40687-17-0Relevant academic research and scientific papers
Synthesis and mesomorphic characterization of some novel steroidal mesogens: A structure–property correlation
Bhat S, Vanishree,Kumar, Sandeep,Raghunathan, V. A.
, (2021/08/25)
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.
Triketonate difluoroboron complexes. Substitution-dependent liquid crystal and photophysical properties
Sánchez, Ignacio,Fernández-Lodeiro, Adrián,Oliveira, Elisabete,Campo, José Antonio,Torres, M. Rosario,Cano, Mercedes,Lodeiro, Carlos
, p. 184 - 200 (2016/09/07)
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+.
Synthesis, characterization and mesomorphic investigations of ester-substituted aroylhydrazones possessing a lateral hydroxyl group
Singh, Sachin Kumar,Singh, Hemant Kumar,Nandi, Rajib,Kumar, Vijay,Tarcea, Nicolae,Popp, Jürgen,Singh, Ranjan K.,Singh, Bachcha
, p. 99 - 112 (2014/04/17)
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.
New mesomorphic benzothiazol derivatives: Synthesis and characterization
Koh, Teck-Ming,Ha, Sie-Tiong,Yeap, Guan-Yeow,Lin, Hong-Cheu
, p. 926 - 928 (2013/09/24)
In this paper, the synthesis of new mesomorphic benzothiazolyl derivatives, 6-ethoxy-2-[4-(4-alkyloxybenzoyloxy)benzylidenamino]benzothiazoles, is presented. The structures of the title compounds were elucidated using spectroscopic techniques, such as FT-IR, NMR (1H and 13C), elemental analysis and EI-MS. The mesomorphic behaviours of these compounds were determined by differential scanning calorimetric and polarizing optical microscopic techniques. Compounds exhibited nematic and tilted smectic phases upon heating from crystal phase. An obvious odd-even effect was observed in this homologous series.
Synthesis and mesomorphic evaluation of new calamitic liquid crystals containing benzothiazole core
Koh, Teck Ming,Ha, Sie Tiong,Lee, Teck Leong,Lee, Siew Ling,Yeap, Guan Yeow,Lin, Hong Cheu,Subramaniam, Ramesh T.
scheme or table, p. 619 - 622 (2012/02/01)
The design and synthesis of new calamitic benzothiazole-based liquid crystals, 2-[4-(4-alkyloxybenzoyloxy)-phenyl]benzothiazoles are presented. The target compound was characterized using spectroscopic techniques, such as FT-IR, NMR (1H and 13C), microanalysis and EI-MS. The liquid crystalline behaviours of these compounds were thoroughly examined by differential scanning calorimetry and polarizing optical microscope techniques. These materials exhibited enantiotropic nematic phase with high thermal stability (>168 °C). Smectic A phase starts to emerge as monotropic (metastable) phase from C10 member and changes into enantiotropic (stable) phase from C12 and persists up to C16 members.
Hydrogen bonding versus van der waals interactions: Competitive influence of noncovalent interactions on 2d self-assembly at the liquid-solid interface
Mali, Kunal S.,Lava, Kathleen,Binnemans, Koen,Defeyter, Steven
supporting information; experimental part, p. 14447 - 14458 (2011/03/21)
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
V-Shaped switching and interlayer interactions in ferroelectric liquid crystals
Petrenko, Alexey,Goodby, John W.
, p. 766 - 782 (2008/02/01)
Linear electrooptic responses in ferroelectric liquid crystals can be achieved via thresholdless switching. The molecular parameters for the design of ferroelectric liquid crystals that may yield a thresholdless response have not been delineated so far. In this article we explore some of the chemical design features that may be utilised in controlling switching processes, and we develop property-structure correlations in order to achieve materials that exhibit thresholdless behaviour. The Royal Society of Chemistry.
Chemistry of Rh(I) complexes based on mesogenic 3,5-disubstituted pyrazole ligands. X-ray crystal structures of 3,5-di(4-n-butoxyphenyl)pyrazole (Hpzbp2) and [Rh(μ-pzR2)(CO)2]2 (R = C6H4OCnH2n+1, n = 10, 12) compounds. Part II
Torralba,Cano,Campo,Heras,Pinilla,Torres
, p. 150 - 161 (2007/10/03)
Four new 3,5-disubstituted pyrazoles HpzR2 containing long-chain 4-n-alkyloxyphenyl substituents [R = C6H4OCnH2n+1; n=4 (1), 6 (2), 12 (5), 14 (6)] have been prepared and characterised. All of them showed mesomorphic behaviour,the stability and the range of the mesophases increasing with the length of the chain on the pyrazole. The X-ray structure of Hpzbp2 (1) showed a highly linear molecular shape. Related results were deduced for the remained HpzR2 and the structural consequences agree with the observed mesomorphic properties. The mesogenic pyrazoles HpzR2 (1-6) were used as ligands towards [RhCl(CO)2] and [Rh(CO)2] fragments. [RhCl(CO)2(HpzR2)] complexes (7-12) showed some physical properties dependant on the long-chained pyrazoles, and related to different molecular arrays in the solid state. In all cases these compounds evolved to [Rh(μ-pzR2)(CO)2]2 in solution. The pyrazolate Rh(I) complexes [Rh(μ-pzR2)(CO)2]2 (3-18) had the usual boat conformation, as deduced by the crystal structure of two of these derivatives [n =10 (16), 12 (17)]. The packing arrangement has both layer and columnar characteristics. No mesophases have been detected for any of the Rh(I) complexes.
Phosphocholine derivatives having antihypertensive action
-
, (2008/06/13)
Phosphocholine derivatives and compositions are described which are useful as hypotensive agents and in the treatment of hypertension in warm-blooded animals.
