Effect Of Side-chain Substituents Research Articles

Effects of Side-Chain Substituents in Benzo-15-Crown-5 on Lithium Extraction

Chloroform–water extraction systems have been studied using crown-ethers as extracting agents, namely: benzo-15-crown-5 (B15C5), 2,3-naphtho-15-crown-5 (N15C5), 4′-nitro-benzo-15-crown-5 (NO2B15C5), 4′-tert-butyl-benzo-15-crown-5 (TBB15C5), and 4′-acetyl-benzo-15-crown-5 (AcB15C5). Extraction isotherms of these systems have been obtained, and an attempt made to elucidate the effect of the structure of extracting agent on extraction characteristics. IR-spectroscopic studies have been performed for selected crown-ethers and their complexes in crystalline form and in chloroform solutions, namely, for N15C5, NO2B15C5, AcB15C5, and B15C5. The complexes LiN15C5H2OClO4 (1), LiN15C5H2OI (2), LiNO2B15C5H2OI (3), LiAcB15C5H2OI (4), and LiTBB15C5H2OI (5) have been isolated for the first time and characterized by IR spectroscopy. Single-crystal X-ray data have been obtained for complexes 1–3.

Effect of side chain substituents on the electron injection abilities of unsymmetrical perylene diimide dyes

Three near-infrared (NIR) absorbing unsymmetrical perylene diimide D–A–D type dyes containing 6-undecanoxy as donor group were utilized in dye-sensitized nanocrystalline TiO 2 solar cells. Structure of the acceptor side of the molecules were improved by adding 4-[2-methyl-5-(cyanoacrylic acid)-3-thienyl]-phenyl ( V), 3-carboxy-2-pyridil ( VI) and 3-carboxy-2-pyrazyl ( VII) moieties attached to one of the N-side of the dye. The relationship between the molecular structure of the acceptor sites of the dyes and the photovoltaic performances were discussed. Electrochemical measurements indicated that band gaps of the dyes were energetically favorable for electron injection from the excited state of the dyes to the conduction band of TiO 2 nanoparticles. However, three dyes gave lower conversion efficiency on DSSC applications. Strong electron-withdrawing nature of perylene core might not permit to transfer the photo-generated electrons to the carboxyl groups anchoring to TiO 2 surface, and then solar-to-electricity conversion efficiencies of the dyes were reduced.

Effect of Side-Chain Substituents on Self-Assembly of Perylene Diimide Molecules: Morphology Control

Effect of side-chain substitutions on the morphology of self-assembly of perylene diimide molecules has been studied with two derivatives modified with distinctly different side-chains, N,N'-di(dodecyl)-perylene-3,4,9,10-tetracarboxylic diimide (DD-PTCDI) and N,N'-di(nonyldecyl)-perylene-3,4,9,10-tetracarboxylic diimide (ND-PTCDI). Due to the different side-chain interference, the self-assembly of the two molecules results in totally different morphologies in aggregate: one-dimensional (1D) nanobelt vs zero-dimensional (0D) nanoparticle. The size, shape, and topography of the self-assemblies were extensively characterized by a variety of microscopies including SEM, TEM, AFM, and fluorescence microscopy. The distinct morphologies of self-assembly have been obtained from both the solution-based processing and surface-supported solvent-vapor annealing. The nanobelts of DD-PTCDI fabricated in solution can feasibly be transferred to both polar (e.g., glass) and nonpolar (e.g., carbon) surfaces, implying the high stability of the molecular assembly (due to the strong pi-pi stacking). The side-chain-dependent molecular interaction was comparatively investigated using various spectrometries including UV-vis absorption, fluorescence, X-ray diffraction, and differential scanning calorimetry. Compared to the emission of ND-PTCDI aggregate, the emission of DD-PTCDI aggregate was significantly red-shifted (ca. 30 nm) and the emission quantum yield decreased about three times, primarily due to the more favorable molecular stacking for DD-PTCID. Moreover, the aggregate of DD-PTCDI shows a pronounced absorption band at the longer wavelength, whereas the absorption of ND-PTCDI aggregate is not significant in the same wavelength region. These optical spectral observations are reminiscent of the previous theoretical investigation on the side-chain-modulated electronic properties of PTCDI assembly.

