Diphenylamino Groups Research Articles

A mechanism-based probe for gp120-Hydrolyzing antibodies

An antigenic peptide analogue consisting of HIV gp120 residues 421–431 (an antigen recognition site probe) with diphenyl amino(4-amidinophenyl)methanephosphonate located at the C-terminus (a catalytic site probe) was synthesized and its trypsin and antibody reactivity characteristics were studied. Antibodies to the peptide determinant recognized the peptidyl phosphonate probe. Trypsin was inhibited equipotently by the peptidyl phosphonate and its simple phosphonate counterpart devoid of the peptide determinant. The peptidyl phosphonate inhibited the gp120-hydrolyzing activity of a catalytic antibody light chain. It was bound covalently by the light chain and the binding was inhibited by the classical active-site directed inhibitor of serine proteinase, diisopropyl fluorophosphate. These results reveal that the peptidyl phosphonate ester can serve as a probe for the antigen recognition and catalytic subsites of proteolytic antibodies.

Evaluation of amino-phosphine compounds as antioxidants and antifatigue agents in NR and SBR vulcanizates

Amino-phosphine derivatives such as tri (di-phenyl amino) phosphine and tri (di-cymyl-di-phenyl amino) phosphine were prepared. These compounds were incorporated into natural rubber (NR) and styrene–butadiene rubber (SBR) mixes. The rheometric characteristics of the green rubber mixes were determined using the oscillating disc rheometer. The prepared compounds were evaluated as antifatigue and antioxidant agents in NR and SBR vulcanizates. It was found from the obtained results that the investigated compounds are good antioxidant and antifatigue agents and their efficiencies are better than that obtained from phenyl-β-naphthyl amine, which is used widely in the rubber industry.

Hole Mobility of Fluorene-Based Dyes

Four fluorene-based dyes were newly prepared and they were demonstrated to possess excellent hole-transporting capability from the conventional time-of-flight measurement. In particular, a fluorene-based dye with diphenylamino groups exhibited high mobility of 1.8 × 10−3 cm2V−1s−1, which is about twice that of typical hole conductor N,N′-diphenyl-N,N′-(m-tolyl)-benzidine (TPD), in vacuum-deposited film

Two-photon absorption of styryl-quinolinium, -pyridinium, and -barbituric acid derivatives, and intramolecular charge transfer

A series of new chromophores, styryl-parent end-capped with various donors, and with barbituric acid, methyl-pyridinium, and methyl-quinolinium as the acceptors, have been synthesized and characterized by element analysis or X-ray diffraction. Using the Z-scan system, their two-photon absorption (TPA) cross-section values (δ) have been determined under excitation with 10 Hz, and 1064 nm, 35 ps mode-locked Nd:YAG laser pulse in DMF with do= 0.05 M. The effective δ value is as high as 10.9 × 10–48 cm4 s per photon for trans-4-(4'-N,N-diphenyl amino) styryl-N-methyl quinolinium iodide (DPASQI). The δ value increases from barbituric acid- to pyridinium- to quinolinium-derivatives apparently due to the increase in both the conjugated degree and planarity; however, when the acceptor is fixed, the δ value increases from dialkyl amino groups to diphenyl amino groups even though the latter is a weaker donor than the dialkyl amino groups. Theoretical calculations confirm that the increased distortion from planarity for the barbituric acid derivative makes its δ value decrease. The relatively large δ value for quinolinium- or pyridinium-derivatives originates from larger intramolecular charge transfer, which can be characterized by the difference of dipole moment (Δµge) between the S0 and S1, and the transition dipole moment (Mee') between S1 and S2.Key words: two-photon absorption, intramolecular charge transfer, styryl-quinolinium, styryl-pyridinium, styryl-barbituric acid.

Novel red organic electroluminescent materials including perylene moiety

We have reported organic electroluminescent (EL) materials with functionally separated molecular structure, which are composed of a luminescent center such as a fused aromatic ring and charge transfer units such as styryl-substituted diphenyl amino groups. This structure is a key to the design of light-emitting materials with controllable EL characteristics. Thus, we have already reported that a naphthalene moiety designed as a luminescent center with styryl-substituted diphenylamino groups as charge transfer unit gives blue light emission with high efficiency [A. Oda, E. Hasegawa, Mol. Electron. Bioelectron. 10 (1999) 12 (in Japanese)]. In this report, we describe the application of a perylene moiety to this structure to obtain red-light-emitting materials. Triple-layered EL devices using five perylene compounds with or without a styryl substituent on diphenylamino groups have a maximum brightness of 4800 to 8700 cd/m 2. In the case of styryl-substituted compounds, the devices have orange to reddish-orange emission with peaks at about 580 nm and shoulders at about 620 nm. Due to the shoulders at longer wavelength side of peaks, the CIE coordinate of the emission of a device shifts to (0.64, 0.35), which is almost the same as that of the red color of CRT. Thus, our molecular design method is proved to be useful for controlling color emission from blue to red. On the other hand, devices using compounds without a styryl substituent have yellowish-green to yellow emission and peaks at about 560 nm. We examined the effects of the substitution on the end of the charge transfer unit. The current density vs. applied voltage characteristics of the devices are affected by methyl substitution on styryl groups. The efficiencies are almost independent of the current density in the devices with styryl-substituted compounds, but rapidly decrease in the case of compounds without a styryl substituent.

