Ferroelectric liquid crystals induced by dopants with axially chiral 2,2′‐spirobiindan‐1,1′‐dione cores: diether vs. diester side‐chains

A series of axially chiral 5,5′‐ and 6,6′‐dialkanoyloxy‐2,2′‐spirobiindan‐1,1′‐dione dopants, (R)‐2 and (R)‐4a–4c were synthesized in optically pure form and their ferroelectric polarization powers, δ_p, measured in four liquid crystal hosts with isotropic (I)–nematic (N)–smectic A (SmA)–smectic C (SmC) phase sequences. The results show that the sign of polarization P _S induced by (R)‐2 and (R)‐4a–4c follows the same trend as that previously reported for the 5,5′‐ and 6,6′‐diheptyloxy‐2,2′‐spirobiindan‐1,1′‐dione dopants, (R)‐1 and (R)‐3. The polarization induced by (R)‐2 in the host DFT is below detection limits, and the sign of P _S was found to invert as a function of temperature at mole fractions as low as 0.01. On the other hand, the polarization power of the 6,6′‐diheptanoyloxy dopant (R)‐4b in the host NCB76 is ?1449 nC cm^?2, the fourth highest value reported so far, and more than three times the δ_p value of the 5,5′‐diheptanoyloxy analogue (R)‐2 in that host (+474 nC cm^?2). Results of ²H NMR experiments suggest that (R)‐4b exerts stronger local perturbations in NCB76 than (R)‐2, and that these perturbations may be chiral in nature.     

Two new lead(II) coordination polymer and discrete complex containing bipyridine ligands with different positioned methyl substituents: synthesis,characterization, crystal structure determination,and luminescent properties

Lead(II) coordination polymer [Pb(5,5′-dmbpy)(μ-NO₃)₂] _n (1) and mononuclear complex [Pb(6,6′-dmbpy)(NO₃)₂] (2) (where 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridine and 6,6′-dmbpy is 6,6′-dimethyl-2,2′-bipyridine) were synthesized from reaction of lead(II) nitrate with 5,5′-dmbpy and 6,6′-dmbpy, respectively. Both complexes were thoroughly characterized by elemental analysis, infrared, ¹H and ¹³C NMR, UV–Vis, emission spectroscopy, as well as single-crystal X-ray diffraction. Polymer 1 possesses one-dimensional (1D) chain structure, whilst complex 2 exhibits a discrete complex which provide an extended chain parallel to the [001] direction, via weak intermolecular C–H···O hydrogen bonding. Coordination number of Pb²⁺ in 1 and 2 are 8 and 6, respectively, with the stereochemically active lone pair, resulting in the hemidirected geometry for both complexes. The nitrate anions exhibit a tridentate chelating/bridging mode in 1, and a bi-chelating mode in 2. The supramolecular features in these complexes are guided/influenced by weak directional intermolecular C–H···O hydrogen bonding (1 and 2) together with π–π and C–H···π (1) interactions. The luminescence studies of 1 and 2 confirmed that the position of methyl substituent on 2,2′-bipyridine rings has a profound effect on the fluorescence emissions.     

Side group functionalized liquid crystalline polymers and blends VIII. Nematic and SmAre phase formation in hydrogen-bonded blends of smectic side group LC polymers and a low molar mass dopant

Hydrogen-bonded blends based on smectic side group functionalized LC copolymers containing 4-alkyloxybenzoic acid fragments (proton donor) and a non-mesogenic low molecular mass dopant 4-cyanophenyl pyridine-4-carboxylate or 4-methoxyphenyl-d₄ pyridine-4-carboxylate (proton acceptor) were obtained. The blends containing 10-35 mol % of low molecular weight dopant form nematic (I-N-SmA) or re-entrant SmA phases (I-SmA-N-SmAre). The temperature dependence of the order parameter S, the birefringence Δn, and the splay K ₁ and bend K ₃ elastic constants of the nematic phase were studied by ²H NMR spectroscopy and the Fréedericksz method of threshold transitions in a magnetic field. A mechanism for the destruction of the SmA phase and the formation of the nematic phase in the hydrogen-bonded blends is suggested.     

