Abstract  Di-(N-butanoic acid-1,8-naphthalimide)-piperazine dithienylethene was covalently linked to a cysteamine monolayer associated with a Au surface to yield a photoisomerizable monolayer composed of the open or closed dithienylcyclopentene isomers (3a or 3b), respectively. Electrochemical and XPS analyses reveal that the association of metal ions to the monolayer is controlled by its photoisomerization state. We find that Cu(2+) ions reveal a high affinity for the open (3a) monolayer state, K(a) = 4.6 × 10(5) M(-1), whereas the closed monolayer state (3b) exhibits a substantially lower binding affinity for Cu(2+), K(a) = 4.1 × 10(4) M(-1). Similarly, Ag(+) ions bind strongly to the 3a monolayer state but lack binding affinity for the 3b state. The reversible photoinduced binding and dissociation of the metal ions (Cu(2+) or Ag(+)) with respect to the photoisomerizable monolayer are demonstrated, and the systems may be used for the photochemically controlled uptake and release of polluting ions. Furthermore, we demonstrate that the photoinduced reversible binding and dissociation of the metal ions to and from the photoisomerizable electrode control the wettability properties of the surface.

Abstract  Fluorene-containing N boolean AND N Pt(II) bisacetylide complexes were prepared, in which the fluorene moieties were connected to the Pt(II) center via acetylide bonds (-C C-). Different aryl groups were attached to the fluorene moiety, such as phenylacetylide (Pt-4), naphthalimide-4-acetylide (Pt-1) and in Pt-2, the fluorene moiety was changed to carbozale moiety. We found that with the fluorene linker between the arylacetylide and the Pt(II) center, the absorption of complexes in the visible range were intensified. All the complexes show room temperature (RT) phosphorescence. Furthermore, Pt-1 shows much longer triplet excited state lifetime (tau = 138.1 mu s) than the analogue Pt-3 (tau = 47.4 mu s). For Pt-2, with changing the fluorene moiety to carbazole moiety, the T-1 state lifetime becomes much shorter (tau = 23.0 mu s). Thus the one-atom (N vs. C) difference is crucial for the photophysical properties. The triplet excited state of Pt-1 was proved to be the intraligand excited state ((IL)-I-3) by nanosecond time-resolved transient absorption spectroscopy, spin density analysis and emission at 77 K. The complexes were used as triplet sensitizers for triplet-triplet annihilation (TTA) upconversion. Upconversion quantum yield (Phi(UC)) up to 24.3% was observed for Pt-1. Under the same conditions the model complex Pt-4 shows no upconversion. The overall upconversion efficiency (eta) of the new complexes are improved compared to the model complexes, such as Pt-2, Pt-3 and Pt-4. The improved upconversion efficiency was attributed to either the prolonged T-1 excited state lifetime or the intensified absorption in the visible range. Our study on the fluorene-containing N boolean AND N Pt(II) bisacetylide complexes will be useful for designing new phosphorescent Pt(II) complexes and for their applications.

Abstract  This paper reports the synthesis and electrochemical and optical properties of two molecular dyads (Dyad 1 and Dyad 2) consisting of a 2,7-bis(4-(diarylamino)styryl)carbazole two-photon-absorbing donor chromophore, connected by different linkers to a perylene diimide (PDI) acceptor. The photoinduced charge transfer in these compounds is characterised using transient absorption measurements. The use of the compounds for optical limiting is discussed; because of spectral overlap between the donor two-photon absorption band and the one-photon absorption band of the PDI radical anion, the dyads exhibit enhanced nonlinear absorption at wavelengths between 700 and 800 nm relative to that seen for the two-photon absorbing donor chromophore. The stronger nonlinear absorption observed for Dyad 1 vs. Dyad 2 is attributed to a higher yield of photo-generated radical ions and a longer lived charge-separated state, resulting from differences in the linker between the donor and acceptor.

