Mesomorphic and dielectric properties of the p-n-hexyloxybenzoic acid-p-n-heptyloxybenzoic acid liquid crystal system

Thep-n-hexyloxybenzoic acid (I)-p-n-heptyloxybenzoic acid (II) system was investigated by thermal and X-ray phase analyses and dielcometry. Solid solutions of three types were found in the low-temperature region of the system, namely, solid solution based on I (up to 15 mol % II); solid solution based on a compound with the equimolar ratio of the components (γ); and solid solution based on II (>15 mol % II). The range of the two-phase equilibrium (N + I) was 2°–4°; a continuous nematic solution (N) formed in the system. The temperature and composition dependences of dielectric anisotropy Δ? were characterized. The γ compound showed negative dielectric anisotropy, Δ? = ?1.4, which was constant over the whole temperature range of the nematic phase.     

Prediction, synthesis and investigation of mesomorphism of new octa(benzo-15-crown-5)-substituted derivatives of phthalocyanine and its metallo complexes [Zn(II), Ni(II)]

First calculation of molecular parameters (MP) of new octa-(benzo-15-crown-5)-substituted phthalocyanine derivatives and of its metallo complexes Zn(II), Ni(II) (Ib, Ic) is carried out. A prediction was made of the possible formation therefrom of metaphases, and for that purpose the synthesis of these compounds and investigation of their mesomorphic properties was performed. For compounds Ia-Ic the formation of high-temperature enantiotropic mesophases was established typical for discotic mesogenes, in good agreement with the prediction. Proceeding from the data on miscibility of 2,3,9,10,16,17,23,24-octa-[(4′-benzo-15-crown-5)-oxy]-phthalocyanine Ia with discotic mesogene 2,3,6,7,10,11-hexa(cyclohexanebenzoyloxy)triphenylene (II) displaying nematic mesomorphism the compound Ia was assigned to the group of nematic mesogenes and by the texture of the mixture to discotic mesogenes forming columnar type nematic phase (N _Col). Convergence of the results of prediction and experimental data is about 83%.     

Peculiarities of the phase behavior of 1,3,3′,5,5′-alkoxybenzoate biphenyls in mixtures with chiral and discotic mesogenes

A synthesis of 1,3,3′,5,5′-alkanoyloxy-(Ia) and 1,3,3′,5,5′-alkoxybenzoate biphenyls (Ib) has been performed. Peculiarities of phase behavior of liquid crystalline 1,3,3′,5,5′-alkoxybenzoate biphenyls (Ib) in mixtures with discotic (1-nitro-2,3,6,7,10,11-hexadecyloxytriphenylene — II and triphenylene 2,3,6,7,10, 11-hexaundecyloxybenzoate — III) and chiral (cholesterol undecylate — IV) were studied with the aim of identifying the type of mesomorphysm. Ib was found to be mutually soluble with II and III and partially soluble with IV. The construction and analysis of the phase diagram of the mixtures of I with II throughout the range of concentrations makes it possible to assign the studied biphenyl Ib to discotic mesogens. An area of the smectic phase, which is formed from the chiral nematic IV and the discotic mesogen Ib (which displays dimorphism in the mesophase) have been found for the first time in the mixtures of these compounds. During cooling, in the mixture with molar ratio 1:1 dendritic textures with grained branches are formed, which are similar to those described in literature for TGB (twist grain boundary) phases. Relying on our studies, we suggest that Ib has a columnar type of the structure in the low-temperature area and a nematic, probably chiral, type in the high-temperature area of the mesophase.     

Novel metallomesogens derived from heterocyclic benzoxazoles

The synthesis, mesomorphic behavior, and optical properties of a new series of transition metal complexes 1a and 1b derived from benzoxazoles 2 are reported. The crystal and molecular structure of copper complex of 6-dodecyloxynaphthalene-2-carboxylic acid 4-(6-hexyloxybenzooxazol-2-yl)-3-hydroxyphenyl ester 1a (n=6; m=12) was determined by means of X-ray structural analysis, and it crystallizes in the triclinic space group P-1. The geometry at copper center is perfectly square-planar, and the overall molecular shape is considered as rod-shape. All precursors 2 with shorter chains (n=0, 1, 4) exhibited nematic, and all others with longer chains (n=6, 7, 8, 10, 12) formed N/SmC phases. In contrast, all copper(II) complexes 1a and palladium complexes 1b formed N phase. On the other hand, the temperature range of mesophase in compound 1a was wider than those in compound 1b. The difference of the mesomorphic properties in compounds 1a and 1b was attributed to the geometry or/and the size of the metal center. The fluorescent properties of these compounds were also examined.     