Phosphorinane and Enol Rings in One Molecule. Evidence for Reciprocal Stabilization of Half-Chair Conformations

Abstract.

The X-ray crystal structure of 2-(2′,4′-dioxo-3′-pentyl)-5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorinane (2) reveals significant half-chair distortion of the axially oriented cisenol ring. The molecule also undergoes in-plane deformations. R(O...O) = 2.410 Å in the enol moiety indicates a very strong hydrogen bonding. The enol content, δ_OH and thermodynamic parameters for the axial-equatorial conformational and keto-enol equilibriums were obtained from ¹H, ³¹P NMR and IR measurements in comparison with the planar 4,6-dimethyl isomer (1) containing equatorially oriented enol ring. The X-ray single crystal structure of 5,5-dimethyl-2-(methoxycarbonyl-3′-oxo-2′-butyl)-2-oxo-1,3,2-dioxaphosphorinane (3) reveals the unusual half-chair conformation of the dioxaphosphorinane cycle disposed a trans-enol ring substituent. ¹H, ³¹P NMR and IR solution data support the same structure displays a strong conformational preference while the minor forms are chair conformers with an axial or equatorial cis-enol ring.     

13C Kinetic Isotope Effect of the Pudovik Reaction

Abstract

¹³C kinetic isotope effect (KIE) was determined by means of ¹³C NMR for the carbonyl atom in 2-nitrobenzaldehyde in its reaction with 2H-2-oxo-5,5-dimethyl-4-phenyl-1,3,2-dioxaphosphorinane in acetonitrile at 25°C. The observed isotope effect k₁₂/k₁₃ = 1.0238 ± 0.0031 evidences that the formation of the P?C bond in the Pudovik reaction catalyzed by triethylamine is less advanced than the π-bond breakage of the aldehyde carbonyl group.     

Solution-Structure and Aggregation Behavior of Two Dilithiostyrene Derivatives

The solution structure and the aggregation behavior of (E)-2-lithio-1-(2-lithiophenyl)-1-phenylpent-1-ene ( 1 ) and (Z)-2-lithio-1-(2-lithiophenyl)ethene ( 2 ) were investigated by one- and two-dimensional ¹H-, ¹³C-, and ⁶Li-NMR spectroscopy. In Et₂O, both systems form dimers which show homonuclear scalar ⁶Li,⁶Li spin-spin coupling. In the case of 2 , extensive ⁶Li,¹H coupling is observed. In tetrahdrofuran and in the presence of 2 mol of N,N,N′,N′-tetramethylethylylenediamine (tmeda), the dimeric structure of 1 coexists with a monomer. The activation parameters for intra-aggregate exchange in the dimers of 1 and 2 ( 1 (Et₂O): ΔH≠ = 62.6 ± 13.9 kJ/mol, ΔS≠ = 5.8 ± 14.0 J/mol K, ΔG≠(263) = 61.1 kJ/mol; 2 (dimethoxyethane): ΔH≠ = 36.9 ± 6.5 kJ/mol, ΔS≠ = ?61 ± 25 J/mol K, ΔG≠(263) = 54.0 kJ/mol) and the thermodynamic parameters for the dimer-monomer equilibrium for 1 (ΔH°; = 26.7 ± 5.5 kJ/mol, ΔS° = 63 ± 27 J/mol K), where the monomer is favored at low temperature, were determined by dynamic NMR studies.     

Liquid crystalline thiadiazole derivatives: new ferroelectric thiadiazole derivatives

A series of optically active thiadiazole Schiff's bases were prepared and their liquid crystalline properties were studied. Chirality was achieved by introducing an asymmetric carbon atom into the alkoxy group. Thus, 2-(p -active-alkoxyphenyl-imine)-5-(p-n-alkoxy)phenyl-1,3,4-thiadiazoles were synthesized. Their structures were characterized using elemental analysis, and IR, ¹H NMR and mass spectroscopies; their thermal properties were determined using DSC and polarized light microscopy. All the compounds are enantiotropic liquid crystals, and most of them exhibited both chiral smectic C^* and cholesteric mesophases. Only one of them did not show a smectic C^* phase.     

