A novel regiospecific cascade synthesis of sulfonamide derivatives from <Emphasis Type="Italic">N</Emphasis>-(2-polychloroethyl)sulfonamides via chloroaziridine intermediates in the presence of mercaptoethanol

N-(1-Aryl-2-polychloroethyl)arenesulfonamides obtained on the basis of N,N-dichlorosulfoamides and polychloroethenes or phenylacetylene undergo a reaction cascade in the presence of mercaptoethanol. The reaction cascade opens a new route to the series of cyclic or open-chain sulfonamide derivatives. The process includes cyclization to aziridine intermediates, their further recyclization, and isomerization to imidoylchlorides or chloroimines, followed by substitution or reduction under the action of mercaptoethanol or hydrolysis. The final sulfonamide structures depend on the starting N-(polychloroethyl)sulfonamides. N-(2,2-Dichloroethyl)sulfonamides were transformed into sulfonamide-containing 1,4-oxathians while N-(2,2,2-trichloroethyl)sulfonamides were converted to N-(2-arylacetyl)arenesulfonamides. N-(2-Phenyl-2,2-dichloroethyl)sulfonamides form enamide derivatives that were transformed into aromatic ketones.     

Infrared Quantitative Study of Acetylation of Microspheres of Polystyrene

Abstract

Fourier transform infrared spectroscopy has been used to study quantitatively the acetylation of monodisperse polystyrene microspheres with diameters ranging from 7 to 9μm. The CH₂ stretching infrared vibration mode at 2921 cm^?1 was used as the internal intensity standard. The acetylation extent could be easily measured by comparing the relative intensities of the bands of acetyl group (1678, 1415, 1359 cm^?1) or the bands due to the para-substituted benzene ring to the band at 2921 cm^?1 from the calibration curve.     

Crystal structure of ethyl (2Z)-2-(3-methoxy-4-acetyloxy benzylidene)-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate

The title compound, C₂₆H₂₄N₂O₆S, (I), crystallizes in the monoclinic space group, P2₁/c, with cell parameters a = 16.248(1), b = 7.927(1), c = 19.371(4) ?, β = 105.295(2)°, Z = 4. The central pyrimidine ring in the compound (I) is significantly puckered, assuming a screw-boat conformation. The C11–C16 benzene ring stands vertical while thiazole and C18–C23 benzene rings are coplanar to the mean plane of pyrimidine ring having dihedral angles of 87.48(12), 3.63(11) and 0.94(12)°, respectively. In the absence of potential hydrogen bonding interaction, the crystal packing is influenced by intramolecular C-H…S interaction and intermolecular C-H…π interactions.     

Fabrication of blue top-emitting organic light-emitting devices with highly saturated color

Blue top-emitting organic light-emitting devices (TOLEDs) with highly saturated color were developed by microcavity effect. The device structure studied was glass/reflective silver/indium-tin oxide (ITO)/organic electroluminescent stack/semi-transparent cathode (calcium/silver). By changing the thicknesses of ITO and organic layers in the microcavity structure device doped with p-bis(p-N, N-di-phenyl-aminostyryl)benzene (DSA-ph), highly saturated color with Commission Internationale de L'Eclairage chromaticity coordinates (CIE_x,y) of (0.14, 0.08) was obtained.     

Synthesis and Luminescent Properties of Lanthanide Complexes with a Novel Multipodal Ligand

Solid complexes of lanthanide nitrates, picrates and perchlorates with a novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2′-benzylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu and Tb complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level T₁ of this ligand matches better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the counter anion on the luminescent intensity was also discussed.     

Saturation recovery electron spin–lattice relaxation studies on benzene anion radical and its derivatives: application of Kivelson–Orbach mechanism of electron spin relaxation

The role of low-lying excited states on the spin–lattice relaxation times (T₁) of organic radicals has been investigated. To test the applicability of Kivelson's electric field fluctuation model (D. Kivelson, J. Chem. Phys. 45, 1324 (1966)), based on the Orbach mechanism of spin relaxation, the T₁s of the anion radicals of benzene, benzene-1-d, toluene, ethyl benzene, isopropyl benzene, t-butyl benzene, p-xylene, 1,2,4-trimethyl benzene and 1,3,5-trimethyl benzene in liquid solutions, with potassium cation as the counter ion, have been measured by the pulse saturation recovery technique. The energy gap between the ground and the first excited electronic states changed with the substitutions to different extent. The spin–lattice relaxation rates showed correlation with this energy gap. Anion radicals of benzene and benzene-1-d showed the shortest T₁ among the radicals studied here. A small but measurable energy splitting due to the deuterium substitution in benzene-1-d radical was obtained from the temperature dependence of T₁. Spin–lattice relaxation times of benzene anion measured here decreased monotonically in the range of ?60 to ?125 °C, in contrast to some reported claims of very unusual temperature dependence, based on the continuous wave microwave power saturation studies. Our results also showed that the ion pairing between benzene anion and potassium cation did not significantly influence the spin–lattice relaxation times.     

