A mixed cyclodextrin‐biphenyl thermotropic liquid crystal: Synthesis,liquid‐crystalline properties,and supramolecular organization

A well‐defined structure liquid crystal heptakis [6‐deoxy‐6‐(1‐H‐1,2,3‐triazol‐4‐yl)(methyl)6‐(4‐methoxybiphenyl‐4′‐yloxy) hexanoyl]‐β‐cyclodextrin (H6B‐β‐CD) was synthesized from propargyl 6‐(4‐methoxybiphenyl‐4′‐yloxy) hexanoate (P6B) and heptakis (6‐deoxy‐6‐azido)‐β‐cyclodextrin ((N₃)₇‐β‐CD) by click reaction. The chemical structure of H6B‐β‐CD was confirmed by ¹H NMR, FTIR, and MALDI‐TOF MS. The thermal stability of the compound was investigated by thermogravimetric analysis (TGA). The liquid crystalline behavior was studied by differential scanning calorimetry (DSC), polarizing optical microcopy (POM), and wide‐angle X‐ray diffraction (WAXD) measurement. These investigations have shown that the supramolecular structure of H6B‐β‐CD are consisted of a large scale ordered lamellar structure and a small scale ordered structure (SmE) at low temperature region. As the temperature increases, the small scale structure becomes disordered relatively in the first instance, from smectic E to smectic A. Then, the lamellar structure collapses and nematic phase and isotropic phase are observed in sequence. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2838–2845, 2010     

1,3-双[4-(4'-甲基)-氧化偶氮苯基-苯氧羰基]苯氧甲基-1,1,3,3- 四甲基二硅 氧烷的合成、晶体结构和液晶性能

合成了[CH3(C6H4)N2O(C6H4)COO(C6H4)OCH2Si(CH3)2]2O,经IR,1^HNMR和元素分析表征,并测定其单晶结构。结果表明,晶体属单斜晶系,空间群为P21/c,晶胞参数a=1.7557(1),b=1.0938(9),c=2.3300(1)nm,β=105.6(6)°,V=4.3116nm^3,Mr=855.07,Z=4,Dc=1.317g/cm^3,μ(CuKα)=6.335cm^-1,F(000)=900,最终的偏离因子R=0.0837,Rw=0.0913。该分子中,柔性的四甲基二硅氧烷嵌段与氧化偶介晶基团形成ABA结构齐聚物。两条刚性的介晶基链节的轴向几乎平行向上伸出。径长比(L/D)为4.23.该液晶化合物的要变温度K174.4N226.8Ⅰ.通过结构分析,讨论了该类化合物的结构对液晶相变行为的影响。     

Synthesis, characterization, mechanochromism and photochromism of [Fe(dm4bt)3][FeCl4]2 and [Fe(dm4bt)3][FeBr4]2, along with the investigation of steric influence on spin state

The complexes [Fe(dm4bt)(3)][FeCl(4)](2) (1) and [Fe(dm4bt)(3)][FeBr(4)](2) (2) were prepared from the reaction of 2,2'-dimethyl-4,4'-bithiazole (dm4bt) with FeCl(3)·6H(2)O and FeBr(3), respectively, in methanol. Both complexes were characterized by IR, UV-Vis and (1)H NMR spectroscopy and their structures were studied by single-crystal diffraction. The methylated bithiazole led to high spin Fe(II) centers in the octahedral cation part of complexes 1 and 2 with Fe-N distance of 2.220 ?, in spite of the low spin octahedral Fe(II) complexes with unsubstituted bithiazole ligands. Crystal structure determination of 2 was performed at 90, 120 and 298 K. Temperature reduction to 90 K resulted in a decrease in the Fe-N bond length to 2.206 ? which is still in the range of high spin Fe(II). Complex 1 shows a reversible mechanochromic effect from the crystalline phase to powder form from red to yellow; it also displays reversible photochromism from yellow to green in solution under sunlight. The magnetic behaviour of the complexes was also studied at 2-300 K. The temperature dependence of χ(m)T curves for the two forms of 1, crystal and powder, demands some changes in their magnetic behavior, causing different colors i.e. red and yellow. At low temperatures, χ(m)T decreases where the decrease starts at around 65 K for compound 1, and at around 100 K for compound 2, due to different counterions. The two complexes exhibit antiferromagnetism at around 4 K.     

