A simple and convenient protocol for the synthesis of seven- and eight-membered phosphorus heterocycles

A simple procedure for the synthesis of eight-membered 6-(2-chloroethyl)/bis(2-chloroethyl)-amino-12-oxo-dibenzo[d,g][1,3,2]dioxaphosphocin 6-oxides (3a–b) and seven-membered 6-(2-chloroethyl)/bis-(2-chloroethyl)aminodibenzo[d,f][1,3,2]dioxaphosphepin 6-oxides (5a–b) from cyclocondensation of equimolar ratios of 2,2′-dihydroxybenzophenone (1) and 2,2′-dihydroxybiphenol (4), respectively with 2-chloroethylphosphonicdichloride (2a) and bis(2-chloroethyl)phosphoramidic dichloride (2b) in dry toluene in the presence of triethylamine at 45–50 °C is described. All synthesized compounds possessed significant growth inhibition for their antibacteria against ‘Bacillus subtilis’ and ‘Klebsiella pneumonia’ and antifungi activity on “Curvularia lunata” and “Aspergillus niger.”     

Curing Studies of New Polyimide Model Compounds with Molecular Weights of About 1000 g/MOL

Abstract

Two new polyimide model compounds with molecular weights of ～1000 g/mol have been synthesized. While the amino terminated compound, 4,4′-bis-N-[N′-(4-aminophenoxy-4′-phenyl)-pyromellitimido]diphenylether,O(PO)₂, undergoes a branching or crosslinking side reaction, the corresponding anhydride terminated oligomer N,N′-bis[4(N-(3′,4′-bishydroxycarbonyl)phthal-imido)phenoxy-4′-phenyl]pyromellitimide dianhydride, P(OP)2, loses its anhydride functionality completely upon thermal treatment. In the case of O(PO)₂, the formed C=N species can be detected with Raman spectroscopy rather than FT-IR spectroscopy because of its low molecular absorptivity in the infrared region. The formation of imine bonds caused by the attack of terminal amino groups on the imide carbonyl group is evident by the appearance of peaks at about 1665 cm-¹ in the Raman spectra. The same behavior can be observed in bulky polyimides blended with an increasing amount of O(PO)2 upon curing.     

DNA-binding and cleavage activity of polypyridyl ruthenium(II) complexes

Polypyridyl ruthenium(II) complexes [Ru^II(3-bptpy)(dmphen)Cl]ClO₄ (1), [Ru^II(3-cptpy)(dmphen)Cl]ClO₄ (2), [Ru^II(2-tptpy)(dmphen)Cl]ClO₄ (3), and [Ru^II(9-atpy)(dmphen)Cl]ClO₄ (4) {where 3-bptpy?=?4′-(3-bromophenyl)-2,2′:6′,2″-terpyridine, 3-cptpy?=?4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine, 2-tptpy?=?4′-(2-thiophenyl)-2,2′:6′,2″-terpyridine, 9-atpy?=?4′-(9-anthryl)-2,2′:6′,2″-terpyridine, dmphen?=?2,9-dimethyl-1,10-phenanthroline} have been synthesized and characterized. The DNA-binding properties of the complexes with Herring Sperm DNA have been investigated by absorption titration and viscosity measurements. The ability of complexes to break the pUC19 DNA has been checked by gel electrophoresis. The experimental results suggest that all the complexes bind DNA via partial intercalation. The results also show that the order of DNA-binding affinities of the complexes is 4?<?3?<?2?<?1, confirming that planarity of the ligand in a complex is very important for DNA-binding.     

