- Synthesis and mesomorphic characterization of some novel steroidal mesogens: A structure–property correlation
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The steroidal derivatives are found to be extremely good mesogens since their inception. Because of their inherent chirality, they have the potential to induce a wide variety of liquid crystalline phases, including frustrated phases depending upon the structure of the steroidal skeleton and the substituents attached. In this report, a series of novel monoalkoxy and dialkoxy benzoate derivatives of ergosterol and a few monoalkoxy derivatives of stigmasterol have been synthesized and their mesomorphic property has been investigated. The derivatives exhibited various mesophases including SmA, SmC*, N*, TGB and blue phases. Also, the gelation ability of some of these derivatives with various organic solvents has been examined. Furthermore, the mesomorphism of these derivatives has been compared with the analogous cholesteryl counterparts.
- Bhat S, Vanishree,Kumar, Sandeep,Raghunathan, V. A.
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- Synthesis and gelation behavior of 4′-propyl-1,1′- bi(cyclohexyl)-4-one 4-alkoxybenzoylhydrazone
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A series of new alkoxybenzoylhydrazones of 4′-propyl-1,1′- bi(cyclohexyl)-4-one were prepared as novel low molecular weight organogelators (LMOGs). Their gelation behaviors in 10 solvents were tested. Some of the compounds could form stable gels in bulk o
- Li, Juan,Chen, Pei,Chen, Xinbing,An, Zhongwei,Li, Yan
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- Design and characterization of novel bis-benzamide liquid crystalline materials
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A new homologous series of symmetric, bent-shaped bis-benzamide dimers have been prepared. Several 1,n-bis(p-aminophenoxy)alkanes (n = 3, 5, 9,10,11) were employed as spacers and p-hexyloxy tails have been synthesized and appended to the spacers by amide linking groups. Different important parameters were explored using computational analysis by semi empirical method. The experimental results were correlated with theoretical studies and relationship between molecular structure and mesogenic behavior has been established. The mesomorphic properties of the resultant dimers were characterized by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) equipped with a hot stage. Change in mesomorphic properties with change of methylene spacers was observed. Enantiotropic mesogenic behavior was exhibited by D3A6, D10A6 and D11A6 and the needle like and blurred schleiren textures were observed. It was observed that increased methylene spacers chain length decreased the melting temperatures. Thermogravimetric analysis revealed the thermal stability of dimers upto 360 °C.
- Iqbal, Asma,Siddiqi, Humaira Masood,Akhter, Zareen,Qaiser Fatmi, Muhammad
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p. 135 - 141
(2017/09/23)
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- Study on some azo liquid crystals as antioxidants for local base oil
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Four new azo compounds namely, 2-(sec-butyl)-4-((4-methoxyphenyl)diazenyl) phenyl-4-(hexyloxy)benzoate (I6a), 2-(sec-butyl)-4-(p-tolyldiazenyl)phenyl-4-(hexyloxy) benzoate (I6b), 4-((4-bromophenyl)diazenyl)-2-(sec-butyl)phenyl 4-(hexyloxy)benzoate (I6c) and 2-(sec-butyl)-4-((4-nitrophenyl)diazenyl)phenyl 4-(hexyloxy)benzoate (I6d) were synthesized. Their structure elucidated via Elemental Analysis, FT-IR, 1H-NMR and Mass Spectroscopy. Their mesophase behavior was investigated by Differential Scanning Calorimetry (DSC). They were tested as antioxidants for local base oil. The efficiency of them was investigated via monitoring the oxidation reaction through the change in total acid number (TAN) and viscosity. The obtained results showed that, the efficiency of these compounds was ranked as follows I6d > I6c > I6b > I6a.
- Ashmawy, Ashraf M.,Attia, Sayed K.,Nessim, Maher I.,Elnaggar, El sayed M.,El-Bassoussi, Ali A.
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- Tuning the self-assembly and photophysical properties of bi-1,3,4-thiadiazole derivatives through electron donor-acceptor interactions and their application in OLEDs
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We report several shape anisotropic molecules that contain two centrally placed 1,3,4-thiadiazole units, which vary from each other with respect to the number and length of the flexible chains at the termini. The number, position and length of the periphe
- Yadav, Abhay Kumar,Pradhan, Balaram,Ulla, Hidayath,Nath, Subrata,De, Joydip,Pal, Santanu Kumar,Satyanarayan,Achalkumar, Ammathnadu S.