THE SYNTHESIS AND SPECTRAL CHARACTERIZATION OF NEW Cu(II), Ni(II), Co(III), AND Zn(II) COMPLEXES WITH SCHIFF BASE

ABSTRACT

Cu(II), Ni(II), Co(III) and Zn(II) complexes with Schiff base have been prepared. Ligand is derived from condensation of 1,2-bis(p>-aminophenoxy)ethane and 2- hydroxynaphthalin-1-carbaldehyde. The complexes have been characterized by elemental analyses, Λ_M, IR, UV-VIS, ¹H NMR, ¹³C NMR and magnetic measurements. The ligand is coordinated to the central metal as a tetradentade ONNO ligand. The four bonding sites are the azomethine nitrogen and aldehydic -OH groups.     

Evidences for charge‐transfer complex formation in the benzene adsorption on sulfated TiO2–a resonance Raman spectroscopy investigation

Benzene adsorbed on highly acidic sulfated TiO₂ (S‐TiO₂) shows an intriguing resonance Raman (RR) effect, with excitation in the blue‐violet region. There are very interesting spectral features: the preferential enhancement of the e_2g mode (1595 cm⁻¹) in relation to the a_1g mode (ring‐breathing mode at 995 cm⁻¹) and the appearance of bands at 1565 and 1514 cm⁻¹. The band at 1565 cm⁻¹ is probably one of the components of the e_2g split band, originally a doubly degenerate mode (8a, 8b) in neat benzene, and the band at 1514 cm⁻¹ is assigned to the 19a mode, an inactive mode in neat benzene. These facts indicate a lowering of symmetry in adsorbed benzene, which may be caused by a strong interaction between S‐TiO₂ and the benzene molecule with formation of a benzene to Ti (IV) charge transfer (CT) complex or by the formation of a benzene radical cation species. However, the RR spectra of the adsorbed benzene cannot be assigned to the benzene radical cation because the observed wavenumber of the ring‐breathing mode does not have the value expected for this species. Moreover, it was found by ESR measurements that the amount of radicals was very low, and so it was concluded that a CT complex is the species that originates the RR spectra. The most favorable intensification of the band at 1595 cm⁻¹ in the RR spectra of benzene/S‐TiO₂ at higher excitation energy corroborates this hypothesis, as an absorption band in this energy range, assigned to a CT transition, is observed. Copyright © 2008 John Wiley & Sons, Ltd.     

Substituent effect study on 13Cβ SCS of styrene series. A Yukawa–Tsuno model and Reynolds dual substituent parameter model investigation

The Yukawa–Tsuno (Y–T) and Reynolds dual substituent parameter (DSP) models have been used to model ¹³C substituent chemical shift (SCS) of the C_β atom of 19 series of para‐substituted styrenes (X‐C₆H₄CR?CYW) with variable electronic and structural demands in the side‐chain. The best fit of the Y–T model was better than that of the Reynolds DSP model for most of the studied series. A high correlation was found between the ρ value of the Y–T model and ρ_F value of the Reynolds DSP model. The ρ value, which reflects the sensitivity of ¹³C_β SCS to the substituent field effect, was found to be influenced by the group W on the C_β atom. A W group that enhances the para‐substituent π‐polarization of the side‐chain has a higher ρ value than its counterpart W groups that induce counter π‐polarization in the side‐chain. The series with W in an E‐configuration to the aryl ring has higher ρ value than corresponding Z series. A lower ρ value is observed when W induces a counter π‐polarization of the side‐chain (as with NO₂ and COMe) or when the R substituent imposes a 65° dihedral angle between the side‐chain and the para‐substituted benzene ring (as with t‐Bu). When the W group is a heterocyclic ring, the closer the heteroatom is to C_β, the lower the ρ value is due to the greater counter π‐polarization. The two components of the substituent effect on ¹³C _β SCS, namely the field effect and resonance effect, behave inversely. The resonance demand (r⁺ value) increases, as the Y and/or W groups become more electron‐withdrawing (EW). The series with W as a hetrocyclic ring develop negative charge at the carbon atom of the hetrocyclic ring adjacent to C_β (and to which the styryl moiety is attached) and has a lower r⁺ value than those which fail to do so. The lowest r⁺ value was for those series with a 65° dihedral angle. Copyright © 2007 John Wiley & Sons, Ltd.     

