The effect of the linking group on mesogenic properties of three‐ring derivatives of p‐carborane and biphenyl

Four series of mesogenic derivatives of p‐carborane (series A[0] and A[1]) and their benzene analogues (series B[0] and B[1]) with variable linking groups were prepared and investigated for phase behaviour. The data allowed a comparison of the effect of the group on the mesophase stability as a function of the adjacent ring (carborane or benzene), the variable central ring (carborane or benzene), and the presence of an oxygen atom in the terminal chain. The results showed that substitution of carborane for a benzene ring in B[m] depresses the clearing point by 50 K to 208 K and eliminates all smectic behaviour in A[m]. The carborane derivatives A[m] are weakly dependent (effectiveness of : –CH = CHCOO–～–COO–～–CH = CH–>–CH = N–～–CH₂CH₂–>–CONH–), whereas the benzene analogues B[m] are strongly dependent (effectiveness of : –CONH–>–CH = CH–>–CH = N–～–CH = CHCOO–>–COO–>–CH₂CH₂–) on the structure of the linking group . The difference in the effectiveness of the amide group on mesophase stability (ΔT _I = 208 K) has been attributed to the stabilizing intermolecular H‐bonding in B[m], which is prevented in A[m] by steric and electronic effects of the carborane cage on the carbonyl group.     

Discotic derivatives of 6-oxoverdazyl radical

Substitution of each phenyl in 1,3,5-triphenyl-6-oxoverdazyl with three alkoxy groups induces an ordered columnar hexagonal phase (Col_h(o)) below 130°C in 1b[n], while in the alkylsulfanyl analogues 1a[n] additional periodicity along the columns was found rendering the phase a true three-dimensional columnar hexagonal phase (Col_h(3D)) below 60°C. Both series exhibit broad absorption bands in the visible region with maxima at 540 and 610 nm in series 1a[n] and at 486 and 614 nm in series 1b[n]. Unusual reversible thermochromism is observed in series 1b[n], in which the dark green isotropic phase turns red in the discotic phase. Analysis of 1a[8] revealed redox potentials E^0/+1_1/2 = +0.99 V and E^{0/ ?1}_1/2 = –0.45 V vs. saturated calomel electrode (SCE), while the potentials in the alkoxy analogue 1b[8] are shifted cathodically by 0.16 V. Photovoltaic studies of 1a[8] demonstrated hole mobility of μ_h = 1.52 × 10^?3 cm² V^?1 s^?1 in the mesophase with an activation energy E_a = 0.06 ± 0.01 eV. Magnetisation studies of 1a[8] revealed nearly ideal paramagnetic behaviour in either the solid or fluid phase above 200 K and weak antiferromagnetic interactions at low temperatures. In contrast, a noticeable drop of about 4% in μ_eff was observed during the I→Col phase transition in 1b[8], which coincide with the thermochromic effect.     

Hockey-stick liquid crystalline 6-oxoverdazyl§

A series of hockey-stick shaped 6-oxoverdazyl radicals 1[n]–3[n], containing CH₃ (a), CF₃ (b) and CN (c) groups in the short ‘arm’, were prepared and their physical properties were investigated. Mesogenic behaviour was found only in the CN derivatives with the COO (1[n]c) and N=N (2[12]c) linking groups, which exhibited a nematic phase. Analysis of binary mixtures of selected compounds with bent-core nematic host 4[12] gave virtual nematic-isotropic transition temperatures, [T_NI], which follow the order 1[12]b < 1[12]c < 1[12]a in one series and 1[12]c < 2[12]c < (3[12]c) in another. The observed effectiveness of the short-arm substituent, CF₃ < CN < CH₃, was related to the magnitude and orientation of the molecular dipole moment calculated with density functional theory methods.     