Dielectric study of ferroelectric side-chain liquid crystalline polysiloxanes with broad temperature ranges of the chiral smectic C phase 1. Structure dependence of dielectric relaxation

The dielectric behavior of a series of ferroelectric side-chain liquid crystalline polysiloxanes containing 1–3 oligooxyethylene units as spacers, and 4-(S)-2-methyl-1-butyl[[[(4-hydroxy-biphenyl-4′-yl)]carbonyl]oxy] benzoate or 4-(S)-2-methyl-1-butyl[[(4-hydroxy-biphenyl-4′-yl)carbonyl]oxy]-3-fluoro benzoate side groups was studied by broadband dielectric spectroscopy. The increase of the spacer length, and incorporation of a strong dipole moment fluoro-substituent into the mesogenic group, resulted in a decrease of the relaxation activation energy and an increase in the intensity of the relaxation. Moreover, the relaxation peak of the Goldstone mode has only been observed for the FLCP with a lateral fluoro-substituent. The relationship between the thermal dynamic behavior and chemical structure is discussed in detail. Furthermore, analysis of the dielectric relaxation behavior of these FLCPs showed that the molecular relaxations could be described by the Cole-Cole equation. © 1996 John Wiley & Sons, Inc.     

Effect of substituents on DNA-binding behaviors of ruthenium(II) complexes: [Ru(dmb)2(dtmi)]2+ and [Ru(dmb)2(dtni)]2+

Two Ru(II) complexes [Ru(dmb)₂(dtmi)](ClO₄)₂ (1) (dmb = 4, 4′-dimethyl-2, 2′-bipyridine, dtmi = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-methoxylisatin) and [Ru(dmb)₂(dtni)](ClO₄)₂ (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. DNA-binding behaviors of these complexes have been investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. The results indicate that the two complexes interact with calf thymus DNA by intercalation.     

Efficient synthesis of a new ditopic bipyridine–terpyridine bridging ligand

Abstract

The novel bipyridine–terpyridine–phenazine ligand 6-pyrid-(tetrapyrido[2,3-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine (I) was prepared by condensation reaction of 5,6-diamino-l,10-phenanthroline (4) and 2-(pyrid-2′-yl)-1,10-phenanthroline-5,6-dione (6) and characterized using conventional methods. Poor solubility of the ligand led us to the preparation of its Ru(II) complexes to investigate the change in its solubility for further characterizing the ligand on the metal ion. [Ru(ttp)(I)](PF₆)₂ complex was prepared using the reaction of the ligand (I) and [Ru(ttp)Cl₃] complex, where ttp is 4′-(4-Methylphenyl)-2,2′:6′,2′′-terpyridine. A different route for the preparation of [Ru(ttp)(I)](PF₆)₂ was introduced. Synthesis of the ligand (I) on the complex by a condensation reaction of [Ru(ttp)(6)](PF₆)₂, where ligand (6) is 2-(pyrid-2′-yl)-1,10-phenanthroline-5,6-dione, with 5,6-diamino-l,10-phenanthroline (4) was conducted. The spectroscopic measurements of both products which have been obtained through the two different routes were compared. We observed that the NMR, LC-MS, and UV spectra of the both products were identical.     

Synthesis and characterization of spiro-, ansa-, and spiro-ansa-cyclic derivatives of cyclotetraphosphazene with the reactions of pentane-1,5-diol