Time‐resolved resonance Raman and density functional theory study of the photochemistry of 4‐benzoylpyridine in acetonitrile and 2‐propanol

A nanosecond time‐resolved resonance Raman (ns‐TR³) spectroscopic investigation of the intermolecular hydrogen‐abstraction reaction of the triplet state of 4‐benzoylpyridine (4‐BPy) in 2‐propanol solvent is reported. The TR³ results reveal a rapid hydrogen abstraction (<10 ns) by the 4‐BPy triplet state (nπ*) with the 2‐propanol solvent, leading to formation of a 4‐BPy ketyl radical and an associated dimethyl ketyl radical partner from the solvent. The recombination of these two radical species occurs with a time constant about 200 ns to produce a para‐N‐LAT (light absorbing transient). The structure, major spectral features, and identification of the ketyl radical and the para‐N‐LAT coupling complex have been determined and confirmed by comparison of the TR³ results with results from density functional theory (DFT) calculations. A reaction pathway for the photolysis of 4‐BPy in 2‐propanol deduced from the TR³ results is also presented. The electron‐withdrawing effect of the heterocyclic nitrogen for 4‐BPy on the triplet state makes it have a significantly higher chemical reactivity for the hydrogen abstraction with 2‐propanol compared to the previously reported corresponding benzophenone triplet reaction under similar reaction conditions. In addition, the 4‐BPy ketyl radical reacts with the dimethyl ketyl radical to attach at the para‐N atom position of the pyridine ring to form a cross‐coupling product such as 2‐[4‐(hydroxy‐phenyl‐methylene)‐4h‐pyridin‐1‐yl]‐propan‐2‐ol instead of attacking at the para‐C atom position as was observed for the corresponding benzophenone reaction reported in an earlier study. Copyright © 2008 John Wiley & Sons, Ltd.     

Molecular structure of nitrophenyl O‐glycosides in relation to their redox potentials

The effect of the non‐electroactive groups on the redox potentials of the active centres of 26 nitrophenyl O‐glycosides possessing various substituents has been studied electrochemically using cyclic voltammetry. The potentials of both redox processes, a two‐electron quasi‐reversible R‐NHOH/R‐NO (E_f) and four‐electron irreversible R‐NO₂/R‐NHOH (E_pc(I)) systems, have been determined and compared for all the compounds under investigations. The nitrophenyl O‐glycosides were chosen as model compounds as they significantly vary in many aspects of their structure such as: (i) the isomeric substitution of nitro group in benzene ring to the sugar moiety (ortho, meta and para isomers); (ii) the size of sugar moieties (the derivatives of mono‐ and disaccharides); (iii) the presence and absence of additional groups in saccharidic fragments (e.g. pentose and hexose); (iv) functionalisation of hydroxyl groups (free or acetylated hydroxyl groups) and (v) absolute configurations of selected sugar carbon atoms (e.g. the pairs of anomers). Among other effects, a significant variation in the increasing order of the two‐electron quasi‐reversible (E_f, ortho > meta > para) and four‐electron irreversible (E_pc(I), meta > ortho > para) redox processes has been found and explained taking into account the negative inductive effect (–I) caused by the glycosidic oxygen atom that facilitates the electroreduction of the nitro group, and the positive mesomeric effect (+M) which makes the electroreduction more difficult. Copyright © 2010 John Wiley & Sons, Ltd.     

Functionalized perylenes: origin of the enhanced electrical performances

In this letter we compare the transistor performances of two solution-processed perylene derivatives: N,N′-bis (n-octyl)- dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI8-CN₂) and N,N′-1H,1H-perfluorobutyl dicyanoperylenediimide (PDIF-CN₂). Perylenediimide nitrogen functionalization with perfluoroalkyl vs. alkyl chains improves the electron mobility of solution-processed organic field effect transistors (OFETs) by one order of magnitude. Time resolved spectroscopy allows attributing this increment to a higher degree of co-facial arrangement of the fluorinated molecules. This supramolecular arrangement enhances the π–π overlap leading to more efficient electron transport.     

