Synthesis and characterization of per-substituted spermine-bridged cyclophosphazene derivatives: the first example of syn/anti conformational polymorphism in a bridged cyclophosphazene

The synthesis and characterization of a series of per-substituted spermine-bridged cyclophosphazene derivatives are reported based on the known compound [N₃P₃X₄(NHCH₂CH₂CH₂N)CH₂CH₂]₂, (1a) (where X = Cl), to give a number of new compounds (1b–1h) in which X = OPh, [spiro-O(CH₂)₃O]_0.5, OCH₂CF₃, NHPh, NC₄H₈, Ph and NHBu^t, respectively. Two synthetic routes were utilized: (i) using the chloro-precursor 1a in nucleophilic substitution reactions with a variety of anionic and neutral nucleophiles to give compounds 1b–1f and (ii) reaction of spermine with the appropriate di-gem tetrasubstituted cyclophosphazene to give compounds 1g and 1h. Bridged compounds such as 1a–1h may exist as syn or anti conformers in the solid state and the first example of syn and anti conformational polymorphism is reported for a bridged cyclophosphazene, viz. for compound 1a.     

Synthesis and Properties of Fully Triphenylamine-based Polyamides Bearing 3,5-bis(Trifluoromethyl) and/or 3,5-dimethyl Substituents on the Pendent Phenyl Units

Four new fully triphenylamine-based polyamides coded as polyamide (CF₃,CF₃), polyamide (CF₃,CH₃), polyamide (CH₃,CF₃), and polyamide (CH₃,CH₃) were synthesized by the phosphorylation polyamidation reaction from various combinations of 3,5-bis(trifluoromethyl)-4′,4″-dicarboxytriphenylamine, 3,5-dimethyl-4′,4″-dicarboxytriphenylamine, 3,5-bis(trifluoromethyl)-4′,4″-diaminotriphenylamine, and 3,5-dimethyl-4′,4″-diaminotriphenylamine. All the polyamides were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent, flexible, and strong films with good mechanical properties. They had useful levels of thermal stability associated with high glass-transition temperatures of 268–287°C and 10?wt%-loss temperatures in excess of 500°C. Cyclic voltammograms of the film of polyamide (CH₃,CH₃) on the indium-tin oxide-coated glass substrates exhibited two oxidation redox couples with E_1/2 around 0.82 and 1.29?V vs. Ag/AgCl in tetrabutylammonium perchlorate/acetonitrile solution, accompanied by a color change from pale yellow neutral state to dark green oxidized state. The CF₃-substituted polyamides displayed a higher oxidation potential and less electrochemical stability as compared to the CH₃-substituted analogues.     

Organic–inorganic composite materials from acrylonitrile–butadiene–styrene copolymers (ABS) and silica through an in situ sol‐gel process

Nonbonded and chemically bonded organic–inorganic composite materials, ABS/SiO₂ and ABS Si(OCH₃)₃/SiO₂, were prepared by the sol‐gel processing of tetraethoxysilane (TEOS) in the presence of ABS and trimethoxysilyl functionalized ABS, ABS Si(OCH₃)₃, under the catalization of NH₄F. The ABS Si(OCH₃)₃ was obtained by oxidizing the cyano group in ABS with hydrogen peroxide, then subsequently underwent ring‐opening reaction with 3‐glycidoxypropyltrimethoxysilane (GPTS). The ABS Si(OCH₃)₃/TEOS sol‐gel liquid solution system, in which the ABS chains formed the covalent bonds with silica network and helped fix the polymer chains in the silica network, had a shorter gelation time than that of the ABS/TEOS system, which linked ABS chains to the silica network only by hydrogen bonding the cyano groups in ABS to the silanol groups. The morphology and properties of composite were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), tensile tests, and thermogravimetry. It was found that the composite prepared from ABS Si(OCH₃)₃ had higher tensile strength, glass transition point (T_g), thermal stability, and more homogeneous morphology because of the existence of the covalent bond between ABS chains and silica network that increased the compatibility between the organic and inorganic phases. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 275–283, 2000     

Synthesis of polyphosphazene random copolymers bearing alkoxyethoxy and trifluoroethoxy functional groups

The anionically initiated copolymerization of (CH₃OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃, and (CH₃OCH₂CH₂OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃ with (CF₃CH₂O)₃ P=N-Si(CH₃)₃ is reported. These materials were characterized by³¹P and¹H NMR, SEC, and DSC.In situ ³¹P NMR studies indicate that monomers are simultaneously consumed, SEC traces show that these random copolymers exhibit monomodal distributions, and there is a gradient in solubilities as well as thermal and mechanical properties which is dependent upon the repeating unit ratios.     

