New substituted 2,2'-dipyridines and their chelation as fe(ii) and cu(i) complex cations

A study has been made of three new substituted 2,2'-dipyridines, the 4,4'-diphcnyl- and diaminodipyridincs and 4,4',6,6'-tetramethyldipyridine. Comparison is made between their chelation properties as Fe(Il) and Cu(I) colored complexes with similarly substituted di- and tripyridines previously described.4,4'-Diphcnyl-2,2'-dipyridinc forms a ferrous complex of exceptionally large molar absorbtivity (21300), and which has two widely separated absorption maxima (386 and 552 mμ) and equal sensitivity at both absorption peaks. The Cu(I) complex is very sensitive to oxidation in contact with air.4,4'-Diamino-2,2'-dipyridinc is noteworthy because of its ability to reduce Fe(IIl) to Fe(II).     

Dosage spectrophotométrique du molybdène par l'o-phénanthroline

Under certain conditions, o-phenanthroline and its derivatives, as well as 2,2',2′-terpyridyl, form relatively unstable red complexes with molybdenum(Vl) in presence of molybdenum(V). o-Phenanthroline is most sensitive, the molecular extinction coefficient being 6,290 at the absorption maximum (508 mμ). Beer's law is valid for the range 2–9 μg Mo/ml.     

Some metallofluorescent derivatives of 2,2'-diamino-diphenyl-n,n,n',n'-tetraacetic acid

The N,N,N',N'-tetraacetic acid derivatives of five 4,4'-disubstituted 2,2'-diaminodiphenyls have been prepared and their fluorescent properties examined. 2,2'-Diaminodiphenyl-4,4'-dicarboxylic acid-N,N,N',N'-tetraacetic acid exhibits intense fluorescence in aqueous solution above pH 4, and forms stable non-fluorescent l:1 complexes with copper(II) and nickel(II) ions at pH 7.5. The quenching of the fluorescence of the compound by nickel(II) may be used in the fluorimetric determination of nickel.     

A new family of heteroleptic ruthenium(II) polypyridyl complexes for sensitization of nanocrystalline TiO2 films

Two new heteroleptic ruthenium(II) photosensitizers that contains 2,2';6,2'-terpyridine with extended π-conjugation with donor groups, a 4,4'-dicarboxylic acid-2,2'-bipyridine anchoring ligand and a thiocyanate ligand have been designed, synthesized and fully characterized by CHN, mass spectrometry, UV-vis and fluorescence spectroscopies and cyclic voltammetry. The new sensitizers have either 3,5-di-tert-butyl phenyl (m-BL-5) or triphenylamine (m-BL-6) groups, where the molar extinction coefficient of both the sensitizers is higher than the analogous ruthenium dyes. Both the sensitizers were tested in dye-sensitized solar cells using two different redox electrolytes.     

Solution-Processed Yellow Organic Light-Emitting Diodes Based on Two New Ionic Ir (III) Complexes

Two new and efficient cationic yellow-emissive Ir (III) complexes (Ir1 and Ir2) are rationally designed by using 2-(4-chloro-3-(trifluoromethyl)phenyl)-4-methylquinoline as the main ligand, and, respectively, 4,4′-dimethyl-2,2′-bipyridyl and 4,4′-dimethoxy-2,2′-bipyridyl as the ancillary ligands. Both complexes show enhanced phosphorescence (546 nm with 572 nm as shoulder and high phosphorescent quantum efficiency in solution, which is in favor of efficient solution-processed phosphorescent organic light-emitting diodes. Compared with Ir2, the Ir1-based device displays excellent device performance, with maximum external quantum efficiency, current efficiency, and power efficiency of up to 7.92%, 26.32 cd/A and 15.31 lm/W, respectively, thus proving that the two new ionic Ir (III) complexes exhibit great potential for future solution-processed electroluminescence.     

A new reagent for the spectrophotometric microdetermination of cadmium

2,2′-Dipyridyl-2-pyridylhydrazone (DPPH) allows a simple, rapid, and sensitive spectrophotometric microdetermination of cadmium in aqueous solution. The yellow 1:2 metal-to-ligand complex formed has a molecular extinction coefficient of 5.5 × 10⁴ liters mole^?1 cm^?1 at the absorption maximum of 444 nm. The determination of cadmium is carried out at pH 12.3 ± 0.2. Beer's law is obeyed over the concentration range of 0.2 to 2 ppm and the Sandell sensitivity of the color reaction is 0.002 μg of cadmium/cm² for an absorbance of 0.001.     

