- Lipophilic tail modifications of 2-(hydroxymethyl)pyrrolidine scaffold reveal dual sphingosine kinase 1 and 2 inhibitors
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The sphingosine 1-phosphate (S1P) signaling pathway is an attractive target for pharmacological manipulation due to its involvement in cancer progression and immune cell chemotaxis. The synthesis of S1P is catalyzed by the action of sphingosine kinase 1 or 2 (SphK1 or SphK2) on sphingosine and ATP. While potent and selective inhibitors of SphK1 or SphK2 have been reported, development of potent dual SphK1/SphK2 inhibitors are still needed. Towards this end, we report the structure–activity relationship profiling of 2-(hydroxymethyl)pyrrolidine-based inhibitors with 22d being the most potent dual SphK1/SphK2 inhibitor (SphK1 Ki = 0.679 μM, SphK2 Ki = 0.951 μM) reported in this series. 22d inhibited the growth of engineered Saccharomyces cerevisiae and decreased S1P levels in histiocytic lymphoma myeloid cell line (U937 cells), demonstrating inhibition of SphK1 and 2 in vitro. Molecular modeling studies of 22d docked inside the Sph binding pocket of both SphK1 and SphK2 indicate essential hydrogen bond between the 2-(hydroxymethyl)pyrrolidine head to interact with aspartic acid and serine residues near the ATP binding pocket, which provide the basis for dual inhibition. In addition, the dodecyl tail adopts a “J-shape” conformation found in crystal structure of sphingosine bound to SphK1. Collectively, these studies provide insight into the intermolecular interactions in the SphK1 and 2 active sites to achieve maximal dual inhibitory activity.
- Li, Hao,Sibley, Christopher D.,Kharel, Yugesh,Huang, Tao,Brown, Anne M.,Wonilowicz, Laura G.,Bevan, David R.,Lynch, Kevin R.,Santos, Webster L.
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- 2-Aryl benzazole derived new class of anti-tubercular compounds: Endowed to eradicate mycobacterium tuberculosis in replicating and non-replicating forms
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The high mortality rate and the increasing prevalence of Mtb resistance are the major concerns for the Tuberculosis (TB) treatment in this century. To counteract the prevalence of Mtb resistance, we have synthesized 2-aryl benzazole based dual targeted molecules. Compound 9m and 9n were found to be equally active against replicating and non-replicating form of Mtb (MIC(MABA) 1.98 and 1.66 μg/ml; MIC(LORA) 2.06 and 1.59 μg/ml respectively). They arrested the cell division (replicating Mtb) by inhibiting the GTPase activity of FtsZ with IC50 values 45 and 64 μM respectively. They were also capable of kill Mtb in non-replicating form by inhibiting the biosynthesis of menaquinone which was substantiated by the MenG inhibition (IC50 = 11.62 and 7.49 μM respectively) followed by the Vit-K2 rescue study and ATP production assay.
- Datta, Dhrubajyoti,Debnath, Joy,Franzblau, Scott G.,Ghosh, Kalyan Sundar,Hari, Natarajan,Ma, Rui,Rana, Shiwani,Velappan, Anand Babu
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- 1,3-Oxazine-2-one derived dual-targeted molecules against replicating and non-replicating forms of Mycobacterium tuberculosis
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The high mortality rate and increasing prevalence of resistant Mtb are the major concerns for the Tuberculosis (TB) treatment in this century. To curtail the prevalence of resistant Mtb, we have prepared 1,3-oxazine-2-one based dual targeted molecules. Compound 67 and 68 were found to be equally active against replicating and non-replicatiing form of Mtb (MICMABA 3.48 and 2.97 μg/ml; MICLORA 2.94 and 2.15 μg/ml respectively). They had found to suppress the biosynthesis of alfa, methoxy and keto-mycolate completely, as well as inhibit enzymatic activity of MenG (IC50 = 9.11 and 6.25 μg/ml respectively for H37Ra; IC50 = 11.76 and 10.88 μg/ml respectively for M smegmatis).