Comb polysiloxanes with ω-hydroxyoligo(oxyethylene) side chains

Summary Comb-like polysiloxanes with pendant chains of the type (CH₂)₃(OCH₂ CH₂)_nOH (n=0, 8 or 15) were synthesized by hydrosilylation of poly(methylsiloxane) with the corresponding monoallyl glycols in which the hydroxyl group was protected with tetrahydropyran. The polymers were characterized by¹H and²⁹Si NMR, and by GPC and DSC. A considerable fraction of small cycles is formed for the n=o compound during the deprotection reaction. Side chain crystallization occurs but is slower than for polymers containing side chains with terminal methoxy groups.     

Combustion of silicon powders containing organic additives in nitrogen gas under pressure: 1. Effect of dopants on combustion phenomenology

Introduction of organic dopants (in amounts up to 5 wt %) to Si powders was found to intensify their combustion in nitrogen gas under pressure without significant influence on the combustion temperature [T _c = 2270 ± 50 K at P(N₂) = 70 atm]. The addition of organic compounds also suppressed the coagulation of Si particles, improved the extent of conversion, and promoted combustion of coarse Si powders. This was associated with the reaction of organic species R (formed upon thermal decomposition of dopants) with solid Si(s) giving gaseous Si(g), which intensifies the processes of mass transport involving organic species R as gas transport agents.      

New organic polymers,II. Synthesis and characterization of poly[3,3′-(6,6′-bis-(2-substituted-4-quinazolonediyl)) alkylene]s

Poly[3,3′-(6,6′-bis-(2-substituted-4-quinazolonediyl))alkylene]s have been synthesized by reacting 6,6′-bis-(2-R-3,1,4-benzoxazinone) (R = Me, Ph, and ? CH₂Ph) with aliphatic diamines H₂N(CH₂)_nNH₂ with n = 0, 2, 3, 4, 6 and 8 in m-cresol. These polymers are insoluble in all common organic solvents but are fairly soluble in concentrated sulfuric acid. The polymers were characterized by IR spectral study, viscometric measurements and thermal analysis. IR spectra of the polymer samples have been compared with those of their model compounds.     

New fluorine-containing polyorganosilsesquioxanes: Preparation and properties

It has been found that hydrolysis of three-functional alkoxysilanes, such as R^FOCH₂Si(OR^F)₃, R^F = CH₂CF₃, CH₂CF₂CF₃, CH₂CF₂CF₂CF₃, and CH₂CF₂CF₂CF₂CF₃, under mild conditions upon exposure to air moisture in the presence of ??-aminopropyltriethoxysilane results in the formation of hydrophobic coatings from fluorine-containing polyorganosilsesquioxanes directly on the substrate. Polymers have a layered ladder structure. The hydrophobicity and low values of refractive indices, surface energy, and its polar component, as well as the simplicity of the preparation, determine the possibility of using polyorganosilsesquioxane films as antireflection protective coatings for laser optics.     

High-sensitive room-temperature NO2 sensor based on a soluble n-type phthalocyanine semiconductor

2(3),9(10),16(17),23(24)-tetrakis(2,2,2-trifluoroethoxy) phthalocyanine H₂Pc(OCH₂CF₃)₄(1) has been synthesized characterized by using MALDI-TOF MS, ¹H NMR, UV–vis spectra and differential pulse voltammetry. Our work addresses this by introducing four electron-withdrawing trifluoroethoxy substituents at the periphery of the phthalocyanine ring to ensure the sufficient solubility and suitable LUMO energy level and thus successfully realize soluble n-type organic semiconductor. Furthermore, H₂Pc(OCH₂CF₃)₄ exhibited the high crystallinity and large specific surface area as well as good conductivity in the thin solid film fabricated by a simple solution-based quasi–Langmuir–Shäfer (QLS) method. Importantly, the highly sensitive, stable and reproducible responses to electron-accepting gas NO₂ in 100–500 ppb range are observed for the QLS film of 1 at room temperature, implying the excellent potential of 1 as the NO₂ sensor for applications in practical environments. In addition, the response of the QLS film of 1 is linearly correlated to the NO₂ concentration. The interaction between the H₂Pc(OCH₂CF₃)₄ film and NO₂ molecules with different concentrations was found to follow first-order kinetics. The present result represents not only the first example of n-type phthalocyanine-based NO₂ sensor obtained by a solution-based method, but more importantly provides a new strategy for the molecular design to obtain soluble n-channel organic semiconductors in the field of sensing device fabrication.     

