On the addition of 4-(N,N-dimethylamino)phenyl cation to norbornene

The photochemically generated 4-(N,N-dimethylamino)phenyl cation adds to norbornene giving a phenylnortricyclene and various 2-exo substituted phenylnorbornanes (main isomers, 3-endo-, 7-anti- and 7-syn-phenyl). Acetamides are obtained in MeCN and ethers in alcohols (MeOH, iso-PrOH, tert-BuOH, CF3CH2OH). The product distribution is closely reminiscent of that obtained in the solvolysis of 2-norbornyl derivatives, supporting that the reaction offers a novel access to a 'non classical' 2-norbornyl cation. The fate of this cation is determined by the basicity/nucleophilicity of the solvent.     

Photoluminescence spectral reliance on aggregation order of 1,1-Bis(2'-thienyl)-2,3,4,5-tetraphenylsilole

1,1-Bis(2'-thienyl)-2,3,4,5-tetraphenylsilole (1) was prepared and characterized crystallographically. Silole 1 exhibited aggregation-induced emission (AIE) behavior like other 2,3,4,5-tetraphenylsiloles. Unexpectedly, aggregates formed in water/acetone (6:4 by volume) mixture emitted a blue light that peaked at 474 nm, while aggregates formed in the mixtures with higher water fractions emitted green light that peaked at 500 nm. Transmission electron microscopy demonstrated that the aggregates formed in the mixture with water fraction of 60% were single crystals, while aggregates that formed in the mixture with water fraction of 90% were irregular and poorly ordered particles. The unusual PL spectral reliance on aggregation order was further confirmed by PL emissions of macroscopic crystal powders and amorphous powders of the silole in the dry state. PL spectral blue shifting was observed upon aging of the poorly ordered aggregates formed in mixtures with water fractions of 70-90%, and they finally exhibited the same blue emission as the crystalline aggregates. The as-deposited thin solid film was amorphous and it could be transformed to a transparent crystalline film upon treatment in the vapor of an ethanol/water (1:1 by volume) mixture, along with PL spectral blue shifting due to changing of aggregation order. It was also found that the crystalline film showed a blue-shifted absorption spectrum relative to the amorphous film and the shift of the absorption edge of the spectra could match that of corresponding PL spectra. The FT-IR spectrum of crystal powders of 1 displayed more vibration modes compared with that of amorphous powders, suggesting the existence of different pi-overlaps or different molecular conformations. The crystals of 1-methyl-1,2,3,4,5-pentaphenylsilole and hexaphenylsilole also showed blue-shifted PL emissions of their amorphous solids, with a comparable PL spectral shift of 1. Developing of a silole solution on a TLC plate readily brought about an amorphous thin layer. Our results suggest that crystalline films of AIE-active siloles are potential emissive layers for efficient blue OLEDs with stable color and long lifetime.     

1-(4-叔丁基苯基)-1,1-二[4-(4-硝基苯氧基)\]苯基乙烷的合成及其溶解性研究

以叔丁基苯为起始原料,经3步反应制得了一种新化合物1-(4-叔丁基苯基)-1,1-二[4-(4-硝基苯氧基)]苯基乙烷（3）,总收率61.14%,其结构经¹H NMR和IR表征。3可溶于非极性溶剂（石油醚除外）和极性非质子溶剂。     

Chemoenzymatic synthesis of chiral 4-(N,N-dimethylamino)pyridine derivatives

Chiral 4-(N,N-dimethylamino)pyridine derivatives have been prepared through a chemoenzymatic synthesis where the enzymatic kinetic resolution of a family of 4-chloro-2-(1-hydroxyalkyl)pyridines is the key step for the formation of potentially important chiral catalysts. Pseudomonas cepacia lipase (PSL) showed excellent enantioselectivity in the acylation of the (R)-enantiomers (E > 200) using vinyl acetate as acylating agent and THF as solvent, obtaining products and substrates enantiomerically pure and with excellent yields.     

Photoinduced intramolecular charge transfer of sodium 4-(N,N-dimethylamino) benzenesulfonate

A new dual fluorescent N,N-dimethylaniline derivative, sodium 4-(N,N-dimethylamino)-benzenesulfonate (SDMAS), is reported. In SDMAS, the electron acceptor is linked to the phenyl ring via a sulfur atom at the para-position of the electron donor. It was found that SDMAS emits dual fluorescence only in highly polar solvent water but not in organic solvents such as formamide, methanol and acetonitrile. In organic solvents only a single-band emission at ca.360 nm was observed in the short wavelength region. The dual fluorescence of SDMAS in water was found at 365 and 475 nm, respectively. Introduction of organic solvent such as ethanol, acetonitrile, and 1,4-dioxane into aqueous solution of SDMAS leads to blue-shift and quenching of the long-wavelength emission. Measurements of steady-state and picosecond time-resolved fluorescence indicate that the long wavelength fluorescence is emitted from a charge transfer (CT) state that is populated from the locally excited (LE) state, with the latter giving off the     

Polyhydrazides based on 2,5-bis(4-carboxymethylene phenyl)-3,4-diphenyl thiophene

