Alkylthio Substituents Research Articles

Characterization of light emission from subphthalocyanine monolayers using scanning tunneling microscopy

Monolayers of subphthalocyanine were prepared by molecular beam epitaxy and self-assembled depositions on the Au (111) surface. Light emission from the monolayers was measured by photoexcitation as well as tunneling current excitation using scanning tunneling microscopy under ultrahigh vacuum. The photoexcited spectra of the monolayers deposited by both methods exhibited the fluorescence bands of π-electronic transition of the subphthalocyanine macrocycle although their lifetime was very shortened due to quenching by the Au surface. The tunneling induced emission was taken from the self-assembled monolayers in which the subphthalocyanine molecules were chemically bound onto the surface by alkylthio substituents. The observed spectra were ascribed to the radiative decay of tip-induced surface plasmon of Au. The molecules in the self-assembled monolayers shifted the emission peak due to modification of the dielectric property and distance between the tip and surface.

Photochromic Dihetarylethylenes. 22. Synthesis and Photochromic Properties of Unsymmetrical Alkylthio-substituted 1,2-Bis(dithienyl)perfluorocyclopentenes

Certain unsymmetrical 1,2-bis(dithienyl)perfluorocyclopentenes have been synthesized containing alkylthio, bromo, carboxy, and benzothiazolyl substituents in the thiophene rings. It was shown that on irradiation with UV light they all display photochromic properties, with the exception of the derivative containing an alkylthio group in the reaction center of one of the thiophene rings.

Synthesis, electrochemical, and spectroelectrochemical properties of tetrakis(13,17-dioxa nonacosane-15-sulphanyl) phthalocyaninato zinc(II)

Tetrakis(13,17-dioxa nonacosane-15-sulphanyl) phthalocyaninato zinc(II), ZnPc(SCH(CH 2OR) 2) 4, where R = C 12H 25, was synthesised and its electrochemical and spectroelectrochemical properties were investigated in dichloromethane. The neutral complex undergoes two quasi-reversible one-electron oxidations and two quasi-reversible one-electron reductions in CH 2Cl 2 containing 0.1 M tetra- n-butylammonium perchlorate (TBAP). The half-wave potentials for oxidation of the complex are located at E 1/2 = 0.61 and 1.38 V, while the two reductions are located at E 1/2 = −0.87 and −1.11 V versus SCE. These potentials show little or no difference compared to those of unsubstituted ZnPc and other SR substituted phthalocyanines under the same experimental conditions, thus suggesting weak electron-donating effects of the peripheral alkylthio substituents on the phthalocyanine rings. The well-defined UV–Vis spectra of electro-reduced and electro-oxidised species, [ZnPc(-3)(SCH(CH 2OR) 2) 4] −, [ZnPc(-4)(SCH(CH 2OR) 2) 4] 2− and [ZnPc(-1)(SCH(CH 2OR) 2) 4] +, were obtained by applied potentials ( E app = −1.04 V, E app = −1.62 V, and E app = 1.20 V, respectively) in a thin-layer cell. The first and second reduction products showed characteristic spectral changes corresponding to mono- and di-anionic species of zinc phthalocyanines, and the first oxidation showed spectral changes corresponding to the formation of a mono-cationic dimer.

Role of Alkylthio Substituents on Tetrathiafulvalene and 1,3-Dithiole Rings: A Theoretical Study

The effect of alkylthio substituents on the redox and nonlinear optical behavior of tetrathiafulvalenes has been studied by Density Functional Theory Calculations.

Highly Conductive and Thermally Stable Self-doping Propylthiosulfonated Polyanilines

A new type of highly conductive self-doping polyaniline, MPS−Pan, containing a sulfonic acid moiety covalently bonded to the polymer backbone through an electron-donating propylthio linkage has been successfully prepared via a novel concurrent reduction and substitution route. At a similar self-doping level, the resultant MPS−Pans displayed much higher conductivity than the corresponding sulfonated polyaniline (S−Pan). Furthermore, for fully doped samples, contrary to the trend of decreasing conductivity with the sulfonation degree in S−Pan, the conductivity of MPS−Pan was found to increase with its substitution degree. These results agreed with the expectation that electron-deficient charge carriers (e.g. semiquinone radical cations) on acid-doped polyaniline chains will be better stabilized by the electron-donating alkylthio substituent. Surprisingly, TG and XPS studies showed that MPS−Pan was thermally much more stable than S−Pan, with S−Pan starting to lose its sulfonic acid dopant at 185 °C, while MP...