Quantitative analysis of the structure–hydrophobicity relationship for di- and tripeptides based on voltammetric measurements with an oil/water interface

The transfer of 18 di- and 27 tripeptides with un-ionizable amino acid side chains at a nitrobenzene/water (NB/W) interface was studied by cyclic voltammetry. The reversible half-wave potential (E(r)(1/2)), i.e., the midpoint potential could be accurately determined at pH 2 for both the facilitated and non-facilitated transfers, respectively, in the presence and absence of dibenzo-18-crown-6 (DB18C6) in NB. A multiple linear regression analysis was then performed for the E(r)(1/2) using the 'corrected' Dubois steric parameter for amino acid side chain substitutents. The result shows that the hydrophobicity of the peptides is governed not only by the intrinsic hydrophobicity of the peptide backbone and side chains, but also by the steric effects of side chain substituents. For the non-facilitated transfer of peptides, the steric effect of a bulky side chain is more significant at the N-terminus than at the C-terminus (and central for tripeptides). The more bulky the side chain at the N-terminus, the less hydrophobic the peptide becomes due to inhibition of the solvation of a terminal -NH(3)(+) group by organic solvents. For the facilitated transfer by DB18C6, however, the steric effect of a bulky side chain is the most significant at the central position of a tripeptide. A MOPAC calculation of optimized structures of DB18C6-peptide complexes has also shown that there is a notable steric hindrance between the central side chain and the benzene rings of DB18C6, which would reduce the 'apparent' hydrophobicity or transferability of the tripeptide.

The effect of side chain substituents on third-order optical nonlinearity of conjugated polymers: a theoretical study

We present a detailed investigation concerning the influence of phenyl side groups, adjacent to a carbon backbone, on the third-order nonlinear optical susceptibility χ (3)( ω) of conjugated polymers. A theoretical calculation of χ (3)( ω is carried out within the simple two-band model of the electronic structure of the polymer based on a tight-binding approximation. Our treatment takes into consideration two sources of optical nonlinearity: the interband transitions of π-electrons and combined (interband—intraband) ones. The influence of the substituent groups upon the electronic structure of the polymer is modeled by changing the Coulomb integral on the sites of the main chain to which the side groups are attached. We adopt the Genkin—Mednis approach to derive analytical expressions for χ (3)( ω) responsible for the third-harmonic generation, the intensity-dependent index of refraction and the two-photon absorption. The spectra χ (3)( ω) are evaluated numerically for all these effects and the resonance structure of the spectra is analyzed depending on the distance between the side groups and their coupling strength with the backbone. It is found that the interaction between the side groups and the backbone results in a change of the sign of χ (3) (0) from positive (which is predicted for polyacetylene) to negative and leads to an enhancement of the χ (3)(0) coefficient with increasing side-group separation along the backbone. The resonance behavior of χ (3)( ω) in the transparency region of the polymer also reveals remarkable differences from that observed experimentally in polyacetylene. Our results show that the optimal positioning of the substituent groups along the backbone may be promising for engineering new polymer materials with significantly enhanced nonlinear optical properties.

Orientation Effect of Side Chain Substituents in Aromatic Substitution. Induced Ortho Nitration

Abstract The presence of a free carboxyl or ester function on the α-carbon of toluene induces the nitration of the phenyl ring in the ortho position at or above the statistical value (chaperon effect), when pure HNO3 is used in CH2Cl2 solution. This is at variance with the results of classical nitration in H2SO4, where p-nitration predominates by far and m-nitration occurs at a remarkable extent. The new finding is explained in terms of precomplex formation.

Hydrophobicity of N‐Acetyl‐Di‐ and Tripeptide Amides Having Unionizable Side Chains and Correlation with Substituent and Structural Parameters

AbstractThe log P value of 53 N‐acetyl‐di‐ and tripeptide amides composed of amino acids having unionizable side chains was measured in a 1‐octanol/pH 7.0 aqueous buffer system. The factors governing the variations in the log P value among these protected peptides were quantitatively analyzed to formulate a correlation equation with free‐energy‐related physicochemical and substructural parameters. The log P value was governed by the sum of the hydrophobicity of side chains and the backbone as well as by the steric effects of side chain substituents on the relative solvation of the backbone CONH groups. The log P value was found to decrease by 0.6 log unit for the peptide bond, other factors being equal. For amino acids with polar side chains, the log P value was also affected by the “polar proximity factor” and/or intramolecular hydrogen bond formation in a way similar to that of zwitterionized peptides reported previously.

ChemInform Abstract: The Effect of Side Chain Substituents on the Intramolecular Diels‐Alder Reaction of the Furan Diene (VI): The Synthesis of (.+‐.)‐1,4‐Epoxycadinane (IX).

