Chromophore Moieties Research Articles

Absolute configurations of phytotoxins seiricardine A and inuloxin A obtained by chiroptical studies

The absolute configuration (AC) of the plant phytotoxin inuloxin A, produced by Inula viscosa, and of the fungal phytotoxin seiricardine A, obtained from Seiridium fungi, pathogen for cypress, has been determined by experimental measurements and theoretical simulations of chiroptical properties of three related methods, namely, Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD). Computational prediction by Density Functional Theory (DFT) of VCD spectra and by Time-dependent DFT (TDDFT) of ORD and ECD spectra allowed to assign (7R,8R,10S) AC to naturally occurring (+)-inuloxin A. In the case of compound (−)-seiricardine A, which lacks useful for the analysis UV–Vis absorption, and thus provides a hardly detectable ECD spectrum and quite low ORD values, an introduction of a suitable chromophore by chemical derivatization was performed. The corresponding derivative, 2-O-p-bromobenzoate ester, gave rise to an intense ECD spectrum and higher ORD and VCD values. The comparison of computed spectra with the experimental ones allowed to assign (1S,2R,3aS,4S,5R,7aS) AC to (−)-2-O-p-bromobenzoate ester of seiricardine A and then to (−)-seiricardine A. This study further supports a recent trend of concerted application of more than a single chiroptical technique toward an unambiguous assignment of AC of flexible and complex natural products. Moreover, the use of chemical derivatization, with insertion of suitable chromophoric moieties has allowed to treat also UV–Vis transparent molecules by ECD and ORD spectroscopies.

Second-Order Polarizability and Temporal Stability of Epoxy Polymers Doped with Chromophore and with Chromophore Moieties in the Main Chain

Second-order nonlinear optical (NLO) properties and temporary stability of epoxy polymers based on diglycidyl ether of bisphenol A (DGEBA) both doped with p-nitroaniline (p-NA) and functionalized linear polymer DGEBA with p-NA moieties (attached to the bearing main chain) in the main chain (DGEBA-p-NA) have been investigated. Second-order polarizabilities of both p-NA and functionalized linear polymer DGEBA-p-NA were determined by a solvatochromic method. It was shown that this method could be successfully applied to determine the molecular second-order polarizabilities of both low-molecular mass chromophores and polymers with chromophore moieties attached to the chains. The relaxation behaviour of the doped and functionalized poled epoxy polymers has been studied. The crosslinked functionalized polymer DGEBA-p-NA exhibits the highest second-order NLO properties and temporal stability.

Photo‐induced controlled radical polymerization of methyl methacrylate mediated by photosensitive nitroxides

AbstractPhotosensitive nitroxides bearing different chromophore groups (benzophenone, naphthalene and quinoline) were synthesized and characterized. The photochemical properties of the synthesized products were investigated by UV−visible and fluorescence measurements. The results indicated that an efficient energy transfer from the chromophore moiety to the nitroxide radical moiety could occur within the molecular distances. The photo‐induced nitroxide‐mediated polymerization of methyl methacrylate (MMA) was performed using the photosensitive nitroxide/2,2‐dimethoxy‐2‐phenyl acetophenone as a bimolecular mediated system. The controlled character of the polymerization was confirmed by the linear tendency of molecular weight evolution with narrow molecular weight distribution (1.3−1.4). The experimental conditions, such as type of chromophore, initiator concentration and molar ratio of initiator/nitroxide, are discussed for a better understanding of the mechanism of the controlled polymerization. Using the polymerization products as macroinitiator, the chain extension reaction of MMA turned out to be able to re‐initiate further polymerization of the monomer. © 2014 Society of Chemical Industry

New “X-type” second-order nonlinear optical (NLO) dendrimers: fewer chromophore moieties and high NLO effects

A larger NLO effect with NLO coefficient of 195.2 pm V−1 was achieved with 3D-extended conformations, even with only 9 chromophore moieties in the dendrimer.

Polymorphism and mechanochromic luminescence of a highly solid-emissive quinoline-β-ketone boron difluoride dye

A highly solid-emissive boron difluoride dye exhibiting polymorphism-dependent and mechanochromic luminescence has been synthesized. Three single-crystal X-ray structures of the polymorphic dye molecule, having different fluorescence emissions, are elucidated. Each polymorph displays different stacking orientations among their chromophore moieties and several different intermolecular interactions, which could be related to their different crystal emissions. The molecule displays piezochromic characteristics, with the fluorescence and quantum yield of both the solid powder and two kinds of crystals being reversibly adaptable to mechanical force and heating. The conversion between the monomer and π–π stacking-induced aggregate has been proposed as the mechanism behind the mechanochromism, according to X-ray diffraction measurements and differential scanning calorimetry analyses.

