Abstract  Novel direction-controlled movements of microribbons self-assembled from perylene diimide molecules are reported on various hydrophobic surfaces under scanning laser irradiation. A "dynamic exciton charge model" is developed to elucidate the underlying mechanism. The findings provide an innovative strategy for the design of microscale systems capable of continuous and directional movement driven by light.

Abstract  Based on a perylene diimide derivatives(PDIs) platform, AM-PDIs was rationally designed and synthesized as a new calorimetric and ratiometric fluorescent sensor for naked-eye detection of fluoride ion with high selectivity over other halide ions. Addition of fluoride ion to a dichloromethane(DCM) solution of AM-PDIs resulted in an obvious color change (from red to blackish green) because of a large red shift (151 nm) in absorption. The recognition mechanism was attributed to the intermolecular proton transfer between a hydrogen atom on the amide N position of sensor and the fluoride anion. The detection limit was calculated to be 0.14 mu M. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  Core-shell (CS) CdSe/ZnS quantum dots (QD) capped with ligands that possess a mercapto or an amino group and a naphthalimide (NI) as chromophore unit, linked by a short ethylene chain (CS@S-NI and CS@H2N-NI, respectively), have been synthesized and fully characterized by infrared and nuclear magnetic resonance spectroscopies, high-resolution transmission electron microscopy, and voltammetry as well as by steady-state absorption and emission spectroscopies. The organic ligands HS-NI and H2N-NI act as bidentate ligands, thereby causing a drastic decrease in the QD emission. This was particularly evident in the case of CS@S-NI. This behavior has been compared with that of commercially available QDs with octadecylamine as the surface ligand and a QD capped with decanethiol ligands (CS@S-D). The interaction between the anchor groups and the QD surface brings about different consequences for the radiative and nonradiative kinetics, depending on the nature of the anchor group. Our results suggest that the naphthalimide group "stabilizes" empty deep trap states due to the carbonyl group capacity to act as both a sigma-donor and a pi-acceptor toward cations. In addition, the thiolate group can induce the location of electron density at shallow trap states close to the conduction band edge due to the alteration of the QD surface provoked by the thiolate binding.

Abstract  Two novel fluorescence resonance energy transfer-based perylenediimide-naphthalimide dendrons with perylenediimides as the energy acceptor, tertiary amines as the proton or metal receptor and naphthalimide as the energy donor were successfully synthesized. The dendrons exhibited high selectivity toward Fe(III) in the presence of various other metal cations and exhibited sensitivity to protons. A 1:2 stoichiometry was found for the complex formed by the probes and Fe(III) using a Job's plot and by non-linear least square fitting of the fluorescence titration curves. The probe molecules present abilities of fast fluorescence detection of Fe(III) and for the fluorescent detection of protons with high energy transfer efficiency of 96-98%. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  A series of potential optical brightening agents - 4-aryloxy-N-(2',6'-diisopropylpheny1)-1,8-naphthalimides are synthesized and their photo-physical properties are experimentally determined. Interestingly, it is found that their quantum efficiencies or quantum yields are exclusively dependent on the substituents on the aryloxy group at the 4-position. It is postulated that the electronic effect of the substituents influences the photo-induced electron transfer process, which causes a variation in quantum efficiencies. Due to analysis of charge transfer from 1,8-naphthalimide molecular part to its substituents in dichloromethane based on the time-dependent density functional theory at Becke 3-parameters Lee-Yang-Parr level coupling with the 6-31G(d) basis set in the conductor-like polarizable continuum model with the united atom topological model computations, it is found that computed charge transfers of these serial compounds correspond well with their experimental quantum yields. Validation of the calculation method is performed by experimental determination of the quantum yield of the nitro-substituted compound. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  Photoluminescent dyes (aminofluorene, naphthalimide, naphtholbenzein, or phenosafranine) were grafted to polyurethane using an allophanate linkage. The photoluminescence properties and the shape recovery effects of polyurethane samples were investigated. The polyurethane was composed of 4,4'-methylenebis (phenylisocyanate), poly(tetramethyleneglycol), and 1,4-butanediol. The dyes were linked through an extra 4,4'-methylenebis(phenylisocyanate) and the carbamate moiety of the polyurethane chains. Polyurethanes with various dye contents were characterised, and the shape recovery and photoluminescence properties were compared. In the case of the tensile mechanical properties, the highest maximum stress was 56 MPa, and the strain remained > 1500% for the entire series. The shape recovery improved as the test cycle was repeated, with up to 100% recovery being achieved, but shape retention decreased as the dye content increased. Finally, the photoluminescence of the polyurethanes was demonstrated by a luminescent light-emission test, together with pH indication capability and the preparation of non-woven fibre using the electrospinning method.

