Monosubstituted Derivatives Research Articles

Varying Electronegativity of OH/O-Groups Depending on the Nature and Strength of H-Bonding in Phenol/Phenolate Involved in H-Bond Complexation

Application of the Domenicano et al. method of estimating group electronegativity from angular geometry of the ring in monosubstituted benzene derivatives allowed us to find how the electronegativity of OH/O(-) groups in H-bonded complexes of phenol and phenolate depends on the nature and strength of H-bond. For complexes in which the OH group is only proton donating in the H-bond, a linear dependence of the estimated electronegativity on O...O(N) interatomic distance was found for experimental (CSD base retrieved) data. The following rule is observed: the weaker the H-bond is, the more electronegative the OH group is. If apart from this kind of interaction the oxygen is proton accepting, then an increase of electronegativity is observed. Modeling (B3LYP/6-311+G) the variation of the strength of the H-bond by the fluoride anion approaching the OH leads to qualitatively the same picture as the scatter plots for experimental data.

Computation of Relative Bond Dissociation Enthalpies (ΔBDE) of Phenolic Antioxidants from Quantum Topological Molecular Similarity (QTMS)

A recently proposed method called quantitative topological molecular similarity (QTMS) generated a model for the computation of the relative substituent effects on the bond dissociation enthalpies (DeltaBDEs) for a set of 39 phenols. The data set includes a diverse set of substituents with monosubstituted and poly-substituted derivatives that exhibit different electronic and steric effects. Many share common structural features with already well-established antioxidants. QTMS reveals the active region of the substituted phenols and identifies the electronic descriptors that best explain the range of DeltaBDEs observed. For substituents in the 4-X position (para) we find that our model requires a correction for radical stabilization enthalpy (RSE). Application of the QTMS methodology yields an unrivalled QSAR with r(2) = 0.98 and q(2) = 0.85 for the bond dissociation enthalpies of this phenolic antioxidant data set.

Use of the olefin metathesis reaction for highly efficient β-cyclodextrin modification

A series of novel primary face mono-substituted β-cyclodextrin derivatives have been synthesised using the olefin metathesis reaction. Mono-6-allylamino-6-deoxy-β-cyclodextrin easily synthesised by nucleophilic substitution of mono-6-tosyl-β-cyclodextrin is the key synthon in the preparation of cyclodextrin derivatives mono-functionalised at the primary face by alkyl, aryl or perfluoroalkyl groups using Grubbs catalyst. In the cases of vinylbenzene and 1H,1H,2H-perfluoro-1-octene, the metathesis reactions yield with 95% stereoselectivity of the E-isomer.

Theoretical investigations of triphenylamine derivatives as hole transporting materials in OLEDs: Correlation of the Hammett parameter of the substituent to ionization potential, and reorganization energy level

Recently, triphenylamine (TPA) and its derivatives become widely used in the organic light emitting diode (OLED) devices as a hole transporting material (HTM). The calculated ionization potential ( I p ) and reorganization energy for the hole transport ( λ +) for a series of triphenylamine (TPA) derivatives are related to their Hammett parameters ( σ and σ +) theoretically. In this study, the semiempirical AM1 method has been used to optimize thirty-three TPA derivatives. The electronic structures of these compounds in the neutral and the radical-cation states were obtained based on the optimized geometrical structure. The I p and λ + values were generated by means of the calculated heat of formation (or total energy) for both the neutral and the radical-cation states. In particular, the calculated I p ’s for these derivatives were consistent with experimental data. The substitution effect for the mono-substituted TPA derivatives is displayed in that the TPA derivatives with the electron-donating substituent have lower I p and those with electron-withdrawing substituent have higher I p , comparing to that of non-substituted TPA derivative. The substituent effect in di- and tri-substituted TPA derivatives is more pronounced than that of the mono-substituted TPA derivatives. According to the calculated results, the calculated I p shows an excellent agreement with the experimental oxidation potentials ( E p/2 ) of these TPA derivatives. Furthermore, these calculated results can be employed to predict the electro-luminescence properties for new and improved HTM.