- Velappan, Anand Babu,Kesamsetty, Dhanunjaya,Datta, Dhrubajyoti,Ma, Rui,Hari, Natarajan,Franzblau, Scott G.,Debnath, Joy
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supporting information
(2020/10/02)
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- Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene) hydrazines
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{1-[4-(n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines (n-alkoxy = O(CH2)nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.
- Awad, Adil A.,Omarali, Al-Ameen Bariz,Al-Karawi, Ahmed Jasim M.,Al-Qaisi, Zyad Hussein J.,Majeed, Samer Ghanim
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- Ferroelectric Liquid Crystals: Synthesis and Thermal Behavior of Optically Active, Three-Ring Schiff Bases and Salicylaldimines
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The chiral ferroelectric smectic C (SmC*) phase, characterized by a helical superstructure, has been well exploited in developing high-resolution microdisplays that have been effectively employed in the fabrication of a wide varieties of portable devices. Although, an overwhelming number of optically active (chiral) liquid crystals (LCs) exhibiting a SmC* phase have been designed and synthesized, the search for new systems continues so as to realize mesogens capable of meeting technical necessities and specifications for their end-use. In continuation of our research work in this direction, herein we report the design, synthesis, and thermal behavior of twenty new optically active, three-ring calamitic LCs belonging to four series. The first two series comprise five pairs of enantiomeric Schiff bases whereas the other two series are composed of five pairs of enantiomeric salicylaldimines. In each pair of optical isomers, the configuration of a chiral center in one stereoisomer is opposite to that of the analogous center in the other isomer as they are derived from (3 S)-3,7-dimethyloctyloxy and (3 R)-3,7-dimethyloctyloxy tails. To probe the structure–property correlations in each series, the length of the n-alkoxy tail situated at the other end of the mesogens has been varied from n-octyloxy to n-dodecyloxy. The measurement of optical activity of these chiral mesogens was carried out by recording their specific rotations. As expected, enantiomers rotate plane polarized light in the opposite direction but by the same magnitude. The thermal behavior of the compounds was established by using a combination of optical polarizing microscopy, differential scanning calorimetry, and powder X-ray diffraction. These complementary techniques demonstrate the existence of the expected, thermodynamically stable, chiral smectic C (SmC*) LC phase besides blue phase I/II (BPI or BPII) and chiral nematic (N*) phase. However, as noted in our previous analogous study, the vast majority of the Schiff bases show an additional metastable, unfamiliar smectic (SmX) phase just below the SmC* phase. Notably, the SmC* phase persists over the temperature range ≈80–115 °C. Two mesogens chosen each from Schiff bases and salicylaldimines were investigated for their electrical switching behavior. The study reveals the ferroelectric switching characteristics of the SmC* phase featuring the spontaneous polarization (PS) in the range 69–96 nC cm?2. The helical twist sense of the SmC* phase as well as the N* phase formed by a pair of enantiomeric Schiff bases and salicylaldimines has been established with the help of circular dichroism (CD) spectroscopic technique. As expected, the SmC* and the N* phase of a pair of enantiomers showed mirror image CD signals. Most importantly, the reversal of helical handedness from left to right and vice versa has been evidenced during the N* to SmC* phase transition, implying that the screw sense of the helical array of the N* phase and the SmC* phase of an enantiomer is opposite.
- Veerabhadraswamy, Bhyranalyar N.,Rao, Doddamane S. Shankar,Yelamaggad, Channabasaveshwar V.
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supporting information
p. 1012 - 1023
(2018/04/23)
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- Mesomorphism dependence on central bridge and tail ended polar group
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A novel azoester homologous series of laterally and terminally substituted viz, RO–C6H4–CH=CH–COO–C6H3–(CH3) –N=N–C6H4–Cl is synthesized, characterized and studied with a view to understand and establish the relation between molecular structure and thermotropic liquid crystalline property of its homologs. Series consists of twelve homologs. LC properties commence from very first member of a series and continue up to last homolog as enantiotropic nematic with absence of smectic property even in the monotropic condition. Transition temperatures of homologs were determined by polarizing optical microscopy equipped with a heating stage. The transition curves Cr?N and N?I behaved in normal manner. Thermal stability for nematic is 196.7?C whose mesophaselength ranges from 35°C to 131°C.
