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1.
Six banana‐shaped compounds with a central core based on a 4,6‐dichloro‐1,3‐phenylene group were synthesized by varying the terminal chains (R = OC10H21 or OC11H21) and the lateral substituents (X = H, F or Cl). Their mesophases were characterized by a combination of differential scanning calorimetry, polarizing optical microscopy, triangular wave method, and X‐ray diffractometry. Mesomorphic properties of the banana‐shaped mesogens with an olefinic group (R = OC11H21) as a terminal chain are sensitive to lateral halogen substituents as much as those of the analogues with a saturated group (R = OC10H21). The compounds with X = F showed an antiferroelectric switchable smectic phase, which has been designated a B2 phase. The compounds without a lateral halogen substituent only formed a nematic phase, while the compounds with X = Cl did not exhibit a mesophase in the melt.  相似文献   

2.
A series of new compounds based on aromatically 2,5‐disubstituted 1,3,4‐oxadiazoles without flexible chains, formulated as p‐R–C6H4–(OC2N2)–(p‐C6H4)2–R′ with (i) R = CH3O, R′ = CH3O, CH3S, F, H (Ia–Id), (ii) R = CH3S, R′ = CH3O, CH3S, F, H (IIa–IId) and (iii) R = F, R′ = CH3O, CH3S, F, H (IIIa–IIId) (p‐C6H4 and OC2N2 represent a p‐phenylene spacer and a 1,3,4‐oxadiazole ring, respectively), were synthesised and characterised by 1H and 13C NMR, MS and HRMS techniques. Mesomorphic properties were investigated using differential scanning calorimetry and polarizing optical microscopy. All of the target compounds (except Id, IId, IIIc and IIId) exhibited an enantiotropic nematic mesophase with high melting temperatures. The liquid crystalline properties of these compounds were influenced greatly by polarity, steric factors and positions of the terminal groups. The effect of the terminal groups on the liquid crystal properties is discussed.  相似文献   

3.
4′‐Ferrocenyl‐1,1′‐biphenyl‐4‐yl 4‐alkoxybenzoates Fc–(C6H4)2–OC(O)–C6H4–O–C n H2n+1 (n = 8, 10, 12) (3ac), representing a new class of ferrocene‐containing thermotropic mesogens with nematogenic properties, were prepared. Two approaches were used for the construction of these mesogens: (i) reaction of 4′‐ferrocenyl‐1,1′‐biphenyl‐4‐ol with 4‐alkoxybenzoylchlorides, and (ii) crosscoupling of tris(4‐ferrocenylphenyl)boroxine with the corresponding halobenzenes. Crosscoupling was also applied for the synthesis of terphenyl‐containing mesogens Fc–(C6H4)3–OC(O)–C6H4–O–C n H2n+1 (n = 10, 12) (6a,b) and (RC5H4)Fe‐[C5H4–(C6H4)3–OC(O)–C6H4–O–C10H21] (11a, R = Et; 11b, R = n?Bu). The latter compounds also form nematic phases. Mesogens 6a,b form mesophases with wider temperature ranges than their biphenyl‐containing counterparts 3b,c. The most pronounced mesomorphism was displayed by compounds 11a and 11b, which have mesophases in the ranges 141–253°C and 120–238°C, respectively. The purity of compounds was established by 1H NMR spectra and elemental analysis. Mesophases were identified by polarizing optical microscopy and differential scanning calorimetry.  相似文献   

4.
Small change in chemical structure of discotic liquid crystals can cause big difference in their mesomorphism. Replacing of the alkoxy peripheral chains of triphenylene by oxygen-atom containing ester chains would result in novel mesomorphism. A series of mixed tail triphenylenes containing propoxyacetyloxy and alkoxy, abbreviated as C18H6(OCnH2n+1)3(OCOCH2OC3H7)3, n=4-8, and hexa(propyloxyacetyloxy)triphenylene, C18H6(OCOCH2OC3H7)6 were synthesized. Thermal gravimetry analysis (TGA) of three discogens showed that they had good thermal stability till 350 ℃. The mesomorphism was investigated through differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The preliminary X-ray diffraction (XRD) results of one compound showed that it exhibited ordered hexagonal columnar (Colho) mesophase. These mixed tail triphenylene derivatives possessed much stable Colho mesophase and wider mesophase ranges than their hexaalkoxytriphenylene C18H6(OR)6 and hexaalkanoyloxytriphenylene C18H6(OCOR')6 analogues. The asymmetrical compounds 2,6,11-trialkoxy-3,7,10-tri(2-propyloxyacetyloxy)triphenylenes with n=5-8 displayed higher clearing points and wider temperature ranges than their symmetrical isomers 2,6,10-trialkoxy-3,7,11-tri(2-propyloxyacetyloxy)- triphenylenes, while C18H6(OCOCH2OC3H7)6 had the highest clearing point due to the β-oxygen-atom effect.  相似文献   