ChemInformVolume 20, Issue 38 Natural Products ChemInform Abstract: The Effect of Side Chain Substituents on the Intramolecular Diels-Alder Reaction of the Furan Diene (VI): The Synthesis of (.+-.)-1,4-Epoxycadinane (IX). C. ROGERS, C. ROGERS Dep. Chem. Biochem., Univ. Windsor, Ontario, Canada N9B 3PASearch for more papers by this authorB. A. KEAY, B. A. KEAY Dep. Chem. Biochem., Univ. Windsor, Ontario, Canada N9B 3PASearch for more papers by this author C. ROGERS, C. ROGERS Dep. Chem. Biochem., Univ. Windsor, Ontario, Canada N9B 3PASearch for more papers by this authorB. A. KEAY, B. A. KEAY Dep. Chem. Biochem., Univ. Windsor, Ontario, Canada N9B 3PASearch for more papers by this author First published: September 19, 1989 https://doi.org/10.1002/chin.198938330AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue38September 19, 1989 RelatedInformation

The effect of side chain substituents on the intramolecular diels-alder reaction of the furan diene: the synthesis of (±)-1,4-epoxycadinane

The effect of side chain substituents on the Intramolecular Diels-Alder reaction of the Furan diene (IMDAF) is reported in which the side chain connecting the furan diene to the dienophile contain four carbon atoms. The synthesis of 1,4-epoxycadinane utilizing this methodology is described.

Hydrophobicity of Di‐ and Tripeptides Having Unionizable Side Chains and Correlation with Substituent and Structural Parameters

AbstractAfter establishing experimental conditions to obtain a reliable partition ratio, P', we measured the value of 59 di‐ and tripeptides composed of amino acids having unionizable side chains in a 1‐octanol/pH 7.0 aqueous phosphate buffer system in order to approximate the true partition coefficient. We then formulated an equation correlating the variations of log P' (pH 7) among peptides with free‐energy‐related physicochemical parameters for the side chain substituents and substructures. The log P' value of di‐ and tripeptides is governed by the sum of the hydrophobicity of the peptide backbone and side chains as well as by the steric effect of side chain substituents on the relative solvation of backbone and terminal functional groups. For peptides containing amino acids with polar side chains, the log P' value is higher than that predicted by these effects. The difference is larger as the polar heteroatom in side chains gets closer to the backbone. This may correspond to the “polar proximity factor” for reductions of hydrophilicity observed when polar groups are crowded together. For the side chain of serine and threonine, the difference is even higher than that expected by the polar proximity effect, presumably due to intramolecular hydrogen bond formation.

ChemInform Abstract: THE TRIPLET STATE OF CHLOROPHYLLS

Chemischer InformationsdienstVolume 7, Issue 36 Physical Organic Chemistry ChemInform Abstract: THE TRIPLET STATE OF CHLOROPHYLLS RICHARD H. CLARKE, RICHARD H. CLARKESearch for more papers by this authorROBERT E. CONNORS, ROBERT E. CONNORSSearch for more papers by this authorTJEERD J. SCHAAFSMA, TJEERD J. SCHAAFSMASearch for more papers by this authorJOOP F. KLEIBEUKER, JOOP F. KLEIBEUKERSearch for more papers by this authorROELOF J. PLATENKAMP, ROELOF J. PLATENKAMPSearch for more papers by this author RICHARD H. CLARKE, RICHARD H. CLARKESearch for more papers by this authorROBERT E. CONNORS, ROBERT E. CONNORSSearch for more papers by this authorTJEERD J. SCHAAFSMA, TJEERD J. SCHAAFSMASearch for more papers by this authorJOOP F. KLEIBEUKER, JOOP F. KLEIBEUKERSearch for more papers by this authorROELOF J. PLATENKAMP, ROELOF J. PLATENKAMPSearch for more papers by this author First published: September 7, 1976 https://doi.org/10.1002/chin.197636037AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue36September 7, 1976 RelatedInformation

Researches on the chemistry of heterocyclic systems

Acidochromic condensation of benzylamides of diarylglycolic acids is used to extend the limits of the method of synthesis of 4, 4-diaryl-3-oxo-1, 2, 3, 4-tetrahydroisoquinolines and the effect of side-chain substituents on heterocyclic ring closure is investigated. The starting benzylamides are synthesized by treating esters of benzyloxamic acids with organomagnesium compounds, and acidochrome condensation of the benzylamides is effected by concentrated sulfuric acid. The UV spectra of the benzylamides and their condensation products have spectroscopic characteristics which closely resemble one another.