Aromaticity of monosubstituted derivatives of benzene. The application of out-of-plane ring deformation energy for a quantitative description of aromaticity

The degree of aromaticity of monosubstituted derivatives of benzene has been investigated using different aromaticity indices calculated on the basis of molecular structure obtained at the MP2/cc-pvdz level of theory. It is demonstrated that, due to the violation of symmetry in π-systems, the introduction of any substituent in the benzene ring results in a decrease in the degree of aromaticity. It has been found that structural Bird and HOMA aromaticity indices do not reflect the strength of substituents and their ability to perturb ring electronic density in the benzene ring. The application of magnetic indices NICS0 and NICS1 results in an overestimation of aromaticity of substituted molecules with respect to benzene. Modifications of these indices (NICS-z and NICS-anis) reproduce well the character of the substituents except for functional groups containing carbonyl bonds. The values of NICS-z and NICS-anis correlate well with the ring out-of-plane deformation energy. However, the values of the ring deformation energy agree very well with the strength of all substituents including those containing carbonyl. Therefore, out-of-plane ring deformability is a more universal and sensitive aromaticity index than the known structural and magnetic indices. The values of ring deformation energy demonstrate linear correlation with the substituent that is constant for electron-donation and electron-withdrawing substituents. However, the former functional groups perturb more significantly the aromatic ring electron density.

Substitution derivatives of the heteronuclear cluster RuOs 3(μ-H) 2(CO) 13: Monosubstituted group 15 derivatives

Tertiary group 15 ligand monosubstituted derivatives of the heteronuclear cluster RuOs 3(μ-H) 2(CO) 13 have been prepared and their solid state and solution structures examined. A number of isomeric structural types have been identified in solution, and these appear to be correlated to disorder in the solid state. Hydride fluxionality and restricted rotation about the metal–phosphorus bond have also been observed.

Sodium Borohydride as the Only Reagent for the Efficient Reductive Alkylation­ of Malononitrile with Ketones and Aldehydes

An efficient and convenient method for the synthesis of primary and secondary monosubstituted malononitriles has been developed. In this method, sodium borohydride in isopropanol has a catalytic effect on the initial condensation between malononitrile and aldehydes or ketones at 0 °C. The sodium borohydride also simultaneously acts as a reagent and reduces the unsaturated intermediate formed in situ by the condensation. This simple reductive alkylation method effectively consumes all malononitrile and selectively produces only monosubstituted malononitriles. Unsymmetrically disubstituted malononitriles are prepared via alkylation of these monosubstituted derivatives.

Geometry, solvent, and polar effects on the relationship between calculated core-electron binding energy shifts (ΔCEBE) and Hammett substituent (σ) constants

According to Lindberg et al. there exists an equation ΔCEBE= κσ for substituted benzene derivatives. Core-electron binding energy shift (ΔCEBE) is the difference between the CEBE of a specific carbon in monosubstituted benzene derivatives (C 6H 5–Z) and in benzene (C 6H 5–H); κ is related to a reaction constant and σ is the experimental Hammett substituent constant. The object of the present work is to investigate geometry, solvent, and polar effects on Lindberg's equation using theoretically calculated ΔCEBE. The CEBEs were calculated using DFT within the scheme ΔE KS (PW86x-PW91c/TZP+C rel). The geometry has only little effect on the CEBE values. A regression relation between ΔCEBE and σ takes the form ΔCEBE= κσ− C with κ≅1.17 and C≅0.17. We estimated 69 σ constants in water that have not been presented in the literature. Theoretical resonance ( σ R) and inductive ( σ I) effects were calculated using Taft equations. ΔCEBE (R) and ΔCEBE (I) effects on ΔCEBE were also calculated using Taft-like equations. The quality of the correlation to the resonance is better than that to the inductive effect, in water. The regression quality in aqueous organic solvent is poorer than in water in both Lindberg and Taft equations. The solvent effect is greater on the resonance than on the inductive effect.