5.
Abstract

Glucosyl‐1,5‐benzodiazepin‐2,4‐diones were synthesized in order to study the influence of the glucidic moiety on the amphiphilic behaviour. The glucosyl groups include 6‐deoxy‐D‐glucopyranos‐6‐yl and 6‐deoxy‐3‐O‐R‐D‐glucopyranos‐6‐yl (R = n ? C n H 2n+1; n = 1, 8, 10 and 12). Variation in the length of the hydrocarbon chain allowed comparison of such amphiphilic data as water solubility (Sw) and surface tension (γ) values. At 25°C, the glucopyranosyl benzodiazepines with R = H and CH3 show a higher water solubility than the starting 1,5‐benzodiazepin‐2,4‐diones. Some other glucidic benzodiazepine derivatives with an appropriate alkyl chain at C‐3 carbon of the D‐glucopyranose present a variable hydrosolubility and surface tension γ values close to 43 to 46 mN · m?1 at the corresponding saturation. Moreover, according to preliminary tests, these compounds seem to show a better affinity for the blood brain barrier.  相似文献   

6.
A series of 2‐(4‐n‐alkylphenyl)indenes (3) with different alkyl substituents (CH3 to C10H21) were synthesized and systematically characterized using differential scanning calorimetry, polarizing optical microscopy and X‐ray diffraction compared with 2‐phenylindene (3a). Depending on the alkyl chain length, highly ordered crystal‐smectic E mesophases were observed and confirmed by X‐ray diffraction for the derivatives 3h–3k with heptyl to decyl chains (n = 6?9). For 3f with a pentyl side chain (n = 4), an X‐ray crystal structure analysis was carried out.  相似文献   

7.
A series of new calamitic liquid crystals, 4-{[(pyridin-4-yl)methylidene]amino}phenyl 4-alkoxybenzoates comprising a heterocyclic (pyridine) and two phenyl rings core system, terminal alkoxy chain, imine and ester linkers were synthesised and characterised. This series consists of nine members wherein the members differ by the length of alkoxy chain (CnH2n+1O–, where n = 2, 4, 6, 8, 10, 12, 14, 16, 18). Spectral analysis results were in accordance with the expected structure. Their thermotropic behaviours were studied by using differential scanning calorimetry, optical polarising microscopy and powder X-ray diffraction techniques. A single mesophase (nematic) was observed for the first three members of the series (n = 2, 4 and 6). As the alkoxy chain increased to n = 8 and n = 10, the nematic phase appeared together with an additional smectic A (SmA) phase. When moving from n = 12 until the highest members (n = 18), the nematic phase disappeared and these compounds only exhibited a single mesophase (SmA).  相似文献   

8.
New nanocomposites, including different loading levels of sandwich-type polyoxometalates [(HOSnIVOH)3(XW9O34)2]n? (X = As (1), P (2) n = 12 and Si (3) n = 14) on Nd-doped TiO2 nanoparticles were prepared by a simple impregnation method. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FTIR), and energy-dispersive X-ray spectroscopy. Compounds 13 were successfully loaded on Nd-doped crystallized anatase-phase TiO2 nanoparticles of 20–25 nm. Catalytic activities of nanocomposites were examined by carrying out the oxidation of sulfides and alcohols with H2O2. Simple synthesis method, reusability, and low amounts of the heterogeneous catalysts with a slight excess of H2O2 and mild reaction conditions make these oxidation reactions an environmentally benign chemical process.  相似文献   

9.
A series of LnIII–SrII heterometallic coordination polymers formulated as [Ln2Sr3(pda)6(H2O)18]·nH2O (Ln = Pr-1, n = 14; Nd-2, n = 12; Sm-3, n = 11; Eu-4, n = 11; Gd-5, n = 16; Tb-6, n = 13; Dy-7, n = 13) were synthesized via assembly of Ln(NO3)3·6H2O, SrCl2·6H2O, pyridine-2,6-dicarboxylic acid (H2pda) and imidazole (im) in H2O/C2H5OH solution. Single crystal X-ray diffraction revealed that they are isostructural. All of these complexes possess ladder-shaped 1-D chain structures. The luminescent properties of Sm-3, Eu-4, Gd-5, Tb-6 and Dy-7 have been investigated. The solid-state quantum yields and the lifetimes of Eu-4 and Tb-6 are also studied.  相似文献   