6‐Alkyl, Alkoxy, or Alkylthio‐Substituted 3‐(4‐Methanesulfonylphenyl)‐4‐phenylpyran‐2‐ones: A Novel Class of Diarylheterocyclic Selective Cyclooxygenase‐2 Inhibitors

AbstractFor Abstract see ChemInform Abstract in Full Text.

3D‐QSAR and Docking Study of the Binding Mode of Steroids to Progesterone Receptor in Active Site

AbstractAutodock 3.0 was applied to the search for the binding mode of a set of steroids with progesterone receptor (PR). The results of docking investigation show that oxygen atom of 3‐keto forms three hydrogen bonds with the residues Gln725 and Arg766 respectively. This is consistent with the reported work of S. P. Williams et al. (Nature, 1998, 393, 392–396). Moreover, we have studied in particular the most affinitive compound, steroid with a para alkylthio substituent of benzene at position 11. We find that there is a deep cavity around this substituent and a wide cavity around the substituent on position 17. This result could help us to select substituents to improve the PR‐binding affinity of steroids. The most probable aligned conformers were selected by a docking‐guided conformation selection method, and all‐orientation and all‐placement searches were applied to optimize CoMFA and CoMSIA models. Stable and highly predictive 3D‐QSAR models were built with cross‐validated coefficients q2 0.773 and 0.699 respectively for CoMFA and CoMSIA. The predictive ability of these models was validated using a test set. The results agree with those obtained from the docking investigations.

6-Alkyl, alkoxy, or alkylthio-substituted 3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones: a novel class of diarylheterocyclic selective cyclooxygenase-2 inhibitors.

A novel class of 3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones possessing a central six-membered lactone (pyran-2-one) ring system, in conjunction with C-6 alkyl (Me, Et or i-Pr), alkoxy (OMe, OEt or O-i-Pr), and alkylthio (SMe, SEt or S-i-Pr) substituents, were designed for evaluation as selective COX-2 inhibitors.

Chloropyrimidines as a new class of antimicrobial agents

In the course of our investigations of pyrimidines as antimycotic agents, we have identified a sub-class, with significant in vitro activity against mycobacteria. The salient feature of these pyrimidine derivatives (3a–o and 7a,b) is their appended aryl, heteroaryl and alkylthio substituent at position 6 and also alkylthio substituent at position 2. The rational design, synthesis, and evaluation of the in vitro antibacterial activity against six pathogenic bacteria including virulent and non-virulent strains of Mycobacterium tuberculosis is described. Some of the synthesized compounds (3c, 3h, 3i, 3o) have displayed only potent in vitro antimycobacterial activity with MIC of 0.75 μg/mL except 3i which also demonstrated activity against Escherichia coli at 12.5 μg/mL concentration. Only two compounds, 3a and 3b, demonstrated antibacterial activity against Pseudomonas aeruginosa and E. coli with MIC 12.5 μg/mL. All the synthesized compounds were also evaluated for their antimycotic activity against five pathogenic fungi but only some of them 3j–n and 7a,b were found most potent against Aspergillus fumigatus and Trichophyton mentagrophytes.

The structure and characteristics of photochromic dithienylethenes

The data on X‐ray diffraction analysis for dihetarylethenes with perfluorocyclopentene (F), maleic anhydride (M) and cyclobutenedione (S) bridges between thienyl fragments were summarized and their photochromic properties were discussed. It was established that benzoxazole and benzothiazole substituents in position 5 of thienyl rings are coplanar to the plane of thiophene cycles. Thienyl fragments in A form of all dithienylethenes are considerably turned relative to the plane of bridging cycle. It means that there is no conjugation between π‐electrons of aromatic heterocycles and double bond of the bridge.Flattening of molecule frameworkand the envelope conformation of thienyl cycles because of aromaticity loss are characteristic features of the form B structure with F‐bridge. In all cases (excluding the compounds with alkylthio substituents in position 2 of thiophene cycle) the photochromic transition A → B is observed independently of different nature and structure of functional groups.