Synthesis, growth and characterization of a new nonlinear optical material: 4-phenylpyridinium hydrogen squarate (4PHS)

A novel organic non-linear optical organic single crystal of 4-phenylpyridinium hydrogen squarate (4PHS) has been synthesized and successfully grown from aqueous solutions by slow evaporation solution growth method. In the present investigation the title compound has been synthesized by taking equimolar quantity of 4-phenylpyridine and squaric acid and mixed thoroughly using double distilled water as the solvent. The prepared concentrated solution was placed in an undisturbed condition, and then the solution was periodically inspected. The good quality single crystals have been harvested in a time span of 3 weeks. Then the grown crystal was characterized as single crystal XRD, differential thermal analysis, thermogravimetric analysis, FTIR, UV-vis-NIR, SHG, (1)H NMR and (13)C NMR analyses, respectively. The observed results from the characterization analyses show its suitability for NLO applications when compared with some of the existing organic crystals. The relative second harmonic generation of this grown crystal was found to be five times higher than that of KDP crystal. The UV cut-off wavelength and decomposition temperature of this grown crystal were also comparatively better. (1)H NMR and (13)C NMR spectroscopic studies were employed to elucidate the structure of the grown specimen.     

4-amino- and 4-nitrodipicolinatovanadium(V) complexes and their hydroxylamido derivatives: synthesis, aqueous, and solid-state properties

A number of 4-substituted, dipicolinatodioxovanadium(V) complexes and their hydroxylamido derivatives were synthesized to characterize the solid state and solution properties of five- and seven-coordinate vanadium(V) complexes. The X-ray crystal structures of Na[VO2dipic-NH2].2H2O (2) and K[VO2dipic-NO2] (3) show the vanadium adopting a distorted, trigonal-bipyramidal coordination environment similar to the parent coordination complex, [VO2dipic]- (1), reported previously as the Cs+ salt. The observed differences in the chemical shifts of the complexes both in the 1H (ca. 0.7-1.4 ppm) and 51V (ca. 1-11 ppm) NMR spectra were consistent with the electron-donating or electron-withdrawing properties of the substituent groups, respectively. Stoichiometric addition of a series of hydroxylamine ligands (H2NOH, MeHNOH, Me2NOH, and Et2NOH) to complexes 1-3 led to the formation of seven-coordinate vanadium(V) complexes. The X-ray crystal structure of [VO(dipic)(Me2NO)(H2O)].0.5H2O (1c) was found to be similar to the previously characterized complexes [VO(dipic)(H2NO)(H2O)] (1a) and [VO(dipic)(OO-tBu)(H2O)]. While only slight differences in the 1H NMR spectra were observed upon addition of the hydroxylamido ligand, the signals in the 51V NMR spectra change by up to 100 ppm. The addition of the hydroxylamido ligand increased the complex stability of complexes 2 and 3. Evidence for a nonstoichiometric redox reaction was found for the monoalkyl hydroxylamine ligand. The reaction of an unsaturated five-coordinate species with a hydroxylamine to form a seven-coordinate vanadium complex will, in general, dramatically increase the amounts of the vanadium compound that remain intact at pH values near neutral.     

Carborane-containing liquid crystals: a comparison of 4-octyloxy-4-(12-pentyl-1,12-dicarbadodecaboran-1-yl)biphenyl with its hydrocarbon analogues

4-Octyloxy-4-(12-pentyl-1,12-dicarbadodecaboran-1-yl)biphenyl ( 1BC ) has been synthesized along with three hydrocarbon analogues in which the 1,12-dicarbadodecaborane is replaced by a phenyl ( 1PH ), trans -cyclohexyl ( 1CH ) or bicyclo\[2.2.2]octyl ( 1BO ) ring. The mesogenic properties of these materials have been compared and contrasted in both their pure states and as binary mixtures. The binary phase diagrams for the liquid crystal 1BC , with its hydrocarbon analogues 1CH and 1BO exhibit excellent miscibility of the smectic A phase while the more highly ordered smectic phases (SmB and SmE) for the hydrocarbons are suppressed by 1BC . In contrast the binary mixture of 1BC with the terphenyl analog ( 1PH ) exhibits complex behaviour in which the thermal stability of the smectic E phase is enhanced. X-ray diffraction data for the 1PH - 1BC binary mixture suggest a strong in-plane molecular ordering which might be attributed to intermolecular associations stabilizing the smectic E phase in preference to other smectic modifications.     