The integration of an “X” type dendron into polymers to further improve the comprehensive NLO performance

Three polymers were designed and synthesized, by utilizing an “X” type dendrimer containing five nitro-based azo chromophore moieties, which exhibit good processability and good nonlinear optical performance, especially for NLO thermostability.

Fluorescent polymeric assemblies as stimuli-responsive vehicles for drug controlled release and cell/tissue imaging

Polymer assemblies with good biocompatibility, stimuli-responsive properties and clinical imaging capability are desirable carriers for future biomedical applications. Herein, we report on the synthesis of a novel anthracenecarboxaldehyde-decorated poly(N-(4-aminophenyl) methacryl amide-oligoethyleneglycolmonomethylether methacrylate) (P(MAAPAC-MAAP-MAPEG)) copolymer, comprising fluorescent chromophore and acid-labile moiety. This copolymer can assemble into micelles in aqueous solution and shows a spherical shape with well-defined particle size and narrow particle size distribution. The pH-responsive property of the micelles has been evaluated by the change of particle size and the controlled release of guest molecules. The intrinsic fluorescence property endows the micelles with excellent cell/tissue imaging capability. Cell viability evaluation with human hepatocellular carcinoma BEL-7402 cells demonstrates that the micelles are nontoxic. The cellular uptake of the micelles indicates a time-dependent behavior. The H22-tumor bearing mice treated with the micelles clearly exhibits the tumor accumulation. These multi-functional nanocarriers may be of great interest in the application of drug delivery.

Spectroscopic, Conductivity and Molecular Modeling Studies of the Inclusion Complex of TNDAB with Cucurbit[7]uril in Aqueous Solution

Abstract In this investigation, a novel surfactant (N, N, N-trimethyl-4-(5-decyloxy naphthalene-1-yloxy) butan-1-aminium bromide, TNDAB) with a naphthalene chromophore moiety was synthesized. The UV, fluorescence, conductivity measurements and molecular modeling have been carried out at 298 K for TNDAB + H2O, and TNDAB + CB[7] + H2O systems. The apparent critical micelle concentrations, the dissociation degree of the micelle, the hydrophobic contribution of the transfer free energy for the hydrocarbon chain of TNDAB, and the stoichoimetry, stability constant, and potential energy surface for the inclusion complex of TNDAB and CB[7] have been determined. The results suggested that CB[7] formed strong complex with TNDAB, the stoichoimetry of CB[7] and TNDAB was found to be almost 1:1, and hydrophobic interactions between the naphthalene nucleus of TNDAB and the cavity of the CB[7] are suggested to be the main driving forces in the association process. It also indicated that the naphthalene chromophore introduced can be as a spectral probe to examine the inclusion behaviors between host and guest molecules.

The influence of pentafluorophenyl groups on the nonlinear optical (NLO) performance of high generation dendrons and dendrimers.

With the aim to make the influence of pentafluorophenyl groups in the periphery of high generation dendrons and dendrimers on their NLO performance clearly, some NLO dendrons and dendrimers with different chromophore moieties or different end-capped groups were carefully designed and investigated in detail. The results demonstrated that some strong Ar-ArF interactions between the pentafluorophenyl groups in the periphery and the normal phenyl rings of the donors, could influence the topological structures of dendrons or dendrimers, and then affect their NLO performance. Furthermore, the optical transparency and the stability of the dendrons and dendrimers with pentafluorophenyl groups as end-capped moieties were all improved, in comparison with normal dendrons and dendrimers containing phenyl ones as the end-capped groups.

Host–Guest Chemistry of 1D Suprachannels and Dihalomethane Molecules: Metallacyclodimeric Ensembles Consisting of Zinc(II)-2,7-bis(nicotinoyloxy)naphthalene Complexes

Self-assembly of ZnX2 (X = Cl, Br, and I) with 2,7-bis(nicotinoyloxy)naphthalene (L) as a hemicircular bidentate ligand containing a chromophore moiety yields a systematic metallacyclodimeric unit, [ZnX2(L)]2. These basic skeletons constitute, via interdigitated π···π interactions, a unique columnar ensemble forming a suprachannel. This can then be employed as an unusual “diiodomethane within the suprachannel” host–guest system, CH2I2@[ZnX2(L)]2. Specifically, the suprachannel significantly stabilizes the CH2I2 molecules in the order [ZnI2(L)]2 > [ZnBr2(L)]2 > [ZnCl2(L)]2. This suprachannel has significant halogen effects on the photoluminescence (PL), thermal properties, and host–guest inclusion.