The reactions of octachlorocyclotetraphosphazatetraene, N₄P₄Cl₈ (1) with difunctional aliphatic reagent, HO-(CH₂)₅-OH (3) have aroused a good deal of attention, and four types of products have been realized: one 2-open chain-(1′-oxy-5′-hidroxy-pentane)-2,4,4,6,6,8,8-heptachlorocylotetraphosphazatetraene, N₄P₄Cl₇[O(CH₂)₅OH] (4); one 2,2-mono-spiro-(1′,5′-pentanedioxy)-4,4,6,6,8,8-hexachlorocyclotetraphosphazatetraene, N₄P₄Cl₆[O(CH₂)₅O] (5); its isomers 2,4-mono-ansa-((1′,5′-pentanedioxy)-2,4,6,6,8,8- hexachlorocyclotetraphosphazatetraene (6) and 2,6-mono-ansa-(1′,5′-pentanedioxy)-2,4,6,6,8,8-hexachlorocyclotetraphosphazatetraene (7); one 2,2,6,6-dispiro-(1′,5′-pentanedioxy)-4,4,8,8-tetrachlorocyclo- tetraphosphazatetraene, N₄P₄Cl₄[O(CH₂)₅O]₂ (8); two isomeric 2,4,6,8-bisansa-(1′,5′-pentanedioxy)-2,4,6,8-tetrachlorocyclotetraphosphazatetraene (9) and 2,6,4,8-bisansa-(1′,5′-pentanedioxy)-2,4,6,8-tetrachloro-cyclotetraphosphazatetraene (10); one 4,4,8,8-dispiro-2,6-ansa- (1′,5′-pentanedioxy)-2,6-dichlorocyclotetra-phosphazatetraene, N₄P₄Cl₂[O(CH₂)₅O]₃ (11), one 2,2,4,4,6,6-trispiro-(1′,5′-pentanedioxy)-8,8-dichlorocyclo-tetraphosphazatetraene, N₄P₄Cl₂[O(CH₂)₅O]₃ (12); and a 2,2,4,4,6,6,8,8-tetraspiro-(1′,5′-pentanedioxy)-cyclotetraphosphazatetraene derivative, N₄P₄[O(CH₂)₅O]₄, (13). The respective structures were deduced by means of elemental analysis, mass spectrum, and ³¹P, ¹H, and ¹³C nuclear magnetic resonance spectroscopic investigations.     

Synthesis,Characterization, and Thermotropic Properties of Liquid Crystals with an Oligo (Ethylene Oxide) Monomethyl Substituent I: Biphenyl-Based Systems

New alkene liquid crystals 4-[oligo(ethylene oxide)_o, monomethylether)carbonyl]phenyl 4-[4(allyloxy) phenyl]benzoate(MBPBEn, n = 1-3), 4′-[oligo(ethylene oxide)_o, monomethylether)carbonyl]biphenyl-4-yl 4-[4-(al1yloxy)phenyl]benzoate(MBPBPEn, n = 1-3), (S)-4-[(2-methyl-I-butoxy)carbonyl]phenyl 4[4-(allyloxy)phenyl]benzoate(MBPBKA), and (S)-4′-[(2-methyl-l-butoxy)carbonyl]biphenyl-4-yl 4-[4(allyloxy)phenyl]benzoate(MBPBPKA) were synthesized and characterized using ¹H-NMR and elemental analysis methods. The thermal transition temperatures, mesomorphic properties, and mesophase textures of these compounds have been determined by differential scanning calorimetry (DSC), by polarizing optical microscopy, and by X-ray diffraction analysis. The effect of changes in chemical structure on the mesophase properties, mesophase and isotropic transition temperatures, and mesophase textures are discussed.     

Carbonyl complexes of rhodium(I) and rhodium(III) with 2,2′-biquinoline

Novel carbonyl complexes of rhodium(I) and rhodium(III) containing the bidenate nitrogen donor ligand 2,2′-biquinoline (biq) have been prepared; they are of the types RhX(CO)₂ biq and RhX(CO)biq (X = Cl, Br, I). Cationic carbonyl and substituted carbonyl complexes of the types [Rh(CO)₂biq]ClO₄ and [Rh(CO)biqL₂]ClO₄, where L is tertiary phosphine or arsine have also been isolated. In spite of considerable steric crowding around the nitrogen atoms, 2,2′-biquinoline behaves much like 2,2′-bipyridine in forming carbonyl complexes of rhodium.     

Synthesis and anticonvulsant activity of some new arylidenehydrazides and 4-thiazolidinones

Summary A number of N,N-bis(arylidene)mono(1-methylpropyl)malonic acid dihydrazides (3a–c), 1,1-bis[[(2-aryl-4-thiazolidinone-3-yl)amino]carbonyl]-2-methylbutanes (4a–e), and 1,1-bis[[(3-alkyl/aryl-4-thiazolidinone-2-yl)hydrazono]carbonyl]-2-methylbutanes (6a–i) have been synthesized, characterized and evaluated for anticonvulsant activity. All tested compounds showed significant activity (10 to 60% protection) against pentylenetetrazole induced seizures.