A series of polyhydrazides was synthesized from a novel dicarboxylic acid, 2,5-bis(4-carboxymethylene phenyl)-3,4-diphenyl thiophene (V) and or terephthalic acid and isophthaloyl or terephthaloyl dihydrazide by Yamazaki’s phosphorylation method using triphenyl phosphite as condensing agent. Polyhydrazides were characterized by IR spectroscopy solubility, viscosity, thermogravimetric analysis and X-ray diffraction studies.The polymers were obtained in quantitative yields. Polyhydrazides had viscosities in the range of 0.25-0.70 dL/g. The polymers derived from novel diacid (V) showed enhanced solubility than the polymers derived from terephthalic acid, which may be attributed to the presence to bulky pendant phenyl group and methylene spacer group in the polymer backbone. Polymers were soluble in most of the common aprotic polar solvents. Polyhydrazides showed considerable weight loss in the temperature range of 300-400 °C which is due to the cyclodehydration, leading to the formation of corresponding polyoxadiazoles. They showed T_max in between 500 and 600 °C which is essentially the decomposition of the polyoxadiazoles. X-ray diffraction studies showed that polyhydrazides were amorphous in nature.     

The crystal structure of 1,1-bis(η5-cyclopentadienyl)-2,3,4,5-tetraphenylzirconole

The crystal and molecular structure of (η⁵-C₅H₅)₂Zr[C₄(C₆H₅)₄] has been determined by single crystal X-ray diffraction methods. The compound is isostructural with its titanium and hafnium analogues, and crystallizes in the monoclinic space group P2₁/n with unit cell parameters a = 13.790(5), b = 11.136(5), c = 18.692(7) », β = 92.82(4)°, and ?_calc = 1.34 g cm^?3 for Z = 4. Full-matrix least-squares refinement converged with a conventional R value of 0.049 for 2986 observed reflections. The metallocyclic ring is planar to within 0.05 », and the π-electron density is largely localized. The two independent ZrC(σ) bond lengths are 2.250(5) and 2.265(6) ». The ZrC(η⁵) distances range from 2.482(6) to 2.546(7) », and average 2.521(20) ». A comparison of zirconium- and hafnium-carbon bonds based on the data available shows that for M = Hf the MC bonds are shorter for all cases: C(sp), C(sp²), C(sp³), C(η⁵).     

Theoretical Study of Origin of Triple Fluorescences of a Squaraine Dye, Bis[4-(N,N-dimethylamino)phenyl]-squaraine

A new scheme of photo‐fluorescent emission origin, described as S₀ (relaxed state)→S_n (Frank‐Condon state)→ S_m (relaxed state)→S₀ (Frank‐Condon state), is presented to explain the multiple fluorescent emissions of squaraine dyes observed experimentally according to the configuration interaction singles calculations of relaxed excited states of a model compound, bis[4‐(N,N‐dimethylamino)phenyl]squaraine (SQ). It is exhibited that all triple fluorescent emissions of SQ have their significant origin in vertical electron transitions of different relaxed excited states. In addition, some important absorption peaks appearing in higher energy region are most likely to be responsible for the higher energy band observed in solid states of many squaraine dyes.     

Lasing and gain properties of a giant dipole molecule: 1-[p-(N,N-dimethylamino)phenyl]-4-(p-nitrophenyl)-1,3-butadiene

Laser tuning spectra, nanosecond gain spectra, and picosecond gain and absorption spectra of 1-[p-(N,N-dimethyl-amino)phenyl]-4-(p-nitrophenyl)-1,3-butadiene (DMANPB) are reported. Its permanent dipole moment is found to be larger than 30 D in the lowest excited singlet state. The tuning ranges are 690–725, 695–745, and 705–755 nm in dioxane-acetone mixed solution with volume ratios of 1:0, 5:1, and 4:1, respectively.     

Synthesis and characterization of soluble polyamides based on 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and 2,2-bis[4-(4-aminophenoxy)phenyl]propane and diacid chlorides

Aromatic soluble polyamides and copolyamides having hexafluoroisopropylidene and isopropylidene moieties in the molecular structure of polymer chain were prepared by reacting the aromatic diacid chlorides and fluorine or nonfluorine containing aromatic diamines using low-temperature polycondensation process. Polymers were produced with high yield and moderate to high inherent viscosity. All polyimides and copolyamides showed thermal stability above 440°C and glass transition temperature above 200°C. Some of the polyamides were cast into transparent bulk films which were further characterized by mechanical, x-ray, and water absorption analysis. Fluoro polyamides showed superior structural properties as compared to nonfluoro polyamides. © 1996 John Wiley & Sons, Inc.     

Photophysics of 4-(N,N-dimethylamino)cinnamaldehyde/ alpha-cyclodextrin inclusion complex.

This paper reports the probing of alpha-cyclodextrin (alpha-CD) cavities with the help of dual emission properties of 4-N,N dimethylamino cinnamaldehyde (DMACA) in aqueous solution. An interesting feature could be observed that due to 1:1 complexation DMACA is encapsulated within alpha-CD in two distinctly different types of orientation as revealed from the relative positions and the intensity of locally excited state localized within donor and acceptor subunits (LE) and twisted intramolecular charge transfer (TICT) bands. In one situation the dimethylamino group is directed towards the larger rim of the cavity and in other the orientation is just the opposite. The different types of complexes were found to be excited selectively in different wavelength regions.     