Abstract  A perylenetetracarboxylic diimide derivative, N-n-hexyl-N'-(2-hydroxyethyl)-1,7-di(4'-t-butyl)phenoxy-perylene-3,4:9,10-tetracarboxylic diimide (HO-PDI), was synthesized and self-assembled as a monolayer thin solid film on the modified surface of a quartz substrate by an ester bond between -OH groups of HO-PDI molecules and -COOH groups of p-phthalic acid grafted onto the hydrophilic pretreated SiO(2) surface. An analysis of the spectral change revealed the J-aggregate nature of HO-PDI molecules in the obtained thin solid film. With this thin solid film of HO-PDI as a template, CdS nanoparticles were deposited on it in situ, which were further characterized by electronic absorption, fluorescence, and energy-dispersive X-ray spectroscopy (EDS). The morphology of CdS nanoparticles is disklike, and the diameter is ca. 140 nm as determined by atomic force microscopy (AFM). Furthermore, electron transfer between the organic layer and CdS nanoparticles was deduced through fluorescence quenching and theoretical analysis.

Abstract  In solution-processed non-fullerene small-molecule solar cells (NF-SMSCs), the bulk-heterojunction active layer is blended by a small molecule donor and a non-fullerene small molecule acceptor. Synthesis of solution-processed small molecule donors is of the same importance as designing non-fullerene small molecule acceptors. In this paper, a new solution-processed diketopyrrolopyrrole (DPP)-based small molecule donor, namely DPP-BDT-T, was synthesized. The pure DPP-BDT-T film covers a broad spectrum from 500 nm to 700 nm with a low band gap of 1.72 eV. By choosing our newly reported perylene diimide (PDI) dimer, bis-PDI-T-EG, as the non-fullerene small molecule acceptor, the best NF-SMSC device showed a low efficiency of 0.12%. When using 2% 1,8-diiodooctane (DIO) as the additive, more acceptor molecules formed into pi-pi-stacks, accompanied by the increase of the phase size from 15 nm to 50 nm and the formation of continuous interpenetrating networks. This in turn enhanced the hole and electron mobilities (mu(h) = 1.6 x 10(-2) vs. 5.8 x 10(-4) cm(2) V-1 s(-1) and mu(e) = 2.3 x 10(-5) vs. 6.1 x 10(-7) cm(2) V-1 s(-1)) and the efficiency was enhanced to 1.6%. In another respect, the fluorescent emission from the blend films was enhanced by 10 times after using 2% DIO as the additive, suggesting less efficient photon-induced exciton separation at the interfaces of the donor and acceptor nanostructures. Accordingly, our case suggests that efficient sweepout of the separated electrons and holes from the nanostructural interfaces plays a role for efficient NF-SMSCs.

Abstract  The properties are discussed of organic-on-inorganic (OI) semiconductor contact barrier diodes, where the 3, 4, 9, 10 perylenetetracarboxylic diimide (PTCDI) and the copper phthalocyanine (CuPc) serve as the organic thin film. The results presented can be fully understood in terms of the thermionic emission-space-charge-limited (TE-SCL) current model introduced for OI structures with prototypical aromatic compound; 3, 4, 9, 10 perylenetetracarboxylic dianhydride (PTCDA) vapour-deposited onto n- and p-Si substrates. Also, under moderate and high reverse bias voltages the results obtained can be understood in terms of the organic-on-inorganic heterojunction (OI-HJ) model. Comparisons between diode performances and theory are made. The contact barrier diodes exhibit high breakdown voltages and reverse dark currents limited by generation and recombination of carriers in the Si bulk. From the forward current-voltage characteristics at several temperatures, apparent OI contact barriers of PHI-bp = (0.63 +/- 0.01) V for PTCDI and PHI-bp = (0.59 +/- 0.02) V for CuPc, are formed with p-Si substrates. Studies of the I-U characteristics suggest the presence of an exponential trap distribution in the band-gap of the organic semiconductors used. The resulting diodes are superior in many respect to conventional Schottky diodes due to enhanced contact barriers and reduced edge effects.

Abstract  Phosphoric acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect transistors (OFETs). This efficient interface modification is helpful for semiconductor layer to form crystal thin film during vapor deposition. Results show that the PDI-i8C based OFETs with PA SAMs exhibit field-effect mobilities up to 0.014 cm(2) V-1 s(-1) (with ODPA as SAMs), which is over 500 times higher than the device without SAMs. Also, transistors with Naph6PA as SAMs show up to 1.5 x 10(-3) cm(2) V-1 s(-1). By studying the morphology of semiconductor layer and SAMs surface, it is found that ODPA bilayer structure plays a key role in inducing PDI-i8C to form orderly crystal thin film. (C) 2016 Elsevier B.V. All rights reserved.

