Synthesis of a novel highly conjugated conducting polymer

The new conjugated polyacetylene derivative dehydrated poly(4-hydroxy-4-phenyl-1-butyne) [dehydrated poly(HPB)] was synthesized from poly(4-hydroxy-4-phenyl-1-butyne) [poly(HPB)], which was obtained by the polymerization of 4-hydroxy-4-phenyl-1-butyne. The resulting dehydrated poly(HPB) was soluble in common organic solvents. The dehydrated poly(HPB) was found to have extended conjugated polyene structure. The dehydrated poly(HPB) was thermally stable up to 300°C. The electrical conductivity of I₂-doped dehydrated poly(HPB) was 10⁻² S cm⁻¹. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 949–953, 1998     

Properties of amorphous and crystallizable hydrocarbon polymers. IV. Melt rheology of linear and star-branched hydrogenated polybutadiene

Some results on the melt rheology of hydrogenated polybutadiene (HPB) with narrow-molecular-weight distribution are reported and compared with the corresponding properties of the precursor polybutadienes (PBD) and fractions of linear polyethylene (PE). In linear samples the dynamic moduli obeyed frequency-temperature superposition. The relationship between melt viscosity and intrinsic viscosity at 190°C for HPB was indistinguishable from that for PE, but their flow activation energies were slightly different (E_a = 7.2 kcal for HPB and 6.4 kcal for PE). Like PE, but unlike the PBD precursors, the dynamic storage modulus at low frequencies was anomalous. Otherwise, the dynamic moduli of HPB and its PBD precursor were essentially superposable. Plateau moduli from different samples were somewhat variable around an average of G = 2.3₁ × 10⁷ dyn/cm². The dynamic moduli for the HPB stars, unlike their PBD precursors, did not obey temperature-frequency superposition. At high frequencies the temperature coefficient approached that for linear HPB, but it increased with decreasing frequency, reaching limiting values which depended on the arm length. The flow activation energy ranged from 9 kcal to more than 15 kcal as arm length increased.     

Crystal structures of [Ru(terpy)(HPB)(H2O)](PF6)2 and [Ru(terpy)(HPB)(2-picoline)](PF6) and the kinetics studies of the aqua ligand substitution by pyridine and substituted pyridines

The crystal structures of [Ru(terpy)(HPB)(H₂O)](PF₆)₂, 1, and [Ru(terpy)(HPB)(2-picoline)](PF₆), 2, (where terpy = 2,2′:6′,2′′-terpyridine and HPB = 2-(2′-hydroxyphenyl)-benzoxazole) have been determined. Both structures show slightly distorted octahedral coordination around the ruthenium center. In complex 1, the imine nitrogen of the HPB ligand occupies an axial position and is trans to the aqua ligand whereas in complex 2, the imine nitrogen is trans to the nitrogen of the 2-picoline ligand. The Ru-N(2-picoline) bond distance is much longer than the other Ru-N bonds in the complex due to steric effects from the methyl group of 2-picoline. In both complexes, the phenolate oxygen of the HPB ligand is in the equatorial position and trans to the center nitrogen of the terpyridine. The reaction of [Ru(terpy)(HPB)(H₂O)](PF₆)2 with pyridine and its analogs, 2-picoline and 4-picoline in dichloromethane was monitored spectrophotometrically. There is an initial reduction of the [Ru(III)-H₂O] complex to [Ru(II)-H₂O] complex prior to the substitution of the aqua ligand. The values of the activation parameters indicate that the substitution of the aqua ligand by pyridine, 2-picoline and 4-picoline follow an associative mechanism.     