Self-quenching in the stepwise photocyclization of 1,4-bis(diphenylamino)butane to 1,4-dicarbazolylbutane

The quantum yields of stepwise cyclization of the first and second diphenylamino groups in 1,4-bis(diphenylamino)butane are 0.3 and 0.02, respectively, which indicates quenching of the excited diphenylamino group by a carbazole unit in the asymmetric semi-cyclized compound.

Two-photon absorption and broadband optical limiting with bis-donor stilbenes

Large two-photon absorptivities are reported for symmetrical bis-donor stilbene derivatives with dialkylamino or diphenylamino groups. These molecules exhibit strong optical limiting of nanosecond pulses over a broad spectral range in the visible. Relative to bis(di-n-butylamino)stilbene, bis(diphenylamino)stilbene exhibits a 90-nm red shift of its optical limiting band but only a minimal shift of ~13 nm of its lowest one-photon electronic absorption band. Mixtures of these compounds offer an unprecedented combination of broad optical limiting bandwidth and high linear transparency.

Spectrophotometric Determination of Ephedrin Hydrochloride

Ephedrin hydrochloride reacts with sodium diphenyl amino sulfonate and potassium periodate to give a yellowish red colour having maximum absorbance at 470 nm. The reaction is selective for ephedrin with 1 μg/ml as visual limit of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer's Law from 0.001 to 0.3 mg/ml of ephedrin. The standard deviation does not exceed 0.050 mg/ml. The method is successfully applied to pure and pharmaceutical preparations of ephedrin. The quantitative assessment of tolerable amounts of other drugs is also studied.

Synthesis and crystal structure of [Li(THF) 4][( tBuCp)Yb(NPh 2) 3

The title complex [Li(THF) 4][ t BuCp)Yb(NPh 2) 3] was synthesized by the reaction of t-butylcyclopentadienyl ytterbium dichloride with 2 equivalents of LiNPh 2 in THF, hexane, and toluene at -78°C. The complex was characterized by elemental analysis, infrared and 1H-NMR spectroscopy. In addition, its crystal structure was determined by X-ray diffraction. The complex consists of isolated ion pairs [Li(THF) 4] + and [( t BuCp)Yb(NPh 2) 3] −. In the anion, the central metal Yb is surrounded by one t-butylcyclopentadienyl and three diphenylamino groups to form a distorted tetrahedron with the average bond length Yb N 2.264(9)A˚.

Crystal and molecular structure of 1-(4-nitrophenyl)-3,5,5-triphenylformazan

1. It has been established by X-ray structural analysis that the highly polar form of 1-(4-nitrophenyl)-3,5,5-triphenylformazan has the structure of the E1,2, E2,3, E3,3-isomer. 2. The specificity of the electronic and spatial structure of this isomer (acceptor NO2 and donor PhN group linked by a fairly planar system of conjugation) permits its high dipole moment to be explained by intramolecular charge transfer. 3. Conjugation plays a fundamental role in the determination of the conformation of sterically hindered hydrazones. 4. The conformation of the diphenylamino group in compounds of various classes is due both to intramolecular factors and to the nature of the packing in the crystal.

Stereospecific polymerization of methacrylonitrile. IV. Polymerization by ate complex‐type catalysts

AbstractMethacrylonitrile was polymerized by a number of ate‐complex catalysts. The catalysts used were NaAlR4, LiAlR4, LiZnR3, Li2ZnR4, RMg[AlR4], and Mg[AlR4]2. It was found that the ate‐complex catalysts in which one of the alkyls is replaced by a diphenylamino group are capable of producing polymers with higher degrees of crystallinity than those of polymers obtained by unmodified catalysts. It was shown that the diphenylamide linkage in these catalytic systems must play an important role in the steric control in the propagation steps of this type of polymerization, although the mechanism is not clear at present. The crystallinity index used in this research gave a linear relation against I measured by NMR, and can be used as a measure of the stereo‐regularity of the polymer.

Diphenylamino Radical Dimer as a Color Center in a Molecular Crystal

Radical pairs of diphenylamino (DPA) can be formed in a single crystal of tetraphyenylhydrazine (TPH) by uv photolysis. The structure of these radical dimers can be elucidated by ESR measurements. These studies show that eight configurationally different dimers occur, which fall into two classes with 3- and 4-Å separation, respectively. Optical measurements reveal long-wavelength charge resonance absorptions arising from the dimers; this interpretation is supported by polarization measurements. Temperature-dependent ESR measurements were used to determine the singlet–triplet splittings of the two spin systems, yielding about 130 and 40 cm−1 for the 3- and 4-Å dimers, respectively. The radical dimer crystal defect can be regarded as a color center in a molecular crystal.

The diphenyl-amino radical dimer

E.S.R. measurements on the photodissociation-products of tetraphenyl-hydrazine in rigid solution at 77°K indicate that the principal product of this dissociation is the dimer of the diphenyl amino radical. This assignment is confirmed by a measurement of a half-field signal and computer simulation of the E.S.R. spectra in rigid solution. A long wavelength charge-transfer band arises through the interaction of the two diphenyl amino radicals. An SCMO calculation is presented, which gives a theoretical background to the latter assignment.

Reaction of Thiols with Tetraphenylhydrazine

SOME years ago, Wieland first reported that tetraphenylhydrazine (TPH) was unstable in solution and dissociated into diphenyl amino radicals1. The presence of the radicals has been confirmed by the rapid reaction: of solutions of TPH with nitric oxide to produce diphenylnitrosamine. The ready formation of radicals from TPH at low temperatures suggested that diphenyl amino radicals could be used as initiators for free radical reactions. In this regard, we have investigated the products resulting from the reaction of various thiols with TPH.