Microstructure and Magnetic Properties of Carbon‐Coated Nanoparticles

Abstract

In the present work, microstructure and superparamagnetic properties of two types of carbon‐coated magnetic Ni and Fe nanoparticles [Ni(C) and Fe(C)] are reviewed. High‐resolution transmission electron microscopy (HRTEM), electron diffraction (SAED), and x‐ray diffraction (XRD) analyses have been used to reveal the distinct structural morphologies of Ni and Fe nanoparticles. Moreover, novel carbon‐coated Ni nanoparticle assemblies offer us great opportunities for studying the mechanism of superparamagnetism in particle assemblies. Magnetization measurements [M(T) and M(H) curves] for assemblies of Ni nanoparticles indicate that modified superparamagnetic properties at T > T _B, have been found in the assemblies of Ni(C) particles. The blocking temperature, T _B, is determined to be near 115K under a certain applied field. Above T _B, the magnetization M(H, T) can be described by the classical Langevin function L using the relation, M/M _s (T = 0) = coth (μH/kT) ? kT/μH. It is suggested that these assemblies of carbon‐coated Ni nanoparticles have typical single‐domain, field‐dependent superparamagnetic relaxation properties. Finally, Mössbauer spectra and hyperfine magnetic fields at room temperature for the assemblies of Fe(C) nanoparticles confirm their distinct nanophases that were detected by structural analysis. Modified superparamagnetic relaxation is observed in the assemblies of Fe(C) nanoparticles, which is attributed to the nanocrystalline nature of the carbon‐coated nanoparticles.     

Synthesis,characterization and properties of N‐maleimide side‐chain liquid crystalline copolymers

A homologous series of side‐chain liquid crystalline (SCLC) poly{[N‐[10‐((4‐(((4′‐n‐hexyloxy)benzoyl)oxy)phenoxy)carbonyl)‐n‐decyl]maleimide]‐co‐[N‐(n‐octadecyl)maleimide]} [(ME6)‐co‐(MI‐18)] random copolymers with various MI‐18 contents have been synthesized and their properties studied. The high content in threo‐disyndiotactic sequences of the maleimide main chain seems responsible for the stability of the highly ordered smectic mesophase. The relationship between structure and composition on thermotropic mesophase was investigated by polarizing optical microscopy, differential scanning calorimetry, and X‐ray diffraction. For copolymers with mesogenic unit contents less than ～0.655 molar fraction the transition from (S_A) texture to isotropic (I) is maintained, as shown by the T_Cl, ΔH_Cl and ΔS_Cl amounts and intermolecular spacing 4.42–4.53 Å and intralayer correlation lengths of 44.2–45.2 Å. The layer thickness does not appreciably depend on copolymer composition. However, copolymers with non‐mesogenic comonomer MI‐18 molar contents larger than >0.655 molar fraction X(M), are no longer liquid crystalline materials, despite its packing is preserved without any detectable appearance of birefringence. Thermodynamic boundaries of the liquid crystalline state have been established through a phase diagram. The properties of this n‐hexyloxy pendant group‐based series are compared to those of the analogous materials containing methoxy pendant groups (ME1), and differences are accounted for in terms of the local side‐chain packing within the mesophase. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,Characterization, Solution Stability Studies,Electrochemistry, and DNA‐Binding Behavior of Cu(II) Complexes of D‐Gluconic Acid

The chemistry of saccharides has emerged as a new subarea of pharmaceuticals. Condensation reactions of D‐gluconic acid with [M(en)₂]Cl₂/[M(ea)₂]Cl₂ where M=Cu, Ni, en=ethylenediamine, and ea=ethanolamine were carried out and a new series of chiral complexes have been isolated and characterized. Molar conductance measurements show that the complexes are ionic, and the spectral data are indicative of octahedral geometry of the complexes [Cu(D‐GlcCO₂H en*)₂ (H₂O)₂] · Cl₂ (1b), [Cu(D‐GlcCO₂H ea*) (H₂O)₂] · Cl₂ (3b) and [Ni(D‐GlcCO₂H ea*) (H₂O)₂] · Cl₂ (4), and the square planar geometry of complex [Ni(D‐GlcCO₂H en*)₂] · Cl₂ (2b). Polarimetric data along with CD spectra establish the chiral nature of complexes. Solution stabilities of these complexes were evaluated by cyclic voltammetric techniques as a function of pH. Electrochemical behavior of the complexes was studied in aqueous solution and showed an irreversible Cu^II/Cu^I couple. Kinetic studies of complex 1b and 3b with calf thymus DNA have been investigated spectrophotometrically under pseudo‐first order conditions, and k _obs values have been evaluated. Circular dichroism, cyclic voltammetry determinations, and viscosity measurements have also been carried out to authenticate the binding of DNA with metal complexes. Complexes 1b and 3b bind to DNA by covalent bond formation.     