Synthesis and mass spectral fragmentation patterns of some nitrogen heterocycles with antimicrobial activity

5-(P-tolyl)-2-[(3-bromo-4-methoxy benzylidene) hydrazino]-thiazole 3, 3-[(3-bromo-4-mehtoxy benzylidine) amino]-2-thiohydantion 5, and 4,6-disubstituted-3-[(3-bromo-4-methoxybenzyliden) amino]-2-thioxo pyrimidines 10 have been prepared via cyclization of 3-bromo-4-methoxy benzaldehyde thiosemicarbazone 2 with 4-methyl phenacyl bromide, ethyl chloroacetate, and dicarbonyl compounds in different conditions. Acetylation of 3 and 5 with acetic anhydride gave the corresponding monoacetyl derivatives 4 and 6, while the acetylation of 5 with acetic anhydride in the presence of fused sodium acetate gave diacetyl derivative 7. Condensation of compound 5 with benzaldehyde in the presence of piperidine yielded the corresponding 3-substituted-5-benzylindene 2-thiohydation 8. Acetylation of compound 8 with acetic anhydride gave the corresponding 1-acetyl-3-substituted-5-benzylidene-2-thiohydantion 9. The mass spectral fragmentation patterns of some prepared compounds are investigated in order to elucidate the structure of the synthesized nitrogen heterocycles.     

Hybrid molecular nanostructures with donor-acceptor chains

We have fabricated hybrid molecular chain structures formed by electron acceptor compound 1 and electron donor molecules 2 and 3 at the liquid/solid interface of graphite surface.The structural details of the mono-component and the binary assemblies are revealed by high resolution scanning tunneling microscopy (STM).Compound 1 can form two well-ordered lamellar patterns at different concentrations.In the co-adsorption structures,compounds 2 and 3 can insert into the space between molecular chains of compound 1 and form large area well-ordered nanoscale phase separated lamellar structures.The unit cell parameters for the coassemblies can be "flexibly" adjusted to make the electron donors and acceptors perfectly match along the molecular chains.Scanning tunneling spectroscopy (STS) results indicate that the electronic properties of individual molecular donors and acceptors are preserved in the binary self-assembly.These results provide molecular insight into the nanoscale phase separation of organic electron acceptors and donors on surfaces and are helpful for the fabrication of surface supramolecular structures and molecular devices.     

Synthesis, X-ray structural analysis, and cytotoxic activity of some new androstane d-homo lactone derivatives

A series of d-homo lactones 4?C10 from dehydroepiandrosterone 1 via 16-hydroximino derivatives 2 and 3 were synthesized. The d-homo lactone 4 was transformed by the Oppenauer oxidation to obtain compound 5. The (Z)-2-hydroxymethylene-4-en-3-one compound 6, was obtained through reaction of 4-en-3-one compound 5 with ethyl formate and sodium hydride. The epoxides 8 and 9 were prepared from compound 7 by oxidation with m-chloroperbenzoic acid. Compound 10 was obtained by treating epoxides 8 and 9 with chromium(VI)-oxide. The structure of compounds 6 and 10 were confirmed by X-ray structural analysis. These derivatives were screened for antitumor activity against three tumor cell lines (human breast adenocarcinoma ER+, MCF-7, human breast adenocarcinoma ER?, MDA-MB-231, prostate cancer AR?, PC-3), and one human non-tumor cell line, MRC-5. Compounds 4, 7, 8, and 10 exhibited significant antitumor activity against MDA-MB-231 cells, while compound 5 showed strong cytotoxicity against MDA-MB-231. No compounds displayed toxicity against MRC-5 cells.     

Synthesis of (zinc(II) phthalocyanine)-containing cellulose derivative using phthalocyanine-ring formation reaction

2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) cellulose (5) was synthesized from cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl cellulose (4). The key reaction was phthalocyanine-ring formation on a cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.     

