Abdul W. Allaf

Fullerene-60 thin films for electronic applications

AbstractC thin films were prepared using sublimation technique. The films were deposited on a wide range of substrates such as KCl, 60 microscopic glasses and semiconductors. Sequential optical and electrical measurements were carried out on these films. Electronicdevices such as rectifying electronic diodes, photo-diodes and solar cells, comprising C films in their structures, were manufactured. 60 These devices show very stable and reproducible performances and give very encouraging indications for future electronic applications.q1999 Elsevier Science S.A. All rights reserved. Keywords: C ; Fullerenes; Thin films; Optical; Electronics devices; Solar cells 60 1. IntroductionFollowing the discovery of C 1 and the subsequentwx 60 developments, to produce purified bulky materials of C 60 wx2 , many interesting researches to discover the physical,optical, chemical and electronic properties of the materialwere carried out 3,4 . Currently, electronic properties iswxconsidered to be one of the most technologically interest-ing applications of bulky C . It is found that, the com-

The gas-phase on-line production of vanadium oxytrihalides, VOX3 and their identification by infrared spectroscopy

A new route has been devised, leading to the production of VOX3 molecules where X=F, Br and I by an on-line process using vanadium oxytrichloride, VOCl3 as a starting compound passed over the following heated salts NaF, KBr and KI at 375, 700 and 550 degrees C, respectively. The products have been characterized by the IR spectra of their vapors. The low resolution gas phase on-line Fourier transform infrared spectra reported for the first time show strong bands with PQR type structure, centered at 1058, 1035, 1030 and 1025 cm(-1) assigned to the v1(a1), the O=V stretching fundamental mode of VOF3, VOCl3 VOBr3 and VOI3, respectively.

Thionitrosyl cyanide (NCNS)

Abstract Thionitrosyl cyanide and its radical-cation have been generated for the first time by dissociative ionization of 1,2,5-thiadiazolo [3,4-c](1,2,5)-thiadiazole and characterized by collisional activation (CA) and neutralization-reionization (NR) mass spectrometry. Both neutral and ionized forms are stable species and do not undergo unimolecular rearrangement under the experiment conditions. The NCNS molecule is further characterized by ab initio molecular orbital calculations using various levels of theory up to QCISD(T)/6-311++G(3df,2p) based on MP2/6-311 ++G(d,p) geometries. The stability ordering of the four possible [C, N 2 , S] isomers is (kcal mol −1 ): NCNS 1 (0) > NCSN 2 (14) > CNSN 4 (25) > CNNS 3 (34) > CN + NS (73). The classical energy barrier for the 1,2-migration of the cyano and thionitrosyl groups connecting 1 with 2 and 1 with 3 amount to 80 and 83 kcal mol −1 , respectively, values being larger than the dissociation energy. The geometry and rotational constants of NCNS were predicted using calculations and empirical corrections based on available data on similar molecules; A = 51.986 ± 0.7 GHz, B = 3.521 ± 0.1 GHz, C = 3.298 ± 0.1 GHz. Vibrational wavenumbers of both NCNS and NCSN isomers were computed using QCISD/6-311G(d) wavefunctions. The protonation of thionitrosyl cyanide occurs preferentially at the cyano-nitrogen with a proton affinity PA (NCNS) = 178 ± 3 kcal mol −1 . Several molecular properties of NCNS have also been computed. Mass spectrometric experiments confirm that the product of the reaction NSCl + AgCN → AgCl + [ C , N 2 , S ] is the isomeric thiazyl cyanide (NCSN).

Gas-phase generation and infrared spectroscopy of metastable OP-SCN molecule

An attempt has been made to generate the metastable phosphorus (III) oxythiocyanide molecule, OP-SCN for the first time by an on-line process using the vapor flow of phosphorus (III) oxychloride, OPCl passed over heated AgSCN at 520 degrees C. The products have been characterized by their IR spectra; values for v1 of 2055 cm(-1) (C[triple bond]N stretch), v2 of 1365 cm(-1) (O=P stretch), v3 of 720 cm(-1) (C-S stretch) and v7 of 680 cm(-1) (P-S stretch) have been obtained.

GAS-PHASE INFRARED SPECTRA OF PHOSPHORUS (III) OXYHALIDE : EXPERIMENTAL AND THEORETICAL STUDY OF OPF AND OPCL

Abstract Phosphorus (III) oxyhalide OP–X molecules (X=F, Cl) are produced by an on-line process of POCl 3 passed over heated silver. The obtained OPCl reacts with sodium fluoride NaF to produce OPF. The low resolution gas-phase Fourier transform infrared spectra, reported for the first time, show four strong bands centered at 1357.2, 1272.8, 821.5 and 491.6 cm −1 . The first two bands refer to the OP stretching of OPF and OPCl, respectively. The other two are referring to the P–X stretching mode for X=F and Cl, respectively. Ab initio self-consistent-field (SCF) molecular orbital (MO) and Moller–Plesset second-order perturbation theory (MP2) calculations were performed to determine the geometry, total energy and vibrational frequency of OPF and OPCl.