Distribution and dynamics of hydrogen in the low-temperature phase of Mg(2)NiH(4) studied by solid-state NMR

Distribution and dynamics of hydrogen atoms in the low-temperature phase of Mg(2)NiH(4) have been studied by means of (2)H and (1)H NMR for Mg(2)NiD(4) and Mg(2)NiH(4), respectively. (2)H NMR spectra have been measured in the temperature range between 200 and 340 K, and the line shapes were simulated. The temperature dependence of (2)H NMR spectra was quite well simulated assuming a distorted tetrahedral configuration and a pseudoisotropic rotation of the NiD(4) unit. The estimated jump frequency obeyed Arrhenius relation with a frequency factor of (0.8 +/- 0.6) x 10(13) Hz and an activation energy of 50.1 +/- 1.4 kJ/mol. (1)H NMR spectra were acquired from 240 to 360 K. The observed (1)H second moments were 202 kHz(2) in the rigid lattice (240 K) and 46.6 kHz(2) in a motional state (360 K). The value in the rigid lattice supported the tetrahedron model, and the value in a motional state indicated the isotropic rotation of the NiH(4) unit. Conclusively, the NiH(4) unit has the distorted tetrahedral configuration and undergoes the pseudoisotropic rotation.     

端基含12个己氧基偶氮苯介晶基元的树状碳硅烷液晶的合成

用发散法合成了周边含12个己氧基偶氮苯介晶基元(M3)端基的树状碳硅烷(D1),并用元素分析、氢谱、激光质谱、红外光谱、紫外-可见光谱、偏光显微镜、DSC和WAXD对产物进行表征.结果表明,D1为向列相,与M3相同,树状物相态由介晶基元相态决定,D1的液晶态相行为:K92N126I124N78K,D1熔点比M3降低了24～30℃,D1清亮点比M3提高了6～8℃,D1液晶态温区比M3加宽30～38℃,在树状物中观察到S=+2的高强向错.     

Synthesis, growth and characterization of 4-bromo-4'chloro benzylidene aniline--a third order non linear optical material

The organic nonlinear optical material of 4-bromo-4'chloro benzylidene aniline (BCBA) was synthesized and single crystal of BCBA was grown from acetone solution by solvent evaporation method at room temperature. Its three dimensional structure was elucidated from single crystal X-ray diffraction analysis at 173 K. Synthesized compound of BCBA was subjected to FTIR and (1)H and (13)C NMR spectral analyses. The range and percentage of optical transmission of BCBA was determined by UV-vis-NIR spectrum and its fluorescence spectrum was recorded using spectrofluorometer. The mechanical strength of the crystal was estimated using Vickers microhardness test on the (001) plane. Dielectric constant of the grown crystal was measured for various frequencies along (001) plane. The third order nonlinear optical properties of BCBA were investigated by Z-scan technique with He-Ne laser radiation of wavelength at 632.8 nm and the corresponding nonlinear refractive index, absorption coefficient and optical susceptibility were calculated.     

Synthesis and Crystal Structure of 1＇-Methyl-4＇-（4-chlorophenyl）-1H-indole-3-spiro-2＇-pyrrolidine-3＇-spiro-4＂-（2＂-phenyloxazole）-2,5＂（3H,4＂H）-dione

The title compound （C26H20ClN3O3） has been synthesized by 1,3-dipolar cycloaddition reaction from isatin, sarcosine and （Z）-4-（4-chlorobenzylidene）-2-phenyloxazol-5（4H）-one through a one-pot procedure, and its structure was confirmed by IR, IH NMR, elemental analysis and single-crystal X-ray diffraction analysis. The crystal belongs to the triclinic system, space group PI, with a = 9.3903（19）, b = 11.398（2）, c = 12.603（3） A, α = 83.495（3）, β = 68.988（3）, γ = 67.178（3）^o, V= 1160.1（4）A^3 Z = 2, Mr= 457.90, Dc= 1.311 g/cm^3, p = 0.198 mm ^-1, F（000） = 476, the final R = 0.0489 and wR = 0.1144 for 3109 observed reflections with I 〉 2σ（I）.     

Temperature-dependent interactions and disorder in the spin-transition compound [Fe(II)(L)2][ClO4]2.C7H8 through structural, calorimetric, magnetic, photomagnetic, and diffuse reflectance investigations

The title compound [Fe (II)(L) 2][ClO 4] 2.C 7H 8 (L = 2-[3-(2'-pyridyl)pyrazol-1-ylmethyl]pyridine) has been isolated while attempting to grow single crystals of the spin-transition (continuous-type) compound [Fe (II)(L) 2][ClO 4] 2, published earlier ( Dalton Trans. 2003, 3392-3397). Magnetic susceptibility measurements, as well as Mossbauer and calorimetric investigations on polycrystalline samples of [Fe(L) 2][ClO 4] 2.C 7H 8 revealed the occurrence of an abrupt HS ( (5) T 2) <--> LS ( (1) A 1) transition with steep and narrow (2 K) hysteresis at approximately 232 K. The photomagnetic properties exhibit features typical for a broad distribution of activation energies, with relaxation curves in the shape of stretched exponentials. We performed a crystal structure determination of the compound at 120, 240, and 270 K. A noteworthy temperature-dependent behavior of the structural parameters was observed, in terms of disorder of both the anions and solvent molecules, leading to a strong thermal dependence of the strength and dimensionality of the interaction network. Additional data were obtained by diffuse reflectance measurements. We model and discuss the antagonistic effects of interactions and disorder by using a two-level cooperative mean-field approach which includes a distribution of barrier energies at the microscopic scale.     