Synthesis and characterization of azocalix[4]arene ester and ketone derivatives incorporated in a polymeric backbone with bisphenol-A and their cation-binding properties

This study comprises synthesis and characterization of azocalix[4]arene compounds having copolymeric structures. The novel bisazocalixphenol-A and copolymer containing pendant azocalix[4]arene units with ester (5) and ketone (6) functionalities at their lower rim have been synthesized via diazo-coupling reaction. The phase transfer study is performed by liquid?Cliquid extraction method. It has been deduced from the observations that their precursors 25,26,27-tribenzoyloxy-28-hydroxy-5-(4-aminophenylazo)calix[4] arene (3), 25,27-diacetoniloxy-26,28-dihydroxy-5,17-(4-aminophenylazo)calix[4]arene (4) and bisazocalixphenol-A (5) show a good phase transfer affinity towards selected transition metal cations, unlike copolymer (6). These compounds are studied by the selective extraction of Fe³⁺ cation from the aqueous phase into the organic phase and it is carried out using compounds 1?C6. It is observed that the reduced azocalix[4]arene 4 is the most efficient (82.93?%) carrier of all compounds (3?C6) in the extraction of Fe³⁺ at pH 5.4.     

Studies on heterocyclization of acetoacetanilide

Base-induced cyclocondensation of acetoacetanilide (1) and benzoyl isothiocyanate (2) afforded mercaptopyridine (4). Compound 4 reacted with NaOCl in presence of NH₄OH/NaOH to produce isothiazolopyridine (6). Heterocyclization of 4 by ethyl bromoacetate and/or phenacyl bromide afforded pyridothiazapene and pyridine derivatives 7, 8, respectively. The synthesis of pyrazolopyridine (9) was achieved by reaction of 4 with hydrazine hydrate. Oxidative cyclization of 4 by Br₂ produced isothiazolopyridine (10). Chlorination of compound 4 yielded isothiazolopyridine dioxide (11). Compound 1 transformed into pyrane derivatives 12 and 13 by reaction with benzylidenemalononitrile and benzylideneacetophenone, respectively. Heterocyclization of compound 1 by ethylcyanoacetate and diethyloxalate afforded pyridine and cyclopentane derivatives 14 and 15, respectively. Compound 1 heterocyclized to indenopyrane (16) or indenopyrrole (17) upon reacted with ninhydrin on cold and hot condition, respectively. Heterocyclization of compound 1 and benzilmonohydrazone afforded pyridazine derivative 18. Coupling of 1 with diazonium salt afforded hydrazone 19 which cyclized using CS₂/KOH gave pyridazine derivative 20.     

One-dimensional metal phosphonates based on 6-phosphononicotinic acid: A structural and magnetic study

The reactions of 6-phosphononicotinic acid (pnaH₃) and metal salts result in three new compounds, namely, M(pnaH)-(H₂O)₃·H₂O [M = Co(II) (1), Ni(II) (2), Zn(II) (3)]. These compounds are isostructural and contain 2₁ helical chains made up of corner-sharing {MO₅N} octahedra and {PO₃C} tetrahedra. The chains are further connected by extensive hydrogen bonds to form a three-dimensional supramolecular structure. Magnetic studies reveal that dominant antiferromagnetic interactions are mediated in both 1 and 2. Interestingly the dehydrated compound 1 shows metamagnetic behavior at low temperature.     

Synthesis and characterization of benzothiazol-2-one derivatives as anti-inflammatory and analgesic agents

A series of new compounds bearing a 1,3-benzothiazol-2-one nucleus have been synthesized using 5,6-dimethyl-3-(2-oxo-propyl)-1,3-benzothiazol-2-one (1) as a key starting compound. The reaction of 1 with some nucleophilic compounds led to the formation of compounds 2, 3, 4, 5a, b, 6 and 7a, b. The thiosemicarbazone derivatives 7a, b were treated with a number of halo ketones to produce the new heterocyclic compounds 9–13, while their reaction with acid anhydrides led to the formation of the derivatives 14 and 15. Also, compound 1 was condensed with different aromatic aldehydes to afford the corresponding chalcones 18–22. The structures of all the novel compounds have been determined by analytical and spectral data. Some of the compounds were selected to be evaluated as anti-inflammatory and analgesic agents.     

Dipyrrolylquinoxaline-bridged hydrazones: a new class of chemosensors for copper(II)

Novel 2,3-bis(1H-pyrrol-2-yl)quinoxaline-functionalized hydrazones were prepared and characterized as new chemosensors for copper(II) ion. The binding properties of the compounds 4, 5, 6 and 7 for cations were examined by UV–vis, fluorescence spectroscopy, and linear sweep voltammetric experiments (LSV). The results indicate that a 1:1 stoichiometric complex is formed between compound 4 (or 5, 6, 7) and copper(II) ion, and the association constant is 1.3?×?10⁵ M^?1 for 4, 2.1?×?10⁶ M^?1 for 5, 4.1?×?10⁵ M^?1 for 6 and 8.0?×?10⁵ M^?1 for 7, respectively. The recognition mechanism between compound 4 (or 5, 6, 7) and metal ion was discussed based on their electrochemical properties, absorbance changes, and the fluorescence quenching effect when they interact with each other. Control experiments revealed that compound 4 (or 5, 6, 7) has a highly selective response to copper (II) ion.     