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supporting information
p. 9345 - 9358
(2017/09/29)
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- Triketonate difluoroboron complexes. Substitution-dependent liquid crystal and photophysical properties
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Novel alkyloxyphenyl-substituted β,δ-triketonate difluoroboron complexes have been efficiently synthesised and thoroughly characterised. Significant features such as liquid crystal behaviour and solid and solution fluorescence are observed in all cases. The mesomorphism was determined by the presence of one, two or three alkyl chains in each substituent aromatic group of the triketonate ligand. So, smectic C mesophases were found for compounds carrying two lateral chains, each of them located at one of each phenyl substituent, while the presence of four or six chains at the whole molecule gave rise to smectic A or discotic lamellar and hexagonal columnar mesophases, respectively. Fluorescence in the solid state and in solution is again proved to be dependent on the ligand substitution as well as to be maintained in the mesophase. These multifunctional materials also present luminescent sensor activity towards Hg2+ and Cu2+.
- Sánchez, Ignacio,Fernández-Lodeiro, Adrián,Oliveira, Elisabete,Campo, José Antonio,Torres, M. Rosario,Cano, Mercedes,Lodeiro, Carlos
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p. 184 - 200
(2016/09/07)
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- Synthesis and anticonvulsant activity evaluation of 4-butyl-5-(4- alkoxyphenyl)-2H-1,2,4-triazole-3(4H)-ones
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A series of 4-butyl-5-(4-alkoxyphenyl)-2H-1,2,4-triazole-3(4H)-ones (6a-6u) was designed and synthesized. The anticonvulsant effects and neurotoxicity of the compounds were evaluated with maximal electroshock test and rotarod test. Among the synthetic compounds, 4-butyl-5-(4-(2-fluorinebenzyl)phenyl)-2H-1,2,4- triazole-3 (4H)-one (6k) was the most potent with ED50 value of 27.4 mg/kg and protective index (PI = TD50/ED50) value of 12.0. Besides the anti-MES efficacy, the potency of compound 6k against seizures induced by pentylenetetrazole (PTZ), 3-mercaptopropionic acid (3-MP), and bicuculline (BIC) was also established, which suggested that the mechanisms of action including enhancing of GABAergic activity might be involved in its anticonvulsant activity.
- Zhu, Zi-Shi,Wang, Shi-Ben,Deng, Xian-Qing,Liu, Da-Chuan,Quan, Zhe-Shan
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p. 628 - 635
(2014/05/20)
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- Synthesis, characterization and mesomorphic investigations of ester-substituted aroylhydrazones possessing a lateral hydroxyl group
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The synthesis, characterization and investigation of a new liquid crystalline series of ester containing aroylhydrazones with a lateral hydroxyl group, N-[4-(4′-alkoxy)benzoyloxy-2-hydroxy-benzylidene]-N′- [4″-alkoxybenzoyl]hydrazine (Cm,nLH), with the same or different peripheral alkoxy chains, and some of their nickel(II) and copper(II) complexes are described. All the ligands, except those with no terminal chains on either end of the molecule, exhibit an enantiotropic SmC mesophase, as evidenced by polarizing optical microscopy and differential scanning calorimetric studies. It has been found that addition of a lateral hydroxyl group along with ester-substitution to the aroylhydrazone core increases the mesomorphic as well as thermal stability of the ligands. Also, the coordination of Ni2+ and Cu2+ with the aroylhydraozone core inhibits the mesomorphic potential of the ligands. A temperature dependent Raman study of one of the members, C12,12LH (m = n = 12) has been made to identify phase transitions and to understand the molecular rearrangement as a result of changes in intermolecular interactions at the phase transition. DFT calculations have been performed to obtain the stable electronic structure of the ligand (C6,6LH) and its nickel(II) complex.
- Singh, Sachin Kumar,Singh, Hemant Kumar,Nandi, Rajib,Kumar, Vijay,Tarcea, Nicolae,Popp, Jürgen,Singh, Ranjan K.,Singh, Bachcha
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- Synthesis and study of vitrescent materials based on the alkoxybenzoic acids derivatives and triethanolamine
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Fifteen new branched triethanolamine esters of the benzoic acid derivatives were designed and the mesomorphism typical of discotic mesogens was forecast for them. In eight of the obtained compounds a manifestation of liquid crystal properties was predicted, for four derivatives equiprobable prognosis was given, and only three compounds were predicted not to form a mesophase. The obtained esters were characterized by elemental analysis, NMR and IR spectroscopy, gas chromatography-mass spectrometry. The main thermal characteristics that allow accounting for their phase behavior were determined.