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Synthese einiger neuer Arylidenhydrazide und 4-Thiazolidinone sowie Untersuchung ihrer krampflösenden Eigenschaften

Zusammenfassung Eine Reihe von N,N-Bis(aryliden)mono(1-methylpropyl)malonsäure dihydraziden, (3a–c), 1,1-Bis[[2-Aryl-4-thiazolidinon-3-yl)amino]carbonyl]-2-methylbutanen (4a–e) und 1,1-Bis[[3-alkyl/aryl-4-thiazolidinon-2-yl)hydrazono]carbonyl]-2-methylbutanen (6a–i) wurden hergestellt, charakterisiert und auf ihre antikonvulsive Wirkung geprüft. Alle getesteten Substanzen zeigen relevante Aktivitäten gegen durch Pentilentetrazol induzierte Krämpfe (10–60% Schutz).

     

三有机锡（4R）-3-[[（2S）-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯的合成、结构和体外抗癌活性

利用三有机锡氢氧化物和手性配体（4R）-3-[[（2S）-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸（HL）反应合成了3个三有机锡（4R）-3-[[（2S）-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯R₃SnL[1,R=c-C₆H₁₁（a）,C₆H₅（b）,C₆H₅C（CH₃）₂CH₂（c）],通过元素分析、IR、¹H NMR和X-射线单晶衍射表征了其结构。化合物1a属正交晶系,P2₁2₁2₁空间群;化合物1b属单斜晶系,P2₁空间群。二者均为由羧基氧和内酰胺羰基氧桥联配位形成的右螺旋链状有机锡配位聚合物,锡原子具有五配位[SnC₃O₂]畸变三角双锥构型。化合物1a和1b对体外2种人癌细胞Colo205和Bcap37增殖均有强的抑制作用,其活性为1b >1a。     

Succinct and Facile Synthesis of Innovative Thiopyrimidines With Antimicrobial and Antitubercular Investigation

Abstract

To develop a series of bioactive heterocycles in minimum number of steps, 3-methyl- 4-(substituted phenyl)-1-phenyl-4,8-dihydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5,7 (1H,6H)-dithione 2(a–j), 4-(4-substituted phenyl)-5-imino-3-methyl-1,6-diphenyl-4,5,6,8-tetrahydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-7(1H)-thione 3(a–j), and N-[4-(subs- tituted phenyl)-3-methyl-1-phenyl-7-thioxo-1,4,7,8-hexahydropyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5-yl]thiourea 4(a–j) have been synthesized from amino nitrile functionality 1(a–j). The structures of the compounds were elucidated by IR, ¹H NMR, elemental analysis, and some representative ¹³C NMR and mass spectra. All the title compounds were screened for antimicrobial and antitubercular activities, while some representative compounds were tested for antioxidant activity. Out of synthesized compounds, compounds 1j (4-CH₃), 2d (4-F), 4c (4-OH), and 4i (3-Br) exhibited maximum inhibition against Mycobacterium Tuberculosis H₃₇Rv. Compound 3c (4-OH) revealed elevated efficacy against all tested bacterial strain, while compounds 1i (3-Br), 2c (4-OH), and 3h (3-NO₂) were found efficacious against Candida albicans as compared to standard drugs.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

三有机锡(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯的合成、结构和体外抗癌活性

利用三有机锡氢氧化物和手性配体(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸(HL)反应合成了3个三有机锡(4R)-3-[[(2S)-5-氧-2-吡咯烷基]羰基]-4-噻唑烷甲酸酯R3SnL[1,R=c-C6H11(a),C6H5(b),C6H5C(CH3)2CH2(c)],通过元素分析、IR、1H NMR和X-射线单晶衍射表征了其结构。化合物1a属正交晶系,P212121空间群;化合物1b属单斜晶系,P21空间群。二者均为由羧基氧和内酰胺羰基氧桥联配位形成的右螺旋链状有机锡配位聚合物,锡原子具有五配位[SnC3O2]畸变三角双锥构型。化合物1a和1b对体外2种人癌细胞Colo205和Bcap37增殖均有强的抑制作用,其活性为1b1a。     