The basicity of sulfonamides and carboxamides. Theoretical and experimental analysis and effect of fluorinated substituent

The basicity of a series of sulfonamides and carboxamides with respect to protonation and hydrogen‐bonded complex formation with phenol was investigated by calculations using the Becke three‐parameter hybrid functional combined with Lee–Yang–Parr correlation functional with the 6‐311G** and 6‐311++G** basis sets and by infrared spectroscopy. The effect of fluorinated substituent was studied for the two series. The proton affinity of nitrogen in sulfonamides is higher than oxygen, in contrast to carboxamides, which are protonated at oxygen. The phenyl group in benzenesulfonamide increases the basicity of both heteroatoms, but more strongly of the nitrogen, whereas in benzamide the effect on the two heteroatoms is about the same. The CF₃ group equally decreases the basicity of nitrogen and oxygen atoms in sulfonamides and carboxamides. The second fluorinated substituent decreases the basicity of oxygen in (CF₃CO)₂NH more strongly than of nitrogen. For sulfonamides, the same effect results in the reverse of the center of basicity from nitrogen in (MeSO₂)₂NH to oxygen in (CF₃SO₂)₂NH. All studied carboxamides give H‐complexes via the carbonyl oxygen, whereas for sulfonamides two types of H‐complexes, with the OH···N and OH···O=S, were found theoretically, the latter being more stable. The exception is bisimide (CF₃SO₂)₂NH, for which only the OH···O=S complex is stable. Experimentally, only the oxygen‐bound complexes are observed. Analysis of the natural charges revealed an ‘abnormal’ increase of the electron density on the NH group by electron‐acceptor substituents in CF₃SO₂NHR, which was explained using the natural bond orbital analysis by loosening of the S–N bond because of orbital interactions with the σ*_S?N orbital. Copyright © 2012 John Wiley & Sons, Ltd.     

Bichromophoric behavior of nitrophenyl‐triazene anions: a resonance Raman spectroscopy investigation

Highly delocalized molecular frameworks with intense charge transfer transitions, known as push‐pull systems, are of central interest in many areas of chemistry, as is the case of nitrophenyl‐triazene derivatives. The 1,3‐bis(2‐nitrophenyl)triazene and 1,3‐bis(4‐nitrophenyl)triazene were investigated by electronic (UV‐Vis) and resonance Raman (RR) spectroscopies. The bichromophoric behavior of 1,3‐bis(4‐nitrophenyl)triazene anion opens the possibility of tuning with visible radiation, two distinct electronic states. The RR profiles of nitrophenyl‐triazene derivatives clearly show that the first allowed electronic state can be assigned to a charge transfer from the ring π system to the NO₂ moiety (ca 520 nm), while the second, as a charge transfer from N₃⁻ to the aromatic ring (ca 390 nm). In the para‐substituted derivative, a more efficient electron transfer and a greater energy separation between the two excited states are observed. Copyright © 2008 John Wiley & Sons, Ltd.     

13C-NMR Spectroscopy of para-Substituted Benzylideneacetones.: I. Long Distance Electronic Effects

para-benzylideneacetones present a characteristic long distance charge transfer pattern, where the olefinic bridge (CH=CH) and the aromatic ring (Ph) carbon centers are perturbed according to the nature of the para-substituent groups.

By means of ¹³C-NMR spectroscopy and AMl molecular orbital calculations we have found that in this molecular series the chemical shifts (Δ) and the charge densities (qAMI) corresponding to the C₃, C₁ and C_β centers follow a functional dependence of the type: Δ = a qAMl + Δ°, while C₂, C_α and C_CO are practically constants.

On the other hand, after a complete spectral assignment of the ¹³C-NMR signals, an analysis of the electron-donor substituent effect at the para-position of the aromatic carbonyl compounds on the C₄ center, has permitted us to find a good correlation between the C₄ spectral shift and the electronegativity of this vicinal center.     

pH‐dependent surface‐enhanced Raman scattering observation of sulfanilamide on the silver surface

