and preparative TLC, a new cadinane sesquiterpene 1,4-epoxymuurolan-5β-ol (1) was isolated from this species. Its structure was established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data. Full article
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Open AccessArticle Heterocyclic-2-carboxylic Acid (3-Cyano-1,4-di-N-oxidequinoxalin-2-yl)amide Derivatives as Hits for the Development of Neglected Disease Drugs
Molecules 2009, 14(6), 2256-2272; https://doi.org/10.3390/molecules14062256
Received: 2 June 2009 / Revised: 15 June 2009 / Accepted: 17 June 2009 / Published: 22 June 2009
Cited by 38 | PDF Full-text (149 KB)
Abstract
Neglected diseases represent a major health problem. It is estimated that one third of the world population is infected with tuberculosis (TB). Besides TB, Chagas disease, affects approximately 20 million people. Quinoxalines display great activities against TB and Chagas. Forty new quinoxaline 1,4-di-
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Neglected diseases represent a major health problem. It is estimated that one third of the world population is infected with tuberculosis (TB). Besides TB, Chagas disease, affects approximately 20 million people. Quinoxalines display great activities against TB and Chagas. Forty new quinoxaline 1,4-di-N-oxide derivatives have been prepared and tested against M. tuberculosis and T. cruzi. Carboxylic acid quinoxaline 1,4-di-N-oxides (CAQDOs) 5 and 17 showed MIC values on the same order as the reference antituberculosis drug, rifampicin. Meanwhile, CAQDOs 12 and 22 presented IC50 values in the same order as the anti-chagasic drug, nifurtimox. Full article
(This article belongs to the Special Issue Neglected Diseases: Medicinal Chemistry and Natural Product Chemistry)
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Open AccessEditorial Full Open Access Journals Have Increased Impact Factors
Molecules 2009, 14(6), 2254-2255; https://doi.org/10.3390/molecules14062254
Received: 20 June 2009 / Published: 22 June 2009
Cited by 8 | PDF Full-text (23 KB) | HTML Full-text | XML Full-text
Abstract
We are pleased to report the increase of the impact factors of MDPI journals during 2007 and 2008. In 2005 and part of 2006, the use of a two tier publication system, whereby we offered full Open Access publication to those authors willing
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We are pleased to report the increase of the impact factors of MDPI journals during 2007 and 2008. In 2005 and part of 2006, the use of a two tier publication system, whereby we offered full Open Access publication to those authors willing to contribute financially to support this option, while providing the alternative choice of free publication without Open Access for those authors who preferred not to pay, resulted in the obviously decreased impact factors seen in 2006 [...] Full article
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Open AccessArticle Two New Steroidal Saponins from Allium macrostemon Bunge and Their Cytotoxity on Different Cancer Cell Lines
Molecules 2009, 14(6), 2246-2253; https://doi.org/10.3390/molecules14062246
Received: 22 April 2009 / Revised: 25 May 2009 / Accepted: 16 June 2009 / Published: 19 June 2009
Cited by 22 | PDF Full-text (212 KB)
Abstract
Two new steroidal saponins (1 and 2) were isolated from the dried bulbs of Allium macrostemon Bunge. Their structures were elucidated by the spectral data as 26-O-β-D-glucopyranosyl-5α-furost-25 (27)-ene-3β, 12β, 22, 26-tetraol-3-O-
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Two new steroidal saponins (1 and 2) were isolated from the dried bulbs of Allium macrostemon Bunge. Their structures were elucidated by the spectral data as 26-O-β-D-glucopyranosyl-5α-furost-25 (27)-ene-3β, 12β, 22, 26-tetraol-3-O-β-D-glucopyranosyl (1→2) [β-D-glucopyranosyl (1→3)]-β-D-glucopyranosyl (1→4)-β-D-galactopyranoside (1) and 26-O-β-D-glucopyranosyl-5β-furost-20 (22)-25 (27)-dien-3β, 12β, 26-triol-3-O-β-D-glucopyranosyl (1→2)-β-D-galactopyranoside (2), respectively. Their cytotoxic activities on several cancer cell lines (MCF-7, NCI-H460, SF-268 and HepG2) were tested. 1 showed special cytotoxity on SF-268, while 2 showed cytotoxity on NCI-H460 and SF-268 cell lines, respectively. Full article
Open AccessArticle A Facile Route to C2-Substituted Imidazolium Ionic Liquids
Molecules 2009, 14(6), 2235-2245; https://doi.org/10.3390/molecules14062235
Received: 14 May 2009 / Revised: 10 June 2009 / Accepted: 16 June 2009 / Published: 19 June 2009
Cited by 16 | PDF Full-text (206 KB)
Abstract