Synthesis and properties of cyclic diester based aliphatic copolyesters

Melt polycondensation was used to prepare a systematic series of random and amorphous copolyesters using the following cycloaliphatic diesters: dimethyl‐1,4‐cyclohexane dicarboxylate (DMCD), dimethyl bicyclo[2.2.1]heptane‐1,4‐dicarboxylate (DMCD‐1), dimethyl bicyclo[2.2.2]octane‐1,4‐dicarboxylate (DMCD‐2), dimethyl bicyclo[3.2.2]nonane‐1,5‐dicarboxylate (DMCD‐3), 1,4‐dimethoxycarbonyl‐1,4‐dimethylcyclohexane (DMCD‐M) and the aliphatic diols: ethylene glycol (EG) and 1,4‐cyclohexane dimethanol (CHDM). The polymer compositions were determined by nuclear magnetic resonance (NMR) and the molecular weights were determined using size exclusion chromatography (SEC). The polyesters were characterized by dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The copolyester based on DMCD‐2 was observed to have a higher glass transition temperature (T_g up to 115 °C) than the other copolyesters of this study. For poly[x(DMCD‐2)y(DMCD) 30(EG)70(CHDM)], T_g increases linearly with increase of DMCD‐2 mole content. DMA showed that all of the cycloaliphatic copolyesters have secondary relaxations, resulting from the conformational transitions of the cyclohexylene rings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2162–2169, 2010     

Synthesis,Structures, and Properties of Two Novel Supramolecular Architectures Constructed from [2,3‐f]Pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic Acid

Two new compounds, [Ag(Hppdb)]_n ( 1 ) and {[Ag₂(Hppdb)₂(bpe)] · 5.5H₂O}_n( 2 ) [H₂ppdb = [2,3‐f]pyrazino[1,10]phenanthroline‐2,3‐dicarboxylic acid, bpe = trans‐1,2‐bis(4‐pyridyl)ethylene], were synthesized and characterized. In 1 , Hppdb^– ions link Ag^I cations to form an infinite 1D [–Ag–(Hppdb)–Ag–]_n chain, furthermore, the dimensionality is extended to 2D layers through synergistic π–π stacking, hydrogen‐bonding and weak Ag ··· O interactions. Correspondingly, the dimeric [(Ag)(Hppdb)]₂ subunits in 2 are connected by bpe ligands to generate a loop‐link‐shaped 1D chain motif, which is further joined through a R₂²(18)C–H ··· O hydrogen‐bonding ring to afford interesting diagonal/diagonal inclined catenation 2D + 2D → 3D supramolecular architectures. In addition, solid‐state properties such as photoluminescence and thermal stability of the two compounds were studied.     

Synthesis and characterisation of chiral liquid crystalline elastomers containing four-arm crosslinking agent

A new series of side-chain chiral liquid crystalline elastomers derived from M₁ (cholest-5-3-ol(3β)-4-(2-propen-yloxy)]benzoate) and M_C(2,5-[3,5-bis(4-(3-(4-(allyloxy)phenyl)propanoyloxy)benzoyloxy)benzoic acid]isosorbide diester). The structures of monomers and elastomers measured by using Proton Nuclear Magnetic Resonance Spectra (¹H-NMR) and Fourier transform infrared spectroscopy (FTIR) separately are consistent with our design. IIP~VIP all appeared blue Grandjean (GJ) texture on the heating cycle or cooling cycle. The glass sheets of IIP~VIP were made under 150°C and measured its ultraviolet–visible spectrophotometry by PerkinElmer Lambda 950 instrument (Shelton, CT, USA). IIP~VIP all have absorptions at about 481~483 and 561~562 nm. The optical activities were measured at different temperatures on heating and cooling cycles. And the blue selective reflection of IIP~VIP on the round glass sheet can be seen. The elastomers containing less than 6 mol% of the crosslinking units displayed elasticity, reversible phase transition and high thermal stability. The glass transition temperatures reduced first and then increased, the isotropisation temperatures and the mesophase temperature ranges increased first and then decreased with increasing content of crosslinking unit. The thermogravimetric analysis (TGA) results showed that the temperatures at which 5% weight loss occurred (T_d) were greater than 310°C for all the polymers.     

