Blue Isomer Research Articles

Design, synthesis and application of tetraphenylbenzene-based blue organic electroluminescent materials with aggregation-induced emission and hot exciton properties

A pair of TPB-based deep blue isomers, TPB-CN-CZ1 and TPB-CN-CZ2, with AIE-hot exciton properties have been designed and synthesized. A TPB-CN-CZ2-based non-doped OLED shows a satisfactory EQEmax of 11.8% with an efficiency roll-off of only 6%.

The susceptibility of Trypanosoma congolense and Trypanosoma brucei to isometamidium chloride and its synthetic impurities

Since the 1950s, the chemotherapy of animal African trypanosomosis in cattle has essentially relied on only two compounds: isometamidium chloride (ISM), a phenanthridine, and diminazene aceturate, an aromatic diamidine. The commercial formulations of ISM, including Veridium® and Samorin®, are a mixture of different compounds: ISM is the major component, mixed with the red isomer, blue isomer and disubstituted compound. To investigate the pharmacological effects of these individual compounds ISM, the blue and red isomers and the disubstituted compound were synthesised and purified by HPLC. The activity of each compound was analysed both in vitro, and in mice in vivo. For the in vitro analysis, a drug sensitivity assay was developed in 96-well tissue culture plates to determine the effective concentration which killed 50% of trypanosome population within 48h of drug exposure (IC50). All compounds tested in vitro possessed trypanocidal activity, and purified ISM was the most active. Veridium® and Samorin® had similar IC50 values to purified ISM for both Trypanosoma congolense and Trypanosoma brucei brucei. The disubstituted compound had the highest IC50 values whereas intermediate IC50 values were obtained for the blue and red isomers. In vivo, single-dose tests were used to evaluate the trypanocidal and prophylactic activity against T. congolense. Interestingly, the prophylactic effect two months post treatment was as efficient with ISM, Veridium®, Samorin® and the disubstituted compound at the highest dose of 1mg/kg whereas the red and blue isomers both showed much lower prophylactic activity. This study on T. congolense implies that it is necessary to limit the quantity of the blue and red isomers in the commercial mixture. Finally, the in vitro sensitivity assay may be useful for screening new trypanocides but also for the testing and detection of resistant trypanosome isolates.

Femtosecond Laser Spectroscopy and DFT Studies of Photochromic Dithizonatomercury Complexes

The ultrafast dynamics of the photochromic reaction of dithizonatophenylmercury(II) was recently reported. For purpose of investigating the effect of electronically different substituents (X = o-F, m-F, p-F, p-Cl, o-CH3, m-CH3, p-CH3, m,p-diCH3, p-OCH3, o-SCH3, and p-SCH3) on this reaction, a series of phenyl-substituted dithizones were synthesized and complexed with phenylmercury(II). A variation of more than 3 ps in ground state repopulation times was observed, with the o-methyl derivative absorbing both at shortest wavelength and having the fastest repopulation time, while the p-S-methyl derivative lies at the opposite extremity. An increase in both decay times and λmax values is generally reflected by an increase in electron density in the chromophore. Ultrafast rates also proved to be dependent on solvent polarity, while a profound solvatochromic effect was observed in the transition state absorbance. Density functional theory realistically simulated isomer stabilities, electronic spectra and molecular orbitals. Increased electron density enhances stability in the photoexcited blue isomer relative to the orange resting state, as seen from a comparison between orange and blue isomer total bonding energies. A linear trend between computed HOMO energies and experimental λmax of related aliphatic substituted derivatives was found.

A DFT Perspective on the Structures and Electronic Spectra of the Orange and Blue Isomers of Photochromic Dithizonatophenylmercury(II)

The molecular structure and electronic spectra of the orange and blue isomers of the photochromic compound dithizonatophenylmercury(II) were theoretically studied utilizing density functional (DFT) methods. Computed structural results are in agreement with previously reported X-ray crystal data of the orange resting state. The herewith newly proposed geometrical structure of the blue photoexcited state is favored by more than 35 kJ x mol-1 relative to the historically hypothesized geometry of the blue isomeric form. The key difference lies in the position of the backbone amine proton, being situated on the N4 position in the newly proposed structure, rather than on the N2 position as in the previously hypothesized geometry. Time dependent density functional theory as implemented in the Amsterdam Density Functional (ADF) and Gaussian 03 (G03) program systems yielded excitation energies for the blue isomer exhibiting bathochromic shifts, as observed in the experimentally determined UV/visible spectrum. B3LYP calculated excitation energies and oscillator strengths gave the best approximation of the experimentally observed electronic spectra of both isomers.