The synthesis of some new imidazole and triazole derivatives: crystal Structure and DFT-TDDFT investigation on electronic structure

A series of new N′-3-(1H-imidazol-1-yl)propylcarbamoyl-4-halogenebenzo hydrazonate (3a–b) were obtained by reaction Ethyl 2-((4-halogene phenyl) (ethoxy) methylene) hydrazinecarboxylate (1) and N-(3-aminopropyl)imidazole (2) at 120–140 °C. Compounds (4a–b) were obtained by the reaction compound 1 and N-(3-aminopropyl)imidazole (2) at 160–180 °C. The structures of compounds 3,4 have been inferred through UV–Vis, IR, ¹H/¹³C NMR, mass spectrometry, elemental analyses, and X-ray crystallography. DFT level 6-31G (d) calculations provided structural information. The electronic structure of compound 3a has been studied by DFT level 6-31G (d) calculations using the X-ray data. The results are accordance with X-ray data.     

Bis(tetraphenylantimony) succinate,malate, and tartrate: Syntheses and structures

The reactions of pentaphenylantimony with succinic, malic, and tartaric acids (mole ratio 2: 1) in toluene afford bis(tetraphenylantimony) succinate (I), malate (II), and tartrate (III) in yields of 98, 92, and 94%, respectively. According to the X_ray diffraction analysis results, molecules I and II are centrosymmetric. In compound II, the hydroxy group in the acid residue is disordered over two positions. Crystal III includes two types of crystallographically independent molecules (a and b). The antimony atoms in compounds I, II, IIIa, and IIIb have distorted trigonal bipyramidal coordination modes. The axial angles C_axSbO_ax are 166.80(8)° (I); 174.8(2)° (II); 176.4(4)°, 177.4(3)° (IIIa); and 173.3(4)°, 172.7(4)° (IIIb). The equatorial angles C_eqSbC_eq vary in the ranges 99.3(1)°–154.5(1)° (I); 115.2(2)°–123.3(2)° (II); 115.7(4)°–123.3(4)° 115.2(5)°–125.6(5)° (IIIa); and 107.9(4)°-129.1(4)°, 113.7(4)°-124.8(5)° (IIIb). The Sb-C and Sb-O bonds are 2.138(3)-2.176(3), 2.319(2) Å (I); 2.111(6)–2.163(5), 2.243(4) Å (II); 2.072(13)–2.169(11), 2.252(7), 2.284(7) Å (IIIa); and 2.047(11)–2.190(11), 2.224(7), 2.256(7) Å (IIIb). The intramolecular distances Sb…O=C are 2.528(3) (I); 3.267(7) (II); 3.381(7), 3.436(7) (IIIa); and 3.351(7), 3.162(7) Å (IIIb). For structures I, II, and III, the CIF files are CCDC 929151, 941542, and 941543, respectively.     

Crystal structures of nitrato-{4-bromo-2-[(2-hydroxyethylimion)methyl]phenolo}-(3,5-Dibromopyridine)copper and nitrato-{2,4-dibromo-6-[(2-hydroxyethylimino)methyl]phenolo}-(3,5-dibromopyridine)copper

The crystal structures of nitrato-{4-bromo-2-[2-hydroxyethylimino)methyl]phenolo}-(3,5-dibromopyridine)copper (I) and nitrato-{2,4-dibromo-6-[(2-hydroxyethylimino)methyl]phenolo}-(3,5-dibromopyridine)copper (II) are determined. The crystals of compound I are orthorhombic: a = 14.157(3) Å, b = 15.420(3) Å, c = 17.494(4) Å, space group Pbca, Z = 8, R = 0.067. The crystals of compound II are monoclinic: a = 10.675 Å, b = 13.973 Å, c = 14.007 Å, β = 111.92°, space group P2₁/n, Z = 4, R = 0.0464. In the structures of compounds I and II, the copper atom coordinates, correspondingly, singly deprotonated 4-bromo-2-[(2-hydroxyethylimino)methyl]phenol and 2,4-dibromo-6-[(2-hydroxyethylimino)methyl]phenol molecules, and 3,5-dibromopyridine, and the nitrate ion. The coordination polyhedron of the copper ion in complexes I and II is a slightly distorted tetragonal pyramid. The bases of the pyramids are formed by the imine and pyridine nitrogen atoms and the phenolic and alcoholic oxygen atoms, and the axial vertices are occupied by the oxygen atoms of the monodentate nitrato groups. In the complexes under study, the six-membered metallocycles have asymmetric gauche conformation. In crystal, complexes I are united, due to the slip plane a, through bifurcate hydrogen bonds into infinite chains along the direction [100]. Complexes II in crystal form two-dimensional networks by means of hydrogen bonds.     