Synthesis and characterization of glucosamide-based trisiloxane gemini surfactants

A new family of glucosamide-based trisiloxane gemini surfactants of the general formula (CH₂OCH₂)_n (Me₃SiOSiMeR¹OSiMe₃)₂ (where R¹=(CH₂)₃NR²(CH₂)₂NHCO (CHOH)₄CH₂OH; R²=CH₂CH(OH)CH₂OCH₂; and n=0, 1, or 2) was prepared and characterized, both structurally and as aqueous surfactants. The monomer was prepared by amidation of the precursor amine functional trisiloxane with d-gluconic acid δ-lactone. Gemini surfactants were then prepared by the alkylation of the precursor secondary amine with oligoethylene glycol diglycidyl ethers. They were structurally and elemental analysis. Members of this family reduced the surface tension of water to approximately 21 mN/m at concentration levels of 10⁻⁵ mol/L. These gemini compounds showed two critical aggregation concentration values. This behavior resulted from the formation of premicellar aggregates before true micelles were formed.     

Ionic Conductivity of Cross-linked Polymethacrylate Derivatives/Cyclophosphazenes/Li<Superscript>+</Superscript> Salt Complexes

The role of cyclophosphazenes with oxyethylene chains (N₃P₃(OCH₂CH₂)_nOCH₃, (n = 3, 3, n = 7.2, 4) and N₄P₄[OC₆H₄O(CH₂CH₂O)_7.2CH₃]₈ (8) for the synthesis and ionic conductivity in polymethacrylate networks was studied. Reflecting the structural features of cyclophosphazenes, the ⁷Li NMR spectra of the mixture of 3 and LiN(SO₂CF₃)₂ showed that more than 40% of the Li⁺ salt could exist as a free ion at room temperature. Similar values were obtained for 4 and 8. Cross-linked methacrylate polymers (12–14, and 16–18) were prepared from the reaction of poly(ethylene glycol) methyl ether methacrylate and poly(ethylene glycol) dimethacrylate both in the presence of these cyclophosphazenes which act as molecular imprinting molecules (method II, M-II) and without the cyclophosphazene (method I) DSC studies of the imprinted polymer, 12(20)/3/Li⁺ system after removal of the cyclophosphazene showed that the glass transition temperature range (ΔT_g) becomes significantly narrower compared to that of the unimprinted 11(20)/3/Li⁺ system, where cross-linked polymer 11(20) was prepared in the absence of the cyclophosphazenes (method I, M-I). The ionic conductivity of the Li⁺/cross-linked polymer system was improved by the subsequent readdition of the cyclophosphazenes. The 12(20)/3/Li⁺ complex showed a conductivity of 1.1 × 10⁻³ S/cm at 90 °C, which was two times higher than that of the 11(20)/3/Li⁺ complex. The effectiveness of the small molecule imprinting technique for the preparation of cross-linked polyelectrolytes with high conductivity and mechanical stability is discussed. We dedicate this paper to Professor Christopher W. Allen for his creative, pioneering work in inorganic ring and inorganic-organic hybrid polymers.     

Hydrothermal synthesis and in situ surface modification of boehmite nanoparticles in supercritical water

In situ surface modification of boehmite (AlOOH) nanoparticles during hydrothermal synthesis in supercritical water was examined by adding CH₃(CH₂)₄CHO and CH₃(CH₂)₅NH₂ as modifier reagents to the reactants. Changes in surface properties of the nanoparticles by surface modification was observed by FTIR, dispersion in solvents and TEM analyses, which demonstrated that reagents chemically binded onto the surface of the AlOOH nanoparticles. The results of SEM and TEM pictures show that the surface modification affects crystal growth and reduces the particle size and changes the morphology of the particles.     

Phosphonitrilic chloride: 27. Synthesis and properties of cyclophosphazene polymers

The products of the reaction between dichlorocyclotriphosphazene, (NPCl₂)₃, and 3,3′-diaminobenzidine, (H₂N)₂C₆H₃C₆H₃(NH₂)₂, in pyridine were shown to be amorphous, black coloured solids and slightly soluble in polar organic solvents, but insoluble in non-polar organic solvents. Measurement of the degree of swelling showed that the products were not crosslinked structures. The products were decomposed by heating at relatively low temperatures and by dilute acids and alkalis.     