Preparation of the Two Isomers of Cu(dien)Cl2

Two isomers of [Cu(dien)Cl2] of two different colours (blue and yellow), where dien = diethylenetriamine have been isolated. They have been synthesized by a slight variation in the procedure. Both complexes turn blue in aqueous, ethanolic and DMSO solutions and attain a stable geometry. The blue isomer is thermally more stable than the yellow one. Both of them have identical electronic spectra and ϵ values in solution.

Synthesis and X-ray characterization of two isomeric dichloro bis-{1-(phenylazo)isoquinoline} complexes of ruthenium(II)

The azoimine functionalized ligand, 1-(phenylazo)isoquinoline (paiq) was synthesized and reacted with RuCl 3 in dry ethanol under nitrogen atmosphere to produce two isomeric dichloro bis-[1-(phenylazo)isoquinoline] ruthenium(II) complexes. They are green isomer ( a) and blue isomer ( b). In the X-ray crystal structure determination, the final reliability indices for isomers ( a) and ( b) are 0.0308 and 0.0448, respectively. Solvents for crystallization are found in both crystal structures. Of the five possible geometrical isomeric configurations of RuL 2Cl 2, L=1-(phenylazo)isoquinoline, in order of the coordinating pairs: (Cl, Cl); (N,N); (N′,N′) where N represents N(isoquinoline), N′ represents N(azo), the two isomers isolated are trans– cis– cis (tcc, a) and cis– cis– cis (ccc, b). Both the green isomer ( a) and the blue isomer ( b) have six coordination. The coordination geometry of ruthenium(II) for the former ( a) compound is distortedly octahedral with the surrounding four nitrogen atoms equatorial and two chlorine atoms axial. That for the latter isomer ( b) is also a distorted octahedron with Cl2, N1, N3 and N6 atoms basal, and Cl1 and N4 atoms apical. The RuCl distances for the green tcc-isomer ( a) are shorter than those for the blue ccc-isomer ( b). The RuN bond lengths in both isomer split into two categories.

Synthesis, spectral and electrochemical studies of isomeric dichloro-bis[N(1)-ethyl-2-(arylazo)imidazole]ruthenium(II) and the reaction of the green isomer with tertiary phosphines

N(1)-Ethyl-2-(arylazo)imidazoles (L) react with RuCl3 giving green (5) and blue RuL2Cl2 (6) isomers. The green isomer is quantitatively transformed into the blue isomer on boiling under reflux in 1,2-dichlorobenzene. The ligand is of the N,N′-chelating type and in principle, provides five geometrical isomers. Considering the coordination pairs in the order: Cl, N(imidazole), N and N(azo),N′ the green isomer is␣spectroscopically characterised as trans-cis-cis-tcc-RuL2Cl2 (5) and the blue isomer is cis-trans-cis-ctc-RuL2Cl2 (6). The green isomer reacts smoothly with tertiary phosphines giving species of type [RuCl(P)L2]+ (7,8) and [Ru(P-P)L2]+2 (9,10) in which Cl, P and P-P respectively occupy cis-positions [P = PPh3, PPh2Me, P-P = Ph2P(CH2)2PPh2 (dppe) and Ph2P(CH2)3PPh2 (dppp)]. All the complexes display allowed t2(Ru) → π* (L) transitions in the visible region. A systematic shift of this MLCT band to higher energy occurs in the order: tcc-RuL2Cl2 (5) 1.2V versus s.c.e.) in phosphine derivatives (7–10). The azo reduction (E0 L) appears at negative values with respect to s.c.e. and is found to be sensitive to substitution in the phenyl ring of the ligand frame. The potential difference (E0 M−E0 L) is linearly related to the MLCT band energies (νCT) of green and blue RuL2Cl2 complexes. The phosphine derivatives behave differently, a linear correlation being observed between νCT and E0 M. The isomer configuration of RuL2Cl2 and the stereochemistries of the phosphine derivatives are established by 1H n.m.r. spectral data. The green (5) and blue (6) isomers exhibit single -Me or -OMe signals indicatives of C2-symmetry. The phosphine complexes [Ru(P)Cl(L2)2]+/[Ru(P-P)(L2)2]+2 show two equally intense methyl signals suggesting C1-symmetry in the derivatives.