Abstract  Two new compounds containing a ferrocene unit and a strongly fluorescent naphthalimide moiety were designed and successfully synthesized. The incorporation of a hydrophilic triethylene glycol unit can enhance the water-solubility and facilitate the dispersion of compounds in aqueous media. The presence of the ferrocene unit in both compounds results in molecules with low quantum efficiencies due to the photo-induced electron transfer (PET) from naphthalimide to ferrocene. However, one of these compounds exhibits a selective fluorescent turn-on by the addition of Au(III) ion with low to negligible interference by 100-fold concentration of other metal ions in acetonitrile/water. Under optimum conditions, the detection limit for Au(III) ion was 95 ppb. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  In this paper, an organic light-emitting device (OLED) with low reflection for the entire visible range and at different viewing angles by using an absorptive and photo-sensitive material, N,N'-Bis(2,6-diisopropylphenyl)-1,7-bis(4-methoxyphenyl)perylene-3,4,9,10-tetracarboxydiimide (MPPDI), as a black layer (BL) structure was demonstrated. A semitransparent double-metal structure, Al/Ag, was used to reduce the driving voltage and enhance the destructive interference of the BL structure. Combined with the broad absorption band of the MPPDI, the reflectance of such a device shows a 12-times decrease compared to the conventional OLED. Also, a photocurrent enhancement effect was observed in our BL-OLED due to the photosensitive quality of the MPPDI. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  We report the first optical waveguide based on perylene diimide (PDI) crystalline microwires. The birefringence, polarized photoluminescence emission, long distance light waveguide as well as electrical-optical modulation were studied. PDI is a good polymeric electrooptic material because of its low relative permittivity, low operating voltage, high thermal and photo-stability, and easy integration on flexible substrates.

Abstract  A series of fluorescent naphthalimide dyes were synthesized via aromatic nucleophilic substitution reaction of 4-bromo-N-alkylnaphthalimides with amines, alkoxides and thiols under microwave irradiation. In this procedure an efficient method for C-N, C-O and C-S bond formation via applying appropriate nucleophiles in the presence of KF/Al2O3 under solvent-free conditions is described. Adducts are produced in good to excellent yields and relatively in short times. The optical properties of three dyes as representative derivatives were examined by UV absorption and steady state fluorescence spectroscopy in solvents with different polarity. (C) 2013 Elsevier Ltd. All rights reserved.