A convenient route for the preparation of C2-substituted imidazolium ionic liquids is reported. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for non-functionalized alkyl chlorides, and less well for
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A convenient route for the preparation of C2-substituted imidazolium ionic liquids is reported. This method involves the alkylation of N-heterocyclic carbenes, which are readily generated from the C2-unsubstituted imidazolium ionic liquids. It works well for non-functionalized alkyl chlorides, and less well for alkyl bromides and iodides, likely due to competing elimination reactions. The resulting C2-substituted salts can be transformed into ionic liquids via standard anion metathesis reactions. Full article
(This article belongs to the collection Ionic Liquids)
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Open AccessArticle Synthesis and Characterization of Photo-Responsive Carbosilane Dendrimers
Molecules 2009, 14(6), 2226-2234; https://doi.org/10.3390/molecules14062226
Received: 2 June 2009 / Revised: 13 June 2009 / Accepted: 17 June 2009 / Published: 18 June 2009
Cited by 8 | PDF Full-text (252 KB)
Abstract
Preparation of photo-responsive carbosilane dendrimers bearing 4-phenylazo-benzonitrile units on their molecular surface has been accomplished, and their both photo and thermal behaviors have also been characterized. These functional dendrimers suggest that the apparent molecular sizes of the cis-isomers are smaller than those
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Preparation of photo-responsive carbosilane dendrimers bearing 4-phenylazo-benzonitrile units on their molecular surface has been accomplished, and their both photo and thermal behaviors have also been characterized. These functional dendrimers suggest that the apparent molecular sizes of the cis-isomers are smaller than those of the corresponding trans-isomers, since the molecular diameter of these dendrimers would be shorter on the basis of transcis photo-isomerization of azobenzene. Full article
Open AccessArticle Examination of Imprinting Process with Molsidomine as a Template
Molecules 2009, 14(6), 2212-2225; https://doi.org/10.3390/molecules14062212
Received: 7 May 2009 / Revised: 4 June 2009 / Accepted: 11 June 2009 / Published: 17 June 2009
Cited by 10 | PDF Full-text (252 KB)
Abstract
Eight different functional monomers were used with ethylene glycol dimethacrylate as a cross-linker and molsidomine as a template to obtain molecularly imprinted polymers (MIPs). Non-covalent interactions between molsidomine and each functional monomer in DMSO prior to thermal bulk polymerization were utilized. On the
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Eight different functional monomers were used with ethylene glycol dimethacrylate as a cross-linker and molsidomine as a template to obtain molecularly imprinted polymers (MIPs). Non-covalent interactions between molsidomine and each functional monomer in DMSO prior to thermal bulk polymerization were utilized. On the basis of calculated imprinting factors, MIP prepared with N,N’-diallyltartaramide was chosen for further investigations. Examination of interactions in the prepolymerization complex between molsidomine and N,N’-diallyltartaramide was performed using the Job method. The absorbance of isomolar solutions reaching a maximum for the molar ratio of template to monomer equal to 1:4. Scatchard analysis was used for estimation of the dissociation constants and the maximum amounts of binding sites. The polymer based on N,N’-diallyltartaramide has two classes of heterogeneous binding sites characterized by two values of Kd and two Bmax: Kd(1) = 1.17 mM-1 and Bmax(1) = 0.8 μmol/mg for the higher affinity binding sites, and Kd(2) = 200 μM-1 and Bmax(2) = 2.05 μmol/mg for the lower affinity binding sites. Furthermore, effects of pH and organic solvent on binding properties of MIP and NIP were investigated, together with release of molsidomine from both MIP and NIP. Full article
(This article belongs to the Special Issue ECSOC-12)
Open AccessEditorial Phenolics: From Chemistry to Biology
Molecules 2009, 14(6), 2202-2211; https://doi.org/10.3390/molecules14062202
Received: 5 June 2009 / Revised: 13 June 2009 / Accepted: 16 June 2009 / Published: 17 June 2009
Cited by 156 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, few classes of natural products have received as much attention as phenolics and polyphenols. This special issue of Molecules, “Phenolics and Polyphenolics”, is a remarkable confirmation of this trend. Several aspects related to phenolics chemistry, comprising the several classes,
[...] Read more.