Gas-phase infrared spectra and ab initio study of phosphorus(III) oxyhalides OPBr and OPI

Abstract Phosphorus(III) oxyhalide OP–X molecules (X=Br, I) were produced by an on-line process. Two routes have been followed to generate OPBr. The obtained OPBr was passed over heated KI to produce OPI. The low-resolution gas-phase Fourier transform infrared spectra, reported here for the first time, show three bands centered at 1268.1, 1253 and 408.2 cm −1 . The first two bands are associated with the OP fundamental stretching mode of OPBr and OPI, respectively. The third band is connected to the P–Br stretching mode of OPBr. Ab initio Hartree–Fock (HF) self-consistent-field (SCF) molecular orbital (MO) calculations and Moller–Plesset second-order perturbation theory (MP2) were performed to determine the geometry, total energy and vibrational frequencies of OPBr and OPI.

Optical nonlinearities of tetracarbonyl-chromium triphenyl phosphine complex

The new tetracarbonyl — chromium-triphenyl phosphine complex was synthesized and characterized using ultraviolet (UV)–visible, Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) techniques. The characterization results confirm the molecular structure of the new complex. The z-scan measurements were done by diode laser [continuous wave (CW)] to estimate the nonlinear optical parameter (χ 3). The results led to calculate three parameters: the ground-state cross sections (), the excited-state cross sections (), and thermo–optic coefficient of the new complex. This study indicated that our complex is a suitable for photonic applications.

The gas-phase on-line formation of antimony oxide trihalides, SbOX3 where X = F and Cl and their identifications by infrared spectroscopy.

Antimony oxide trihalides, SbOX3 molecules, where X = F or Cl have been produced, by means of an on-line process, using antimony trichloride, SbOCl3 as starting material passed over heated silver oxide at 230 degrees C. The antimony oxide trichloride SbOCl3 formed is then reacted with sodium fluoride, NaF at 550 degrees C to produce antimony oxide trifluoride, SbOF3. The products have been characterized by the IR spectra of their vapors. Low resolution gas-phase Fourier transform infrared spectra show strong bands centered at 1272 and 1217 cm(-1), assigned to nu1(a1), the O=Sb stretching fundamental of SbOF3 and SbOCl3, respectively. Both observed bands show typical PQR-type structure with a strong Q-head.

The gas-phase on-line production of phosphorus thiotrihalides, SPX3 and their identification by infrared spectroscopy

A new route has been devised, leading to the production of phosphorus thiotrihalides, SPX3 where X = F, Br and I by an on-line process using phosphorus thiotrichloride, SPCl3 as starting compound gassed over the following heated salts NaF, KBr and KI at 530, 800 and 440 degrees C, respectively. The products have been characterized by their IR spectra, showing bands with PQR type structure, centered at 985, 762, 744 and 715 cm(-1). These bands are assigned to v1(a1), the S=P stretching fundamental modes of SPF3, SPCl3, SPBr3 and SPI3, respectively.

Isolation, Structural characterization, and antiproliferative activity of phycocolloids from the red seaweed Laurencia papillosa on MCF-7 human breast cancer cells

Hydrocolloids from seaweeds (phycocolloids) have interesting functional properties like antiproliferative activity. Marine algae consumptions are linked to law cancer incidences in countries that traditionally consume marine products. In this study, we have investigated water-soluble sulfated polysaccharides isolated from the red seaweed Laurencia papillosa and determined their chemical characteristics and biological activities on the human breast cancer cell line MCF-7. Total polysaccharides were extracted and fractionated from L. papillosa and characterized using FTIR-ATR and NMR spectrometry. In addition, their approximate molar mass was determined by GPC method. The chemical characterization of purified polysaccharides reveals the presence of sulfated polysaccharides differentially dispersed in the algal cell wall. They are the three types of carrageenan, kappa, iota and lambda carrageenans, named LP-W1, -W2 and -W3 respectively. Biological effects and cytotoxicity of the identified of the three sulfated polysaccharide fractions were evaluated in MCF-7 cell line. Our results showed a significant inhibition of MCF-7 cell viability by dose-dependent manner for cells exposed to LP-W2 and LP-W3 polysaccharides for 24h. The mechanistic of LP fractions-mediated apoptosis in MCF-7 cells was demonstrated. The biological effects of L. papillosa SPs indicate that it may be a promising candidate for breast cancer prevention and therapy.