N-Thiolated Bicyclic and Monocyclic β-Lactams

In this study, we describe the synthesis and features of β-lactam ring systems having an alkylthio substituent on the lactam nitrogen center. The sulfur group acts to enhance the electrophilic character of the lactam carbonyl through electron withdrawal, and in bicyclic systems, reduces pyramidalization of the nitrogen center. Despite their electrophilic nature, these ring systems are chemically stable towards hydrolysis in aqueous media, but can be cleaved at the N–S bond by reducing agents such as triphenylphosphine. N-Methylthio substituted lactams favor a conformation having the sulfur–carbon bond of the SMe group aligned orthogonally with respect to the ring, with a facile interconversion between the cis and trans rotamers. These N-methylthio substituted lactams show potent antimicrobial behavior towards Staphylococcus aureus, including drug-resistant forms, and are not hydrolyzed by β-lactamases. From the data presented, there is a strong suggestion that these lactams may operate through a chemical and biological mechanism of action that is different from all previous classes of β-lactam drugs.

Novel sulphur-containing banana-shaped liquid crystal molecules

In this preliminary report we present the mesomorphic properties and electro-optic investigations of three new 'banana-shaped' mesogens. The materials are structurally similar to Niori's the original bent-core materials but possess alkylthio substituents in place of alkoxy substituents. Microscopic investigations revealed an unusual 'spiral-domain texture', similar to that observed in the 'B7' phase of related materials. Further investigations support our earlier observations that the materials display antiferroelectric switching in this phase, in two of the new materials studied. The nature of this phase, in comparison with the 'switchable' (B2) and 'chiral-domain' (B4) phases of the original materials, is discussed.

Catalytic enantioselective Michael additions to unsaturated ester derivatives using chiral copper(II) Lewis acid complexes.

[formula: see text] Chiral Cu(II) bisoxazoline (box) Lewis acids have been developed as catalysts of the Michael addition of enolsilanes to unsaturated ester derivatives. While enantioselection is stereoregular, the sense of diastereoselection is directly related to thioester enolsilane geometry: (E) enolsilanes give anti adducts and (Z) enolsilanes afford syn adducts. The size of the enolsilane alkylthio substituent directly impacts the magnitude of diastereoselection.

Fundamental Solution Properties of 4-Hydroxy-1,3,3a,7-tetraazaindenes

The ultraviolet (UV) spectra and the pKa and pKsp of 14 different variations of 4-hydroxy-1,3,3a,7-tetraazaindene (TAI) measured in water at 25°C are discussed in this report. The acidity of the tautomeric proton correlated with the inductive electronic effect of the substituent as measured by Hammett' σρ constants; pKa values obtained potentiometrically and spectrophotometrically ranged from 3.4 to 6.5. The solubility products of the 1:1 TAI:Ag salts were measured at equilibrium using a solid-state silver sulfide electrode. The pKsp values ranged from 9.6 to 12.9 and increased with substituent bulk at the 2 position and with electron-withdrawing substituents at the 5 position. Oxidation of an alkylthio substituent at either the 2 or 5 position decreased the pKsp value. A carboxylic acid group at the 2 position yielded a soluble silver complex with log β1 of 7.9; however, carboxylic acid substitution at the 5 position yielded a sparingly soluble salt with pKsp of 10.4. Values of pKa and pKsp were observed to be correlated only for substituents in definite homologous series; however, there was no general correlation within the 14 examples.