10.
The orientation of E7 liquid crystal (LC) confined within 200 nm diameter cylindrical cavities of Anodisc membranes are investigated by FTIR dichroism techniques. The cavity walls of the confining pores were chemically modified with different length perfluorinated carboxylic acids (PCAs, C n F2n+1COOH, n = 3, 4, 5, 6) at 1, 3 and 5 mM concentrations. From the FTIR spectra of PCA‐treated alumina Anodsic membranes, we found salt formation between the –COOH group of the PCAs and the Anodisc membranes. From the FTIR spectra of LC‐filled Anodisc membranes, we found an abrupt alignment direction change, from parallel to perpendicular, of the LC molecules along the long axis of the cavities between n = 4 and n = 5 for the 1 mM concentration of PCA. However, for the 5 mM concentration of PCA, the parallel‐to‐perpendicular alignment direction of LC molecules changed between n = 3 and n = 4. These LC orientation changes for PCA‐treated Anodisc membranes occurred at shorter length than for hydrocarbon carboxylic acid (HCA, C n H2n+1COOH)‐treated Anodisc membranes. This change may be caused by the lower surface energy of the –(CF2) n CF3 chain of PCA than that of the –(CH2) n CH3 chain of HCA.  相似文献   

11.
Two series of discotic dimers T3Dn and T5Dn based on hexapropoxytriphenylene (HAT3) and hexapentyloxytriphenylene(HAT5), respectively, with polymethylene linkage O(CH2)nO (n = 3–12) have been synthesised. Their mesomorphism was investigated by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. The results showed that side chains induced a phase transition from colhp phase to colh phase, namely dimers T3Dn (n = 6–12) based on HAT3 exhibiting a single colhp phase, dimers T4Dn (n = 6, 7, 11, 12) based on HAT4 showing a highly ordered colhp phase in low-temperature region and a colh phase in high-temperature region, dimers T4Dn (n = 8–10) based on HAT4 displaying a single colhp phase and dimers T5Dn (n = 6–11) based on HAT5 indicating a single colh phase. Dimers T4Dn showed a phase competition between colh phase and colhp phase induced by linkages. Surprisingly, a unique phenomenon was found by us, that is, those compounds in which linkage lengths were twice those of side chains showed the largest enthalpies, the smallest intracolumnar spacings and the highest charge-carrier mobilities among their homologues, respectively, which implied that they formed the most highly ordered phase among their homologues.  相似文献   

12.
A series of new trialkoxytrialkanoyloxytriphenylene TP(OCnH2n+1)3(OCOCmH2m+1)3 (5a-5e) (n =m+1 =4- 8) discotic liquid crystals were prepared and their mesomorphic properties were investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The symmetrical and shorter chain triphenylenes display higher melting points and clearing points, more highly ordered and stable columnar mesophase than the asymmetrical and longer chain triphenylenes respectively.  相似文献   

13.
ABSTRACT

In the Triton X ? 100/n-CnH2n + 1OH/H2O system, the lamellar liquid crystalline region increases and the regions of O/W, W/O and bicontinuous microemulsion domains shrink, simultaneously, with the length of the chain in the unbranched aliphatic alcohol. In the O/W region, the Gibbs free energy for alcohol transfer from the water continuous phase to Triton X ? 100 micellar phase increases linearly with the chain length of alcohol. In the W/O region of the Triton X ? 100/n ? CnH2n + 1OH/n ? C7 H16/H2O system, as the solubilized water content increases, the effective radius (R e ), the inner water radius (R W ), the thickness of the interfacial layer (L) and the average aggregation number ([nbar]) of the reverse micelles increase, whereas the total number (N d ), the total interfacial area (A d ) and the change of the standard free energy (Δ c ? i G 0) for alcohol transfer from the oil continuous phase to the interfacial layer of the reverse micelles decrease; and with the longer chain alcohols, the values of R e , R W , L, and [nbar] all increase, while the Δ c-i G0 value decreases drastically with increasing chain length. In the lamellar liquid crystalline region, increasing the alcohol chain length can increase the stability of the lamellar liquid crystalline domain. All the results show that the alcohols, n ? C n H2n + 1OH, can be used as cosurfactants in the nonionic surfactant system and function similarly as in ionic surfactant systems.  相似文献   