Molecular structure and characterization of a pair of hydrate isomers for dinuclear copper(II) complexes with a 26-membered hexaazamacrocycle

A pair of seldom seen hydrate isomers with a formula of LCu2(CH3COO)2(H2O)2(ClO4)2, where L is the dinucleating macrocyclic ligand bis-p-xytylBISDIEN, have been prepared and characterized by X-ray crystallography, UV⧹Vis spectra and magnetic measurements. The blue isomer, [LCu2(CH3COO)2(H2O)2] (ClO4)2, crystallizes in the triclinic system and the violet isomer, [LCu2(CH3COO)2](ClO4)2 · 2H2O, crystallizes in the orthorhombic system. The blue complex consists of one cation [LCu2(CH3COO)2(H2O)2]2 and two ClO4− anions. The two copper atoms are independent to each other with a separation of 6.781(9) Å. Each has a square pyramidal geometry and is five-coordinated by three N atoms from the macrocycle and two O atoms from the monodentate acetate anion and the coordinated water molecule, respectively. In violet isomer, both central copper atoms are located in an approximately square planar environment and are not coordinated by the water molecules. The isomers have different reflectance spectra due to the different coordination geometry but can rapidly interchange in solution at ambient temperature. Both compounds exhibit quite weak antiferromagnetic couplings verified by the small but negative Weiss constant (θ = −5.72 K for the blue and −25.6 K for the violet isomer).

Syntheses and crystal structures of two isomers of CuL2(NO3)2 · 2H2O (L=N1-isopropyl-2-methyl-1,2-propanediamine) and their thermochromism in the solid state

Two isomeric complexes, [CuL2](NO3)2 · 2H2O, (1, red) and [CuL2](H2O)](NO3)2 · H2O, (2, blue) (L=N1-isopropyl-2-methyl-1,2-propanediamine) have been synthesised and their X-ray crystal structures have been determined. Both the isomers possess the same space group, P21\ . However, 1 is square planar and 2 is square pyramid having N4 and N4O chromophore, respectively around copper(II). The red isomer (1) upon heating loses water molecules yielding a violet dehydrated species, 1a which on further heating undergoes an exothermic phase transition accompanied by thermochromism, violet (1a) to blue-violet (1b) in the solid state. (1a) and (1b) are probably conformational isomers and they revert to 1 in humid atmosphere. The blue isomer (2) upon heating transforms to blue-violet species on dehydration, which reverts immediately after cooling in open atmosphere.

Chemistry of Azoimidazoles: Synthesis, Spectral Characterization, Electrochemical Studies, and X-ray Crystal Structures of Isomeric Dichloro Bis[1-alkyl-2-(arylazo)imidazole] Complexes of Ruthenium(II)

Several new ligands, azoimidazoles belonging to the class 1-methyl-2-(arylazo)imidazoles (L1 (3)) and 1-benzyl-2-(arylazo)imidazoles (L2 (4)) (R = H (a), Me (b), OMe (c), Cl (d), NO2 (e)) have been synthesized and reacted with RuCl3 in ethanol under refluxing conditions. Two isomers of the composition RuL2Cl2, green (i) and blue (iii), are chromatographically separated. The green isomer is quantitatively transformed to the blue isomer on refluxing in a high boiling solvent. The isomeric structures have been confirmed by X-ray crystallography. Crystal data are as follows. Green complex C38H34Cl2N8Ru (6a): crystal system monoclinic; space group C2/c; a = 15.680(8) A; b = 22.766(14) A; c = 11.473(5) A; β = 119.27(4)°; V = 3573(3) A3 Z = 4; R = 3.59%; Rw = 4.38%. Blue complex C22H24Cl2N8Ru (7b): crystal system monoclinic; space group P21/n, a = 9.547(6) A; b = 22.554(14) A; c = 11.748(8) A; β = 99.07(5)°; V = 2498(3) A3; Z = 4; R = 3.15%; Rw = 4.51%. With reference to the pairs of Cl, N(imidazole), and N(az...