- Ranchchh, Avani R.,Chavda, Kavita,Bhanderi, Roshani,Patel, Suman,Bhoya
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- Efficient and practical method for the synthesis of hydrophobic azines as liquid crystalline materials
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A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, n-alkoxy: O(CH2)nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method. These compounds have been synthesized via the condensation reaction of hydrazine hydrate and appropriately 4-(n-alkoxy) benzaldehydes in acidic medium under ambient conditions. The prepared organic compounds have been characterized and their structures were elucidated depending upon micro-elemental analysis and spectral data (IR, UV-Vis, 1HNMR, 13C{1H}NMR, 2D 1H-1H-cozy, 2D 1H-13C-HSQC, and mass spectra). Liquid crystalline behavior of the prepared compounds was studied using polarized light optical microscopy and differential scanning calorimetry techniques. This study revealed that all the compounds displayed enantiotropic liquid crystal properties, exhibiting smectic and nematic mesophases.
- Hammood, Ali Jasim,Kased, Ahmed Fadhel H.,Al-Karawi, Ahmed Jasim M.,Raseen, Sameem R.,Tomi, Ivan Hameed R.,Omar Ali, Al-Ameen Bariz
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p. 114 - 129
(2017/07/04)
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- Synthesis, spectroscopic and computational characterization of the tautomerism of pyrazoline derivatives from chalcones
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In the present study a series of novel pyrazolines derivatives has been synthesized, and their structures assigned on the basis of FT-Raman, 1H and 13C NMR spectral data and computational DFT calculations. A joint computational study using B3LYP/6-311G(2d,2p) density functional theory and FT-Raman investigation on the tautomerism of 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carbothioamide and 3-(4-substituted-phenyl)-4,5-dihydro-5-(4-substituted-phenyl)pyrazole-1-carboxamide are presented. The structures were characterized as a minimum in the potential energy surface using DFT. The calculated Raman and NMR spectra were of such remarkable agreement to the experimental results that the equilibrium between tautomeric forms has been discussed in detail. Our study suggests the existence of tautomers, the carboxamide/carbothioamide group may tautomerize, in the solid state or in solution. Thermodynamic data calculated suggests that the R(CS)NH2 and R(CO)NH2 species are more stable than the R(CNH)SH and R(CNH)OH species. Additionally, results found for the 1H NMR shifting, pointed out to which structure is present.
- Miguel, Fbio Balbino,Dantas, Juliana Arantes,Amorim, Stefany,Andrade, Gustavo F.S.,Costa, Luiz Antnio Sodr,Couri, Mara Rubia Costa
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p. 318 - 326
(2015/08/06)
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- Optically active, three-ring calamitic liquid crystals: The occurrence of frustrated, helical and polar fluid mesophases
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Herein, we report on the synthesis, characterization, liquid crystalline behavior and chirooptical properties of five (R)-4-{[(4-(octan-2-yloxy)phenyl)imino]methyl}phenyl 4-(n-alkoxy)benzoates and their enantiomers, namely, (S)-4-{[(4-(octan-2-yloxy)phenyl)imino]methyl}phenyl 4-(n-alkoxy)benzoates. These three-ring rod-like mesogens were prepared by acid catalyzed condensation of (R)-/(S)-4-(octan-2-yloxy)anilines with 4-formylphenyl 4-(n-alkoxy)benzoates. Thus, each pair of enantiomers comprises (R)-2-octyloxy and (S)-2-octyloxy chiral tails. In order to understand the structure-property correlations, the length of the paraffinic chain incorporated at the other end has been varied from n-octyloxy to n-dodecyloxy. A detailed study carried out by means of several complimentary techniques reveals the stabilization of liquid crystal phases that hold great promise in applied sciences especially in various device applications. In particular, the occurrence of mesophases such as the blue phase-I/II (BPI or BPII) and chiral nematic (N) and chiral smectic C (SmC) phases has been evidenced unequivocally with the help of polarizing microscopy, differential scanning calorimetry, X-ray diffraction and electrical switching. Besides, the occurrence of an unknown, metastable smectic (SmX) phase below the SmC phase has been noted. This study shows that the length of the terminal tail seems to determine the thermal range of the SmC phase. The enantiotropic SmC phase exhibiting ferroelectric switching behavior occurs over 60 °C thermal range; notably, the spontaneous polarization (Ps) value crosses over 100 nC cm-2. The photophysical properties and chirooptical behavior of the mesogens have been studied with the aid of UV-vis absorption and circular dichroism (CD) spectroscopic methods, respectively; the latter technique has been especially used to ascertain the twist sense of the N and SmC phases formed by a pair of enantiomers. The reversal of the helix-sense (from right to left and vice versa) during the N-SmC phase transition has been observed for the first time.