Synthesis and Application of Novel Reactive Disperse Dye Based on Tetrahydrobenzo[b] Thiophene Moiety

Ethyl 2-diazo-4, 5, 6, 7-tetrahydrobenzo[b] thiophene-3-carboxylate is reacted with malononitrile to give a hydrazone derivative. The latter product is reacted with 1-diazobenzene-4-β-sulphatoethylsulphone (PABSES) to give a disperse dye. The dye is synthesised by diazotisation and coupling reactions. First, it is synthesised with the chromophoric moiety of ethyl 2-hydrazomalononitrilo-4,5,6,7-tetrahydrobenzo[b] thiopheen- 3-carboxylate and coupled with diazonium salts that have the aforementioned reactive groups, thus yielding the new target reactive. The synthesised dye is applied onto wool, polyester and wool-polyester (blend) fabrics under typical exhaust dyeing conditions and their dyeing properties are investigated. The structure of this dye is characterised and confirmed by melting point, elemental analysis, infrared, ultraviolet-visible spectroscopy (UV/VIS) and nuclear magnetic resonance (1H-NMR) data. The dyeing of polyester, wool and polyester/wool blend fabrics with a reactive disperse dye gives very good build up and fastness properties by using a nonionic vinylsulphone (VS) derivative, which increases the substantivity of the dye towards wool fabric. Maximum exhaustion as well as total fixation efficiency by using a sulfatoethylsulfone (SES)-based dye on wool fabric is achieved at a neutral pH of 7. This feature of the dye structure significantly improves the union dyeing of wool/polyester blend fabrics with very good build up and fastness properties.

Lamellar‐Twisting‐Induced Circular Dichroism of Chromophore Moieties in Banded Spherulites with Evolution of Homochirality

Banded spherulites are formed by crystallization of a chiral polymer that is end-capped with chromophore. Induced circular dichroism (ICD) of the chromophore can be found in the crystallized chiral polymers, giving exclusive optical response of the ICD. The ICD signals are presumed to be driven by the lamellar twisting in the crystalline spherulites, and the exclusive optical activity is attributed to the chirality transfer from molecular level to macroscopic level. To verify the suggested mechanism, the sense of the lamellar twisting in the crystalline spherulite is determined using PLM for the comparison with the ICD signals of the chromophore in the electron circular dichroism spectrum. The conformational chirality of the chiral polymer is determined by the vibrational circular dichroism spectrum. On the basis of the chiroptical results, evolution of homochirality from helical polymer chains (conformational chirality) to lamellar twisting in the banded spherulite (hierachical chirality) is suggested.

Lamellar‐Twisting‐Induced Circular Dichroism of Chromophore Moieties in Banded Spherulites with Evolution of Homochirality

AbstractBanded spherulites are formed by crystallization of a chiral polymer that is end‐capped with chromophore. Induced circular dichroism (ICD) of the chromophore can be found in the crystallized chiral polymers, giving exclusive optical response of the ICD. The ICD signals are presumed to be driven by the lamellar twisting in the crystalline spherulites, and the exclusive optical activity is attributed to the chirality transfer from molecular level to macroscopic level. To verify the suggested mechanism, the sense of the lamellar twisting in the crystalline spherulite is determined using PLM for the comparison with the ICD signals of the chromophore in the electron circular dichroism spectrum. The conformational chirality of the chiral polymer is determined by the vibrational circular dichroism spectrum. On the basis of the chiroptical results, evolution of homochirality from helical polymer chains (conformational chirality) to lamellar twisting in the banded spherulite (hierachical chirality) is suggested.

Room temperature enhanced blue–green, yellow–orange and red phosphorescence from some compounds of the type (CH3NH3)n−1(1-naphthylmethyl ammonium)2Pbn(ClxBr1−x)3n+1 (with n=1, 2 and 0≤x≤1) and related observations from similar compounds

The photoluminescence spectra of particulate organic–inorganic hybrid compounds, such as (CH3NH3)(C10H7CH2NH3)2Pb2Cl7, (CH3NH3)(C10H7CH2NH3)2Pb2(Cl0.65Br0.35)7 or (C10H7CH2NH3)2PbBr4 and (C10H7CH2NH3)2PbBr4-water, observed with 350nm excitation, exhibit a blue–green, a yellow–orange and a red phosphorescence band, respectively. The observation of enhanced light emission with a naked eye, even at room temperature, is attributed to the energy transfer from Wannier excitonic levels of inorganic to several states of the organic moiety, namely to the energy levels close to those of dimers, trimers, and tetramers of chromophore moieties. The experimental results are in qualitative agreement with those obtained theoretically by others, applying ab initio calculations. The results were compared with those obtained from 2-naphthylmethyl, 4-phenylbenzyl and 9-pyrenylmethyl analogues.