- Gruzdev,Akopova,Frolova
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p. 652 - 658
(2013/07/05)
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- Self-assembly of imidazolium-based rodlike ionic liquid crystals: transition from lamellar to micellar organization
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By using aryl-amination chemistry, a series of rodlike 1-phenyl1H- imidazole-based liquid crystals (LCs) and related imidazolium-based ionic liquid crystals (ILCs) has been prepared. The number and length of the C-terminal chains (at the noncharged end of the rodlike core) and the length of the N-terminal chain (on the imidazolium unit in the ILCs) were modified and the influence of these structural parameters on the mode of self-assembly in LC phases was investigated by polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For the single-chain imidazole derivatives nematic phases (N) and bilayer SmA2 phases were found, but upon increasing the number of alkyl chains the LC phases were lost. For the related imidazolium salts LC phases were preserved upon increasing the number and length of the C-terminal chains and in this series it leads to the phase sequence SmA-columnar (Col)-micellar cubic (Cuby1/Pm3n). Elongation of the N-terminal chain gives the reversed sequence. Short Nterminal chains prefer an end-to-end packing of the mesogens in which these chains are separated from the C-terminal chains. Elongation of the N-terminal chain leads to a mixing of N- and C-terminal chains, which is accompanied by complete intercalation of the aromatic cores. In the smectic phases this gives rise to a transition from bilayer (SmA2) to monolayer smectic (SmA) phases. For the columnar and cubic phases the segregated end-to-end packing leads to core-shell aggregates. In this case, elongation of the N-terminal chains distorts core-shell formation and removes Cub1 and Col phases in favor of single-layer SmA phases. Hence, by tailoring the length of the N-terminal chain, a crossover from taper-shaped to polycatenar LC tectons was achieved, which provides a powerful tool for control of self-assembly in ILCs.
- Cheng, Xiaohong,Bai, Xueqing,Jing, Shan,Ebert, Helgard,Prehm, Marko,Tschierske, Carsten
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supporting information; experimental part
p. 4588 - 4601
(2010/08/19)
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- Oxime Carbamate-Discovery of a series of novel FAAH inhibitors
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A series of novel oxime carbamates have been identified as potent inhibitors of the key regulatory enzyme of the endocannabinoid signaling system, fatty acid amide hydrolase (FAAH). In this Letter, the rationale behind the discovery and the biological evaluations of this novel class of FAAH inhibitors are presented. Both in vitro and in vivo results of selected targets are discussed, along with inhibition kinetics and molecular modeling studies.1.
- Sit,Conway, Charles M.,Xie, Kai,Bertekap, Robert,Bourin, Clotilde,Burris, Kevin D.
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supporting information; experimental part
p. 1272 - 1277
(2010/06/17)
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- Hydrogen bonding versus van der waals interactions: Competitive influence of noncovalent interactions on 2d self-assembly at the liquid-solid interface
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The structures of the self-assembled monolayers of various 4-alkoxybenzoic acids physisorbed at the liquid-solid interface were established by employing scanning tunnelling microscopy (STM). This study has been essentially undertaken to explore the competitive influence of van der Waals and hydrogen-bonding interactions on the process of two-dimensional self-assembly. These acid derivatives form hydrogen-bonded dimers as expected; however, the dimers organise themselves in the form of relatively complex lamellae. The characteristic feature of these lamellae is the presence of regular discommensurations or kinks along the lamella propagation direction. The formation of kinked lamellae is discussed in light of the registry mechanism of the alkyl chains with the underlying graphite substrate. The location of the kinks along a lamella depends on the number (odd or even) of carbon atoms in the alkyl chain. This result indicates that concerted van der Waals interactions of the alkyl chain units introduce the odd/even chain-length effect on the surface-assembled supramolecular patterns. The odd/even effects are retained even upon complexation with a hydrogen-bond acceptor. However, as the solvent is changed from 1-phenyloctane to 1-octanoic acid, the kinked lamellae as well as the odd/even effects disappear. This solvent-induced convergence of supramolecular patterns is attained by means of co-crystallisation of octanoic acid molecules in the 2D crystal lattice, which is evident from high-resolution STM images. The solvent co-adsorption phenomenon is discussed in terms of competing van der Waals and hydrogen-bonding interactions. Discontinuous but ordered: Noncovalent interactions play an exceedingly decisive role in the process of self-assembly. To gain better insight into the role of noncovalent interactions, the competitive influence of hydrogen-bonding and van der Waals interactions was explored in the monolayers formed by simple 4-alkoxybenzoic acids at the liquid-solid interface (see image). Copyright