- Veerabhadraswamy,Rao, D. S. Shankar,Prasad, S. Krishna,Yelamaggad
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p. 2011 - 2027
(2015/03/30)
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- Stable ferroelectric liquid crystals derived from salicylaldimine-core
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Five pairs of enantiomers derived from salicylaldimine-core have been prepared by condensing (R)- or (S)-4-(octan-2-yloxy)anilines with 4-formyl-3-hydroxyphenyl 4-(n-alkoxy)benzoates. They have been designed to probe the correlation between molecular structure and mesomorphism, and especially to provide stable mesogens having potential for applications in ferroelectric liquid crystal devices. Thus, they have been substituted with a chiral tail at one end and by n-alkoxy chains of varying length at the other terminal. A detailed study confirms an indistinguishable behavior of all ten mesogens exhibiting an enantiotropic chiral smectic C (SmC) phase besides blue phase (BP) and chiral nematic (N) phase. The SmC phase occurring over a 50-70 °C thermal width shows ferroelectric switching with spontaneous polarization (Ps) value crossing over 100 nC/cm2. Circular dichroism spectroscopic study of the mesophases confirms the chromophores of the molecules being in the macroscopic chiral (helical) environment.
- Veerabhadraswamy, Bhyranalyar N.,Rao, D. S. Shankar,Yelamaggad, Channabasaveshwar V.
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p. 4539 - 4551
(2015/04/14)
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- Identification of 6-benzyloxysalicylates as a novel class of inhibitors of 15-lipoxygenase-1
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Lipoxygenases metabolize polyunsaturated fatty acids into signalling molecules such as leukotrienes and lipoxins. 15-lipoxygenase-1 (15-LOX-1) is an important mammalian lipoxygenase and plays a crucial regulatory role in several respiratory diseases such as asthma, COPD and chronic bronchitis. Novel potent and selective inhibitors of 15-LOX-1 are required to explore the role of this enzyme in drug discovery. In this study we describe structure activity relationships for 6-benzyloxysalicylates as inhibitors of human 15-LOX-1. Kinetic analysis suggests competitive inhibition and the binding model of these compounds can be rationalized using molecular modelling studies. The most potent derivative 37a shows a Ki value of 1.7 μM. These structure activity relationships provide a basis to design improved inhibitors and to explore 15-LOX-1 as a drug target.
- Eleftheriadis, Nikolaos,Thee, Stephanie,Te Biesebeek, Johan,Van Der Wouden, Petra,Baas, Bert-Jan,Dekker, Frank J.
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p. 265 - 275
(2015/03/30)
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- Non-symmetric dimers comprising chalcone and cholesterol entities: An investigation on structure-property correlations
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Four series of new dimers formed by interlinking chalcone and cholesterol mesogenic entities through spacers of varying length and parity have been synthesized and characterized by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction and electrical switching studies. The structure of the chalcone core has been systematically modified to investigate the effect of the molecular structure on the thermal behaviour of the dimers. The study demonstrates the dramatic dependence of thermal behaviour of these dimers on the nature of the chalcone as well as the length and parity of the spacer. the Partner Organisations 2014.
- Achalkumar, Ammathnadu S.,Shankar Rao, Doddamane S.,Yelamaggad, Channnabasaveshwar V.