New fluorinated aromatic poly(ether-amide)s derived from 2,2′-bis(3,4,5-trifluorophenyl)-4,4′-diaminodiphenyl ether and various dicarboxylic acids

A new class of highly fluorinated aromatic poly(ether-amide)s was prepared through triphenyl phosphite-activated polycondensation of 2,2′-bis(3,4,5-trifluorophenyl)-4,4′-diaminodiphenyl ether (FPAPE) and four dicarboxylic acid comonomers. All the resulting polymers were thoroughly characterized by FT-IR, UV, and NMR spectroscopic methods. The effects of the fluorine atoms directly linked to the lateral phenyl rings as well as fluoro-containing phenyl groups attached to the macromolecular chains on some properties of the polymers were investigated by comparing with poly(ether-amide)s prepared from 4,4′-oxydianiline (4,4′-ODA) and 2,2′-diphenyl-4,4′-diaminodiphenyl ether (PAPE). The FPAPE-derived polymers exhibited excellent solubility in a variety of organic solvents. Results obtained from X-ray studies showed that the presence of the bulky fluoro-containing phenyl groups attached to the chains disrupts their structural order in a great amount, and leads to a decrease in crystallinity extent of the macromolecules. Furthermore, the highly fluorinated polymeric chains showed a significant enhancement in organo-solubility, heat-stability and T_g values when compared to their non-fluorinated counterparts.     

Dibenzyl Structuresin a Macromolecular Chain. III. Dibenzyldiisocyanates Reactivity

The reactivity of the 2,2′-, 2,4′-, 4,4′-dibenzyldiisocyanate (2,2′-, 2,4′-, 4,4′-DBDI) with n-butanol in benzene has been studied. The concentrations of all species were monitored by using high performance liquid chromatography (HPLC). The reactivity of 4,4′-DBDI is similar to that of 4,4′-diphenylmethanediisocyanate (4,4′-MDI). Very strong intramolecular catalytic effects were noticed in the case of 2,2′-DBDI, probably due to the variable molecular geometry. These effects are responsible for the whole reaction pattern. The 2,4′-DBDI NCO ortho and para groups reactivities are different and comparable to that of 2,4-toluylenediisocyanate (2,4-TDI).     

Phenomenally high molar extinction coefficient sensitizer with "donor-acceptor" ligands for dye-sensitized solar cell applications

A phenomenally high molar extinction coefficient heteroleptic ruthenium(II) complex [Ru(4,4'-carboxylic acid-2,2'-bipyridine)(4,4'-(4-{4-methyl-2,5-bis[3-methylbutoxy]styryl}-2,5-bis[3-methylbutoxy]-2,2'-bipyridine)(NCS) 2] ( DCSC13) was synthesized by incorporating donor-acceptor ligands. The absorption spectrum of the DCSC13 sensitizer is dominated by metal-to-ligand charge-transfer transitions (MLCT) in the visible region, with absorption maxima appearing at 442 and 554 nm. The lowest MLCT absorption bands are red-shifted, and the molar extinction coefficients of these bands are significantly higher at 72,100 and 30,600 M(-1) cm(-1), respectively, when compared to those of the analogous [Ru(4,4'-carboxylic acid-2,2'-bipyridine)(4,4'-dimethyl-2,2'-bipyridine)(NCS)2] (N820) sensitizer. The DCSC13 complex, when anchored on nanocrystalline TiO 2 films, exhibited increased short-circuit photocurrent and consequent power-conversion efficiency when compared with the N820 sensitizer.     

Mechanism of the oxidation of alkyl aryl and diphenyl sulphoxides by peroxomonosulphate

Detailed kinetic investigations of the oxidation of methyl phenyl sulphoxide and diphenyl sulphoxide by peroxomonosulphate in aqueous acetic acid medium reveal that the reactions are first-order, both in the sulphoxide and in the oxidant. Studies with substituted phenyl methyl sulphoxides and 4,4′-disubstituted diphenyl sulphoxides show that electron-releasing groups accelerate the rate of oxidation and electron-withdrawing groups retard it. A fair correlation between log k₂ and Hammett substituent constants has been observed in the two series. The mechanism proposed involves the rate-determining nucleophilic attack of the sulphoxide sulphur at the outer terminal peroxo oxygen atom of HSO ₅ ⁻ .     