Abstract  N-type organic field-effect transistors (OFET's), based on two perylene diimide semiconductors (PDI-8 and PDI-8CN(2)) exhibiting very different air sensitivities, have been fabricated on Si/SiO2 substrates. These OFETs have been electrically characterized in vacuum both in the dark and under white-light illumination by dc transfer and output curves, bias stress experiments and variable temperature measurements. In particular, the combination of variable temperature and light illumination experiments is shown to be a powerful tool to clarify the influence of charge trapping on the device operation. Even if, in vacuum, the air-sensitive PDI-8 devices display slightly better performances in terms of field-effect mobility and maximum current values, according to our results, charge transport in PDI-8 films is much more affected by charge trap states compared to PDI8-CN2 devices. These trapping centers are mainly active above 180 K, and their physical nature can be basically ascribed to the interaction between silanol groups and water molecules absorbed on SiO2 surface that is more active above the H2O supercooled transition temperature.

Abstract  Composites of the tetra-anion of he perylene dye N,N'-di(phenyl-3,5-disulfonic acid) perylene-3,4,9,10-tetracarboxydiimide (PBITS) with layered double hydroxides (LDHs) were formed by direct synthesis (co-precipitaiton at constant pH). The LDHs were of the hydrotalcite (Mg-Al-OH and Zn-Al-OH compositions). During synthesis of the hydrocalumite type (Ca-Al-OH), partial destruction of the dye occurs, being more pronounced at higher pH values. The composites were characterized with regard to their composition by elemental and thermal analysis. From UV-vis spectroscopic data and powder X-ray diffraction, a structural model is developed for the composites. In the galleries between the hydroxide layers, the chromophore molecules are stacked in an J-type arrangement. The compounds have brilliant colors and are insoluble in common solvents. With regard to a possible application as pigments, their photostability and their chemical resistance against a typical application environment was tested. The photostability of the dye molecules and their chemical resistance against setting cement are slightly raised by the occlusion within the LDH structure, however, the photostability of the LDH-cement is lower than that of cement with the pure perylene dye.

Abstract  Langmuir-Blodgett (LB) films formed of some fluorescent dyes, namely derivatives of 4-aminonaphthalimide, and their binary mixtures with the liquid crystal 4-heptyl-4'-cyanobiphenyl (7CB) have been studied. The electronic absorption and fluorescence spectra were recorded. On the basis of these spectra, the spectral properties of the dyes and the intermolecular interactions in ultrathin ordered films were determined. The conclusions about the tendency to the creation of aggregates by dye molecules in LB films have been drawn. The measurements of absorption by using linearly polarised light have allowed us to determine the arrangement of the dye and liquid crystal molecules on the air-solid substrate interface.

Abstract  A new method for the synthesis of 4-allyloxy-1,8-naphthalimide derivatives (fluorescent brighteners) using phase transfer catalysis is reported. Four, 4-allyloxy-1,8-naphthalimide fluorescent brighteners were synthesized in good yield and their absorption and fluorescent spectra were determined. The suitability of the monomeric fluorescent brighteners for copolymerization with styrene was also demonstrated. The content of the chemically bound fluorescent brightener in the polymer chain was estimated. (C) 2001 Elsevier Science Ltd. All rights reserved.