In recent years, few classes of natural products have received as much attention as phenolics and polyphenols. This special issue of Molecules, “Phenolics and Polyphenolics”, is a remarkable confirmation of this trend. Several aspects related to phenolics chemistry, comprising the several classes, will be discussed. In addition, the increasing interest in phenolics’ biological activities is covered, and several works addressing this matter are referred. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessCommunication Determination of the Volatile Composition of Rhodobryum giganteum (Schwaegr.) Par. (Bryaceae) Using Solid-phase Microextraction and Gas Chromatography/Mass Spectrometry (GC/MS)
Molecules 2009, 14(6), 2195-2201; https://doi.org/10.3390/molecules14062195
Received: 26 April 2009 / Revised: 29 May 2009 / Accepted: 12 June 2009 / Published: 17 June 2009
Cited by 15 | PDF Full-text (235 KB) | HTML Full-text | XML Full-text
Abstract
A total of 38 volatile components were identified in Rhodobryum giganteum (Schwaegr.) Par. collected from two different geographic regions by headspace solid-phase microextraction (HS-SPME), combined with gas chromatography/mass spectrometry (GC/MS). The volatile components included some aliphatic and aromatic aldehydes, monoterpene hydrocarbons and a
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A total of 38 volatile components were identified in Rhodobryum giganteum (Schwaegr.) Par. collected from two different geographic regions by headspace solid-phase microextraction (HS-SPME), combined with gas chromatography/mass spectrometry (GC/MS). The volatile components included some aliphatic and aromatic aldehydes, monoterpene hydrocarbons and a sesquiterpene (α-farnesene), with 1-methoxy-2-propyl acetate and n-hexanal being found to be the most abundant volatile components. Analysis of the chemical constituents in the volatile oil of the two samples showed that ten compounds were shared. Full article
Open AccessArticle Synthesis of Two New Hemisynthetic Diterpenylhydroquinones from Natural Ent-Labdanes
Molecules 2009, 14(6), 2181-2194; https://doi.org/10.3390/molecules14062181
Received: 10 May 2009 / Revised: 26 May 2009 / Accepted: 2 June 2009 / Published: 17 June 2009
Cited by 3 | PDF Full-text (494 KB) | HTML Full-text | XML Full-text
Abstract
The synthesis and structural determination of two new diterpenylhydroquinones: 2β-acetoxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-diene(1) and 2β-hydroxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-dieneis reported (2). These compounds were obtained by coupling via Electrophilic Aromatic Substitution (EAS) of 1,4-hydroquinone with primary or tertiary allyl alcohol
[...] Read more.