Hybrid liquid crystals tetrazolyl and isoxazolyl cinnamates

In this work, a series of isoxazolyl and tetrazolylcinnamic ester hybrid liquid crystals (HLCs) were synthesised and their mesomorphic behaviour was analysed. Cinnamic acid derivatives were prepared by Knoevenagel condensation of malonic acid and arylaldehydes. Five-membered tetrazoles and isoxazoles were prepared by [3 + 2] 1,3-dipolar cycloaddition. Tetrazoles were synthesised by sodium azide addition to arylnitrile, while isoxazoles were synthetised by arylnitrile oxide addition to alkenes to form isoxazolines, followed by MnO₂-oxidation. Tetrazolyltolane compounds were also synthesised and their LC behaviour compared with cinnamic esters. HLCs containing isoxazole rings displayed a large mesophase range with high clearing temperature (T_c), with predominance of smectic mesophases SmA and SmC. The HLCs decomposed upon heating due to their high clearing temperature (>250°C). HLCs with tetrazole rings showed a narrow nematic mesophase range with enantiotropic or monotropic behaviour.     

Synthesis and crystal structures of two new uranyl coordination compounds obtained in aqueous solutions of 1-butyl-2,3-dimethylimidazolium chloride

Abstract

Two new uranyl coordination compounds, [C₉H₁₇N₂]₃[(UO₂)₂(CrO₄)₂Cl₂(H₂O)₂]Cl·5H₂O (1) and (C₉H₁₇N₂)[(UO₂)(C₂O₄)Cl] (2), have been synthesized by adding potassium dichromate (K₂Cr₂O₇) or oxalic acid dihydrate (H₂C₂O₄·2H₂O) solution into an aqueous solution of uranyl nitrate and 1-butyl-2,3-dimethylimidazolium chloride [Bmmim]Cl. [Bmmim]Cl provides the charge balance and Cl ions that coordinate with uranyl ions. The fundamental building units of 1 and 2 are UO₆Cl pentagonal bipyramidal structures. Compound 1 exhibits a graphene-like structure with a system molar ratio of 1:1 for U:Cr and crystallizes in the orthorhombic space group Pbca, with a = 25.644(3) Å, b = 12.996(14) Å and c = 29.198(4) Å. 16-Membered rings are formed by CrO₄^2? and UO₂²⁺ in the crystal structure of 1. Compound 2 crystallizes in monoclinic space group P2₁/n, with a = 10.759(3) Å, b = 11.395(3) Å, c = 14.149(4) Å, β = 102.962(9)° and shows one-dimensional (1D) serrated chains. Within the crystal structures of 1 and 2, C–H_[Bmmim]Cl?O hydrogen bonds are identified. O–H_water?Cl hydrogen bonds are also detected in the crystal structure for 1.     

Oligo(p‐phenyleneethynylene) (OPE) Molecular Wires: Synthesis and Length Dependence of Photoinduced Charge Transfer in OPEs with Triarylamine and Diaryloxadiazole End Groups