A theoretical investigation about the excited state behavior for 2‐(6'‐hydroxy‐2'‐pyridyl)benzimidazole: The water‐assisted excited state proton transfer process

In this work, based on density functional theory (DFT) and time‐dependent DFT (TD‐DFT) methods, we theoretically investigate the excited‐state process of the 2‐(6'‐hydroxy‐2'‐pyridyl)benzimidazole (2HPB) system in acetonitrile and water solvents. Since acetonitrile is an aprotic solvent, it has no effect on the solvent‐assisted excited‐state proton transfer (ESPT) process. Therefore, the 2HPB molecule cannot transfer the proton in acetonitrile, which is consistent with previous experimental observation. On the other hand, 2HPB can combine one water molecule (which is a protic solvent), forming the 2HPB–H₂O complex in the S₀ state. After photoexcitation, the intermolecular hydrogen bonds O1 H2···O3 and O3 H4···N5 both get strengthened in the S₁ state, which leads to the possibility of a water‐assisted ESPT process. Further, the charge redistribution reveals the tendency of ESPT. By exploring the potential energy curves for the 2HPB–H₂O complex in water, we confirm that a stepwise double proton transfer process occurs in the S₁ state. Water‐assisted ESIPT can occur along O1 H2···O3 or O3 H4···N5 because of their similar potential barriers. Based on the stepwise ESPT mechanism, we reinterpret the absorption and fluorescence spectra mentioned in the experiments and confirm the rationality of the water‐assisted ESPT process.     

Fluorescent Dendritic Organogels Based on 2‐(2′‐Hydroxyphenyl)benzoxazole: Emission Enhancement and Multiple Stimuli‐Responsive Properties

A new highly efficient and versatile poly(benzyl ether) dendritic organogelator HPB‐G₁ with 2‐(2′‐hydroxyphenyl)benzoxazole (HPB) at the focal point has been designed and synthesized. HPB‐G₁ can form stable organogels toward various apolar and polar organic solvents. Further studies revealed that intermolecular multiple π–π stacking interactions are the main driving forces for the formation of the organogels. Notably, dendron HPB‐G₁ exhibited a significantly enhanced emission in the gel state in contrast to weak emission in solution. Most interestingly, these dendritic organogels exhibited multiple stimuli‐responsive behaviors upon exposure to environmental stimuli, including temperature, sonication, shear stress, and the presence of anions, metal cations, acids/bases, thus leading to reversible sol–gel phase transitions.     

Structure and Reactivity of Five- and Six-Ring N,N-, N,O-, and O,O-acetals: A lesson in allylic 1, 3-strain (A1, 3 strain)

The X-ray structures of fifteen 1, 3-imidazolidine, 1, 3-oxazolidine, 1, 3-dioxan-4-one, and hydropyrimidine-4(1H)-one derivatives are described (Table 2) and compared with known structures of similar compounds (Figs. 1–20). The differences between structures containing exocyclic N-acyl groups and those lacking this structural element arise from the A^1,3 effect of the amide moieties. Even t-Bu groups are forced into axial positions of six-ring half-chair or into flag-pole positions of six-ring twist-boat conformers by this effect (Figs. 16–20). In the N-acylated five-membered heterocycles, a combination of ring strain and A^{1, 3} strain leads to strong pyramidalizations of the amide N-atoms (Table 1) such that the acyl groups wind up on one side and the other substituents on the opposite side of the rings (Figs. 4–9 and Scheme 3). Thus, the acyl (protecting!) groups strongly contribute to the steric bias between the two faces of the rings. Observed, at first glance surprizing stereoselectivities of reactions of these heterocycles (Schemes 1 and 2) are interpreted (Scheme 3) as an indirect consequence of the amide A^{1, 3} strain effect. The conclusions drawn are considered relvant for a better understanding of the ever increasing role which amide groups play in stereoselective syntheses.     

Spectroscopic study of the complexes of poly(N-methacryloyl-L-asparagine) with palladium (II)

The complexes formed between palladium (II) and a polymeric ligand derived from L -asparagine, poly(N-methacryloyl-L -asparagine) (PNMAsn) have been investigated by electronic absorption and circular dichroism. N-isobutyroyl-L -asparagine (NIBAsn) was also synthesized and studied with the purpose of comparison with its polymeric analog. NIBAsn gives two complexes: at low pH, an optically active complex between one carboxylate and one secondary amide nitrogen (so-called 1N complex), and at higher pH, a 2N complex involving the primary and secondary amide group. This complex is also optically active. PNMAsn gives at low pH a 1N complex similar to that of NIBAsn, but at higher pH the 2N complex is formed between two carboxylate groups and two secondary amide groups of two different side chains of the polymer. At very high pH this 2N complex is hydrolyzed, i.e., the carboxylate-palladium bonds are replaced by hydroxyle-palladium bonds, and the complex becomes optically inactive.     

