62443-20-3Relevant academic research and scientific papers
Covalent and ionic Cu(II) complexes with cyclam and substituted benzoato ligands: Structural, thermal, redox and mesomorphic properties
Abdullah, Norbani,Arifin, Zainudin,Tiekink, Edward R. T.,Sharmin, Naima,Ahmad Tajidi, Nur Syamimi,Mat Hussin, Siti Amira
, p. 862 - 878 (2016)
A covalent mononuclear complex, [Cu(p-HOC6H4COO)2(cyclam)] (1), and two ionic mononuclear complexes, [Cu(cyclam)(H2O)2](p-CH3OC6H4COO)2 (2) and [Cu(cyclam)(
Columnar self-assembly of luminescent bent-shaped hexacatenars with a central pyridine core connected with substituted 1,3,4-oxadiazole and thiadiazoles
Pradhan, Balaram,Gupta, Ravindra Kumar,Pathak, Suraj Kumar,De, Joydip,Pal, Santanu Kumar,Achalkumar, Ammathnadu S.
, p. 3781 - 3798 (2018/03/06)
Bent-shaped molecules with a central pyridine core flanked with substituted 1,3,4-oxadiazole and thiadiazole derivatives with a variation in the number and length of terminal tails were synthesized. Thiadiazole based compounds exhibited a wider mesophase
Star-shaped fluorescent liquid crystals derived from s-triazine and 1,3,4-oxadiazole moieties
Pradhan, Balaram,Pathak, Suraj Kumar,Gupta, Ravindra Kumar,Gupta, Monika,Pal, Santanu Kumar,Achalkumar, Ammathnadu S.
supporting information, p. 6117 - 6130 (2016/07/06)
Star-shaped molecules with a central triazine core appended with three 1,3,4-oxadiazole arms have been designed with the variation in the number, length and pattern of peripheral chain substitution. These compounds were investigated for their thermal, electrochemical and photophysical behavior. These nonconventional molecules stabilized wide range columnar phases and demonstrated how one can tune the liquid crystal self-assembly through simple structural modification. The photophysical properties of these star shaped molecules are extremely dependent on the number and pattern of peripheral chain substitution. These compounds exhibit blue and green luminescence in the solid/liquid crystal state. The ability to overcome aggregation induced quenching is due to the favorable packing of these molecules in the solid state. These solid-state emissive materials with good thermal stability and lower band gap may find applications in the construction of emissive displays and organic lasers.
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.
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.
A new way to access chiral liquid crystals: Organocatalyst-mediated synthesis of chiral rod-like liquid crystals
Wang, Li,Liu, Xiao-Jun,Huang, Ping,Gong, Qing-Ping,Li, Yong-Hong,Wang, Bi-Qin,Zhao, Ke-Qing
scheme or table, p. 53 - 59 (2012/07/14)
In this article, an asymmetric organocatalytic way to prepare chiral liquid crystals from non-chiral starting materials was described. By using L-proline as the organocatalyst, several new chiral rod-like liquid crystals that are elusive with traditional methods were prepared. In addition, a series of novel enone-containing rod-like liquid crystals were also obtained as side-products. Mesomorphic properties of all new compounds were studied by Polarized Optical Microscope and Differential Scanning Calorimetry. Copyright Taylor & Francis Group, LLC.
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
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
Qu, Songnan,Chen, Xiaofang,Shao, Xiang,Li, Fan,Zhang, Hongyu,Wang, Haitao,Zhang, Peng,Yu, Zhixin,Wu, Kai,Wang, Yue,Li, Min
scheme or table, p. 3954 - 3964 (2010/02/28)
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.
Synthesis and characterization of 1,3,4-oxadiazole derivatives containing alkoxy chains with different lengths
Zhang, Xiao-bing,Tang, Ben-chen,Zhang, Peng,Li, Min,Tian, Wen-jing
, p. 55 - 64 (2008/03/13)
The synthesis, optical properties, electrochemical properties, electronic structures and applications in electroluminescent device of three series of 1,3,4-oxadiazole derivatives, 1,4-bis[(4-methylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD1), 5,5′-di-(4-methyl)-2,2′-p-(2,5-bisalkoxyphenylene)-bis-1,3,4 -oxadiazole (OXD2-n) and 1,4-bis[(4-alkoxyphenyl)-1,3,4-oxadiazolyl]phenylene (OXD3-n) are reported. The molecular structures of the oxadiazole compounds were confirmed by FT-IR, 1H NMR spectroscopy and elemental analysis. The optical and electrochemical properties of the compounds were investigated by UV-vis absorption and photoluminescence spectroscopy as well as cyclic voltammetry. The results show that introduction of two alkoxy groups whose electron-donating ability is stronger than that of methyl groups increases the electron density of the conjugated segment of OXD2-n (with side-on alkoxy substituents) and OXD3-n (with end-on alkoxy substituents), and thus leads to the absorption maximum bathochromic-shift compared to that of OXD1. The HOMO and LUMO energy levels of the compounds studied are in the range of -2.78 to -2.89 and -5.75 to -6.20 eV. Calculations on the representative compounds by the Dmol3 package of MS Modeling 3.0 revealed that the increase of energy levels in both OXD2-n and OXD3-n was due to the change of the frontier molecular orbital distribution in the central benzene ring. The light-emitting devices have been fabricated using blends of MEH-PPV and these compounds as emissive layers, among which, maximum brightness up to 11810 cd m-2 (8.5 V) has been observed, which is 40 times brighter than that with MEH-PPV. The result of the devices suggested that oxadiazole derivatives studied function well as electron-transporting materials and can be used in LEDs, and thus to enhance the efficiency of LEDs.