Salicylate Activity. 3. Structure Relationship to Systemic Acquired Resistance

Salicylic acid (2-hydroxybenzoic acid; SA) is a primary signal inducing plant defenses against pathogens. This plant disease resistance, known as systemic acquired resistance (SAR), is an attractive target for the development of new plant protection agents. SAR induction is a multistep process that includes accumulation of pathogenesis-related (PR) proteins. The structure-activity profile of salicylates and related compounds has been evaluated using an inducible PR protein (PR-1a) and plant resistance to tobacco mosaic virus (TMV) as markers. Among the 47 selected monosubstituted and multiple-substituted salicylate derivatives tested, all 8 derivatives that induced more PR-1a protein than SA were fluorinated or chlorinated in the 3- and/or 5-position (3,5-difluorosalicylate > 3-chlorosalicylate > 5-chlorosalicylate > 3,5-dichlorosalicylate > 3-chloro-5-fluorosalicylate > 3-fluorosalicylate > 3-fluoro-5-chlorosalicylate > 3,5-dichloro-6-hydroxysalicylate > SA). In general, substitutions for or on the 2-hydroxyl group or at the 4-position of the ring reduced or eliminated PR-1a protein induction. In contrast, substitutions in positions ortho (3-position) or para (5-position) to the hydroxyl group with electron-withdrawing groups other than chlorine or fluorine decreased induction, and electron-donating groups in these positions also had a deleterious effect on PR-1a induction. PR-1a protein accumulation and reduction in TMV lesion diameter exhibited a log-linear relationship. The seven salicylate derivatives that were the most active TMV resistance inducers were all halogenated in the 3- and/or 5-position (3-chlorosalicylate > 3,5-difluorosalicylate > 3,5-dichloro-6-hydroxysalicylate > 3,5,6-trichlorosalicylate > 5-chlorosalicylate > 5-fluorosalicylate > 3,5-dichlorosalicylate > 4-fluorosalicylate > 3-fluorosalicylate > 3-chloro-5-fluorosalicylate > 4-chlorosalicylate > SA). The correlation between PR-1a protein induction and resistance to TMV confirms the value of using PR-1a induction as a screening tool for developing new plant disease control agents.

Synthesis and properties of mono-substituted liquid crystalline polyacetylene derivatives—doping, magnetic orientation, and photo-isomerization

Mono-substituted acetylene monomers with a liquid crystalline (LC) group are polymerized using rhodium, iron or molybdenum complex catalysts. LC polyacetylene derivatives with number-averaged molecular weights of 4000–330000 were obtained in 5–92% yield. The LC behavior is examined by X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The polymers prepared using rhodium or iron catalyst are confirmed to assume a cis form and to undergo an irreversible isomerization to the trans form upon heating. Photo-responsive polyacetylene derivatives are successfully synthesized through the introduction of an azobenzene moiety as a mesogenic core into the side-chain, and these forms exhibit a reversible photochemical cis-to- trans isomerization of the azobenzene moiety.

Ligand substitution in the heterometallic cluster Cp*IrOs 3(μ-H) 2(CO) 10

The reactions of the heterometallic cluster Cp*IrOs 3(μ-H) 2(CO) 10 with phosphines, isonitriles and pyridine under TMNO activation afforded the substitution products Cp*IrOs 3(μ-H) 2(CO) 10− n L n ( n = 1, 2; L = PPh 3, P(OMe) 3, t BuNC, CyNC or py) in good yields. For the monosubstituted derivatives, the substitution site was exclusively at an osmium atom in an axial position for L = phosphine or phosphite. Spectroscopic evidence suggested the presence of isomers in solution for the PPh 3 derivative. In contrast, for L = isonitrile, the ligand occupied an equatorial site. In the disubstituted derivatives, the group 15 ligands were coordinated to two different osmium atoms, one each at an axial and an equatorial site. The isomerism and fluxional behaviour of some of these clusters have also been examined.