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supporting information
p. 4235 - 4248
(2014/11/07)
-
- 3-(2-AMINO-ETHYL)-ALKYLIDENE)-THIAZOLIDINE-2,4-DIONE AND 1-(2-AMINO-ETHYL)-ALKYLIDENE-1,3-DIHYDRO-INDOL-2-ONE DERIVATIVES AS SELECTIVE SPHINGOSINE KINASE 2 INHIBITORS
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3-(2-amino-ethyl)-5-[3-(4-substituted-phenyl)-alkylidene)-thiazolidine-2,4-dione and l-(2-amino-ethyl)-3-alkylidene-l,3-dihydro-indol-2-one and derivatives thereof are provided for use as selective SphK2 inhibitors and for use in the treatment of human diseases, such as cancer.
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-
Page/Page column 27
(2013/08/28)
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- Discovery of a novel activator of 5-lipoxygenase from an anacardic acid derived compound collection
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Lipoxygenases (LOXs) and cyclooxygenases (COXs) metabolize poly-unsaturated fatty acids into inflammatory signaling molecules. Modulation of the activity of these enzymes may provide new approaches for therapy of inflammatory diseases. In this study, we screened novel anacardic acid derivatives as modulators of human 5-LOX and COX-2 activity. Interestingly, a novel salicylate derivative 23a was identified as a surprisingly potent activator of human 5-LOX. This compound showed both non-competitive activation towards the human 5-LOX activator adenosine triphosphate (ATP) and non-essential mixed type activation against the substrate linoleic acid, while having no effect on the conversion of the substrate arachidonic acid. The kinetic analysis demonstrated a non-essential activation of the linoleic acid conversion with a KA of 8.65 μM, αKA of 0.38 μM and a β value of 1.76. It is also of interest that a comparable derivative 23d showed a mixed type inhibition for linoleic acid conversion. These observations indicate the presence of an allosteric binding site in human 5-LOX distinct from the ATP binding site. The activatory and inhibitory behavior of 23a and 23d on the conversion of linoleic compared to arachidonic acid are rationalized by docking studies, which suggest that the activator 23a stabilizes linoleic acid binding, whereas the larger inhibitor 23d blocks the enzyme active site.
- Wisastra, Rosalina,Kok, Petra A.M.,Eleftheriadis, Nikolaos,Baumgartner, Matthew P.,Camacho, Carlos J.,Haisma, Hidde J.,Dekker, Frank J.
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p. 7763 - 7778
(2014/01/06)
-
- Synthesis and antimicrobial activity of novel amphiphilic aromatic amino alcohols
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We report in this work the preparation and in vitro antimicrobial evaluation of novel amphiphilic aromatic amino alcohols synthesized by reductive amination of 4-alkyloxybenzaldehyde with 2-amino-2-hydroxymethyl-propane-1,3- diol. The antibacterial activity was determined against four standard strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa) and 21 clinical isolates of methicillin-resistant Staphylococcus aureus. The antifungal activity was evaluated against four yeast (Candida albicans, Candida tropicalis, Candida glabrata and Candida parapsilosis). The results obtained showed a strong positive correlation between the lipophilicity and the antibiotic activity of the tested compounds. The best activities were obtained against the Gram-positive bacteria (MIC = 2-16 μg ml-1) for the five compounds bearing longer alkyl chains (4c-g; 8-14 carbons), which were also the most active against Candida (MIC = 2-64 μg ml-1). Compound 4e exhibited the highest levels of inhibitory activity (MIC = 2-16 μg ml-1) against clinical isolates of MRSA. A concentration of twice the MIC resulted in bactericidal activity of 4d against 19 of the 21 clinical isolates.
- De Almeida, Angelina M.,Nascimento, Thiago,Ferreira, Bianca S.,De Castro, Pedro P.,Silva, Vania L.,Diniz, Claúdio G.,Le Hyaric, Mireille
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p. 2883 - 2887
(2013/06/27)
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- IMIDAMIDE SPHINGOSINE KINASE INHIBITORS
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Imidamide (amidine) analogs that can inhibit the activity of sphingosine kinase 1 and sphingosine kinase 2 (SphK1 and SphK2) are provided. The compounds can prevent angiogenesis in tumors.