Tetrahydropyrrolization of Resveratrol and Other Stilbenes Improves Inhibitory Effects on DNA Oxidation

The inhibitory effect of resveratrol on DNA oxidation caused by 2,2′‐azobis(2‐amidinopropane hydrochloride) (AAPH) was found to be enhanced if the C=C bond in resveratrol was converted into tetrahydropyrrole by reaction with azomethine ylide (CH₂=N⁺(CH₃)CH₂^?). This encouraged us to explore whether the inhibitory activities of other stilbenes could also be increased by the same method. We found that the inhibitory effects of the tetrahydropyrrole derivatives on AAPH‐induced oxidation of DNA were higher than those of the corresponding stilbenes, because the tetrahydropyrrole motif can provide hydrogen atoms to be abstracted by radicals. Therefore, the tetrahydropyrrolization offered an advantage for enhancing the antioxidant effects of stilbenes. Notably, (CH₃)₃SiCH₂N(CH₃)CH₂OCH₃ (in the presence of CF₃COOH) and (CH₃)₃NO (in the presence of LiN(iPr)₂) can be used to generate azomethine ylide for the tetrahydropyrrolization of stilbenes containing electron‐withdrawing and ‐donating groups, respectively.     

Convenient Modular Syntheses of Fluorous Secondary Phosphines and Selected Derivatives

Reactions of the fluorous primary phosphines R_fn(CH₂)₂PH₂ [R_fn=(CF₂)_n−1CF₃; n=6, 8, 10] and R_fn′CHCH₂ [(n′=6, 8, 10) (1 : 1; THF, reflux) in the presence of AIBN give the title compounds [R_fn(CH₂)₂][R_fn′(CH₂)₂]PH [n/n′=6/6 ( 4 , 55%), 8/8 ( 5 , 58%), 10/10 ( 6 , 53%), 8/6 ( 7 , 52%), 10/8 ( 8 , 51%)] as low-melting white solids on up to 10-g scales. The chiral tertiary phosphine [R_f6(CH₂)₂][R_f8(CH₂)₂][R_f10(CH₂)₂]P ( 9 ) is similarly prepared from 7 and R_f10CHCH₂ in the presence of VAZO (neat, 100 °C; 67%). The reaction of 5 and THF⋅BH₃ yields the phosphine borane 5 ⋅BH₃ (95%). Additions of triphosgene [(CCl₃O)₂CO] to 5 or R_f8(CH₂)₂PH₂ give [R_f8(CH₂)₂]₂PCl or R_f8(CH₂)₂PCl₂, which are characterized in situ. The CF₃C₆F₁₁/toluene partition coefficients of 4 – 9 increase with the number and lengths of the R_fn segments.     

Phosphonitrilic chloride. XXVI. Synthesis of cyclophosphazene polymer by polycondensation reaction of tetrachlorodiphenyl triphosphazene and aromatic diamine compounds

Tetrachlorodiphenyl cyclotriphosphazene N₃P₃Cl₄(C₆H₅)₂ (TPC) has been synthesized by Friedel-Crafts reaction. The polycondensation of TPC with aromatic diamine compounds has been carried out in pyridine. The products obtained from the reaction of TPC with aromatic diamine compounds were slightly soluble in polar organic solvents. The molecular weights measured by the method of end group analysis were about 2800 to 10800. The products were amorphous, brown, yellow or white coloured solids. The softening points of all polycondensation products were found to be in the region of 100°C to 120°C. The electrical conductivity of the products obtained from TPC with p-phenylenediamine and p,p′-diaminodiphenyl sulfone was determined to 5 × 10¹² (Ωcm)^?1 and 1 × 10¹⁵ (Ωcm)^?1, respectively.     

Synthesis of silicon-substituted hydroxyapatite by a hydrothermal method with two different phosphorous sources

Silicon-substituted hydroxyapatite (Si-HA) with up to 1.8 wt% Si content was prepared successfully by a hydrothermal method, using Ca(NO₃)₂, (NH₄)₃PO₄ or (NH₄)₂HPO₄ and Si(OCH₂CH₃)₄ (TEOS) as starting materials. Silicon has been incorporated in hydroxyapatite (HA) lattice by partially replacing phosphate (PO₄³⁻) groups with silicate (SiO₄⁴⁻) groups resulting in Si-HA described as Ca₁₀(PO₄)_6−x(SiO₄)_x(OH)_2−x. X-ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), inductively coupled plasma AES (ICP-AES) and scanning electron microscopy (SEM) techniques reveal that the substitution of phosphate groups by silicate groups causes some OH⁻ loss to maintain the charge balance and changes the lattice parameters of HA. The crystal shape of Si-HA has not altered compared to silicon-free reference hydroxyapatite but Si-incorporation reduces the size of Si-HA crystallites. Based on in vitro tests, soaking the specimens in simulated body fluid (SBF), and MTT assays by human osteoblast-like cells, Si-substituted hydroxyapatite is more bioactive than pure hydroxyapatite.     