Abstract  The synthesis of new 9-phenylxanthene dyes, containing hindered amine stabilizer fragment is reported. Two polymerizable dyes, a combination of Fluorescein or Eosin with 2,2,6,6-tetramethylpiperidine, as well as two 9-phenylxanthene intermediates were synthesized in good yields under variable reaction conditions. Their light absorption and fluorescence properties in solution have been determined and discussed. Photooxidative stability of the new fluorophores has been studied and compared to other similar fluorescent dyes, not containing hindered amine fragment in their molecules. It was shown that the presence of a HALS (hindered amine light stabilizer) fragment in the dyes' molecules improved their photostability. The ability of the dyes to co-polymerize with vinyl monomers such as methyl methacrylate was demonstrated. (c) 2006 Published by Elsevier Ltd.

Abstract  Composite nanofibrous thin films of a cationic, water-soluble perylene diimide and oppositely charged polyelectrolyte are prepared by sequential deposition from separate aqueous solutions of the two precursors. These materials may find future applications as semiconducting "wires" in organic electronics and photovoltaics. A new asymmetrically substituted perylene diimide (designated C11OPDI+) incorporating a hydrophobic ether tail is employed in their synthesis. Poly(acrylate) is used as the polyelectrolyte. Solution-phase and thin-film spectroscopic data show the composites form by binding and aggregation of C11OPDI+ to the polyelectrolyte. Tapping-mode AFM data show that the resulting nanofibers are tens of micrometers in length and are highly curved. Cross-sectional fiber size is shown to depend on the number of deposition cycles. Polarization-dependent fluorescence microscopy indicates the C11OPDI+ chromophores align perpendicular to the local long axis of the nanofibers. The C11OPDI+ molecules are concluded to form tail-to-tail parallel d-stacked structures that run along the fiber axis and are sandwiched between polyelectrolyte regions. In comparison to alternative methods, nanofiber formation is shown to be greatly enhanced when the composite is prepared by sequential deposition. A mechanism for enhanced fiber formation involving slow growth and solvent annealing of the composites is proposed.

Abstract  A series of quadrupolar and tribranched molecules were synthesized in order to examine the role of the edge substituents on their photophysical and two-photon absorption properties. Two-photon absorption cross sections, delta, of the molecules were determined in THF solution using a two-photon excited fluorescence technique with femtosecond pulsed excitation. The quadrupolar molecules contained a fluorene or alcoxy-substituted phenylene central core together with various electron accepting edge substituents such as pyridine, terpyridine, phthalimide and naphthalimide. The tribranched molecules contained triphenylamine at the center and terpyridine or phthalimide substituents at the periphery. It was found that edge phthalimide substituent favour high h values. 6 Values as high as 1660 GM and 1500 GM were obtained from the phthalimide-fluorene-phthalimide and phthalimide-phenylene-phthalimide molecules. respectively; in the case of the tribranched molecule with a phthalimide substituent, a delta-value of 1200 GM was found. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  The preparation of smart photonic gels composed of two orthogonally self assembled fibrillar networks is reported. The molecular gelators are a light acceptor derived from 4-amino-1,8-naphthalimide and an acridine-based energy donor. Fibrillar orthogonal assembly of both chromophores is a requisite for light harvesting to be observed which results in emission from the naphthalimide-based acceptor upon irradiation of the acridine-derived donor with a significant Stokes shift of ca. 200 nm. Energy transfer is present both in the form of molecular gels in acetonitrile and in the solid-like xerogels and efficiently visualized both by fluorescence spectroscopy and confocal laser scanning microscopy. The chameleonic, stimuli responsive behavior is linked to the fact that the gel network formed by the acridine derivative can be selectively disassembled by means of temperature changes or chemical species. For example, the light harvesting process can be switched off/on by addition of HCl or NaOH respectively, affording a new type of stimuli responsive photonic soft materials.