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Page/Page column 22
(2012/09/05)
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- Multifunctional organic fluorescent materials derived from 9,10-distyrylanthracene with alkoxyl endgroups of various lengths
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A series of remarkable multifunctional 9,10-distyrylanthracene derivatives (DSAn, n = 7-12) was synthesized. All derivatives possess typical aggregation-induced emission (AIE) property. Some of the derivatives exhibit multifunctional properties, including AIE, mechanofluorochromism, vapochromism, thermochromism, and mesomorphism, which are rarely found to exist simultaneously in a single compound.
- Zhang, Xiqi,Chi, Zhenguo,Xu, Bingjia,Jiang, Long,Zhang, Yi,Liu, Siwei,Xu, Jiarui,Zhou, Xie
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supporting information
p. 10895 - 10897,3
(2020/09/16)
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- Expeditious preparation of isoxazoles from Δ2-isoxazolines as advanced intermediates for functional materials
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A collection of isoxazoles derivatives has been efficiently synthesized in three steps. The oximation reaction of aldehydes followed by nitrile oxide [3+2] 1,3-dipolar cycloaddition and MnO2-oxidation reaction furnished the title compounds which were purified by simple filtration on celite.
- Vilela, Guilherme D.,Da Rosa, Rafaela R.,Schneider, Paulo H.,Bechtold, Ivan H.,Eccher, Juliana,Merlo, Aloir A.
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supporting information; experimental part
p. 6569 - 6572
(2012/01/03)
-
- Synthesis, characterization and fluorescent property evaluation of 1,3,5-triaryl-2-pyrazolines
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A series of 1,3,5-triaryl-2-pyrazolines was synthesized by dissolving the corresponding 4-alkoxychalcones in glacial acetic acid containing a few drops of concentrated hydrochloric acid. This step was followed by the addition of (3,4-dimethylphenyl) hydrazaine hydrochloride. Finally the target compounds were precipitated by pouring the reaction mixture onto crushed ice. The structures of the synthesized compounds were established by physicochemical and spectroscopic methods. The 1,3,5-triaryl-2-pyrazolines bearing homologous alkoxy groups were found to possess fluorescence properties in the blue region of the visible spectrum when irradiated with ultraviolet radiation. The fluorescent behavior of these compounds was studied by UV-Vis and emission spectroscopy, performed at room temperature.
- Hasan, Aurangzeb,Abbas, Asghar,Akhtar, Muhammed Nadeem
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experimental part
p. 7789 - 7802
(2011/11/05)
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- Convenient synthesis of functionalized 4,4′-disubstituted-2,2′- bipyridine with extended π-system for dye-sensitized solar cell applications
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Exploration of new ruthenium-based sensitizers for dye-sensitized solar cell (DSC) applications requires an easy access to multifunctionalized ligands for efficient screening of sensitizers' properties. Based on the Horner-Emmons-Wadsworth reaction, a convenient synthetic route for the extension of the π-system on 4,4′-disubstituted-2,2′-bipyridines was used to develop a novel series of functionalized 2,2′-bipyridine ligands with either electron-withdrawing or donating end-capping group. 1H NMR spectroscopy revealed that all the new bipyridyl ligands were obtained exclusively in their fully E isomers.
- Klein, Cédric,Baranoff, Etienne,Nazeeruddin, Md. Khaja,Gr?tzel, Michael
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scheme or table
p. 6161 - 6165
(2011/01/04)
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- Synthesis of perfluorinated heterocyclic compounds having a long alkyl chain functionality by 1,3-dipolar cycloaddition
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Regioselective perfluorinated isoxazolidine (5 and 7), isoxazoline (9) and 1,2-addition products (6 and 8) having a long alkyl chain functionality have been prepared by 1,3-dipolar cycloaddition between a 1,3-dipole (NH-nitrone or nitrile oxide) and dipol
- Lee, Chan Woo,Hwang, Ho Yun,Park, Joo Yuen,Chi, Ki-Whan
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experimental part
p. 1305 - 1308
(2010/10/21)
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- 3,5-disubstituted isoxazolines as potential molecular kits for liquid-crystalline materials
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A collection of 3,5-disubstituted isoxazolines have been synthesized by 1,3-dipolar [3+2] cycloaddition reactions. Some isoxazolines were selected and transformed into liquid crystals. These new liquid crystals exhibit nematic and smectic C mesophases.