14.
Seven new metal-organic coordination polymers, [M(tzda)(H2O)4] n [M = Co(1), Ni (2) and Zn(3)], [Zn(tzda)(4,4′-bipy)] n (4), [Cd(tzda)(4,4′-bipy)0.5(H2O)] n (5) and [M(tzda)(4,4′-bipy)(H2O)] n [M = Co(6), Ni(7)] [H2tzda = (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally synthesized and structurally characterized by X-ray single crystal diffraction. Compounds 13 display similar 1D zigzag chain structure. Compound 4 possesses a 2D-layered architecture generated from [Zn(tzda)] n moiety with double-chain structure cross-linking 4,4′-bipy spacers, while compound 5 consists of –Cd–OCO–Cd–OCO– chains cross-linked through –CH2SC2N2SSCH2– spacers of tzda anions and 4,4′-bipy, also showing a 2D-layered structure. The structures of 6 and 7 seem more complicated, in which the [M(tzda)] n layered subunits are extended to unique 3D framework by the bridging 4,4′-bipy ligand. Photoluminescence investigations reveal that 4 and 5 both display strong blue emissions in the solid state at room temperature, which could be significant in the field of luminescent materials. The magnetic studies of 6 and 7 show both display the characteristics of a weak antiferromagnetic coupling between metal ions in the system mediated by carboxylate bridges.  相似文献   

15.
New symmetrical and asymmetrical triphenylene-containing discotic liquid crystals with two different peripheral alkyl chains, known as sym-TP(OC6H13)3(OR)3 and asym-TP(OC6H13)3(OR)3, were synthesized. Their thermotropic liquid crystal properties were investigated through polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. The asyrranetdcal discogens are 2,6,11-rialkoxy-3,7,10-trihexyloxytriphenylenes, with the alkyl chain carbon numbers varying from 3-10, 12, and 14, while the symmetrical compounds are 2,6,10-trialkyloxy-3,7,11-trihexyloxytriphenylene. Two fluoroalkoxy substituted triphenylene discogens, 2,6,10-td(4,4,4-trifluorobutoxy)-3,7,11-trihexyloxytriphenylene and its asymmetrical isomer 2,6,11-tri(4,4,4-trifluorobutoxy)-3,7,10-trihexyloxytdphenylene were prepared. These two compounds show higher melting and clearing points than their alkoxy analogs, which implies that fluorophilic effect exists in the formation and stabilization of discotic columnar mesophase. The triphenylene derivatives TP(OC6H13)3(OR)3 with two different peripheral chains, symmetrically or asymmetrically attached on triphenylene cores, have lower melting points and clearing points than those of the higher symmetrical compounds TP(OR)6 with the same total chain carbon numbers. The mixed-chain-triphenylenes with longer alkoxy chains (n=9,10,12,14) show columnarmesophase at room temperature.  相似文献   

16.
Six transition metal coordination compounds with H2mand and different N-donor ligands, [Co(Hmand)2(2,2′-bipy)]·H2O (1), [Ni(Hmand)2(2,2′-bipy)]·H2O (2), [Ni(Hmand)2(bpe)] (3), [Zn(Hmand)2(2,4′-bipy)(H2O)]·2H2O (4), [Zn(Hmand)(bpe)(H2O)]n[(ClO4)]n·nH2O (5), and [Zn(Hmand)(4,4′-bipy)(H2O)]n[(ClO4)]n (6), were synthesized under different conditions (H2mand = (S)-(+)-mandelic acid, bpe = 1,2-di(4-pyridyl)ethane, 4,4′-bipy = 4,4′-bipyridine, 2,4′-bipy = 2,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine). Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectra, thermogravimetric analysis, powder X-ray diffraction, and circular dichroism. Compounds 1 and 2 are isostructural (0-D structures), which are extended to supramolecular 1-D chains by hydrogen bonding. Compound 3 exhibits 1-D straight chain structures, which are further linked via hydrogen bond interactions to generate a 3-D supramolecular architecture. Compound 4 displays a discrete molecular unit. Neighboring units are further linked by hydrogen bonds and ππ interactions to form a 3-D supramolecular architecture. Compound 5 displays a 2-D undulated network, further extended into a 3-D supramolecular architecture through hydrogen bond interactions. Compound 6 possesses a 2-D sheet structure. Auxiliary ligands and counteranions play an important role in the formation of final frameworks, and the hydrogen-bonding interactions and ππ stacking interactions contributed to the formation of the diverse supramolecular architectures. Compounds 1, 2, 4, 5, and 6 crystallize in chiral space groups, with the circular dichroism spectra exhibiting positive cotton effects. Furthermore, the luminescent properties of 46 have been examined in the solid state at room temperature, and the different crystal structures influence emission spectra significantly.  相似文献   