Abstract  A fluorophorel-spacer-receptor-spacer-fluorophore, dyad was prepared and photophysically characterized. The two spectrally well-differentiated fluorophores are 1,8-naphthalimide and its 4-amino-substituted derivative, the latter showing strong ICT emission. The receptor unit consists of a tertiary amine, which leads to site-selective PET (only the 1,8-naphthalimide part gets quenched). This process can be blocked by protonation of the tertiary amine, which, on the other hand, results in enhanced singlet-singlet energy transfer between the 1,8-naphthalimide and 4-amino-1,8-naphthalimide parts (Phi(EET) = 0.27 and 0.59 for neutral and monoprotonated form, respectively). In acetonitrile, the monoprotonated form can be deprotonated by sufficiently basic anions like fluoride in micromolar concentration (<20 mu M). The observed fluorescence\ quenching, due to PET-reactivation, is ca. 41%. Further addition of fluoride in concentrations > 1 mM leads to deprotonation of the 4-amino group of one of the naphthalimides, which is accompanied by more fluorescence quenching (ca. 93%). The resulting double-sigmoidal titration curve enables the implementation of ternary logic. Using fluoride anions as degenerate inputs results in a ternary NOR logic gate, which is demonstrated for the first time.

Abstract  A series of galactosyl naphthalimide-piperazine derivatives have been synthesized as intracellular pH and lysosome-targeting imaging probes for live human hepatoma cells. The probes show good sensitivity in both aqueous buffer and intracellular environments. Incorporation of the galactose moiety with the pH probes facilitates their specific endocytosis and, thus targeted trafficking to lysosome, by the asialoglycoprotein receptor of human hepatoma cells. The acidic intracellular pH of live human hepatoma cells gives rise to a fluorescence "turn-on" signal of the probes probably via a modulation of the photo induced electron transfer (PET) mechanism. Additionally, galactosylation of the probes enhances their selective accumulation in lysosome and decreases the cytotoxicity. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (Ia and Ib, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA-CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (Ia and Ib, respectively) for the use of single-molecule fluorescence microscopy measurements. (C) 2013 Elsevier Ltd. All rights reserved.

Abstract  Solubility studies were performed in aqueous solutions of 1,8-naphthalimides and 1,4,5,8-naphthalenediimides (Scheme 1). A large solubility increase was found for N-butyl-1,8-naphthalimide (MBN) and N,N'-dibutyl-1,4,5,8-naphthalenediimide (DBN) in the presence of a-cyclodextrin (alpha-CD), indicating the formation of inclusion complexes. The presence of the N-butyl group is required for complex formation, leading to the conclusion that the butyl groups are the binding sites for alpha-CD. Accordingly, the analysis of solubility isotherms for the systems MBN/alpha-CD and DBN/alpha-CD showed the presence of 1:1 complexes for the former and of both 1:1 and 1:2 complexes for the latter. Association constants for the two systems were estimated, giving K = 470 M-1 for the MBN/alpha-CD complex and K-11 = 1316 M-1 and Kit = 329 M-1 for the stepwise association constants in the DBN/alpha-CD system. MBN undergoes hydrolysis in water, but the reaction is inhibited upon complexation with alpha-CD. The remarkable solubilization in water and stabilization toward hydrolysis makes these novel complexes of imides and diimides with alpha-CD potentially useful in the pharmaceutical applications known for these imides, as well as in the preparation of new materials, like polyimide-based polyrotaxanes.

Abstract  Perylenediimide (PDI)-based materials exhibit great potential as non-fullerene acceptors in bulk-heterojunction (BHJ) organic solar cells (OSCs). Recent investigations have revealed that PDI molecules with a twisted structure could disrupt aggregation of perylene unit. Here, we present a PDI monomer via bay-substitutions with four fused naphthalene units by three-step reactions, named TN-PDI. The introduction of four fused naphthalene rings into the bay positions of PDI unit leads to a strong steric hindrance with a twist angle of 33 degrees between the two PDI subplanes. Blended with a wide-band gap polymer donor (PDBT-T1), the TN-PDI based non-fullerene solar cells show power conversion efficiency (PCE) of 3.0%. Our results indicate that the bay-substitutions with fused aromatic substitutions could be an efficient approach to develop monomeric PDI acceptors.