Smectic A liquid crystals from dihydrazide derivatives with lateral intermolecular hydrogen bonding

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 calorimetry, polarized optical microscopy and wide angle X-ray diffraction. The compounds exhibit smectic A₁ phase. Based on the results of ¹H NMR and variable temperature FT-IR spectroscopy, lateral intermolecular hydrogen bonding between -CO and -N-H groups was proposed and the effect of hydrogen bonding on the phase transitions was discussed. It was concluded that the combination of lateral intermolecular hydrogen bonding and microphase segregation stabilized the smectic A phase.     

Synthesis and properties of (−)-menthol-derived chiral liquid crystals by introducing adipoyloxy spacer between mesogenic core and chiral menthyl

A homologous series of new chiral liquid crystal compounds, M6BnB (n = 2, 4, 6, 8, 10, 12, 14, 16, 18), with varying length of n-alkoxy chains at one end, was formed by covalently linking a chiral (?)-menthyl with biphenyl-benzoate via adipoyloxy spacer group. A combination of analysis methods such as Fourier transform infrared, ¹H NMR spectra, differential scanning calorimetry, polarised optical microscopy and X-ray diffraction was carried out to systematically investigate their phase structures and phase transition behaviours. The length of the flexible terminal alkoxy group has a profound influence on the clearing points (T_iso) and T_iso decrease with the increase of alkoxy chain (n). In addition, increasing the length of the terminal alkoxy group tends to narrow the temperature range of the N* phase and favour the development of chiral smectic C phase.     

Synthesis,characterization, photocleavage,cytotoxicity in vitro,apoptosis, and cell cycle arrest of ruthenium(II) complexes

Two new ruthenium(II) complexes, [Ru(dmp)₂(BHIP)]²⁺ (1) and [Ru(dmb)₂(BHIP)]²⁺ (2), were synthesized and characterized by elemental analysis, ESI-MS, and ¹H NMR. DNA-binding constants of these complexes with calf-thymus DNA (ct-DNA) were determined to be 2.09 (±0.18)?×?10⁴ (mol?L^?1)^?1 (s?=?2.58) and 1.48 (±0.17)?×?10⁵ (mol?L^?1)^?1 (s?=?1.57), respectively. Viscosity measurements show that 1 and 2 interact with ct-DNA by intercalation. Upon irradiation at 365?nm, 1 and 2 induce cleavage of pBR322 DNA. The cytotoxicity of these complexes was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The apoptosis induced by the complexes was studied by flow cytometry. The results of the cell cycle arrest show that 2 can inhibit the proliferation of BEL-7402 cells in the G0/G1 phase.     

Effect of spacer length on mesomorphic behaviours of chiral liquid crystal compounds containing (-)-menthyl

ABSTRACT

A homologous series of new chiral liquid crystal compounds, MnBEB (n = 4–10), was prepared by covalently linking a chiral (–)-menthyl with biphenyl-benzoate via a dicarboxylic spacer of varying length and parity. A combination of analysis methods, such as FT-IR, ¹H NMR spectra, differential scanning calorimetry (DSC), polarised optical microscopy (POM) and X-ray diffraction was carried out to systematically investigate their phase structures and phase transition behaviours. The length and parity of the flexible spacers has a profound influence on the T_m and T_c and a modest odd-even effect is observed for the chiral liquid crystal compounds MnBEB. Only compound M4BEB developed an N* phase with selectively reflection on heating and a blue phase on cooling process. In addition, increasing the length of the flexible spacers tends to narrow the temperature range of the N* phase and widen the smectic phase, moreover, the pitch becomes longer with the spacer increases.     