Effect of para substituents of 2-(N,N-dimethylamino)ethyl phenyl phenylphosphonates on inhibition of human pseudocholinesterase

Human serum pseudocholinesterase inhibition by nineteen of the title phosphonates was studied and the effect of para substituents of the phenoxy and phenyl groups on inhibition rates was compared. The effect of substituents of the phenoxy group on the reaction rate is in some cases even 60 times as great as the effect of substituents of the phenyl group. Logarithms of rate constants correlate linearly with sigma po substituent constants of the phenoxy group, but no linear dependence is observed for para substituents of the phenyl group. The role of the apicophilicity of substituents of phosphorus in the enzyme--inhibitor complex is discussed.     

Synthesis and characterization of thermally stable poly(ether-azomethine)s derived from 1,1-bis[4-(4-benzaldehyde oxy)-3-methyl phenyl] cyclopentane

A new dialdehyde 1,1-bis[4-(4-benzaldehyde oxy)-3-methyl phenyl] cyclopentane (BBMPC) was synthesized starting from cyclopentanone and O-cresol to give 1,1-bis(4-hydroxy-3-methyl phenyl)cyclopentane (BHMPC); followed by reaction with 4-fluorobenzaldehyde in N, N-dimethyl formamide (DMF), containing anhydrous potassium carbonate. New series of poly(ether-azomethine)s were synthesized from (BBMPC) with different diamines such as 4,4′- diamino diphenyl ether (ODA); 4,4′-diaminodiphenyl methane (MDA); 4-aminophenyl sulfone (SDA); p-phenylene diamines (p-PDA), etc. in N, N’- dimethyl acetamide (DMAc) with 5 wt% LiCl by the solution polycondensation method. Inherent viscosities of these polymers were in the range 0.20 to 0.38 dL/g indicating formation of moderate molecular weights. These polymers exhibited good solubility in various polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), DMAc, DMF, etc. However some polymers showed partial solubility in DMF and DMAc. X-Ray diffraction pattern of polymers showed amorphous nature. Thermal stability was assessed by 10% weight loss temperature and the degradation temperature of the resultant polymers falls in the ranges from 444-501°C in nitrogen. The glass transition temperature was in the range of 155-205°C. The structure-property correlation among these polyazomethines were studied; in view of their potential applications as high performance polymers.     

Synthesis and properties of new pyridine-bridged poly(ether-imide)s based on 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine

A novel pyridine-containing aromatic diamine monomer, 4-(4-trifluoromethylphenyl)-2,6-bis[4-(4-aminophenoxy)phenyl]pyridine (FAPP), was synthesized via the modified Chichibabin pyridine synthesis of 4-(4-nitrophenoxy)-acetophenone with 4-trifluoromethyl-benzaldehyde, followed by a catalytic reduction. A series of fluorinated pyridine-bridged aromatic poly(ether-imide)s were prepared from the resulting diamine monomer with various aromatic dianhydrides via a conventional two-step process. The resulting polyimides exhibited good solubility in aprotic amide solvents and m-cresol, such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., which possessed the inherent viscosities of 0.76-0.91 dL/g. Strong and flexible poly(ether-imide) films were obtained, which showed excellent thermal properties with the glass transition temperatures of 268-353 °C, the temperature at 5% weight loss of 547-595 °C, and the residue at 700 °C of 65-74% in nitrogen, good mechanical properties with the tensile strengths of 87.6-104.2 MPa and elongations at breakage of 8.9-12.6%, and good optical transparency with the cut-off wavelengths of 357-380 nm, as well as low dielectric constants in the range of 2.49-3.04 at 1 MHz and low water uptake 0.43-0.69%. Furthermore, the resulted polyimides derived from FAPP were compared with non-fluorinated analogous polyimides and fluorinated analogous polyimides with trifluoromethyl groups in different positions, and the effects of substituents were also investigated and discussed.     

4-(N,N-dimethylamino)pyridine-embedded nanoporous conjugated polymer as a highly active heterogeneous organocatalyst

We report herein for the first time the incorporation of a versatile organocatalyst, 4-(N,N-dimethylamino)pyridine (DMAP), into the network of a nanoporous conjugated polymer (NCP) by the "bottom-up" approach. The resulting DMAP-NCP material possesses highly concentrated and homogeneously distributed DMAP catalytic sites (2.02?mmol g(-1)). DMAP-NCP also exhibits enhanced stability and permanent porosity due to the strong covalent linkage and the rigidity of the "bottom-up" monomers. As a result, DMAP-NCP shows excellent catalytic activity in the acylation of alcohols with yields of 92-99?%. The DMAP-NCP catalyst could be easily recovered from the reaction mixture and reused in at least 14 consecutive cycles without measurable loss of activity. Moreover, the catalytic acylation reaction could be performed under neat and continuous-flow conditions for at least 536?h of continuous work with the same catalyst activity.