Syntheses,Structures and Sorption Properties of Three Isoreticular Trinuclear Indium‐Based Amide‐Functionalized Metal–Organic Frameworks

Amide‐functionalized metal–organic frameworks (AFMOFs) as a subclass of MOF materials have received great interest recently because of their intriguing structures and diverse potential applications. In this work, solvothermal reactions between indium nitrate and two mixed‐linkers afforded two new isoreticular 8‐connected trinuclear indium‐based AFMOFs of [(In₃O)(OH)(L2)₂(IN)₂]?(solv)_x ( 2‐In ) and [(In₃O)(OH)(L2)₂(AIN)₂]?(solv)_x ( NH₂‐2‐In ) (H₂L2=4,4′‐(carbonylimino)dibenzoic acid and HIN=isonicotinic acid or HAIN=3‐aminoisonicotinic acid), respectively. Moreover, by means of reticular chemistry, an extended network of [(In₃O)(OH)(L3)₂(PB)₂]?(solv)_x (3‐In) (H₂L3=4,4′‐(terephthaloylbis(azanediyl))dibenzoic acid, HPB=4‐(4‐pyridyl)benzoic acid) was also successfully realized after prolongation of the former dicarboxylate linker and HIN, resulting in a truly 8‐connected isoreticular AFMOF platform. These frameworks were structurally determined by single‐crystal X‐ray diffraction (SCXRD). Sorption studies further demonstrate that 2‐In and NH₂‐2‐In exhibit not only high surface areas and pore volumes but also relatively high carbon capture capabilities (the CO₂ uptakes reach 60.0 and 75.5 cm³ g^?1 at 298 K and 760 torr, respectively) due to the presences of amide and/or amine functional groups. The selectivity of CO₂/N₂ and CO₂/CH₄ calculated by IAST are 10.18 and 12.43, 4.20 and 4.23 for 2‐In and NH₂‐2‐In , respectively, which were additionally evaluated by mixed‐gases dynamic breakthrough experiments. In addition, high‐pressure gas sorption measurements show that both materials could take up moderate amounts of natural gas.     

[(1,4,8,11‐Tetraazacyclotetradeca‐1,4,8,11‐tetrayl)tetraacetamide‐κ6N1,N4,N8,N11,O1,O8]copper(II) sulfate 4.5‐hydrate

The crystal structure of the title copper(II) complex, [Cu(C₁₈H₃₆N₈O₄)]SO₄·4.5H₂O, formed with the tetra­amide cyclam derivative 2‐(4,8,11‐triscarbamoyl­methyl‐1,4,8,11‐tetra­aza­cyclo­tetradec‐1‐yl)­acet­amide (TETAM), is described. The macrocycle lies on an inversion centre occupied by the hexacoordinated Cu atom. The four macrocyclic tertiary amines form the equatorial plane of an axially Jahn–Teller elongated octahedron. Two O atoms belonging to two diagonally opposite amide groups occupy the apical positions, giving rise to a trans‐III stereochemistry, while both the remaining pendant side arms extend outwards from the macrocyclic cavity and are engaged in hydrogen bonds with sulfate anions and co‐crystallized water mol­ecules.     