Influence of methyl group position in bipyridine ligand on structure and luminescence of related zinc(II) nitrate complexes

Three new zinc(II) complexes of [Zn(6-mbipy)(η²-NO₃)₂] (1), [Zn(6,6′-dmbipy)(η²-NO₃)₂] (2) and [Zn(5,5′-dmbipy)(η²–NO₃)(H₂O)₂](NO₃).H₂O (3) were prepared from the reaction of 6-methyl-2,2′-bipyridine (6-mbipy), 6,6′-dimethyl-2,2′-bipyridine (6,6′-dmbipy) and 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) with Zn(NO₃)₂·4H₂O in methanol, respectively. These three complexes were thoroughly characterized by elemental analysis, thermal gravimetric analysis, differential thermal analysis, infrared, UV–Vis, ¹H NMR and ¹³C{¹H} NMR spectroscopy, and their structures have all been determined by the single-crystal X-ray diffraction. The luminescence spectra of the title complexes show that the intensity of their emission bands is stronger than the bands for the free ligands.     

Ferroelectric liquid crystals induced by dopants with axially chiral 2,2'-spirobiindan-1,1'-dione cores

The axially chiral dopants (R)-5,5'-, 5,6'-, and 6,6'-diheptyloxy-2,2'-spirobiindan-1,1'-dione ((R)-2, -3, and -4) were synthesized in optically pure form, and their absolute configurations were assigned by the exciton chirality method using circular dichroism spectroscopy. These new compounds were doped in four achiral liquid crystal hosts to give chiral smectic C* (SmC*) phases with spontaneous polarizations (Ps) that vary with the core structure of the host. The spontaneous polarization induced by the 5,5'-dialkoxy derivative (R)-2 is uniformly positive, whereas that induced by the 6,6'-dialkoxy derivative (R)-4 is uniformly negative and shows a different trend in host dependence. Polarization power (delta(p)) values range from +21 nC/cm2 for (R)-2 in 2',3'-difluoro-4-heptyl-4' '-nonyl-p-terphenyl (DFT) to -1037 nC/cm2 for (R)-4 in 4-(4'-heptyl[1,1'-biphen]-4-yl)-1-hexylcyclohexanecarbonitrile (NCB76). The unsymmetrical dopant (R)-3 behaves like a hybrid of the two symmetrical isomers, with lower absolute values of delta(p), on average, and varying signs of Ps. 2H NMR spectra of the doped mixtures using racemic mixtures of 2-4 with -OCD2C6H13 side-chains, in combination with phase diagrams, show that relatively minor changes in the dopant structure, that is, moving the alkoxy side-chains from the 5,5' to the 6,6' positions of the spirobiindandione core, have profound effects on dopant-host compatibility, and on the propensity of the dopant to exert chiral perturbations in the host environment. The variations in sign and magnitude of delta(p) as a function of alkoxy group positions are rationalized based on an analysis of zigzag conformations that conform to the binding site of the SmC host according to the Boulder model.     

New lipoxygenase and cholinesterase inhibitory sphingolipids from Carthamus oxyacantha

Two new sphingolipids: oxyacanthin A [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol; 1] and B [(2S,3S,4R)-2-{[(2R,5E)-2-hydroxyoctadec-5-enoyl]amino}hexaeicosane-1,3,4-triol-1-O-β-D-glucopyranoside; 2], together with 1-octacosanol, β-sitosterol, β-sitosterol 3-O-β-D-glucopyranoside and luteolin 7-O-β-glucopyranoside were isolated from the methanolic extract of the whole plant of Carthamus oxyacantha. Their structures were elucidated using ¹H and ¹³C NMR spectra and 2D NMR analyses (HMQC, HMBC and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS and HR-FAB-MS) experiments and in comparison with the literature data of the related compounds. Both the compounds 1 and 2 showed inhibitory potential against lipoxygenase (LOX) in a concentration-dependent manner with IC₅₀ values 83.3 ± 1.3 and 245.7 ± 1.1 µM, whereas compound 2 showed inhibition against enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC₅₀ values 65.3 ± 0.1 and 93.6 ± 0.1 µM, respectively.     