Nucleotides. Part L. Aglycone protection by the (2-dansylethoxy)carbonyl (= {2-{[5-(dimethylamino)naphthalen-l-yl]sulfonyl}ethoxy}carbonyl; dnseoc) group a new variation in oligodeoxyribonucleotide synthesis

The (2-dansylethoxy)carbonyl (= {2-{[5-(dimethylamino)naphthalen-l-yl]sulfonyl}ethoxy}carbonyl; dnseoc) group was employed for protection of the amino functions of the aglycone residues. The lactam function of 2′-deoxyguanosine was on the one hand unprotected and on the other hand alkylated at O⁶ of the aglycone with the 2-(4-nitrophenyl)ethyl (npe) and 2-(phenylsulfonyl)ethyl (pse) group, respectively. The syntheses of monomeric building blocks, both phosphoramidites and nucleoside- functionalized supports, are described for the three common 2′-deoxynucleosides (2′-deoxycytidine, 2′-deoxyadenosine, 2′-deoxyguanosine). As kinetic studies with the tritylated nucleosides showed, the dnseoc group is more labile towards DBU cleavage than the corresponding 2-(4-nitrophenyl)ethyl-(npe) and [2-(4-nitrophenyl)ethoxy]carbonyl(npeoc)-protected analogues (see Table 2). These results were confirmed by the very fast deprotection rate of the dnseoc groups at some oligonucleotides.     

Synthesis and total 1H- and 13C-NMR assignment of cephem derivatives for use in ADEPT approaches

We report the synthesis and total NMR characterization of 5-thia-1-azabicyclo-[4.2.0]oct-2-ene-2-carboxylic acid-3-[[[(4'-nitrophenoxy)carbonyl]oxy]-methyl]-8-oxo-7-[(2-thienyloxoacetyl)amino]-diphenylmethyl ester-5-dioxide (5), a new cephalosporin derivative. This compound can be used as the carrier of a wide range of drugs containing an amino group. The preparation of the intermediate product, 5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid-3-[methyl 4-(6-methoxyquinolin-8-ylamino)pentylcarbamate]-8-oxo-7-[(2-thienyloxoacetyl)amino]-diphenylmethyl ester-5-dioxide (6), as well as the synthesis of the antimalarial primaquine prodrug 5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid-3-[methyl 4-(6-methoxyquinolin-8-ylamino)pentylcarbamate]-8-oxo-7-[(2-thienyloxoacetyl)amino]- 5-dioxide (7) are also described, together with their total (1)H- and (13)C-NMR assignments.     

Heteroleptic ruthenium(II) polypyridine complexes with a series of substituted 2,2′-bipyridine ligands

Five substituted-2,2′-bipyridine ligands L, (4-(p-methylphenyl)-6-phenyl-2,2′-bipyridine (L1), 4-(p-bromophenyl)-6-(p-bromophenyl)-2,2′-bipyridine (L2), 4-(p-bromophenyl)-6-phenyl-2,2′-bipyridine (L3), 4-phenyl-6-(p-bromophenyl)-2,2′-bipyridine (L4), and 4-(p-fluorophenyl)-6-(p-fluorophenyl)-2,2′-bipyridine (L5) were synthesized by stepwise formation. Reaction of cis-[RuCl₂(bpy)₂]?2H₂O or cis-[RuCl₂(phen)₂]?2H₂O and the substituted-2,2′-bipyridine ligands in the presence of KPF₆ afforded the corresponding cationic polypyridine-ruthenium complexes of the type [(bpy)₂Ru(L)](PF₆)₂ (bpy = 2,2′-bipyridine, 1–5) or [(phen)₂Ru(L)](PF₆)₂ (phen = 1,10-phenanthroline, 6–10), respectively. All complexes have been spectroscopically characterized by UV–vis, luminescence, and electrogenerated chemiluminescence. The structures of 1?CH₃COCH₃, 3?CH₃COCH₃, 5?2CH₃COCH₃, 6, 8, 9, and 10 have been determined by single-crystal X-ray diffraction.     