Crystal structure of monosubstituted ferrocene derivatives

Crystal structure of monosubstituted ferrocene derivatives

On the reactions of chlorodithiophosphoric acid pyridiniumbetaine with polyfunctional nucleophiles. Part III: Reactions with monoalkylderivatives of thiosemicarbazide

Reactions of chlorodithiophosphoric acid pyridiniumbetaine, py · PS 2Cl ( I) with monosubstituted thiosemicarbazide derivatives RN(H)C(S)N(H)NH 2, (R = methyl, ethyl), in acetonitrile media and in the presence of pyridine as an HCl acceptor were studied. New five-membered heterocyclic compounds were prepared, pyridinium salts of 4-methyl-3-sulfido-3,5-dithioxo-1,2,4,3λ 5-triazaphospholidine ( II) and 4-ethyl-3-sulfido-3,5-dithioxo-1,2,4,3λ 5-triazaphospholidine ( III). The substances II and III were completely characterized by 31P NMR, FT-IR, Raman spectroscopies and their molecular structures were determined by the X-ray diffraction analysis.

Convenient synthesis of new water-soluble monosubstituted functional ferrocene derivatives

Two new water-soluble monosubstituted functional ferrocene derivatives, p-ferrocenyl benzene sulfonic acid (BSAFc) and 4-ferrocenyl-1,1′-azobenzene-3,4′-disulfonic acid (AYFc), bearing sulfonic groups and/or azo structure have been successfully synthesized in aqueous media according to the self-designed synthetic route. The preparation process is quite simple and convenient. 1H NMR, FT-IR and element analysis data demonstrated the structures of the target products. UV–Vis spectra and cyclic voltammetry (CV) measurements explained the electrophilic group that linked to BSAFc and AYFc was an influence on the orbital energy level of ferrocene. The CVs in different concentration and type of anion existing in the solution demonstrated that the electrochemical activities of BSAFc and AYFc firmly rely on the anion.

Synthesis of Substituted BEDT‐TTF Derivatives for the Preparation of Bifunctional Materials

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Comparison of the Ability of DMXAA and Xanthenone Analogues to Activate NF-κB in Murine and Human Cell Lines

DMXAA (5,6-dimethylxanthenone-4-acetic acid), the most potent of a series of xanthenone (XAA) analogues developed in this laboratory, is currently undergoing combination clinical trials as an antivascular agent for cancer treatment. XAAs have a complex mode of action, and in vitro assays that are predictive of in vivo antitumor activity have been difficult to develop. In this study, we have utilized a series including XAA, DMXAA, and mono-substituted XAA derivatives to determine firstly whether in vitro NF-kappaB activation of mouse cell lines predicts for the in vivo antitumor potential of this class of agents, and secondly whether the relative activity of these analogues is similar in murine and human cell lines. Electromobility shift assays were used to measure NF-kappaB activation in murine HECPP endothelial and 70Z/3 pre-B cells, and in human HPLNEC.B3 endothelial and Raji B-lymphoma cells. A significant correlation was obtained between NF-kappaB activation in HECPP cells by a series of XAA analogues at 100 microg/ml (r = 0.78, p = 0.008) and at 300 microg/ml (r = 0.75, p = 0.01) and the amount of hemorrhagic necrosis induced in Colon 38 tumors. Different structure-activity relationships were observed in human and murine cell lines. 8-MeXAA, which was inactive in HECPP and 70Z/3 murine cell lines, showed similar NF-kappaB activation to DMXAA in human HPLNEC.B3 cells and Raji B-lymphoma cells. These results suggest that the receptor protein(s) in human cells that mediate the human response may have a lower stringency to that for murine cells. We also noted differences in the dose-response relationships for NF-kappaB activation between lymphoid and endothelial lines that were species independent. With increasing concentrations of DMXAA, NF-kappaB activation in both murine and human lymphoid lines showed a reproducible fluctuation, while in endothelial lines, the intensity of NF-kappaB activation was relatively constant above a threshold concentration. The results demonstrate interspecies differences in the NF-kappaB response to XAA analogues, and may also reflect the complex nature of NF-kappaB regulation.