Kinetic and thermodynamic inclusion complexes of symmetric teramethyl-substituted cucurbit[6]uril with HCl salts of N,N′-bis(pyridylmethyl)-1,6-hexanediamine

The host–guest interaction of symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) with the hydrochloride salts of N,N′-bis(4-pyridylmethyl)-1,6-hexanediamine (P6), N,N′-bis(3-pyridyl-methyl)-1,6-hexanediamine (M6) and N,N′-bis(2-pyridylmethyl)-1,6-hexanediamine (O6) was investigated via single crystal X-ray diffraction, ¹H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy. Single crystal X-ray diffraction showed that the hexyl moiety of P6 or M6 was incorporated in the cavity of TMeQ[6], while the two pyridylmethyl moieties of O6 were incorporated in the TMeQ[6] cavity in the solid state. The ¹H NMR results in aqueous solution revealed that the TMeQ[6]-P6 and TMeQ[6]-M6 host–guest interaction systems produce a kinetic dumbbell-shaped inclusion complex at the initial stage and then an equilibrium pseudorotaxane-shaped inclusion complex as the only product after heating. However, only the pseudorotaxane-shaped inclusion complex was observed for the TMeQ[6]-O6 host–guest interaction system. Aqueous absorption spectrophotometric analysis showed that the dumbbell-shaped inclusion complexes were stable at pH 5.6, had a host–guest ratio of 2:1 and formed quantitatively at ～10¹¹ l²/mol² for the TMeQ[6]-M6 and TMeQ[6]-O6 systems. The transformation from dumbbell to pseudorotaxane-shaped inclusion complexes for the TMeQ[6]-P6 and TMeQ[6]-M6 host–guest systems yielded activation energies of 59.35 ± 1.55 and 78.7 ± 3.45 kJ/mol, respectively. The pseudorotaxane-shaped inclusion complexes were stable at pH 5.6, had a host–guest ratio of 1:1 and formed quantitatively at ～10⁷ l/mol for the TMeQ[6]-M6 and TMeQ[6]-P6 systems.     

Synthesis and properties of new ionic liquid crystals based on para-nitroazobenzene with substitution vinylimidazolium ion group

A new series of ionic liquid crystals (ILCs), 1-(4-(4-nitrophenylazo)phenyloxy) vinyl-3-methyl-1H-imidazol-3-ium bromide salts (C _n , n?=?6, 10) were synthesised. Their chemical structures were determined by ¹H NMR, ¹³C NMR, UV spectroscopy and elemental analysis. The liquid crystalline properties were investigated by differential scanning calorimetry, polarising optical microscopy, and powder X-ray diffraction. These measurements showed that C _n (n?=?6, 10) exhibit smectic liquid crystalline phases with focal-conic fan-shaped textures. The introduction of vinylimidazolium group onto the azobenzene enhances the thermal stability of the smectic state, which play an important role in forming the smectic layer structure.     

Synthesis and antitumor activity of novel pyridazinone derivatives containing 1,3,4-thiadiazole moiety

Abstract

A series of novel pyridazinone derivatives containing the 1,3,4-thiadiazole moiety were synthesized and characterized by ¹H NMR, 13C NMR, spectroscopies HRMS and IR. Among them, the structure of compound 5c (2-(Tert-butyl)?4-chloro-5-((5-((2-ethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was unambiguously confirmed via single crystal X-ray diffraction analysis. The inhibitory activity of all the target compounds against MGC-803 and Bcap-37 was determined by MTT assay, with doxorubicin (the inhibition rates were 95.5?±?0.4% and 95.7?±?1.0% respectively) as a control. The preliminary results showed that the inhibitory activity of compound 5n (2-(Tert-butyl)?4-chloro-5-((5-((3-fluorophenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was superior to the others. The inhibition rates of MGC-803 and Bcap-37 cells were 86.3?±?2.2% and 92.3?±?0.6% at a concentration of 10?μmol/L, respectively. The preliminary structure-activity relationship showed that when the 2-position of the benzene ring was substituted by a methyl group, such as compound 5j (2-(Tert-butyl)?4-chloro-5-((5-((2,3-dimethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), it exhibited good anticancer activity on MGC-803 cells. Besides, introducing fluorine, chlorine, or trifluoromethyl group onto the benzene ring, such as compound 5?m (2-(Tert-butyl)?4-chloro-5-((5-((4-(trifluoromethoxy)phenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), displayed good anticancer activity on MGC-803 and Bcap-37 cells.     