Synthesis and properties of 5-(1,2-dihaloethyl)-2′-deoxyuridines and related analogues

The regiospecific reaction of 5-vinyl-3′,5′-di-O-acetyl-2′-deoxyuridine ( 2 ) with HOX (X = Cl, Br, I) yielded the corresponding 5-(1-hydroxy-2-haloethyl)-3′,5′-di-O-acetyl-2′-deoxyuridines 3a-c . Alternatively, reaction of 2 with iodine monochloride in aqueous acetonitrile also afforded 5-(1-hydroxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3c ). Treatment of 5-(1-hydroxy-2-chloroethyl)- ( 3a ) and 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with DAST (Et₂NSF₃) in methylene chloride at -40° gave the respective 5-(1-fluoro-2-chloroethyl)- ( 6a , 74%) and 5-(1-fluoro-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6b , 65%). In contrast, 5-(1-fluoro-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6e ) could not be isolated due to its facile reaction with methanol, ethanol or water to yield the corresponding 5-(1-methoxy-2-iodoethyl)- ( 6c ), 5-(1-ethoxy-2-iodoethyl)- ( 6d ) and 5-(1-hydroxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3c ). Treatment of 5-(1-hydroxy-2-chloroethyl)- ( 3a ) and 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with thionyl chloride yielded the respective 5-(1,2-dichloroethyl)- ( 6f , 85%) and 5-(1-chloro-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6g , 50%), whereas a similar reaction employing the 5-(1-hydroxy-2-iodoethyl)- compound 3c afforded 5-(1-methoxy-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6c ), possibly via the unstable 5-(1-chloro-2-iodoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine intermediate 6h . The 5-(1-bromo-2-chloroethyl)- ( 6i ) and 5-(1,2-dibromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6j ) could not be isolated due to their facile conversion to the corresponding 5-(1-ethoxy-2-chloroethyl)- ( 6k ) and 5-(1-ethoxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 61 ). Reaction of 5-(1-hydroxy-2-bromoethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 3b ) with methanolic ammonia, to remove the 3′,5′-di-O-acetyl groups, gave 2,3-dihydro-3-hydroxy-5-(2′-deoxy-β-D-ribofuranosyl)-furano[2,3-d]pyrimidine-6(5H)-one ( 8 ). In contrast, a similar reaction of 5-(1-fluoro-2-chloroethyl)-3′,5′-di-O-acetyl-2′-deoxyuridine ( 6a ) yielded (E)-5-(2-chlorovinyl)-2′-deoxyuridine ( 1b , 23%) and 5-(2′-deoxy-β-D-ribofuranosyl)furano[2,3-d]pyrimidin-6(5H)-one ( 9 , 13%). The mechanisms of the substitution and elimination reactions observed for these 5-(1,2-dihaloethyl)-3′,5′-di-O-acetyl-2′-deoxyuridines are described.     

Syntheses,characterization, and X-ray crystal structures of two cis-dioxovanadium(V) complexes of pyrazole-derived,Schiff-base ligands

Two mononuclear cis-dioxovanadium(V) complexes of pyrazole-derived, Schiff-base ligands have been synthesized and characterized. Single crystal X-ray analyses were performed with N ′-[(3-methyl-1H-pyrazole-5-yl)carbonyl]pyridine-2-carbohadrazonamido cis-dioxovanadium(V), {[VO₂(PzOAP)] · H₂O} (1), and 5-methyl-N-[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazonate cis-dioxovanadium(V), {[VO₂(PzCAP)]} (2). Both complexes crystallize in monoclinic crystal systems with different space groups. Complex 1 crystallizes in the space group P21/c, 2 in space group C2/C. In each complex, the vanadium sits within a distorted square pyramidal geometry with an N₂O₃ chromophore. The τ parameters of the complexes (0.33 for 1, 0.22 for 2) support their square pyramidal geometry. The interesting finding in the work is that the alkoxide oxygen, imino nitrogen, and pyridine nitrogen take part in the coordination process leaving the pyrazole rings inactive in coordination.     