- Tavares, Aline,Schneider, Paulo H.,Merlo, Aloir A.
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supporting information; experimental part
p. 889 - 897
(2009/07/19)
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- Synthesis and characterization of mesogenic 1,3,4-oxadiazole derivatives
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A synthesis of homologous series of mesogenic 2-amino-5-alkkloxyphenyl-1,3, 4-oxadiazoles were prepared by the oxidative cyclisation of alkyloxybenzaldehyde semicarbozones (4) using chloramines-T (CAT) as osidate via intramolecular cycloaddition reaction. The reaction proceeds in better yield (75-85%) giving the product as solid with low melting points. The optical texture studies have been carried out using Leitz polarizing microscope to identify the liquid crystalline phases at different temperatures and it is found that the synthesized compounds exhibit nematic (N), smectic C (Sm C), smectic I (Sm I) and smectic G (Sm G) phases, sequentially at different temperatures. Copyright Taylor & Francis Group, LLC.
- Mahadeva,Umesha,Rai,Nagappa
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scheme or table
p. 274 - 282
(2011/08/02)
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- Smectic polymorphism of 4-nonyloxybenzylidene-4′-alkyloxyanilines
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This paper describes liquid-crystalline polymorphism of the homologous series of 4-nonyloxybenzylidene-4′-alkyloxyanilines. Based on the polarization microscopy (POM, TOA) and the calorimetric (DSC) measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I and smectic G. The presence of these mesophases was confirmed by the miscibility method, using: 4-heptyloxybenzilidene-4′-pentylaniline, 4-hexyl-4′-decyloxyazobenzene and 4-nonyloxybenzilidene-4′-butylaniline as mesophase references. Influence of the alkyl chain length on the type of mesophases and entropic effects of phase transition are discussed.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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p. 259 - 267
(2008/03/13)
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- Selecting against S1P3 enhances the acute cardiovascular tolerability of 3-(N-benzyl)aminopropylphosphonic acid S1P receptor agonists
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Structurally modified 3-(N-benzylamino)propylphosphonic acid S1P receptor agonists that maintain affinity for S1P1, and have decreased affinity for S1P3 are efficacious, but exhibit decreased acute cardiovascular toxicity in rodents than do nonselective agonists.
- Hale, Jeffrey J.,Doherty, George,Toth, Leslie,Mills, Sander G.,Hajdu, Richard,Keohane, Carol Ann,Rosenbach, Mark,Milligan, James,Shei, Gan-Ju,Chrebet, Gary,Bergstrom, James,Card, Deborah,Forrest, Michael,Sun, Shu-Yu,West, Sarah,Xie, Huijuan,Nomura, Naomi,Rosen, Hugh,Mandala, Suzanne
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p. 3501 - 3505
(2007/10/03)
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- Synthesis and mesomorphic behaviour of 3-[4-alkyloxyphenyl]-5-[3,4- ethylenedioxybenzyl]-2-isoxazolines
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A simple homologous series of 3-[4-alkyloxyphenyl]-5-[3,4- methylenedioxybenzyl]-2-isoxazolines having chiral sources have been synthesized by the reaction of nitrile oxides isolated from the dehydrogenation of 4-alkyloxyphenyl aldoximes using chloramine-T with safrole. Synthesized compounds structures have been confirmed by 1H NMR, 13C NMR, mass spectral analysis and optical texture studies have been carried out using Leitz polarizing microscope. The synthesized compounds exhibit cholesteric phase or chiral nematic phase (N*), smectic A (SA) and chiral smectic phases (SC*), some at and just above room temperature.