Pyrene-conjugated porphyrins for efficient mesoscopic solar cells: the role of the spacer

Pyrene-conjugated porphyrin dyes with various π-spacers between the porphyrin chromophore and carboxylic acid moiety have been designed and synthesized in this study, showing an overall power conversion efficiency of 8.7% under full sunlight (AM 1.5G, 100 mW cm−2) irradiation.

Attempt to Improve the Performance of Pyrrole-Containing Dyes in Dye Sensitized Solar Cells by Adjusting Isolation Groups

Four new pyrrole-based organic sensitizers with different isolation groups were conveniently synthesized and applied to dye sensitized solar cells (DSCs). The introduction of isolation group in the side chain could both suppress the formation of dye aggregates and electron recombination. Especially, when two pieces of D-π-A chromophore moieties shared one isolation group to construct the "H" type dye, the performance was further improved. Consequently, in the corresponding solar cell of LI-57, a short-circuit photocurrent density (Jsc) was tested to be 13.85 mA cm(-2), while 0.72 V for the open-circuit photovoltage (Voc), 0.64 for the fill factor (FF), and 6.43% for the overall conversion efficiency (η), exceeding its analogue LI-55 (5.94%) with the same isolation group. The results demonstrated that both the size (bulk and shape) and the linkage mode between the D-π-A chromophores and the isolation groups, could affect the performance of sensitizers in DSCs in a large degree, providing a new approach to optimize the chemical structure of dyes to achieve high conversion efficiencies.

2‐Methoxynaphthylnaphthoquinone and its solvate: synthesis and structure–properties relationship

Because of their unique visual optic and electronic properties, substituted quinones are commonly used as dyes and pigments; nevertheless, a theoretic background of relationship between the structures and optical properties of such compounds seems to be still undeveloped. Two crystalline forms of 2‐methoxynaphth‐1‐yl‐naphthoquinone (MNQ) have been synthesized and characterized by means X‐ray, NMR, UV–VIS, as well as, MS spectroscopy. The interpretation of intriguing optical properties of two crystalline forms of MNQ, based on detailed spectral and structural characterization, as well as, DFT and MP2 computations clearly connects the conformation of the molecules with their optical and electronic properties. Thus, flatter conformation, stabilized by crystal net force, favours the intense electron density transition from auxochrome to chromophore moiety (which corresponds excitation from HOMO to LUMO), as well as, favours the π‐stacking interaction, that eventually results in colour enhancement. At the same time, small molecules of solvents included into the crystal net allow molecules of arylnaphthoquinones to adopt less rigid conformation what has a dramatic optical outcome. Copyright © 2013 John Wiley & Sons, Ltd.

Second-order nonlinear optical hyperbranched polymer containing isolation chromophore moieties derived from both “H”-type and star-type chromophores

An NLO hyperbranched polymer (HP1) derived from both “H”-type and star-type chromophores was synthesized successfully for the first time with high yield via one-pot “A2 + B3” Suzuki polymerization reaction. Isolation chromophore was also introduced to further improve its performance. Although under the test conditions, the films of HP1 could not be poled completely, it still demonstrated satisfactory macroscopic NLO effect with the second harmonic generation (SHG) coefficient d 33 value of 36 pm/V.

Introduction of an Isolation Chromophore into an "H"-Shaped NLO Polymer: Enhanced NLO Effect, Optical Transparency, and Stability.

In this study, a new polymer P1 embedded with "H"-type chromophore moieties was designed and synthesized through Suzuki coupling copolymerization, in which the isolation chromophore was introduced to further improve its comprehensive performance. This polymer demonstrated good solubility and film-forming ability. In comparison with normal "H"-shaped NLO polymers only containing one type of chromophore, nearly all the performance of P1 was improved. Its NLO coefficient was as high as 134 pm V-1 , and its onset temperature for decay was up to 150 °C. Coupled with its improved optical transparency, all these properties made it a promising candidate for practical applications in photonic fields.

Second-order nonlinear optical (NLO) polymers containing perfluoroaromatic rings as isolation groups with Ar/ArF self-assembly effect: Enhanced NLO coefficient and stability

Four new polyaryleneethynylenes P1–P4, which contained different aromatic or perfluoroaromatic isolation groups, were successfully prepared, via the palladium-catalyzed Sonogashira coupling reaction. Among them, P2, due to the presence of the self-assembly effect between the perfluoroaromatic and chromophore moieties, demonstrated much larger NLO effect (d33 value of 162.3 pm/V) and better stability with onset temperature for decay (111 °C). The research on the polymer conformation suggested that perfluorophenyl groups in different positions would result in different effects on the NLO coefficient, providing some useful information for the design of NLO polymers with better performance.