Synthesis and Crystal Structure of (2S,2'S,4'R)-2-(1-Hydroxy-1-ethylpropyl)-1-[(1'-p-tosyl-4'-hydroxypyrrolidin-2'-yl)methyl]pyrrolidine

1 INTRODUCTION In recent years, chiral β-amino alcohols have attracted much attention due to their special bio- logical functions and catalytic activities. Chiral β- amino alcohol moieties are usually found not only in natural products (e.g., cinchona alkaloids, ephe- drine, toxal, etc.) with special biological activities[1, 2], but also critical structural segments of some syn- thesized biologically active compounds, such as adrenergic agonists or antagolist[3, 4] and inhibitors for HI…     

Synthesis,spectroscopic and crystal structure analysis of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)imidazo[2,1-b][1,3,4]thiadiazole and its morpholinomethyl derivative

The preparation of 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)-5-morpholin-1-ylmethyl imidazo[2,1-b][1,3,4]thiadiazole via the intermediate 2-(4-fluorobenzyl)-6-(4-methoxyphenyl)Imidazo[2,1-b][1,3,4] thiadiazole is described. Elemental analysis, IR spectrum, ¹H NMR and X-ray crystal structure analyses were carried out to determine the compositions and molecular structures of the two compounds. The crystal packing exhibits intermolecular C–H?O, C–H?N, C–H?F and π–π stacking interactions leading to the formation of the supramolecular network.     

5-甲基-3-硝基-4-异噁唑甲酰腙的晶体结构、电子光谱、抑菌活性及其量化计算

将3-硝基水杨醛和5-甲基-4-异噁唑甲酰肼于中温混合溶剂热体系中合成了标题化合物5-甲基-3-硝基-4-异噁唑甲酰腙(C12H10O4N4,3),并对其进行了单晶结构解析、紫外、荧光和热重分析等表征.结果表明,晶体属正交晶系,Pna21空间群.晶胞参数:a=1.28783(6)nm,b=1.13108(6)nm,c=0.86535(4)nm,V=1.2605nm3,Z=4.标题物3的水溶液在486nm处呈现一强蓝色荧光发射峰,归属于激发态分子内质子转移电荷发光;标题物3对枯草芽孢杆菌、铜绿脓杆菌、大肠杆菌和金黄色葡萄球菌等都有明显的抑菌活性;分子的静电势图(EPM)再现其具有较强的广谱抗菌活性.     

meso-四(对烷氧苯基)卟啉金属配合物的合成和性能研究(II)

合成了Zn、Pb两个系列卟啉金属配合物12个,其中6个为未见文献报道的新化合物,用元素分析、IR、UV、^1HNMR、MS确证了其结构。总结了Zn、Pb与卟啉类配体配合的IR、UV、^1HNMR判据。研究了这两个系列化合物的液晶性能,发现9个化合物具有液晶性。     

Synthesis, Crystal Structure and Biological Activities of 2- （4-Fluorophenyl） -2-oxo-1-（1H-1,2,4-triazol-1-yl） ethyl morpholine-4-carbodithioate

The title compound, 2-（ 4-fluorophenyl ） -2-oxo-1-（ 1H-1, 2,4-triazol-1-yl ） ethyl morpholine-4-carbodithioate, was synthesized and its structure was confirmed by means of IR, MS, 1 H NMR and elemental analysis. The single crystal structure of the title compound was determined by X-ray diffraction. The preliminary biological test showed that the synthesized compound possesses some biological activities.     