Synthesis of some fused heterocyclic systems and their nucleoside candidates

A series of pyridofuro compounds were synthesized from 4-(4-chlorophenyl)-1,2-dihydro-2-oxo-6-(thiophen-2-yl)pyridine-3-carbonitrile (1) as starting material. Alkylation of 1 with ethyl bromoacetate gave the corresponding ester 2, which was condensed with hydrazine hydrate to afford the corresponding acid hydrazide derivative 3. Thrope-Ziegler cyclization of 2 with sodium methoxide gave furo[2,3-b]pyridine derivative 4, which was reacted with thiosemicarbazide, allyl isothiocyanate, formamide or hydrazine hydrate to give furopyridine derivatives 5–8, respectively. The latter compound 8 was cyclized with acetylacetone or formic acid to give the corresponding compounds 9 and 10, respectively. Furthermore, sulfurization of 1 with P₂S₅ gave the corresponding thioxopyridine 11, which was reacted with glycosyl (or galactosyl) bromide, morpholine or piperidine to give the corresponding thioglycoside 12a,b and Mannich base 14a,b derivatives. The deacetylation of 12a,b gave the corresponding deacetylated thioglycosides 13a,b, respectively. All the newly synthesized compounds were characterized by the elemental analyses and spectroscopic evidences (IR, ¹H- and ¹³C NMR).     

Distinct phase transitions and dielectric anomalies in two 4-methylanilinium salts

Solid-state phase transitions of 4-methylanilinium perchlorate (4-CH 3 C 6 H 4 NH 3 ·ClO 4 , 1) and tetrafluoroborate (4-CH 3 C 6 H 4 - NH 3 ·BF 4 , 2) were investigated with variable-temperature X-ray single-crystal structure analysis and thermal studies. Both 1 and 2 undergo first-order phase transitions and exhibit distinct dielectric anomalies at 385 and 247 K, respectively.     

Synthesis and characterization of novel calix[4]arene piperazine derivative for the extraction of transition metals and dichromate ions

This article displays the synthesis of N-(2-tosylato)ethylpiperazine (ii) and 5,11,17,23-tetra-tert-butyl-25,27-bis-(2-piprazinoethyl)-26,28-dihydroxycalix[4]arene (3). Compounds (ii) and 3 were characterized through elemental analysis, FT-IR, ¹H NMR and/or ¹³C NMR studies. The transition metal cations (Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Cd²⁺) and dichromate anion were studied by liquid–liquid extraction experiment. The results showed that compound 3 has moderate but selective extraction ability for Hg²⁺ and dichromate anion. Comparison between extraction properties of compound 3 with previously reported 5,11,17,23-tetra-tert-butyl-25,27-bis(isoniazidylcarbonylmethoxy)-26,28-dihydroxy-calix[4]arene (4) and protonated pyridinium form of 4 (5) is also described.     

Spectral properties of protonated naphthylpyridine in the presence of cyclodexrins

Electronic absorption and fluorescence spectroscopy showed that the addition of 2-hydroxypropyl cyclodextrin derivatives (HP-α-CD, HP-β-CD, and HP-γ-CD) to an aqueous solution of 4-(2-naphthyl)pyridinium perchlorate (2) results in its partial deprotonation and formation of an inclusion complex of 4-(2-naphthyl)pyridine (1) with the cavitand. The stoichiometry and stability of the inclusion complexes of compounds 1 and 2 and 1-methyl-4-(2-naphthyl)-pyridinium perchlorate (3) with cyclodextrins and their hydroxypropyl derivatives (logK = = 1.5–2.7) were studied by ¹H NMR titration. Cyclodextrins with the neutral form 1 form more stable complexes than with ionic compounds 2 and 3. The protonation of the nitrogen atom of compound 2 in aqueous solutions can occur in both the ground and excited states, and the fluorescence spectrum exhibits only the band of the protonated form. Quantum chemical simulation of the deprotonation/protonation processes in an aqueous solution of compound 2 in the absence and presence of HP-β-CD was performed. A tendency for shifting the acid-base equilibrium towards the formation of deprotonated form 1 is observed upon the addition of 2-hydroxypropyl cyclodextrin derivatives to the solution.