Thermodynamic and kinetic studies on the complexation reactions of aqua(rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) copper (II)(blue) with neutral monodentate ligands

In order to study the charge effects of the entering and leaving groups in substitution reactions of five-co-ordinate complexes, the equilibrium constants (K) of the complexation reactions of a trigonal-bipyramidal complex, aqua(rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)-copper(II), [CuL(H2O)]2+(blue isomer), with eight neutral monodentate ligands (L′), ammonia, methyl-, dimethyl-, trimethyl- and ethyl-amine, aniline, pyridine and piperidine, as well as the rate constants for the formation (kf) and the aquation (kaq) of [CuL(L′)]2+ have been determined in 0.20 mol dm–3 NaClO4 at 25.0°C. The formation rate constants are discussed in relation to a combination of the basicity, the softness and the size of the entering group. A plot of log kf against log K gives a straight line with a slope of 0.98. The kinetic results are consistent with an associative-interchange, Ia, mechanism.

Photochemical Ring Slippage of Bis(pentafluorophenyl)titanocene: Reaction kinetics and matrix isolation of the primary photoproduct

AbstractLaser flash photolysis and matrix‐isolation techniques were applied to elucidate the photochemistry of the orange complex bis(pentafluorophenyl)titanocene ( = bis(η5‐cyclopentadienyl)bis(pentafluorophenyl)titanium‐ (IV), Cp2TiIV{C6F5}2, Cp = η5‐C5H5, 1) which is used as a polymerization photo‐initiator. The primary photo‐reaction of 1 is the formation of a highly reactive blue isomer X with unit quantum yield. In carefully dried and degassed benzene solution, the photoisomer X rearranges to starting material 1 with a first‐order reaction, k = 5 · 103 s−1 at room temperature. X is highly reactive towards H2O, MeOH, acetone, MeCN, MeNO2, butane‐1,4‐diyl diacrylate, 2,2,6,6‐tetramethylpiperidine N‐oxide, CO, O2, and N2; absolute bimolecular rate constants range from 106 to 109 M−1 · s−1. The primary photoisomerization 1→X is tentatively ascribed to a cyclopentadienyl ring slippage from η5 to a lower hapticity, a process that opens up coordinative unsaturation.

ChemInform Abstract: Photochromic Systems. Part 2. Studies on the Photoreactions and the Photopolychromic Properties of (E)‐(2,5‐Dimethoxyphenyl‐substituted)methylene Isopropylidenesuccinic Anhydrides.

AbstractIrradiation of the yellow fulgide (E)‐(Ia) in toluene leads to a purple colored solution which contains the red (thermally stable) dihydronaphthalene derivative (IIIa) and its blue (unstable) isomer (IVa).

Crystal structures and interrelationships of the blue and green conformational isomers of tetrakis(trimethylarsine sulphide)cobalt(II) perchlorate

Blue and green compounds, [Co(Me3AsS)4][ClO4]2, which are conformationally isomeric, crystallise when cobalt(II) perchlorate reacts with trimethylarsine sulphide in ethanol and acetone respectively. Their crystal structures show that the cation field spreading from the AsMe3 groups permits side-by-side packing of the cations into columns with the methyl groups pointing outwards. The column packing, together with S–Co–S valence angles and S–Co–S–As torsion angles, differs in the two isomers. For the blue isomer the S–Co–S angles fall in pairs: 120.4, 117.0; 108.6,107.1; 102.5,102.0°. For the green isomer two angles are 90° and four are close to 120°, with the sulphur atoms forming a tetragonal sphenoid. The green isomer and the nickel compounds [Ni(Me3AsS)4][ClO4]2 and [Ni(Me3AsS)4][BF4]2 are isomorphous. For these nickel compounds the sphenoidal configuration is associated with ligand-field stabilisation. It is suggested that the ligand-field effect, though smaller for cobalt, helps stabilise the green isomer.