Abstract  A series of novel naphthalimide dyes with amino or hydroxyl functional groups were synthesized by the condensation reaction of 4-bromonaphthalic anhydride with primary amines to form the naphthalimide, followed by regio-selective aromatic nucleophilic substitution in basic media. Four of the dyes were selected as representative compounds for analysis by UV absorption and steady state fluorescence spectroscopy in solvents with different polarity. In addition, fluorescence intensity decays of these dyes in dichloromethane were measured. The results suggest that various combinations of the dyes make good donor-acceptor pairs for energy transfer experiments. To anticipate the application of these dyes in the synthesis of dye-labeled polymers by radical polymerizations, the synthesis of a monomer dye containing a methacrylate ester and a dye containing initiator for ATRP polymerization is described. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  New azomethine-phthalic (AzPhDIs) and azomethine-naphthalene (AzNDIs) diimides were synthesized in condensation reaction of diamines containing phthalic or naphthalene diimide core and two aldehydes: 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde and 4-octadecyloxybenzaldehyde. The phase behavior of azomethine-diimides was examined by differential scanning calorymetry (DSC) and polarized optical microscopy (POM). AzPhDIs exhibited liquid crystalline properties in wide temperature range, whereas AzNDIs were not liquid crystalline. Thermal stability was investigated by thermogravimetric analysis (TGA). Azomethine-diimides exhibited high decomposition temperatures in the range between 360 and 401 degrees C. Optical properties were studied by UV-vis and photoluminescence (PL) measurements. Azomethine-diimides emitted blue light in NMP solution and blends with PMMA. The investigated compounds were electrochemically active and underwent reversible reduction and irreversible oxidation processes as evidenced by cyclic voltammetry (CV). Azomethine-diimides exhibited LUMO and HOMO levels in the range of -3.87 to -4.2 eV and -5.56 to -6.02 eV, respectively. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  A novel, soluble, perylene oligomeric diimide dye, termed EOPPI was synthesized in high yield; for comparison, a small dye molecule, termed EOPDI, was also synthesized; both products readily dissolved in a wide range of organic solvents. The compounds were characterized using NMR, IR, MS, UV-vis, MS, GC-MS, HRMS, DSC, TGA, elemental analysis and cyclic voltammetry. The average molecular mass of EOPPI was 4460, its intrinsic viscosity was 0.3 dl g(-1) in m-cresol at 20 degrees C. The band gap energy (E-g), LUMO and HOMO energy values were 2.25, -3.78 and -6.03 eV for the small dye molecule and 2.24, -3.85 and -6.09 eV for the oligomer, respectively. The temperatures at which the monomer and oligomer began to lose mass were 300 and 375 degrees C, respectively. The oligomer showed concentration-dependent color tunability. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  Photophysical properties of some 4-alkylamino-N-alkyl-1,8-naphthalimides and 3-bromo-4-alkylamino-N-alkyl-1,8-naphthalimides in ethanol solution have been investigated. It was demonstrated that the bromine atom in a C-3 position alters their properties. The bromine derivatives have a lower quantum yield of fluorescence owing to the influence of the bromine atom on the polarization of naphthalimide chromophoric system. On the other case, the photodegradation of these derivatives is higher and the reaction of photodegradation follows a pseudo first order. (C) 2003 Elsevier Science Ltd. All rights reserved.

Abstract  Two novel yellow-green emitting 1,8-naphthalimides, containing a 4-amino-2,2,6,6-tetramethylpiperidinyl moiety, were configured as "fluorophore-spacer-receptor" systems. The photophysical characteristics of the dyes were investigated in both DMF and water/DMF (4:1, v/v) solutions. The ability of the new compounds to detect cations was evaluated by means of the changes in their fluorescence intensity imparted by the presence of transition metal ions (Cu(2+), Pb(2+), Zn(2+), Ni(2+)) and protons. The presence of metal ions and protons was found to disallow photoinduced electron transfer resulting in enhanced fluorescence intensity. The results clearly show that only Cu(2+) ions and protons were effectively detected, indicating the potential of the novel compounds as highly efficient "off-on" switchers for CU(2+) ions and protons. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  In order to eliminate problems linked to the use of small emitting molecules or conjugated polymers, a novel type of electroluminescent material is investigated. Side-chain polymers have been conceived, synthesized and tested. Blue, green and orange diodes have been made. It is demonstrated that a hole-transporting layer increases the light emission of the green diode. Doping of side-chain polymers has been studied to produce orange light.

Abstract  In this work, we presented a naphthalimide-rhodamine based fluorescence resonance energy transfer system (FRET) NR1 as a ratiometric and intracellular pH probe, in which 1,2,3-triazole was identified as an ideal bridge and biocompatibility. It could selectively monitor pH variations in methanol/HEPES solution at room temperature. When the pH changed from 6.20 to 2.00, both the fluorescence intensities at 580 nm and the intensity ratios, R (I-580 nm/I-538 nm) increased, which allowed the detection of pH changes by both normal fluorescence and ratiometric fluorescence methods. The observation is consistent with the increased FRET from the 1,8-naphthalimide (donor) to the ring-opened, colored form of rhodamine (acceptor). Moreover, as NR1 is lysosomal with low cytotoxicity, it will be helpful for investigating the pivotal role of H+ in a biological context, especially in lysosomes through direct intracellular imaging. (C) 2013 Elsevier Ltd. All rights reserved.