- Mali, Kunal S.,Lava, Kathleen,Binnemans, Koen,Defeyter, Steven
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supporting information; experimental part
p. 14447 - 14458
(2011/03/21)
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- Self-assembly of highly luminescent bi-1,3,4-oxadiazole derivatives through electron donor-acceptor interactions in three-dimensional crystals, two-dimensional layers and mesophases
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We report on the synthesis and self-assembly of a new series of highly luminescent bi-1,3,4-oxadiazole derivatives [2,2′-bis(4-alkoyphenyl)-bi-1, 3,4-oxadiazole, BOXD-n, n = 1, 3, 4, 5, 6, 7, 10, 16]. Fully conjugated conformations were demonstrated either by computer simulation or in a single-crystal state. Well-defined 3D donor-acceptor (DA) architectures with strong face-to-face and edge-to-edge donor-acceptor interactions were observed in the single-crystal structure of BOXD-1. Highly oriented face-on two-dimensional DA layered structures due to edge-to-edge donor-acceptor interactions were observed on highly oriented pyrolytic graphite (HOPG) in BOXD-7 and BOXD-16. Nematic phase, smectic C phase with large tilted angle ( ≈ 50°) and relatively large transition enthalpic values and a highly ordered smectic X phase were demonstrated in BOXD-n (n = 5, 6, 7, 8, 10, 16) through tailing the terminal chains and relatively large scale monodomains were prepared in the smectic X phase of BOXD-5 even without any surface treatment. Strong blue fluorescent emissions were observed in BOXD-6 either in cyclohexane (ΦF ≈ 92%) or in solid state (ΦF ≈ 57%). The donor-acceptor interactions between alkyoxyphenylene rings and 1,3,4-oxadiazole rings were thought to be the driving force for the molecules to self-assemble into a large angle tilted layered structure.
- Qu, Songnan,Chen, Xiaofang,Shao, Xiang,Li, Fan,Zhang, Hongyu,Wang, Haitao,Zhang, Peng,Yu, Zhixin,Wu, Kai,Wang, Yue,Li, Min
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scheme or table
p. 3954 - 3964
(2010/02/28)
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- Smectic A liquid crystals from dihydrazide derivatives with lateral intermolecular hydrogen bonding
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Six dissymmetrical dihydrazide derivatives, N-(4-alkoxybenzoyl)-N′- (4′-nitrobenzoyl) hydrazine (Cn-NO2) and N-(4-alkoxybenzoyl)- N′-(4′-biphenyl carbonyl) hydrazine (Cn-Ph), were synthesized and investigated by means of differential scanning c
- Pang, Dongmei,Wang, Haitao,Li, Min
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p. 6108 - 6114
(2007/10/03)
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- Study of activation energy and order of reaction of some liquid crystals
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Liquid crystals of the type p-phenylene-di-p-n-alkoxy benzoate have been prepared. Kissinger isothermal decomposition method has been used for determination of activation energy values of liquid crystals. Kissinger's assessment for shape index of DTA peaks is used to find the order of reaction. There is no direct relationship between the carbon atoms in terminal methylene groups and Ea values. Order of reaction value decreases with increase in heating rate upto carbon atoms 10 in the terminal methylene group but beyond this the order increases or decreases.
- Mundhe
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p. 246 - 249
(2007/10/03)
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- Aroylhydrazinatonickel(II) and Copper(II) Complexes; a New Class of Metallomesogens
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A series of aroylhydrazinato-nickel(II) and -copper(II) complexes have been synthesised in high yield and shown to form a new class of metallomesogens, which form smectic C and nematic phases; the nickel(II) complexes were found to be highly stable even i
- Abser, Mohammed N.,Bellwood, Martin,Holmes, Michael C.,McCabe, Richard W.
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p. 1062 - 1063
(2007/10/02)
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