The systematic synthesis and photophysical, electrochemical and computational studies on an extended series of triphenylamine‐[C?C‐1,4‐C₆H₂(OR)₂]_n‐C?C‐diphenyl‐1,3,4‐oxadiazole dyad molecules (the OR groups are at 2,5‐positions of the para‐phenylene ring and R=C₆H₁₃; n=0–5, compounds 1 , 2 , 3 , 4 and 5 , respectively) are reported. Related molecules with identical end groups, triphenylamine‐C?C‐1,4‐C₆H₂(OR)₂‐C?C‐triphenylamine (R=C₆H₁₃; 6 ) and diphenyl‐1,3,4‐oxadiazole‐[C?C‐C₆H₂(OR)₂]₂‐C?C‐diphenyl‐1,3,4‐oxadiazole (R=C₆H₁₃; 7 ) were also studied. These D–B–A 1 – 5 , D–B–D 6 and A–B–A 7 (D=electron donor, B=bridge, A=electron acceptor) systems were synthesized using palladium‐catalysed cross‐coupling reactions of new p‐phenyleneethynylene building blocks. Steady‐state emission studies on the dyads 1 – 5 reveal a complicated behavior of the emission that is strongly medium dependent. In low polarity solvents the emission is characterized by a sharp high‐energy peak attributed to fluorescence from a locally excited (LE) state. In more polar environments the LE state is effectively quenched by transfer into an intramolecular charge‐transfer (ICT) state. The medium dependence is also observed in the quantum yields (QYs) which are high in cyclohexane and low in acetonitrile, thus also indicating charge‐transfer character. Low‐temperature emission spectra for 2 – 5 in dichloromethane and diethyl ether also reveal two distinct excited states, namely the LE state and the conventional ICT state, depending on solvent and temperature. Hybrid DFT calculations for 1 – 7 establish that the OPE bridge is involved in both frontier orbitals where the bridge character increases as the bridge length increases. Computed TD‐DFT data on 1 – 5 assign the emission maxima in cyclohexane as LE transitions. Each time‐resolved emission measurement on 2 – 7 in cyclohexane and diethyl ether reveals a wavelength dependent bi‐exponential decay of the emission with a fast component in the 5–61 ps range on blue detection and a slower approximately 1 ns phase, independent of detection wavelength. The fast component is attributed to LE fluorescence and this emission component is rate limited and quenched by transfer into an ICT state. The fast LE fluorescence component varies systematically with conjugation length for the series of D–B–A dyads 2 – 5 . An attenuation factor β of 0.15 Å^?1 was determined in accordance with an ICT superexchange mechanism.     

Pyridine effected tunable luminescence properties of a 1D cadmium(II) polymer with tetranuclear second building units

One novel 1D polymer, [Cd₂(m-BrPhHIDC)₂(4,4′-bipy)(H₂O)₂]_n (1) (m-BrPhH₃IDC = 2-(3-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid; 4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesised and characterised by single-crystal X-ray diffraction, elemental analysis, IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis. Polymer 1 composed of tetranuclear square [Cd₂(m-BrPhHIDC)₂] second building units and 4,4′-bipy bridges shows the interesting tunable luminescence properties aroused by pyridine. A luminescence enhance mechanism has been proposed.     

Synthesis,structure, and urease inhibitory activities of Co(III), Mn(II) and Zn(II) complexes with hydrazone derived from protocatechuic acid

[Co^III(L₁)₂·H₂O]NO₃ (1), [Mn^II(L₁)₂·H₂O] (2), and [Zn^II(L₁)₂·H₂O] (3) with a hydrazone derived from protocatechuic acid (HL₁ = C₁₅H₁₃N₃O₃) were designed, synthesized, and characterized by C, H, N elemental analyses, single-crystal X-ray diffraction, and IR spectra, which revealed that the three complexes are similar structures. Docking study has been done. The urease inhibitory activities of the three complexes were tested. Complexes 1 and 3 showed strong inhibitory activity against jack bean urease with IC₅₀ values of 45.9 and 11.64 μM. Complex 2 had no obvious inhibitory activity to urease; the IC₅₀ was > 50 μM.     