Azomesogens containing a β-chloroethyl terminal chain: synthesis and characterisation

In this paper, we present the synthesis and characterisation of two new mesogenic homologous series, β-chloroethyl 4-(4′-n-alkoxyphenylazo) benzoates (I) and the β-chloroethyl [4-(4′-n-alkoxybenzoyloxy)phenylazo]-4”-benzoates (II), containing a terminal β-chloro ethyl chain. Series I was synthesised by alkylation of β-chloroethyl 4-(4′-hydroxy phenylazo) benzoate with an appropriate alkyl halide, whereas series II was synthesised by esterification of β-chloroethyl 4-(4′-hydroxyphenylazo) benzoate with an appropriate 4-n-alkoxybenzoic acid. The molecular structures of these new compounds of both the series were characterised by combination of element analysis and a standard spectroscopic method. The mesomorphic behaviour was studied mainly by use of a polarised microscope and, in some cases, differential scanning calorimeter as well. In series I, all nine members synthesised exhibited only an enantiotropic smectic A mesophase. In series II, all 12 homologues exhibited an enantiotropic nematic mesophase; a smectic A phase appeared in the n-octyloxy derivative as an enantiotropic phase and persisted through to the n-hexadecyloxy member. The mesomorphic properties of both series were compared with each other and also with the properties of other structurally related series to evaluate the effects of the β-chloroethyl tail on mesomorphism.     

SYNTHESIS AND CHEMISTRY OF SOME NEW 2-MERCAPTOIMIDAZOLE DERIVATIVES OF POSSIBLE ANTIMICROBIAL ACTIVITY

4,5-Diaryl-2,3-dihydro-2-mercaptoimidazoles (2a–e) were synthesized. They reacted with chloroacetic acid in gl. acetic acid/Ac ₂ O in presence of anhyd. sodium acetate afforded 5,6-diaryl-2,3-dihydro-imidazo[2,1-b]thiazol-3-ones (3a–d). Also these compounds were prepared by the action of chloroacetyl chloride on compounds (2) in pyridine. Compounds (3a–d) on condensation with aromatic aldehydes yield 2-arylmethylene-5,6-diaryl-2,3-dihydroimidazo[2,1-b]-thiazol-3-ones (4a–q). The latter compounds were prepared directly by the reaction of (2) with chloroacetic acid and the aromatic aldehydes. Compounds (3a–d) coupled with aryldiazonium salts in pyridine to give 2-arylhydrazono-5,6-diaryl-2,3-dihydroimidazo[2,1-b]thiazol-3-ones (5a–r). Also compounds (2) when reacted with 2 or 3-bromopropionic acid afford 2,3-di-hydro-5,6-diaryl-2-methylimidazo[2,1-b]thiazol-3-ones (6a–d) and 2,3-di-hydro-6,7-diaryl imidazo-[2,1-b]-1,3-thiazin-4-ones (7a–d), respectively. Compounds (3, 6, and 7) have been cleaved by aromatic amines to give the corresponding 2-(4′,5′-diaryl-2′,3′-dihydroimidazol-2′-yl)thioacetanilide (8a–f), 2-(2′,3′-dihydro-4′,5′-diaryl imidazol-2′-yl)thiopropionamide (9a–c), and 3-(2′,3′-dihydro-4′,5′-diaryl-imidazol-2′-yl)thiopropionamide (10a–d) respectively. All the prepared compounds show considerable antimicrobial activity against bacteria, yeast, and fungi.