Synthesis,characterization, and antibacterial activities of two new copper(II) glycinate complexes incorporating 2-(4′-thiazolyl)benzimidazole/2-(2-pyridyl)benzimidazole

Two new complexes, [Cu(TBZ)(Gly)(H₂O)]Cl (1) and [Cu(HPB)(Gly)Cl]?·?2H₂O (2) (TBZ?=?2-(4′-thiazolyl)benzimidazole, HPB?=?2-(2-pyridyl)benzimidazole, and Gly?=?glycinate), have been synthesized and characterized by elemental analysis, molar conductivity, UV-Vis, and IR methods. The complexes, structurally characterized by single-crystal X-ray crystallography, show a slightly distorted square-pyramidal coordination geometry in which two nitrogen atoms of TBZ or HPB and the carboxylate oxygen and amino nitrogen of glycinate bind in the plane and a water or chloride coordinated at the axial site. The complexes, free ligands, and copper(II) chloride were tested for their ability to inhibit growth of Bacillus subtilis, Staphylococcus aureus, and Salmonella. The results show that the complexes have good antibacterial activities against the microorganisms compared with their ligands and copper(II) chloride.     

Cyano-, nitro-, and alkoxycarbonyl-activated observable stable enols of carboxylic acid amides

A search for the enol structures of several amides YY'CHCONHPh with Y,Y' = electron-withdrawing groups (EWGs) was conducted. When Y = CN, Y' = CO(2)Me the solid structure is that of the enol (8b) MeO(2)CC(CN)=C(OH)NHPh, whereas in solution the NMR spectrum indicate the presence of both the amide MeO(2)CCH(CN)CONHPh (8a) and 8b. When Y = NO(2), Y' = CO(2)Et the main compound in CDCl(3) is the amide, but <10% of enol(s), presumably EtO(2)CC(NO(2))=C(OH)NHPh (9b), are also present. When Y = COEt, Y' = CO(2)Me or Y = COMe, Y' = CO(2)Et (10 and 11) enolization in solution and of 11 also in the solid state occurs at the carbonyl rather than at the ester site. With Y = Y' = CN a rapid exchange between the amide (NC)(2)CHCONHPh (12a) and a tautomer, presumably the enol, take place in several solvents on the NMR time scale. With YY' = barbituric acid moiety the species in DMSO-d(6) is an enol of an amide although which CONH group enolizes is unknown. B3LYP/6-31G calculations showed that the enol (NC)(2)C=C(OH)NH(2) (13b) is more stable by DeltaG of 0.4 kcal/mol than (NC)(2)CHCONH(2) (13a) due to a combination of stabilization of 13b and destabilization of 13a and both are much more stable than the hydroxyimine and ketene imine tautomers. The effect of Y,Y' and the solvent on the relative stabilization of enols of amides is discussed.     

Mixed polymer brushes by sequential polymer addition: anchoring layer effect

Smart surfaces can be described as surfaces that have the ability to respond in a controllable fashion to specific environmental stimuli. A heterogeneous (mixed) polymer brush (HPB) can provide a synthetic route to designing smart polymer surfaces. In this research we study HPB comprised of end-grafted polystyrene (PS) and poly(2-vinyl pyridine) (P2VP). The synthesis of the HPB involves the use of an "intermolecular glue" acting as a binding/anchoring interlayer between the polymer brush and the substrate, a silicon wafer. We compare anchoring layers of epoxysilane (GPS), which forms a self-assembled monolayer with epoxy functionality, to poly(glycidyl methacrylate) (PGMA), which forms a macromolecular monolayer with epoxy functionality. The PS and P2VP were deposited onto the wafers in a sequential fashion to chemically graft PS in a first step and subsequently graft P2VP. Rinsing the HPB in selective solvents and observing the change in water contact angle as a function of the HPB composition studied the switching nature of the HPB. Scanning probe microscopy was used to probe the topography and phase imagery of the HPB. The nature of the anchoring layer significantly affected the wettability and morphology of the mixed brushes.     