Oriented crystallization of poly(L‐lactic acid) in uniaxially oriented blends with poly(vinylidene fluoride)

This article describes the oriented crystallization of poly(L ‐lactic acid) (PLLA) in uniaxially oriented blends with poly(vinylidene fluoride) (PVDF). Uniaxially drawn films of PLLA/PVDF blend with fixed ends were heat‐treated in two ways to crystallize PLLA in oriented blend films. The crystal orientation of PLLA depended upon the heat‐treatment process. The crystal c‐axis of the α form crystal of PLLA was highly oriented in the drawing direction in a sample cold‐crystallized at T_c = 120 °C, whereas the tilt‐orientation of the [200]/ [110] axes of PLLA was induced in the sample crystallized at T_c = 120 °C after preheating at T_p = 164.5–168.5 °C. Detailed analysis of the wide‐angle X‐ray diffraction (WAXD) indicated that the [020]/ [310] crystal axes were oriented parallel to the drawing direction, which causes the tilt‐orientation of the [200]/ [110] axes and other crystal axes. Scanning electron microscopy (SEM) suggested that oriented crystallization occurs in the stretched domains of PLLA with diameters of 0.5–2.0 μm in the uniaxially drawn films of PVDF/PLLA = 90/10 blend. Although the mechanism for the oriented crystallization of PLLA was not clear, a possibility was heteroepitaxy of the [200]/[110] axes of the α form crystal of PLLA along the [201]/[111] axes of the β form crystal of PVDF that is induced by lattice matching of d₁₀₀(PLLA) ≈ 5d₂₀₁(PVDF). © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1376–1389, 2008     

Multi‐Dimensional Cobalt(II) and Nickel(II) Coordination Polymers

A series of metal coordination polymers, [Co₂(NB)₄(bpp)₂(H₂O)]·H₂O ( 1 ), [Co₂(e,e‐trans‐chdc)(e,a‐cis‐chdc)(bpp)₂] ( 2 ), [Ni(e,e‐trans‐chdc)(bpp)(H₂O)₂] ( 3 ), [Ni₂(PDA)₂(bpp)₂(H₂O)₃]·H₂O ( 4 ), and [Ni‐(mBDC)(bpp)] ( 5 ) (NB = 3‐nitrobenzoate anion; bpp = 4,4′‐trimethylene dipyridine; chdc = cyclohexane‐1,4‐dicarboxylate anion; PDA = 1,4‐phenylenediacetate anion; mBDC = 1,3‐benzene dicarboxylate anion), were synthesized from metal ions and organic mixed‐ligands by hydrothermal reactions. The single crystal structure analysis revealed that 1, 3, and 4 were 2D sheets with bilayer (1 and 4) and 2‐fold interpenetrated layers (3), 2 is a 3D binodal (4,5)‐connected framework, and 5 is a 1D chains. The non‐covalent interactions of H‐bonds and π–π stacking caused this conformation of highly cross‐linked networks. Compounds 1‐5 were further characterized by thermal gravimetric analysis, powder X‐ray diffraction, UV‐vis, infrared, and PL spectroscopy.     

Syntheses and properties of organosoluble poly(ether imide)s from 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride and aromatic diamines

A bis(ether anhydride) monomer, 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride ( IV‐A ), was synthesized from the nitro displacement of 4‐nitrophthalodinitrile by the phenoxide ion of 1,1‐bis(4‐hydroxyphenyl)cyclohexane ( I‐A ), followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and dehydration of the resulting bis(ether acid). A novel series of organosoluble poly(ether imide)s ( VI _a–i )(PEIs) bearing cyclohexylidene cardo groups was prepared from the bis(ether anhydride) IV‐A with various aromatic diamines V _a–i via a conventional two‐stage process. The PEIs had inherent viscosities in the range of 0.48–1.02 dL/g and afforded flexible and tough films by solution‐casting because of their good solubilities in organic solvents. Most PEIs showed yield points in the range of 89–102 MPa at stress‐strain curves and had tensile strengths of 78–103 MPa, elongations at breaks of 8–62%, and initial moduli of 1.8–2.2 GPa. The glass‐transition temperatures (T_g's) of these PEIs were recorded between 200–234 °C. Decomposition temperatures of 10% weight loss all occurred above 490 °C in both air and nitrogen atmospheres, and their residues were more than 43% at 800 °C in nitrogen atmosphere. The cyclohexane cardo‐based PEIs exhibited relatively higher T_g's, better solubilities in organic solvents, and better tensile properties as compared with the corresponding Ultem® PEI system. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 788–799, 2001     