Abstract  The system surface was labeled with blue emitting 1,8-naphthalimide "donor" dyes capable of absorbing light and efficiently transferring the energy to a single yellow-green emitting 1,8-naphthalimide "acceptor" dye. The overlap between the blue emission of the donor and the absorbance of the acceptor (focal dye) was >70%. Due to the energy transfer from the periphery to the focal 1,8-naphthalimide chromophore (67%) the core fluorescence (lambda(ex) = 360 nm) was enhanced >36 times. It was also found that the novel light harvesting system displayed sensitive fluorescence signaling over a wide pH scale, which was ascribed to photoinduced electron transfer from the dendron bone to the blue emitting periphery. In acidic media the electron transfer was "switched off" and, in turn, the periphery emission was "switched on", resulting in energy transfer enhancement to the focal chromophore up to 92%. This indicates the high potential of the novel light harvesting system as an efficient pH hemosensing material. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  Four unsaturated derivatives of 1,8-naphthalimide have been synthesized and their spectrophotometric properties and Cielab colour coordinates determined. They can copolymerize with styrene, and the coloured polymers thus obtained have good resistance to wet treatments and to organic solvents.

Abstract  The present study describes the infrared characterization of some newly synthesized photoactive poly(amidoamine) dendrimers, whose peripheries have been modified with 1,8-naphthalimides. Main attention is being paid to the effect that different substituents at C-4 position of the naphthalene ring have upon the dendrimers polarization. Infrared studies have shown that the dendrimer generations have similar polarizations as the dendrimer molecules wherein no intermolecular hydrogen bonds occur. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract  Novel poly(propylenamine) first and second generation dendrimers in which the periphery was modified with 1,8-naphthalimide units were synthesized. Acetonitrile solutions of the materials were subjected to photophysical investigation to evaluate their capability to detect metal cations, by monitoring changes in their absorption and fluorescence spectra in the presence of Ag(+), Cu(2+), Co(2+), Ni(2+), Fe(3+) and Zn(2+). The potential of the dendrimers to detect metal ion pollutants was estimated. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  Novel non-fullerene acceptors with an A(1)-A-A(1) framework were designed and synthesized, in which benzothiadiazole and diketopyrrolopyrrole building blocks were employed as the A unit and naphthalimide units were incorporated as the A(1) units. Both acceptor systems exhibited a broadened absorption spectra from 300 nm to 700 nm in contrast to that of fullerene derivatives. Meanwhile, high lying LUMO energy levels were also observed for both developed acceptors. To investigate photovoltaic properties of the acceptors, bulk-heterojunction organic solar cells were fabricated using an established electron donating polymer as the donor material. As anticipated, efficient non-fullerene OSCs with high Voc values up to 1.01-1.12 V were achieved when the new molecules were employed as electron acceptors, leading to the PCE values of 1.23% and 1.64% in their solar cells. Our results here demonstrate that the A(1)-A-A(1) type small molecule containing naphthalimide building blocks in molecular backbone could be the promising electron acceptor in organic solar cells. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  In this paper, the surface modi. cation of silk fiber using anhydrides to graft the polysaccharide chitosan and dyeing ability of the grafted silk were studied. Silk fiber was degummed and acylated with two anhydrides, succinic anhydride (SA) and phthalic anhydride (PA), in different solvents (dimethyl sulfoxide (DMSO) and N,N-dimethyl formamide (DMF)). The effects of anhydrides, solvents, anhydride concentration, liquor ratio (L: R) and reaction time on acylation of silk were studied. The polysaccharide chitosan was grafted to the acylated silk fiber and dyed by acid dye (Acid Black NB. B). The effects of pH, chitosan concentration, and reaction time on chitosan grafting of acylated silk were investigated. The physical properties show sensible changes regardless of weight gain. Scanning electron microscopy (SEM) analysis showed the presence of foreign materials firmly attached to the surface of silk. FTIR spectroscopy provided evidence that chitosan was grafted onto the acylated silk through the formation of new covalent bonds. The dyeing of the chitosan grafted-acylated silk fiber indicated the higher dye ability in comparison to the acylated and degummed silk samples. The mechanism of chitosan grafting over degummed silk through anhydride linkage was proposed. The findings of this research support the potential production of new environmentally friendly textile fibers. It is worthwhile to mention that the grafted samples have antibacterial potential due to the antibacterial property of chitosan molecules. (C) 2008 Elsevier B. V. All rights reserved.