Stress–strain behavior of low‐density polyethylene/poly(methyl methacrylate) blends with modulated interfaces with a hydrogenated polybutadiene‐block‐poly(methyl methacrylate) diblock copolymer

The stress–strain diagrams and ultimate tensile properties of uncompatibilized and compatibilized hydrogenated polybutadiene‐block‐poly(methyl methacrylate) (HPB‐b‐PMMA) blends with 20 wt % poly(methyl methacrylate) (PMMA) droplets dispersed in a low‐density polyethylene (LDPE) matrix were studied. The HPB‐b‐PMMA pure diblock copolymer was prepared via controlled living anionic polymerization. Four copolymers, in terms of the molecular weights of the hydrogenated polybutadiene (HPB) and PMMA sequences (22,000–12,000, 63,300–31,700, 49,500–53,500, and 27,700–67,800), were used. We demonstrated with the stress–strain diagrams, in combination with scanning electron microscopy observations of deformed specimens, that the interfacial adhesion had a predominant role in determining the mechanism and extent of blend deformation. The debonding of PMMA particles from the LDPE matrix was clearly observed in the compatibilized blends in which the copolymer was not efficiently located at the interface. The best HPB‐b‐PMMA copolymer, resulting in the maximum improvement of the tensile properties of the compatibilized blend, had a PMMA sequence that was approximately half that of the HPB block. Because of the much higher interactions encountered in the PMMA phase in comparison with those in HPB (LDPE), a shorter sequence of PMMA (with respect to HPB but longer than the critical molecular weight for entanglement) was sufficient to favor a quantitative location of the copolymer at the LDPE/PMMA interface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 22–34, 2005     

Enantioselective inclusion of amide guests into a chiral N,N′-ditrityl amino amide host to compensate the loss of hydrogen bonds broken by installation of trityl groups

A new crystalline N,N′-ditrityl amino amide host included several amide guests in the host cavity to form inclusion crystals. Although the installation of trityl groups into (S)-2-aminopropanamide broke its inherent hydrogen bonds of amide groups, inclusion of guest amides compensated the loss of hydrogen bonds. X-ray crystallography showed that these inclusion cavities and host–guest interactions such as hydrogen bonds, van der Waals interaction, and CH?O interactions play important roles for highly enantioselective inclusion. The enantiomeric inclusion was 67% ee (S-form) for N-phenyl 2-methylbutanamide, 82% ee (S-form) for N-phenyl 2-chlorobutanamide, and 83% ee (S-form) for N-phenyl 2-bromobutanamide.     

Di­methyl N,N′‐ox­alamido­diethano­ate

The title compound, dimethyl 2,2′‐(oxalyldiimino)diethanoate, C₈H₁₂N₂O₆, exhibits a network of hydrogen bonds between amide and ester groups. Molecules lie on inversion centres and show a planar conformation for both the oxal­amide and ester groups. The glycine residues adopt a conformation close to the polyglycine II structure.     

脂肪醇对杂多酸P2Mo186-激发态的还原作用

近年来,杂多酸和氧化物催化剂表面的类似性引起了人们的广泛兴趣。钼杂多酸具有光化学活性,在不同种类有机溶剂存在下,紫外或可见光辐照就形成杂多蓝还原产物及相应的有机物氧化产物。从乙醇或1,4-二噁烷中沉淀出来的杂多酸化合物(简称HPC)在日光下也变成蓝色。HPC还原时形成多电子还原产物—杂多蓝(简称HPB)。这种多个还原电子体系可能作为还原N_2,CO和H_2O的还原剂。杂多酸光催化大量有机物的氧化反应,以及水放氢的还原反应,是一个活跃的研究领域之一。本文研究了Dawson结构P_2Mo_(18)~(6-)的光化     

Synthesis, spectroscopic and electronic characterizations of two half sandwich ruthenium(II) complexes with 2-(2′-hydroxyphenyl)-benzoxazole and 4-picolinic acid ligands

The [(C₆H₆)RuCl(HPB)] and [(C₆H₆)RuCl₂(C₅H₄NCOOH)] complexes have been prepared and studied by IR, UV-Vis spectroscopy and X-ray crystallography. The complexes was prepared in reaction of [(C₆H₆)RuCl₂]₂ with 2-(2′-hydroxyphenyl)-benzoxazole or 4-picolinic acid in methanol. The electronic spectra of the obtained compounds have been calculated using the TDDFT method. The luminescence property of the half sandwich complex [(C₆H₆)RuCl(HPB)] was studied by the DFT method and the mechanism was suggested.     