Synthesis,structure and photoluminescence of three 2D Cd(II) coordination polymers based on varied dicarboxylate ligand

Three coordination polymers (CPs) based on different dicarboxylic acids and Cd(II), [Cd₃(tpa)₃(DMA)₄] (1), [Cd₂(thpa)₂(DMA)₂·DMA] (2), and [Cd₃(eba)₃(DMA)] (3) (H₂tpa = terephthalic acid, H₂thpa = thiophenedicarboxylic acid, H₂eba?=?(ethene-1,2-diyl)dibenzoic acid, DMA = N,N′-dimethylacetamide), were synthesized under solvothermal conditions. The CPs were characterized by elemental analysis (EA), single-crystal X-ray crystallography, powder X-ray diffraction, infrared spectroscopy (IR), and thermogravimetric analyses. X-ray crystallographic analysis shows that 1 and 3 exhibit a 2D six-connected hxl network based on hourglass-like [Cd₃(COO)₆] SBUs, whereas 2 displays a 2D 4⁴-sql network based on [Cd₄(COO)₈] SBUs. Thermal stabilities and photoluminescence behaviors of the CPs are also discussed.     

Unusual Effects of Pure Nonionic and Mixed Nonionic–Cationic Micelles on the Rate of Alkaline Hydrolysis of N-Hydroxyphthalimide

Pseudo-first-order rate constants, k_obs, for the alkaline hydrolysis of N-hydroxyphthalimide, 1, at 0.02 M NaOH and 30°C remain essentially independent of the total concentration of C₁₂E₂₃, [C₁₂E₂₃]_T, at ≤0.005 M C₁₂E₂₃. The increase in [C₁₂ E₂₃]_T from 0.005 to 0.015 M causes a nonlinear decrease in k_obs. The rate of hydrolysis becomes either too slow or the change in absorbance values becomes significantly small to allow a reliable observed data fit to a first-order kinetic equation at ≥0.020 M C₁₂E₂₃ in the absence and presence of total concentration of cetyltrimethylammonium bromide, [CTABr]_T ranging from 0.003 to 0.020 M. The values of fraction of nonionized 1, F_SH, obtained at reaction time t = 0 and 0.02 M NaOH, remain ～0 at ≤0.010 M C₁₂E₂₃ while they increase from 0.39 to 0.89 with the increase of [C₁₂E₂₃]_T from 0.015 to 0.10 M. The values of k_obs show a nonlinear decrease of ～5-fold with the increase of [C₁₂E₂₃]_T from 0.0 to 0.010 M in the presence of 0.02 M NaOH and [CTABr]_T range of 0.003 to 0.020 M. The values of F_SH remain ≤～0.10 at ≤0.015 M C₁₂E₂₃ while they vary between 0.40 and 0.90 within a [C₁₂E₂₃]_T range 0.02 to 0.05 M in the presence of 0.02 M NaOH and [CTABr]_T ranging from 0.003 to 0.020 M. The values of F_SH represent the fraction of nonionized 1 trapped almost irreversibly by pure C₁₂E₂₃, and mixed C₁₂E₂₃–CTABr micelles.     

Reaction of o‐Carboryne with Furans: Facile Synthesis of Carborane‐ Fused Oxanorbornenes and Their Derivatives

o‐Carboryne (1,2‐dehydro‐o‐carborane) is a very useful synthon for the synthesis of a variety of carborane‐functionalized molecules. Diels‐Alder reaction of o‐carboryne with furans gave a series of carborane‐fused oxanorbornenes in moderate to high yields using 1‐OTf‐1,2‐C₂B₁₀H₁₁ as carboryne precursor. The resultant cycloadducts can undergo hydrogenation, cyclic oxidation, bromination, [4 + 2]/[2 + 2] cycloaddition and nucleophilic ring opening reaction to afford a variety of highly functionalized carboranes that may find applications as useful basic units in medicine and materials science.