- Umesha,Rai,Nagappa,Mahadeva
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p. 2635 - 2640
(2007/10/03)
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- Synthesis and characterization of new mesogenic oximes
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Synthesis of a homologous series of mesogenic 4-(n-alkoxy)benzaldehyde oximes starting from 4-hydroxybenzaldehyde with n-alkyl bromide under phase transfer condition is described. Optical texture studies have been carried out using Leitz polarizing microscope and it is found that the synthesized compounds exhibit Smectic B, Smectic I and Smectic H phase.
- Rai, K.M. Lokanatha,Prasad, K. Rajashekar,Nagappa,Mahadeva
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p. 1676 - 1680
(2007/10/03)
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- Synthesis and properties of Schiff's bases derived from 1,3,4-thiadiazole as a mesogenic unit
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Some new liquid crystalline 2,5-disubstituted 1,3,4-thiadiazole derivatives incorporating a central group (-CH=N-) have been synthesized by treating 2-amino-5-(4-alkoxyphenyl)-1,3,4-thiadiazole with corresponding p-alkoxybenzaldehyde. Their structures have been characterized with Elementary Analysis, IR, 1HNMR and MS, and their properties were determined by using DSC and Texture. All 12 compounds are enantiotropic liquid crystals, and most of them exhibit nematic mesomorphism and broad smectic C mesomorphic ranges. Several compounds show only the smectic C mesophase. By introducing an -OH group into the phenyl ring the thermal stability of the mesophases increases due to the formation of a hydrogen bond.
- Xu,Lu,Tai
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p. 151 - 159
(2007/10/03)
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- Thermotropic phase transitions in 5,15-bis(4-alkoxyphenyl)octaalkylporphyrins
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Nineteen novel alkyl substituted porphyrins have been synthesized and their thermal phase behaviour has been investigated in detail. Twelve compounds showed a reversible phase transition below the isotropization temperature. From time resolved microwave conductivity (TRMC) measurements and powder X-ray diffractometry it was concluded that the molecular packing does not change significantly at the lower phase transition temperature and that the porphyrin cores occupy isolated positions. Single X-ray diffraction measurements showed that the porphyrins are arranged in a layered structure and that the space between the layers is occupied by the alkyl substituents of the pyrrole units. The phase transitions at the lower temperature were therefore identified as changes in the crystal ordering of the porphyrins.
- Sudhoelter, Ernst J. R.,Van Dijk, Marinus,Teunis, Cees J.,Sanders, Georgine M.,Harkema, Sybolt,Van De Velde, Gerrit M. H.,Schouten, Pieter G.,Warman, John M.
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p. 357 - 363
(2007/10/03)
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- 5,10,15,20-meso-Tetraarylethynylporphirins
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Examples of the title porphyrins are prepared via Lindsey's method from arylpropynals and pyrrole, and their spectroscopic properties reported.They are green with uv/visible spectra more extensively red-shifted than previously observed for alkynyl-substit
- Milgrom, Lionel R.,Yahioglu, Gokhan
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p. 9061 - 9064
(2007/10/02)
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- SYNTHESIS AND MESOMORPHISM OF COMPOUNDS CONTAINING DIAMINODIBENZO-18-CROWN-6 FRAGMENT
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A new series of compounds containing diaminodibenzo-18-crown-6 fragment was synthesized.Their mesomorphism and the influence of cis and trans substitution in the crown-ether fragment on the formation of the mesomorphic phase were studied.On heating, three compounds of this series form a nematic phase, which exists in the temperature range 50-80 deg C.
- Akopova, O. B.,Shabyshev, L. S.
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p. 604 - 610
(2007/10/02)
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- New Liquid Crystalline Compounds Based on 1,4-Diarylbuta-1,3-dienes
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The first group of fully characterised mesogenic (E,E)-1,4-diarylbuta-1,3-dienes, substituted in the para-position of one aryl ring by an alkoxy-group and in the para-position of the other aryl group by a cyano- or halogeno-group has been prepared by a Wadsworth-Emmons procedure; their physical properties of high birefringence and low viscosity in combination make them particularly suitable for use in liquid crystal display devices when mixed with known liquid crystalline materials.
- Brettle, Roger,Dunmur, David A.,Hindley, Nigel J.,Marson, Charles M.
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p. 410 - 411
(2007/10/02)
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