Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl

A new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002     

Ethyl 3‐amino‐6‐phenyl‐4‐tolylthieno[2,3‐b]pyridine‐2‐carboxylate

In the title compound, C₂₃H₂₀N₂O₂S, the central thieno­pyridine ring system is essentially planar, the dihedral angle between the planes of the two rings being 0.3 (2)°. The terminal ethyl carboxyl­ate group is twisted by 26.7 (3)° away from the central ring system. A short intramolecular hydrogen bond involving the amino N atom and the carbonyl O atom [N⋯O = 2.806 (4) Å] forms a pseudo‐six‐membered ring. Significant intermolecular C—H⋯N, C—H⋯O and C—H⋯π interactions contribute strongly to the stability of the structure, along with weak π–π‐stacking interactions.     

Hydrotris(triazolyl)borate complexes as functional models for Cu nitrite reductase: the electronic influence of distal nitrogens

Hydrotris(triazolyl)borate (Ttz) ligands form CuNO(x) (x = 2, 3) complexes for structural and functional models of copper nitrite reductase. These complexes have distinct properties relative to complexes of hydrotris(pyrazolyl)borate (Tp) and neutral tridentate N-donor ligands. The electron paramagnetic resonance spectra of five-coordinate copper complexes show rare nitrogen superhyperfine couplings with the Ttz ligand, indicating strong σ donation. The copper(I) nitrite complex [PPN](+)[(Ttz(tBu,Me))Cu(I)NO(2)](-) has been synthesized and characterized and allows for the stoichiometric reduction of NO(2)(-) to NO with H(+) addition. Anionic Cu(I) nitrite complexes are unusual and are stabilized here for the first time because Ttz is a good π acceptor.     

Higher Dimensional Strange Quark Matter Coupled to the String Cloud with Electromagnetic Field Admitting One Parameter Group of Conformal Motion

We solve Einstein＇s field equations in higher-dimensional spherically symmetric spacetime with strange quark matter attached to the string cloud, assuming one parameter group of con formal motions. The solutions match with the higher-dimensional Reissner-Nordstroem metric on the boundary at r=ro. The features of the solutions are also discussed in the framework of higher-dimensional spacetime.     

Diphenyldiselenide As Novel Non–salt Photoinitiator for Photosensitized Cationic Polymerization of N-Vinyl Carbazole

Photoinitiated cationic polymerization of N-vinyl carbazole (NVC) with diphenyldiselenide (DPDS) as an initiator and aromatic nitriles such as dicyanonaphthalene (DCN) and dicyanoanthracene (DCA) as sensitizer was studied at λ > 290 nm in CH₂Cl₂ solvent using single electron transfer (SET) reactions in this investigation. Aromatic nitriles were found to be effective photosensitizer in initiating polymerization at wavelength λ > 290 nm where DPDS (λ_max = 246 nm) do not absorb. However, the DPDS works well as an initiator with both DCN and DCA. An initiation mechanism is also proposed that involves the formation of selenium radical cation as actual initiating species. Upon photoirradiation, these radical cations are formed by single electron transfer between the excited singlet state sensitizer and the ground state of DPDS.     

Sheath formation in the presence of non-extensive electron distribution

The main aim of this article is to recognize the sheath formation in the presence of non-extensive electron distribution. The role of ion–neutral collision parameter K and the non-extensive parameter “q” has been discussed. Existing literature suggests that the presence of non-extensive electrons potentially modifies the plasma sheath behaviour. However, numerical calculations over the full plasma range, jointly addressing the sheath and presheath, are rare. Sheath formation, being a very fundamental phenomenon, deserves enough investigation in the region of non-extensive distribution of particles. This study attempts to bridge the gap in understanding the formation of the sheath in collisional plasma in the light of both Boltzmann and q-distributed non-extensive electrons.     

Synthesis and characterization of azo–bisbenzylidene‐based polymers for second order nonlinear optics

Main chain polymers containing azo and bisbenzylidene moiety were synthesized by polycondensation method. The successful polymerization reaction was characterized by UV–vis absorption, FT‐IR and NMR spectroscopy. The resulting polymers were soluble in polar solvents like dimethyl formamide (DMF) and showed good thermal stability up to 250 °C. These polymers were blended with poly methyl methacrylate (PMMA) and corona poled for characterizing second harmonic generation (SHG) property. Temperature stability study of SHG intensity of poled polymer showed that it is stable up to 80 °C. To improve temperature stability further the crosslinking of polymer under UV light is proposed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4317–4324