Tetrathia Macrocycle-bridged Dimeric with Hexakis (alkylthio) Substituents and Network Polymer Phthalocyanines

1,4,7,10-Tetrathia (12-crown-4)-bridged new polymeric phthalocyanines 9 and 10 have been synthesized by the reaction of tetracyanodibenzo[1,4,7,10-tetrathia (12-crown-4)] in the presence of a strong organic base or Zn ( OAc )2 respectively. Furthermore, 1,4,7,10-tetrathia (12-crown-4)-linked peripherally octa-substituted dimeric phthalocyanine 12, which contains a combination of hexakis(alkylthia) side chains was synthesized by the reaction of subphthalocyanine 11 with the iminoisoindoline derivative 8. The new compounds have been characterized by elemental analyses, IR, UV/vis, mass, 1 H NMR and 13 C NMR spectroscopy. The thermal stabilities of the compounds were determined by thermogravimetric analysis. The electrical conductivity of the polymeric, 9 and 10, and dimeric phthalocyanines, 12 and 13, are in the semiconductor range; chemical doping with NOBF 4 increases the d.c. conductivity of 10 by a factor of four.

Tetrathia macrocycle‐bridged dimeric with hexakis (alkylthio) substituents and network polymer phthalocyanines

Tetrathia macrocycle‐bridged dimeric with hexakis (alkylthio) substituents and network polymer phthalocyanines

Electronic Structures of the Polydiacetylene Derivatives Bearing Sulfur Atoms Directly Bound to the Polymer Main Chains

We synthesized new types of polydiacetylenes (PDAs) bearing alkylthio groups directly bound to the conjugated main chains. Exciton absorption maxima of the obtained PDAs appeared at 750 nm, which was 50 nm longer than those of PDAs substituted with arylthio groups. The stronger electron donating ability of alkylthio substituents led to the smaller energy band gap in those PDAs.

Hexakis(alkylthio)‐Substituted Unsymmetrical Phthalocyanines

Cyclotrimerization of 4,5‐bis(hexylthio)phthalodinitrile (1) in 1‐chloronaphthalene in the presence of BCl3 leads to the subphthalocyanine 4. Unsymmetrical phthalocyanines (5, 6) with six alkylthio substituents on three of the benzenoid units are synthesized by the reaction of 4 with an diiminoisoindoline derivative (R′ = H or NO2). These extremely soluble compounds are characterized by IR, 1H‐ and 13C‐NMR as well as UV/Vis spectra.

Synthesis and antimicrobial activity of novel 3-[(aminopyrimidiniumyl)thio]methyl cephalosporins.

A series of novel cephalosporin compounds which have 3-[(aminopyrimidiniumyl)thio]methyl substituents was synthesized. They show high antimicrobial activity against various bacterial species including Pseudomonas aeruginosa. Structure-activity relationships with various thiopyrimidines, thiopyrimidiniums, bicyclic thiotriazolopyrimidiniums, and bicyclic thioimidazolopyrimidiniums as 3'-substituents were also studied; cephalosporins with quarternized pyrimidinium moieties have better antimicrobial activities than neuteral pyrimidine cephalosporins, and stabilization of the positive charge on the pyrimidinium moieties is essential for better activity. According to semiempirical PM3 calculations, amino and alkylthio substituents on the pyrimidinium rings play a major role in charge stabilization and delocalization.

Oxidation of alkylthio substituted tricarbonyl(η6-arene)chromium(0) complexes to alkylsulfinyl substituted tricarbonyl(η6-arene)chromium(0) complexes

Dimethyldioxirane efficiently oxidises tricarbonylchromium(0) complexes of alkylthio substituted arenes to tricarbonylchromium(0) complexes of alkylsulfinyl substituted arenes. The diastereoselectivity of oxidation of ortho substituted complexes, which was determined by inter alia X-ray crystal structure analyses of tricarbonyl[η6-1-methoxy-2-(methylsulfinyl)benzene]- chromium(0)20x, [η6-1-(tert-butylsulfinyl)-2-methoxybenzene]tricarbonylchromium(0)23x and tricarbonyl[η6-1-(ethylsulfinyl)-2-methoxybenzene]chromium(0)21y, is dependent on the alkylthio substituent and is reversed when this substituent is changed from methylthio to tert-butylthio.