Influence of alkoxy tail length on the self‐organization of hairy‐rod polymers based on mesogen‐jacketed liquid crystalline polymers

A series of hairy‐rod polymers, poly{2,5‐bis[(4‐alkoxyphenyl)oxycarbonyl]styrenes} (P‐OCm, m = 1, 2, 4, 6, 8, 10, 12, 14, 16, and 18) were designed and successfully synthesized via free radical polymerization. The chemical structure of the monomers was confirmed by elemental analysis, ¹H NMR and ¹³C NMR. The molecular characterizations of the polymers were performed with ¹H NMR and gel permeation chromatography. The phase structures and transitions of the polymers were investigated by the combination of techniques including differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized optical microscopy, and rheological measurement. The experimental results revealed that the self‐assembly behaviors of P‐OCm changed with the increase in m. First, the P‐OCm (m = 1, 2) showed only a stable liquid crystalline phase above T_g. Second, with the increasing length of alkoxy tails, the P‐OCm (m = 4, 6, 8) presented a re‐entrant isotropic phase above T_g and a liquid crystalline phase at higher temperature. Third, the P‐OCm (m = 10, 12, 14, 16, 18) exhibited an unusual re‐entrant isotropic phase which was separating SmA (in low temperature) and columnar phases (in high temperature). It was the first time that mesogen‐jacketed liquid crystalline polymers formed smectic phase, re‐entrant isotropic phase, and columnar phases in one polymer due to the microphase separation and the driving force of the entropy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Liquid crystalline behavior and fluorescent property of calix[4]arene containing azobenzene photochromic group

The reaction of 4′-hydroxy-4-methyl azobenzene (1) and 1,6-dibromohexane afforded 6-bromo-1-((4-((4-met hylphenyl)azo)phenyl)oxy)hexane (2), which further reacted with p-tert-butylcalix[4]arene to give the calix[4]arene derivative (3) whose lower rim had been modified by the azobenzene photochromic group. The structure of 3 was characterized by ¹H-nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS). The fluorescence intensity of compound 3 was two to four times higher than that of compounds 1 and 2 as the azobenzene group concentration in the range of 1.6 × 10⁻⁵ to 8.0 × 10⁻⁴ mol/L, indicating that the fluorescence quantum yield of the azobenzene group had been improved through being attached to the calix[4]arene skeleton. The liquid crystalline behavior of compound 3 was studied by polarized microscopy (POM) and differential scan calorimeter (DSC). Compound 3 exhibited the enchased texture of a smectic liquid crystal from 209.4°C to 219.5°C on heating, while 2 exhibited a liquid crystalline phase from 87.4 to 83.2°C on cooling. It was found that the calix[4]arene skeleton was a good platform for conformation immobilization of azobenzene photochromic group and the formation of liquid crystalline. Translated from Chinese Journal of Applied Chemistry, 2006, 23(9): 1023–1026 [译自: 应用化学]     

The rα-structure and the 1H and 199Hg shielding anisotropies of dimethylmercury as determined in nematic and smectic liquid crystal solvents

The complete r_α-structure of dimethylmercury in the nematic ZLI 1167 liquid crystal was determined. This study confirms the earlier results, indicating that the structure is practically independent of the liquid crystal solvent, although some minor deviations exist. The Hg? C distance was found to be 207.97±0.05 pm, when the vibration corrections in the dipole-dipole coupling constants were taken into account. This is rather similar to the distances obtained with other spectroscopic methods. The anisotropies of the ¹H and ¹⁹⁹Hg chemical shifts were obtained by using a smectic liquid crystal and recording the corresponding spectra, the optical axis being parallel with or perpendicular to the external field direction. The experimental ratio-2.007±0.017 of the D∥ (HgH) and D? (HgH) coupling constants proves that the indirect contributions in these coupling constants are negligible. Shielding anisotropies of 3.70±0.3 ppm and 7325±55 ppm for ¹H and ¹⁹⁹Hg, respectively, were obtained.