The synthesis and structural determination of two new diterpenylhydroquinones: 2β-acetoxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-diene(1) and 2β-hydroxy-15-phenyl-(22,25-dihydroxy)-ent-labda-8(17),13(E)-dieneis reported (2). These compounds were obtained by coupling via Electrophilic Aromatic Substitution (EAS) of 1,4-hydroquinone with primary or tertiary allyl alcohol derivatives of the natural ent-labdanes 3 and 4. With this new method, the best results were observed when mixtures of the primary alcohol derivatives 5-6 (26% yield of compound 1) and diol derivatives 9-10 (28% yield of compound 2) were used. Full article
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Open AccessArticle Effect of Extraction Solvent/Technique on the Antioxidant Activity of Selected Medicinal Plant Extracts
Molecules 2009, 14(6), 2167-2180; https://doi.org/10.3390/molecules14062167
Received: 25 April 2009 / Revised: 27 May 2009 / Accepted: 11 June 2009 / Published: 15 June 2009
Cited by 313 | PDF Full-text (157 KB) | HTML Full-text | XML Full-text
Abstract
Theeffects of four extracting solvents [absolute ethanol, absolute methanol, aqueous ethanol (ethanol: water, 80:20 v/v) and aqueous methanol (methanol: water, 80:20 v/v)] and two extraction techniques (shaking and reflux) on the antioxidant activity of extracts of barks of Azadirachta indica, Acacia nilotica,
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Theeffects of four extracting solvents [absolute ethanol, absolute methanol, aqueous ethanol (ethanol: water, 80:20 v/v) and aqueous methanol (methanol: water, 80:20 v/v)] and two extraction techniques (shaking and reflux) on the antioxidant activity of extracts of barks of Azadirachta indica, Acacia nilotica, Eugenia jambolana, Terminalia arjuna, leaves and roots of Moringa oleifera, fruit of Ficus religiosa,and leaves of Aloe barbadensis were investigated. The tested plant materials contained appreciable amounts of total phenolic contents (0.31-16.5 g GAE /100g DW), total flavonoid (2.63-8.66 g CE/100g DW); reducing power at 10 mg/mL extract concentration (1.36-2.91), DPPH. scavenging capacity (37.2-86.6%), and percent inhibition of linoleic acid (66.0-90.6%). Generally higher extract yields, phenolic contents and plant material antioxidant activity were obtained using aqueous organic solvents, as compared to the respective absolute organic solvents. Although higher extract yields were obtained by the refluxing extraction technique, in general higher amounts of total phenolic contents and better antioxidant activity were found in the extracts prepared using a shaker. Full article
Open AccessArticle Extraction with SPME and Synthesis of 2-Methyl-6-vinylpyrazine by a ‘One Pot’ Reaction Using Microwaves
Molecules 2009, 14(6), 2160-2166; https://doi.org/10.3390/molecules14062160
Received: 20 April 2009 / Revised: 30 May 2009 / Accepted: 2 June 2009 / Published: 15 June 2009
Cited by 2 | PDF Full-text (224 KB) | HTML Full-text | XML Full-text
Abstract
A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound
[...] Read more.
A synthesis of 2-methyl-6-vinylpyrazine was carried out by way of a ‘one pot’ reaction. In order to establish the efficiency of this synthesis the extraction of the volatiles released by male papaya fruit flies was performed by SPME (solid phase micro-extraction). The compound was separated and identified using GC/MSD (gas chromatography/mass spectrometry detector). Full article
(This article belongs to the Special Issue Microwave Assisted Synthesis)
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Open AccessArticle Cyclization of Hydrazones of 2-Acetyl-1-naphthol and 1-Acetyl-2-naphthol with Triphosgene. Synthesis of Spiro Naphthoxazine Dimers
Molecules 2009, 14(6), 2147-2159; https://doi.org/10.3390/molecules14062147
Received: 25 April 2009 / Revised: 15 May 2009 / Accepted: 5 June 2009 / Published: 12 June 2009
Cited by 13 | PDF Full-text (166 KB) | HTML Full-text | XML Full-text
Abstract
Cyclization of hydrazones derived from 2-acetyl-1-naphthol and 1-acetyl-2-naphthol with triphosgene gave naphtho[1,2-e]-1,3-oxazines, naphtho[2,1-e]-1,3-oxazines or their spiro dimers depending on the molar ratio of triphosgene used for the cyclization. Full article
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