Synthesis of （3aS,6aR）- 1,3-Dibenzyl-tetrahydro- 1H-thieno[3,4-d]-imidazole-2（3H）-one-4-ylidenepentanoic Acid and Characterization of Its Crystal

1 INTRODUCTION The title compound, (3aS,6aR)-1.3-dibenzyl- tetrahydro-1H-thieno[3,4-d]-imidazole-2(3H)-one- 4-ylidenepentanoic acid 3, is a key intermediate for the synthesis of d-biotin 1 (VITH, Fig. 1) which has been widely used not only as a pharmaceu…     

Analysis of phase transition pathways in X3H(SO4)2 (X=Rb, NH4, K, Na): variable temperature single-crystal X-ray diffraction studies

Evaluation of phase transitions in a series of hydrogen sulfates (Rb3H(SO4)2, (NH4)3H(SO4)2, K3 H(SO4)2, and Na3H(SO4)2) based on the single-crystal structure analysis has revealed the exact nature of such transitions and has sorted out the various ambiguities involved in earlier literature. Rb3H(SO4)2 at 293 K is C2/c. It is isostructural to its ammonium analogue, (NH4)3H(SO4)2, at room temperature. However, the variable temperature single-crystal diffraction studies indicate that the phase transition mechanism is different. When cooled to 100 K, the structure of Rb3H(SO4)2 remains C2/c. When heated to 350 K, it transforms to C2/m (with double the volume at room temperature), which changes to C2/c (with 4 times the volume at room temperature) at 425 K. The high-temperature (420 K) structural phase transition in (NH4)3H(SO4)2 is shown to be Rm. The structure of Na3H(SO4)2 remains invariant (P21/c) throughout the range of 100-500 K except for the usual contraction of the unit cell at 100 K and expansion at 500 K. The structural phase transitions with temperature for the compound K3H(SO4)2 are very different from those claimed in earlier literature. The hydrogen atom participating in the crucial hydrogen bond joining the two sulfate tetrahedra controls the structural phase transitions at low temperatures in all four compounds. The distortion of the SO4 tetrahedra and the coordination around the metal atom sites control the phase evolution in the Rb compound, while the Na and K analogues show no phase transitions at high temperature, and the NH4 system transforms to a higher symmetry space group resulting in a disorder of the sulfate moiety.     

Synthesis,Crystal Structure,and Flame Retardance of 2-(3-Silatranyl-Propylamino)-4-(2,4-Dichlorophenyl)-5,5-Dimethyl-1,3,2-Dioxaphosphinane-2-Sulfide

Abstract

2-(3-Silatranylpropylamino)-4-(2,4-dichlorophenyl)-5,5-dimethyl-1,3,2-dioxa phosphinane-2-sulfide 4 was synthesized by a nucleophilic substitution reaction of 2-chloro-1,3,2-dioxaphosphinane-2-sulfide 2 with γ-aminopropylsilatrane 3, which was prepared by the cyclization reaction of triethanolamine and γ-aminopropyltriethoxysilane. The structure of the title compound was confirmed by IR, ¹H NMR, ³¹P NMR, EI-MS, and elemental analysis as well as by single crystal X-ray diffraction and its thermal properties were studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). Thermal analysis and preliminary fire retardance testing suggest that compound 4 should function as a good flame retardant.     

A solid-state NMR, X-ray diffraction, and ab initio computational study of hydrogen-bond structure and dynamics of pyrazole-4-carboxylic acid chains

Using high-resolution solid-state (15)N CMAS NMR, X-ray crystallography, and ab initio calculations, we have studied the structure of solid pyrazole-4-carboxylic acid (1). The crystal structure was determined at 295 and 150 K. Molecules of 1 are located on a two-fold axis, implying proton disorder of the NH and OH groups; no phase transition was observed between these two temperatures. The compound forms quasi-linear ribbons in which the molecules are linked by cyclic hydrogen bonds between pyrazole and carboxylic acid groups with disordered hydrogen-bonded protons. Crystallography is unable to decide whether the disorder is dynamic or static. NMR shows that this disorder is dynamic, that is, consisting of very fast degenerate double proton transfers between two rapidly interconverting O-H.N and O.H-N hydrogen bridges. However, at low temperature, NMR shows a proton disorder-order transition where the protons are preferentially localized on given nitrogen and oxygen atoms. An amorphous phase exhibiting proton order is observed when the compound is precipitated rapidly. In this case, the defects are annealed by moderate heating. Ab initio calculations performed on oligomers of 1 show that the O-H.N hydrogen bridge is about 0.064 A shorter and less bent ( approximately 171 degrees ) than the O.H-N hydrogen bridge ( approximately 150 degrees ). For an isolated ribbon, this result leads to structures with localized protons, either to a cycle with about 200 molecules, or to a quasi-linear ribbon involving an undulated structure, or to a combination of both motifs. Only the undulated structure is compatible with the linear ribbon observed by X-ray crystallography, where the fast proton transfer in the high-temperature phase is assisted by the motions of the undulated chain. A disordered structure is assigned to the amorphous phase, which exhibits the combination of the curved and the undulated motifs.