Synthesis of arylferrocenylketones

The synthesis of a family of mono- and 1,1'-bis-substituted ferrocenylaryl and heteroaryl ketones is described. The key transformation was the Liebeskind-Srogl cross-coupling reaction between ferrocenylthiol esters and boronic acids. The yields ranged from 22 to 99% in the monosubstituted ferrocenyl derivatives and from 26 to 77% in the case of the 1,1'-bis-substituted analogues.

Theoretical investigation of carbazole derivatives as hole-transporting materials in OLEDs

Carbazole and its derivatives were widely used as the hole-transporting material. In this study, ab initio DFT B3LYP/6-31G* was performed for the carbazole and 1-, 2-, 3-, 4- and 9-mono-substituted as well as 3,6-di-substituted carbazoles with electron-donating and -withdrawing substituents. The total energies, HOMO and LUMO orbital energies of these compounds at neutral, cation and anion states were obtained based on the optimized geometrical structures. The ionization potential ( I p) and electron affinity ( E a) were generated by means of the DFT calculated total energy of neutral, cation and anion states. These theoretical I p and E a were consistent with experimental data. Further investigation on 1-, 2-, 3- and 4-mono-substituted carbazole, we conclude that these carbazole derivatives with electron-donating substituents should decrease their I p and E a values while increasing the HOMO and LUMO energies. On the contrary, the mono-substituted carbazole with electron-withdrawing substituent have the opposite results to those carbazole derivatives with electron-donating substituents. Comparing to carbazole, Δ E decreased in the mono-substituted carbazole derivatives with electron-donating and -withdrawing substituents. The substituent effect in 3,6-di-substituted carbazoles is more obvious than that of 3-substituted carbazole. According to the calculated results, the calculated I p has an excellent agreement with the experimental one-electron oxidation potential ( E p/2). Presumably, this calculation can be employed to predict EL character for other OLED materials.

Theoretical investigation of electronic structures of the ground and excited states of pyrene and its derivatives

The low-lying electronic states of pyrene and substituted pyrenes have been studied in detail by high level ab initio and density functional methods to aid in the development of the efficient luminescent properties of pyrenes. The electronic structures of the ground and the low-lying singlet excited states have been examined by the complete active space SCF (CASSCF) method. The energy gaps between the ground state and the low-lying excited states have been estimated by means of the multireference perturbation theory based on CASSCF wavefunctions as well as time-dependent density functional theory (TDDFT). The changes in electronic structure of pyrene, in particular, the excitation energies of the excited states by several different substituents have been investigated by the TDDFT method. Both mono-substituted and di-substituted pyrene derivatives have been considered, and the effects on the energy gap between HOMO and LUMO by electron donor and electron acceptor groups have been discussed.

Fluorescence of Metal–Ligand Complexes of Mono- and Di-Substituted Naphthalene Derivatives

In this work, metal ion complexes for several naphthalene derivatives have been investigated. Different working pH values were chosen: 2.5 for complexes with Zr(IV), 4.0 for complexes with Fe(III), 5.0 for complexes with Al(III), and 7.5 for complexes with Cu(II). A stoichiometry of 1:1 for all complexes except two has been established by use of the Benesi-Hildebrand method and the stability constants have been calculated. All complexes between naphthalene derivatives and Cu(II) and Fe(III) show fluorescence quenching. In the case of Al(III), all complexes provided enhanced fluorescence. For Zr(IV), only the complex with 3-hydroxy-2-naphthoic acid provided enhanced fluorescence. The value of the stability constants as a function of the substituents of naphthalene derivatives has been analyzed. One can conclude that Cu(II) showed the largest binding affinity for the mono-substituted derivatives. However, Al(III) and Zr(IV) produced greater selectivity for the di-substituted derivatives. Iron(III) showed no specific binding with any of the naphthalene derivatives.