Mononuclear and dinuclear tertiary phosphine molybdenum complexes. oxo-molybdenum(IV), dinuclear Mo 2Cl 4L 4 and related derivatives

Green and blue isomers of the oxo derivative MoOCl 2(PMe 3) 3 have been obtained by an oxygen-atom abstraction reaction between MoCl 4(thf) 2 and equimolar amounts of water in the presence of PMe 3. Methatesis with KX(X = NCO, NCS) yields MoOX 2(PMe 3) 3 and with NaS 2CNEt 2, MoO(S 2CNEt 2) 2(PMe 3). The latter complex readily loses PMe 3 to give MoO(S 2CNEt 2) 2 from which it can be prepared by addition of the phosphine ligand. Reaction of the blue purple complex, MoCl 3(thf) 3 ( I), with excess PMe 3 gives mer-MoCl 3(PMe 3) 3 which loses PMe 3 on heating in toluene to afford [MoCl 3(PMe 3) 2] 2. Reduction of ( I) with phosphines and zinc in tetrahydrofuran gives the dinuclear molybdenum(II) halide complexes Mo 2Cl 4L 4 (L = PMe 3, PEt 3, PhMe 2Ph, PEt 2Ph; L 2 = dppm), while Zn-acetic acid reduction yields Mo 2(CO 2Me) 4. Interaction of the chlorocarbonyl species MoCl 2(CO) 2(PMe 3) 3 with Tl(acac) affords Mo(acac)Cl(CO)(PMe 3) 3 which has an unusually low CO stretching frequency for a terminal carbonyl group (1755 cm −1).

Metal isotope effects on the vibrational spectra of polymeric metal complexes. V. Infrared spectra of bis(L- and DL-phenylalaninato)copper(II).

The infrared spectra of bis (L-and DL-phenylalaninato) copper (II) and their N-deuterated analogues have been recorded in the region between 4000 and 200cm-1. The vibrational assignments of the Cu-ligand stretching vibrations have been made by means of the metal isotope technique, 63Cu and 65Cu substitution. Three bands of trans-bis (L-phenylalaninato) copper at 400, 380, and 339cm-1 shift appreciably on 63Cu-65Cu substitution. The blue isomer of bis (DL-phenylalaninato) copper also shows three copper isotope-sensitive bands at 380, 340, and 328cm-1, analogous to those of trans-bis (D-alaninato)-and (L-phenylalaninato) copper. However, the blue-violet isomer of the DL complex shows only two sensitive bands at 370 and 322cm-1, as in the case of cis-bis (D-alaninato) copper. Frequency shifts on N-deuteration suggest that one of the Cu-N stretching vibrations is at higher frequency than the Cu-O stretching vibrations for bis (L-phenylalaninato) copper, but this frequency order is reversed for the two isomers of bis (DL-phenylalaninato) copper, but this frequency order is reversed for the two isomers of bis (DL-phenylalaninato) copper.

AtActivation and transfer of oxygen XIV. The successive accumulation of a 10 a-hydroxy pseudobase and an ESR-silent blue isomer in the n 1-alkylflavin model series.

Kinetic studies have substanciated the idea that the 10 a-hydroxy pseudobase 2 is in equilibrium with a blue transient for which structure 3 has been proposed. The rate-constants and the molar absorbances of the intermediates were estimated.

ChemInform Abstract: THE REACTIONS OF TETRAHYDRIDOTETRAKIS(METHYLDIPHENYLPHOSPHINE)‐MOLYBDENUM(IV) AND ‐TUNGSTEN(IV) WITH ACIDS

AbstractDer Tetrahydrido‐W‐Komplex (I) läßt sich von Säuren schnell unter Bildung der kationischen Pentahydrido‐Derivate (II) protonieren.

Crystalline and molecular structures of complexes of copper with N-substituted ?-aminoacids part III. The red and blue isomers of (N-benzyl-D-valinato) (N-benzyl-L-valinato) copper (2+) dihydrate

Crystalline and molecular structures of complexes of copper with N-substituted ?-aminoacids part III. The red and blue isomers of (N-benzyl-D-valinato) (N-benzyl-L-valinato) copper (2+) dihydrate

Complex nickel nitrites. II. Linkage isomerism in complexes of ethylenediamine and N,N'-diethylethylenediamine

Two pairs of linkage isomers, NiL2X2, have been prepared. When L = N,N?- diethylethylenediamine, the blue dinitrito form (X = ONO) is stable at room temperature, but the metastable dinitro form (X = NO2) can be prepared and stored for several days as red octahedral crystals. At -60� the dinitro complex is the stable form. ��� When L = ethylenediamine there is a transition temperature at 74�2�. The known stable red dinitro complex is converted into a blue dinitrito isomer by heating. The blue form is metastable at room temperature but again can be stored for several days. In each case the isomerization reaction of the metastable to the stable isomer can be followed by infrared spectrometry.