Polyhalogenoaromatic compounds : XXXV. Metal-halogen exchange between n-butyllithium and polyhalogenobipyridines

Metal—halogen exchange between n-butyllithium and 2,2'-dibromohexachloro-4,4,bipyridine takes place at the 2- and 2'-positions; no rearrangement leading to 3-(5-)lithiobipyridines is observed. In the transition state for the metal—halogen exchange reaction the substrate probably has partial carbanionic character.     

Evaluation of diimine ligand exchange on Cu(I)

Four ligands have been prepared, 8,8-dimethyl-6,7,9-trihydropyrido[1,2-b]acridine and three 4,4',6,6'-tetrasubstituted derivatives of 2,2'-bipyrimidine where the substituents are methyl, phenyl, and p-tolyl. The corresponding [CuL(2)](+) salts of these ligands evidence nonequivalent NMR signals that allow an estimation of the ligand exchange barrier in both acetonitrile and chloroform solution. Lower barriers are found in the former solvent and attributed to solvent participation in the exchange process. Corresponding differences in the oxidation potentials of the complexes are explained in a similar manner. The electronic absorption properties of the complexes are also consistent with the steric and electronic properties of the ligands. [Cu(2c)(2)](PF(6)), where 2c = 4,4',6,6'-tetraphenyl-2,2'-bipyrimidine, was analyzed by X-ray diffraction and found to crystallize in the space group Pccn with a = 14.761(2) A, b = 15.007(2) A, c = 24.407(4) A, and Z = 4. The internal and external phenyl rings are disposed quite differently, with the internal rings interacting strongly with the orthogonal ligand.     

Structure effects on the photobehaviour of 2,2-diphenyl(2H)chromenes

The photochromic behaviour of a series of 2,2-diphenyl(2H)chromenes, bearing different substituents (methyl, thienyl, B(OH)₂ and nitro groups), has been investigated. The photochromism of these molecules is described in terms of absorption spectra, photocolouration and photobleaching quantum yields, kinetics of thermal bleaching and competition between photochemical and photophysical relaxation. The quantum yield of UV photocolouration is generally fairly high (0.7–1.0), but decreases for compounds with thienyl and nitro substituents. The ring-open coloured form thermally rearranges to the closed uncoloured form, whereas visible photobleaching is substantially negligible (≤10⁻³). The thermal bleaching process is markedly affected by the substituents and, in the case of the nitro-derivatives, is characterised by a drastic decrease of activation entropy and enthalpy.     

Novel heat-resistant and organosoluble poly(amide-imide)s containing laterally-attached phenoxy phenylene groups

In this research a new diimide-diacid monomer, 2,2′-bis(4-phenoxyphenyl)-4,4′-bis(N-trimellitoyl)diphenyl ether (BPDPE) containing two laterally-attached phenoxy phenylene groups was prepared by the reaction of 2,2′-bis[(p-phenoxy phenyl)]-4,4′-diaminodiphenyl ether (PPAPE) with trimellitic anhydride in refluxing glacial acetic acid. Ether-hinged wholly aromatic poly(amide-imide)s with limited viscosity number values of 0.61–0.87 dL g⁻¹ were prepared by triphenyl phosphate (TPP)-activated polycondensation of BPDPE with diamines including PPAPE and 4,4′-diaminodiphenyl ether (DADPE). For comparative purposes, reference poly(amide-imide)s were also prepared by reacting diimide-diacid monomer lacking phenoxy phenylene lateral groups namely 4,4′-bis(N-trimellitoyl)diphenyl ether (BTDPE) with the same diamines under similar conditions. A model compound MODEL was also synthesized by the reaction of BTBPE with two mole equivalents of aniline to compare the spectral characteristics results. Number and weight average molecular weights were determined by gel permeation chromatography (GPC) technique. The phenoxy phenylene-containing poly(amide-imide)s (all, except that of resulted from BTDPE and DADPE) had excellent organosolubility in common polar solvents. A low crystallinity extent was only observed using their wide-angle X-ray diffractograms (WAXD). A qualitative study showed the prepared polymers could also be cast into optically-transparent and flexible thin films. The ether-containing lateral groups attached to the ether-hinged macromolecular main chains had no substantial diminishing effect on the thermal stability of these structurally-modified poly(amide-imide)s.     

