Synthesis And Characterization Of Some Calamitic Liquid Crystals Consisting Of Cholesterol, Rod-Like Imine And Biphenyl-4-Carboxylate Components [QD923. H111 2006 f rb].

Sebanyak tujuh siri hablur cecair kalamitik berjaya disintesis dan dicirikan. Kesemua hablur cecair tersebut dibahagikan kepada tiga jenis yang berlainan berdasarkan struktur teras masing-masing, sama ada komponen kolesterol, imina aromatik berbentuk rod atau bifenil-4-karbosilat. Seven series of calamitic liquid crystals were successfully synthesized and characterized. These liquid crystals are categorized into three different types according to their core structure; either a cholesterol, rod-like aromatic imine or biphenyl-4-carboxylate component

Synthesis And Characterization Of Some Calamitic Liquid Crystals Consisting Of Cholesterol, Rod-Like Imine And Biphenyl-4-Carboxylate Components

Sebanyak tujuh siri hablur cecair kalamitik berjaya disintesis dan dicirikan. Seven series of calamitic liquid crystals were successfully synthesized and characterized

Synthesis and mesomorphic properties of new heterocyclic liquidcrystals with Central Ester–Chalcone linkages

A series of new calamitic liquid crystals, 4-[3-(pyridin-4-yl)prop-2-enoyl]phenyl 4-alkyloxybenzoates, comprising a pyridyl core,ester–chalcone central linkage and terminal alkyloxy chain were synthesized and characterized. This series consists of four membersthat differ by the length of the alkyloxy chain (CnH2n+1O , where n = 10, 12, 14, 16). The structures of the title compounds wereelucidated using spectroscopic and spectrometric techniques, such as FT-IR, NMR (1H and13C) and EI-MS. The mesomorphicproperties were studied using differential scanning calorimetry and optical polarizing microscopy. The decyloxy-containing com-pound was found to be non-mesogenic, whilst the compounds containing n-dodecyloxy to n-hexadecyloxy chains exhibited anenantiotropic smectic A phase with a fan-shaped texture. From the structure–property relationship study, it was proposed that thenumber of carbons in the alkyloxy chain must be at least 12 (n ≥ 12) to generate the smectic phase in the corresponding substitutedArCOOArCOCH CHC5H4N compounds

Synthesis and comparative studies of phase transition behaviour of new dimeric liquid crystals consisting of dimethyluracil and biphenyl cores

A new homologous series of mesogens containing 6-amino-1,3-dimethyluracil moiety have been synthesized. The structures of the compounds were characterised by elemental analysis, FT-IR, 1H and 13C NMR spectroscopic techniques. Their mesomorphic properties were studied by polarising optical microscopy attached to a heating stage. Microscopy data were supported with transition temperatures and enthalpy change values obtained from the differential scanning calorimetry analysis. The studies have shown that the mesomorphic properties of the compounds are dependent on the lengths of alkoxy-spacers. Compounds 4a-f with a shorter alkoxy-spacer chain (n = 6) exhibited smectic A phase, while compounds 4g-r with a alkoxy-spacer chain (n = 8 or 10) displayed nematic phase

Preliminary in vitro cytotoxic assay of human liver carcinoma cells (HepG2) of organotin(IV) complexes: Synthesis and characterization of organotin(IV) complexes of 2,4-dinitrobenzoic and 3,5-dinitrobenzoic acids

A total of five organotin(IV) carboxylate complexes was successfully synthesized and characterized quantitatively and qualitatively. Results of the infrared spectroscopy of the parent acids and complexes showed that the coordination took place via oxygen atoms from the carboxylate group. From the preliminary in vitro cytotoxic assay study, triorganotin(IV) complexes (2 and 5) were found to exhibit better activity as compared to diorganotin(IV) complexes (1, 3 and 4) but lower activity as compared to the reference drug. In addition, within the diorganotin(IV) complexes, monomeric type (3) exhibited a slightly better activity as compared to the organodistannoxane dimer types (1 and 4).Keywords: Preliminary in vitro cytotoxic assay, organotin(IV) complexes, comparison stud

Viscoelastic Properties of p-n Alkyl Benzoic Acid Mesogens

Abstract: Dynamic rheological behaviour, such as storage modulus (G') and loss modulus (G'') are measured as a function of frequency at different temperatures in nematic region and also studied linear viscoelastic behaviour of p-n alkyl benzoic acid (nBA) mesogens. Different zones are exhibited by the samples, -a plateau zone at low frequencies, a transition zone at high frequencies and a zone entire plateau showing for crossover frequencies and relaxation times. The dependence of the elastic (G′) and loss (G′′) moduli on frequency is strong. The observed crossover points of G′, G′′ in the study of frequency range is indicating that nematic phase of nBA has behaved like both viscoelastic solid and liquid for small deformations (<1% strain). A typical shear thinning behaviour of viscosity has been displayed when the samples are subjected to shearing at a constant temperature. This typical shear thinning has approached slowly moving to Newtonian viscosity at high shear rates showing progressive development of nematic molecular orientation along flow direction on increasing shear rate. Rheological behaviour of the nBA nematic phases is in general consistent like the other reported compounds except the one thermotropic liquid crystals. The higher shear force and lower viscosity ratio is observed in these compounds in which pentyl benzoic acid has high ratio indicating the high molecular orientation may be due to low chain entanglement

Removal of dyes from wastewaters by low-cost adsorbents

Dyes represent an objectionable pollutant to the environment. The removal of dyes has been of great concern because of their toxicity and persistency. The usage of commercial activated carbon to remove dyes in wastewater is limited due to its high cost. This prompted the search for alternative low-cost adsorbents. This chapter examines (i) historical aspects and pollution issues concerning dyes; (ii) main treatment technologies and their limitations; (iii) various studies using waste materials from agriculture and industry or naturally occurring biosorbents; and (iv) equilibrium and kinetic models used in batch and continuous systems that are important for design purpose

Removal of Hazardous Heavy Metals From Aqueous Environment by Low-Cost Adsorption Materials

The rapid growth of the human population and industrialization in the world has indirectly increased environmental problems such as water, air and land pollution. Amongst all, heavy metals can be considered as the most problematic pollutants. Numerous efforts have been attempted to minimize the impact of heavy metals. This chapter discusses the recent developments and technical applicability of different treatment methods for heavy metal removal. The adsorption process using various low-cost materials as the potential alternative for heavy metal removal is being highlighted and summarized

Dye Waste Treatment

© 2011 by the authors. Dye wastes represent one of the most problematic groups of pollutants because they can be easily identified by the human eye and are not easily biodegradable. This literature review paper highlights and provides an overview of dye waste treatments performed over the three years period from 2008-2010. Noteworthy processes for the treatment of dye waste include biological treatment, catalytic oxidation, filtration, sorption process and combination treatments

(2-Chloro-4-nitro­benzoato)(methanol)triphenyl­tin(IV)

In the title complex, [Sn(C6H5)3(C7H3ClNO4)(CH4O)], the five-coordinate SnIV atom exists in a trigonal–bipyramidal environment, formed by a monodentate carboxyl­ate group, three phenyl rings and a methanol mol­ecule. The axial sites are occupied by the O atoms of the methanol mol­ecule and the carboxyl­ate group, while the equatorial plane is formed by the C atoms of three phenyl rings. The benzene ring of the 2-chloro-4-nitro­benzoate ligand makes dihedral angles of 66.18 (7), 74.71 (7) and 77.39 (7)° with respect to the three phenyl rings. In the crystal, the mol­ecules are linked via inter­molecular O—H⋯O and C—H⋯O hydrogen bonds into a column along the b axis