New members in the [Mn10] supertetrahedron family

Two manganese complexes, [Mn^II₄Mn^III₆Cl₄(CH₃OCH₂CH₂O)₁₂ O₄][Mn^II₃Ti^IVCl₆(CH₃OCH₂CH₂O)₆] (1) and [Mn^II₄Mn^III₆Cl₄(CH₃OCH₂CH₂O)₁₂O₄] [Mn₄^II Cl₁₀(CH₃OCH₂CH₂OH)₄]∙0.5CH₃OCH₂CH₂OH, (2) have been obtained and characterized by single-crystal X-ray diffraction. Both structures consist of the decametallic dicationic [Mn^II₄Mn^III₆Cl₄(CH₃OCH₂CH₂O)₁₂O₄]^2 + core constructed by four vertex-sharing [Mn^III₃Mn^IIO]^9 + tetrahedra. Also, these compounds contain the different tetrametallic dianions: [Mn^II₃Ti^IVCl₆(CH₃OCH₂CH₂O)₆]^2 − (in complex 1) and [Mn₄^IICl₁₀(CH₃OCH₂CH₂OH)₄]^2 − (in complex 2). Magnetic dc and ac susceptibility measurements for compound (1) show that the dicationic decanuclear magnetic cluster possesses an S = 12 ± 1 spin ground-state.     

Photolithography based on organosilane self-assembled monolayer resist

Micropatterning of organosilane self-assembled monolayers (SAMs) was demonstrated on the basis of photolithography using an excimer lamp radiating vacuum ultraviolet light of 172 nm wavelength. This lithography is generally applicable to micropatterning of organic thin films including alkylsilane SAMs, since its patterning mechanism involves cleavage of CC bonds in organic molecules and subsequent decomposition of the molecules. In this study, SAMs were prepared on Si substrates covered with native oxide by chemical vapor deposition in which an alkylsilane, that is, octadecyltrimethoxysilane [CH₃(CH₂)₁₇Si(OCH₃)₃, ODS] was used as a precursor. SAM was photoirradiated through a photomask placed on its surface so that it was decomposed and removed in the photoirradiated area while the masked areas remained undecomposed. Accordingly, the photomask image was printed on the SAM as a removed/unremoved pattern. The patterned SAM could be used as a mask for plasma etching or area-selective Ni electroless plating.     

Synthesis and characterization of soluble polyphosphazenes having pendent Cp* Fe(dppe) groups

Summary The reaction of HOC₆H₄CH₂CN , N₃P₃(O₂C₁₂H₈)₂(OC₆H₄CH₂CN)₂ and – [{NP(O₂C₁₂H₈)}_0.8 {NP (OC₆H₄CH₂CN)₂}_0.18 ]_n with Cp*Fe(dppe)I in dichloromethane solution and in the presence of TIPF₆ affords the new compounds [Cp*Fe(dppe)NCCH₂C₆H₄OH][PF₆]1 Cp* = C₅(CH₃)₅ [{N₃P₃ (O₂C₁₂H₈)₂(OC₆H₄CH₂CN•Cp*Fe(dppe))₂] [PF₆]₂ 2 and the copolymer [{NP{(O₂C₁₂H₈}_0.8 {NP(OC₆H₄CH₂CN•[Cp*Fe(dppe)][PF₆])₂}_O.8]_n 3 respectively. The σ coordination of the Cp*Fe(dppe) fragment toward the nitrile group is indicated by spectroscopic data. The copolymer 3 is soluble in several organic solvents with no significant cross-linking and has a Mw on the order of 1.260.000. Thermal effects of the incorporation of the organometallic fragment to the copolymer were investigated using differential scanning calorimetry (DSC) and therrnogravimetric analysis (TGA). Received: 7 May 2002/Revised version: 21 March 2003/ Accepted: 27 March 2003 Correspondence to C. Diaz