17.
The synthesis and characterization of a series­of 4 ‐ (4′‐ n ‐alkoxybenzylideneimino)phenyl‐­mercury<?tw=97.2%>(II) dithizonates, [CnH2n+1OC6H4CH­NC6H4Hg<?tw>(Hdptc)] (H2dptc = 1,5‐diphenylthiocarbazone = dithizone; n = 1, 4, 12, 14 or 18), is described. The intermediate long‐chain organomercury(II) acetates were obtained by condensation of 4‐aminophenylmercury(II) acetate with the appropriate 4‐n‐alkoxybenzaldehydes. The thermal behaviour of the complexes was studied by polarized optical microscopy and differential scanning calorimetry but revealed no mesophases. All of the complexes, however, were reversibly photochromic (yellow ⇌ blue) upon irradiation of chloroform solutions with visible light, and the half‐lives of the metastable blue forms were substantially increased relative to that of the parent mercury(II) bis(dithizonate). The compounds were not photochromic in the solid state. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

18.
The reaction of dirhodium tetrakis(3,4,5-trialkoxy)benzoates Rh2(B3OCn)4 (n = 10, 14, and 18) with three different dinitrogenated axial ligands (Lax), namely tetrazine (tz), phenazine (phz), and 4,4′-bipyridine (bpy), gave rise to three homologous series of mesogenic coordination polymers, [Rh2(B3OCn)4]Lax. All of them exhibited thermotropic columnar mesophases that were of the hexagonal type for tz and phz and rectangular for bpy. The lighter n = 10 homologs of the three series are liquid crystals (LC) at room temperature. Their mesomorphic properties have been compared with those of the previously studied Lax = pyrazine series. Models for the supramolecular organization of the three polymeric series in their Col LC phases are proposed on the basis of their structural parameters, as measured by XRD and SAXS. The differences are interpreted in terms of different coordination features of the axial ligands.  相似文献   

19.
A new series of Schiff base calamitic liquid crystal; methyl 4-(4′-n-alkoxybenzylideneamino)benzoate (MABAB), H2n+1C n OC6H4C(H)=NC6H4COOCH3 (n = 6, 8, 10, 12, 14, 16) has been synthesised and characterised by elemental analyses, Fourier transform infrared spectroscopy (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy. The mesomorphic properties of these compounds were studied by differential scanning calorimetry (DSC) and polarising optical microscopy (POM). All members of the series exhibit enantiotropic smectic A (SmA) mesophase. Temperature-dependent micro-Raman study of one of the members, MABAB-10 has been employed to identify phase transitions and the molecular rearrangement therein. Analysis of Raman marker bands; C–H in-plane bending, C–C stretching of phenyl rings and –C(H)=N– linking group of core confirms the transitions clearly as observed through DSC and POM. An in situ Raman measurement of C–H in-plane bending mode has also been performed to visualise the molecular changes more clearly. The Raman study gives an evidence of induced co-planarity of rings at Cr→SmA phase transition. The density functional theoretical (DFT) optimisation of monomer, dimer and rotational conformer of MABAB-10 also support the induced co-planarity at Cr→SmA phase transition.  相似文献   

20.
Four coordination polymers, namely, [Zn2(TIYM)(2,6‐PYDC)2]n · n(CH3OH) · 3n(H2O) ( 1 ), [Cu(TIYM)(2,6‐PYDC)]n · 3n(H2O) ( 2 ), [Co(TIYM)(2,6‐PYDC)]n · n(CH3OH) · 3n(H2O) ( 3 ), and [Cd2(TIYM)(2,6‐PYDC)2(H2O)]n · n(H2O) ( 4 ) with the flexible N‐containing ligand [tetrakis(imidazol‐1‐ylmethyl)methane (TIYM)] and the N‐containing dicarboxylic acid [2,6‐pyridinedicarboxylic acid (2,6‐PYDC)] were prepared. Compounds 1 – 4 show various structures because of different N–Ccenter–N angles (θ) of TIYM ligands and changing coordination modes of 2,6‐PYDC. Compounds 1 , 2 , and 3 display a similar 1D ladder‐like chain, whereas 4 gives a 1D quad‐core lifting platform shaped belt. The structural diversities in 1 – 4 suggest that the multiple coordination modes or the different freely twist angles of ligands and the presence of different metal atoms play important roles in the resulting structures of the coordination polymers. Furthermore, the solid‐state luminescence properties of 1 and 4 , and the magnetic properties of 3 were investigated.  相似文献   

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