Spectrophotometric constants in glacial acetic acid of 2,2'-dipyridine and its 4,4'-disubstituted derivatives as fe(ii) complex cations

A continuing study of of previous work involving; the same organic reagents – 2,2'-dipyridine and lts 4.4'-disubstituted derivatives as Fe(II)complex caution – in glacial acetic acid and in buffered aqueous solutions. Determination of the spectrophotometric Constants (wave length of maximum absorbtion and molar absorptivity) in glacial acetic acid for the visual and near ultraviolet region. of the spectrun has been supplied     

The structure analysis of triaryl derivatives of the group V elements: V. Spectra,crystal and molecular structure of trimesitylarsine,C27H33As

The complete X-ray structure analysis of trimesitylarsine (TMAS), C₂₇H₃₃As, has been performed. The crystals are triclinic, a 18.718, b 16.418, c 8.204 Å, α 99.99, β 97.85, γ 104.56°, Z = 4, space group P1̄ (two independent molecules in the asymmetric unit); the final value of the R-factor is 0.038. In the electronic spectrum of TMAS the long-wave band has the maximum at 276 nm which differs significantly from that of triphenylarsine (TPAS) at 249 nm. The bathochromic spectral shift and the molecular conformation are caused by the steric effects as a result of bulky methyl groups in the positions 2,4 and 6 in the phenyl rings. Two independent molecules are connected by a pseudo-axis of symmetry.     

Measurements of sub-nanosecond lifetimes by means of nanosecond laser pulses

It is shown that the lifetimes of excited states of molecules which give a reasonably strong absorption (molar decadic extinction coefficient ∈ > 10⁴M^?1cm^?1) at the frequency of the ruby laser can be determined from the saturation of the optical transitions. This is illustrated for DDI (1,1'-diethyl-2,2'-dicarbocyanine iodide) in glycerol, which appears to have a lowest excited state with a lifetime of 110 psec. This value agrees fairly well with that calculated from the formula for the rate of internal conversion derived from Siebrand's work. Under favourable conditions lifetimes as short as 10 psec can be measured.     

Tuning and switching MLCT phosphorescence of [Ru(bpy)3]2+ complexes with triarylboranes and anions

Four new Ru(II) complexes, [Ru(bpy)(2)(4,4'-BP2bpy)][PF(6)](2) (1), [Ru(t-Bu-bpy)(2)(4,4'-BP2bpy)][PF(6)](2) (2), [Ru(bpy)(2)(5,5'-BP2bpy)][PF(6)](2) (3), and [Ru(t-Bu-bpy)(2)(5,5'-BP2bpy)][PF(6)](2) (4) have been synthesized (where 4,4'-BP2bpy = 4,4'-bis(BMes(2)phenyl)-2,2'-bpy; 5,5'-BP2bpy = 5,5'-bis(BMes(2)phenyl)-2,2'-bpy (4,4'-BP2bpy); and t-Bu-bpy = 4,4'-bis(t-butyl)-2,2'-bipyridine). These new complexes have been fully characterized. The crystal structures of 3 and 4 were determined by single-crystal X-ray diffraction analyses. All four complexes display distinct metal-to-ligand charge transfer (MLCT) phosphorescence that has a similar quantum efficiency as that of [Ru(bpy)(3)][PF(6)](2) under air, but is at a much lower energy. The MLCT phosphorescence of these complexes has been found to be highly sensitive toward anions such as fluoride and cyanide, which switch the MLCT band to higher energy when added. The triarylboron groups in these compounds not only introduce this color switching mechanism, but also play a key role in the phosphorescence color of the complexes.     

An investigation of the applicability of 2,2'-dianthrimide in spectrophotometry: The determination of selenium(IV)

2,2'-Dianthrimide was studied as an analytical reagent and compared with the properties of 1,1'-dianthrimide. While 1,1'-dianthrimide reacts with B, Ge, Se and Te, 2,2'-dianthrimide was found to react only with selenium(IV).A straight line calibration curve is obtained up to 50 μg of selenium under the optimum conditions but the value of 2,2'-dianthrimide as a reagent for selenium(IV) is reduced by the high absorption of the reagent itself.     

Spectrophotometric determination of aluminium with stilbazo

The use of stilbazo as a spectrophotometric reagent for aluminium has been investigated. The reagent forms a stable coloured complex with aluminium showing an absorption maximum at 500 mμ. The system obeys Beer's law from 0.1–0.8 p.p.m. aluminium. The molar extinction coefficient and the stoichiometric composition of the coloured complex have been determined.