Syntheses,Crystal Structure and Reactivity of Tin(II) Bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide]

Metallation of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with n‐butyllithium in toluene yields lithium N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 1 ), which crystallizes as a tetramer. Transamination of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine with an equimolar amount of Sn[N(SiMe₃)₂]₂ leads to the formation of monomeric bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ). The addition of another equivalent of N‐(diphenylphosphanyl)(2‐pyridylmethyl)amine gives homoleptic tin(II) bis[N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide] ( 3 ). In these complexes the N‐(diphenylphosphanyl)(2‐pyridylmethyl)amido groups act as bidentate bases through the nitrogen bases. At elevated temperatures HN(SiMe₃)₂ is liberated from bis(trimethylsilyl)amido tin(II) N‐(diphenylphosphanyl)(2‐pyridylmethyl)amide ( 2 ) yielding mononuclear tin(II) 1,2‐dipyridyl‐1,2‐bis(diphenylphosphanylamido)ethane ( 4 ) through a C–C coupling reaction. The three‐coordinate tin(II) atoms of 2 and 4 adopt trigonal pyramidal coordination spheres.     

Pyrene-appended calix[4]crowned logic gates involving normal and reverse PET: NOR, XNOR and INHIBIT

As a novel sensing system, N-(1-pyrenylmethyl) amide-appended calix[4]crown-5 (2) and crown-6 (3) have been newly synthesized. Judging from the fluorescence changes upon the addition of cations, 3 having crown-6 ring showed the Pb²⁺ ion selectivity over other cations tested regarding fluorescence quenching. Upon the Pb²⁺ ion coordination to two amide oxygen atoms with aid of crown ring, a reverse-photo-induced electron transfer (PET) occurs in such a way that electrons transfer from the pyrene groups to the electron deficient amide oxygen atoms to give a quenched fluorescence. By the addition of either HClO₄ or triethylamine in the solution of 3, the fluorescence intensity decreased because of the reverse-PET from pyrene groups to protonated amide oxygen atoms and because of normal PET from the nitrogen anion formed by triethylamine to pyrene groups, respectively. For 3, NOR logic gate in which the strong fluorescence signal appears at 395 nm (output: 1) is operated only when neither of triethylamine nor Pb(ClO₄)₂ (inputs A and B) is added (A=B: 0). XNOR gate is also operated only when both of two inputs are added (triethylamine and HClO₄, A=B: 1) or when neither of two inputs is added (A=B: 0). Then, for 3, new INHIBIT gate system was also designed using such combinational inputs as HClO₄, Pb(ClO₄)₂ and triethylamine.     

Hybrid plasma bonding for void-free strong bonded interface of silicon/glass at 200 °C

A novel hybrid plasma bonding (HPB) that combines sequential plasma activation (reactive ion etching followed by microwave radicals) with anodic bonding has been developed to achieve void-free and strong silicon/glass bonding at low temperature. The interfacial voids were observed at the silicon/glass interface both in the anodic bonding and in the plasma activated anodic bonding, but the voids were completely disappeared in the HPB method at 200 °C. The bonding strength of the silicon/glass in the HPB was as high as 30 MPa at 200 °C, which was higher than that in the individual treatment of anodic and plasma activated bonding methods. The improved characteristic behavior of the interface in the HPB is attributed to the higher hydrophilicity and smooth surfaces of silicon and glass after sequential plasma activation. These highly reactive and clean surfaces enhance the mobility of alkaline cations from the glass surface across the interface toward the bulk of glass in the HPB. This transportation resulted in a ∼353 nm thick alkaline depletion layer in the glass and enlarged the amorphous SiO₂ across the interface. The void-free strong bonding is attributed to the clean hydrophilic surfaces and the amorphous SiO₂ layer across the interface.