Monolayers of sulfanilamide on metallic surface can serve as an ideal model for understanding the interaction mechanism between the metal and the sulfanilamide molecule. In the present paper, the surface‐enhanced Raman scattering (SERS) technique was employed to obtain the SERS spectra of sulfanilamide monolayers formed on the silver surface under different pH values. Assignments of the spectra were carried out with the aid of density functional theory (DFT) calculations (BLYP/6‐311G). It can be found that the adsorption function of sulfanilamide on the silver surface was influenced by the pH value. The fully protonated sulfanilamide molecule adsorbed on the silver surface through N¹³H₂ group and the benzene ring anchored in a relatively perpendicular manner leading to N⁷H₂ and S¹⁰O₂ groups near the surface, while the completely deprotonated sulfanilamide molecule attached on the silver surface via N⁷H₂ and the benzene ring was perpendicular to, and the N¹³H₂ and S¹⁰O₂ groups were far from the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Paramagnetic susceptibility of additively colored CdF2:In photochromic crystals

The paramagnetic susceptibility K _para of CdF₂:In crystals with metastable indium centers has been measured in darkness after photobleaching the crystals in visible light in the temperature interval 4–300 K. For crystals cooled in darkness to liquid-helium temperature K _para is wholly determined by the accompanying impurity Mn²⁺ with magnetic moment J=5/2. Illumination of the crystals leads to the appearance of an induced signal δ K _para due to the formation of centers with J=1/2. The results of the experiments indicate the absence of paramagnetism in the deep state of the indium center and its existence in the shallow (donor) state, i.e., they confirm the two-electron (negative-U) nature of the deep indium level in CdF₂. Fiz. Tverd. Tela (St. Petersburg) 39, 1205–1209 (July 1997)     

The effect of fluorine substitutions on the refractive index properties for π-conjugated calamitic nematic materials

In order to reveal the effect of fluorine substitutions on the refractive index properties for calamitic nematic materials, we carried out a comparative study with respect to non-fluorinated and two types of laterally fluorinated 1,4-bis[4-(hexyloxy)phenyl]ethynylbenzene molecules. Phase transition behaviours were investigated by differential scanning calorimetry and polarised optical microscopy. Additionally, extraordinary and ordinary refractive index and birefringence were evaluated from each single component system. All the analogues exhibited high birefringence values beyond 0.3 at 550 nm, of which an analogue with a fluorine substitution at the central benzene ring showed the highest Δn-value of 0.43. With respect to an analogue with the highest level of fluorination, Δn as well as n_e and n_o values were declined due to decreased order parameter and diluted molecular density. Not only the mesomorphic behaviours but also optical properties strongly relied on the manner of fluorine substitution including the number and position.     

The Schiff Base Probe With J-aggregation Induced Emission for Selective Detection of Cu2+

Here, three Schiff bases 3a-c, differing by the substitutions (–H, –Cl, and –N(CH₃)₂) on the phenyl ring, have been designed and synthesized via the reaction of ortho-aminophenol with benzaldehyde, 2,4-dichlorobenzaldehyde and para-dimethylamine benzaldehyde in 1:1 molar ratio with favourable yields of 89–92%, respectively. Their structural characterizations were studied by FT-IR, NMR, MALDI-MS and elemental analysis. The fluorescence behaviours of compounds 3a and 3b exhibited a severe aggregation caused quenching (ACQ) effect in EtOH/water system. On the contrary, compound 3c had an obvious J-aggregation induced emission (AIE) feature in EtOH/water mixture (v/v?=?1:1), and exhibited excellent sensitivity and anti-interference towards Cu²⁺ with the limit of detection (LOD) of 1.35?×?10^–8 M. Job’s plot analysis and MS spectroscopic study revealed the 2:1 complexation of probe 3c and Cu²⁺. In addition, probe 3c was successfully applied to the determination of Cu²⁺ in real aqueous samples.

     

Synthesis and Luminescent Properties of Lanthanide Complexes with Structurally Related Novel Multipodal Ligands

To explore the relationship between the structure of the ligands and the luminescent properties of the lanthanide complexes, a series of lanthanide nitrate complexes with two novel structurally related multipodal ligands, 1,3-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^I ) and 1,2-bis{[(2’-(2-picolylaminoformyl))phenoxyl]methyl}benzene (L ^II ), have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Eu(III) and Tb(III) nitrate complexes in solid state and the Tb(III) nitrate complexes in solvents were investigated at room temperature. Under the excitation of UV light, these complexes exhibited characteristic emissions of central metal ions. The lowest triplet state energy levels T₁ of these ligands both match better to the lowest resonance energy level of Tb(III) than to Eu(III) ion. The influence of the structure of the ligands on the luminescent intensity of the complexes was also discussed.