Abstract  Successful amination of 4-bromo-1,8-naphthalimides with 'lengthy' imide N-functionality has been achieved using a general palladium mediated approach (conventional thermal protocols were suboptimal). Only readily available Pd/ligand combinations were considered and the resulting Buchwald-Hartwig procedure using Pd-2(dba)(3), Xantphos and Cs2CO3 is high yielding, relatively mild (40-80 degrees C, 24 h, yields 50-90%), requires only a modest excess of amine (3.0 equiv) and works equally well with other imide N-substituents. As such, the protocol complements existing methods but is superior for more complex substrates. Herein we compare this Pd mediated approach to the methods most commonly used and further demonstrate its utility by synthesising a number of new, highly fluorescent, 4-aminonaphthalimides. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  The light intensity dependence of the main photoelectrical parameters of the nonfullerene small-molecule bulk heterojunction (BHJ) solar cells p-DTS(FBTTh2)(2):perylene diimide (T1:PDI) shows that the nongeminate recombination losses play an important role in this system. A simple approach for the quantitative analysis of capacitance spectroscopy data of the organic BHJ solar cells, which allows to determine the density of free charge carriers as a function of applied bias under standard working conditions, is demonstrated. Using the proposed capacitance spectroscopic technique, the nongeminate recombination losses in the T1: PDI solar cells are quantitatively characterized in the scope of the bimolecular-and trap-assisted recombination mechanisms. Their contributions are separately analyzed within a wide range of the applied bias.

Abstract  The modification of two synthetic layered silicates, fluorohectorite (Coming) and laponite (Laporte). with two reactive silanes functionalized with fluorescent rhodamine or naphthalimide led to the grafting of the silicate particles selectively at the particle edges. The small amounts of grafted silanes were neither detected by infrared spectra nor X-ray diffraction (XRD) patterns. The larger extent of modification with cationic rhodamine-based silane was detected by XRD. The absorption and fluorescence spectra of the colloids of grafted silicates were similar to those of silane-dye precursors. Confocal fluorescence microscopy and fluorescence lifetime imaging detected the fluorohectorite-naphthalimide monolayer films to be optically heterogeneous, which was attributed to the selective location of the bound naphthalimide moieties at the particle edges. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  We used a side-chain polymer based on a high-electron affinity TEA) naphhalimide moiety (PNI), to fabricate single and double-layer light-emitting diodes (LEDs) with improved efficiency in the green spectral region. The chromophore is attached to a polymethacrylate backbone through a spacer and is characterised by a 30% photoluminescence quantum yield. In single-layer light-emitting diodes we find that the electroluminescence efficiency is not limited by Al cathodes a!, for poly(p-phenylene vinylene), PPV, as expected from consideration of the EA. We also report maximum internal quantum efficiencies of about 1.7% for Ca and 0.9% for Al in double-layer devices where PPV serves as both hole-injector and emitter. Tuning of emission in the red is possible by dye-doping (at high concentration) the PNI and causing the emission to happen in this layer. Unexpectedly, not only does the dye-doping of PNI red-shifts the emission spectrum, but also affects significantly the charge transport properties and in particular reduces the driving field necessary for electroluminescence in both single-and double-layer LEDs and we propose this effect as one of the factors for the lifetime increase upon doping recently reported in the literature [J. Shi, C.W. Tang, Appl. Phys. Lett. 70 (1997) 1665.]. (C) 1998 Elsevier Science B.V.

Abstract  Multifunctional switches, as well as gated photochromism, are particularly challenging. Here, a ferrocene (Fc)-modified photochromic diarylethene (DAE) with sterically hindered ethene bridge, in which the photo-inactive parallel conformer and photoactive antiparallel conformer are individually investigated, is reported. The photoswitchable triad system (parallel conformer p-Fc and anti-parallel ap-Fc) contains three functional parts: photochromic DAE unit, naphthalimide chromophore, and redox-active ferrocene. Upon incorporation of ferrocene unit, the photochromic efficiency in the anti-parallel triad conformer ap-Fc is blocked to a great extent in the ferrocene state but distinctly enhanced in the ferrocenium state via chemical or electrochemical stimuli, thereby constructing redox-gated photochromism. Meanwhile, the reversible redox between ferrocene and ferrocenium states can also switch "OFF/ON" the fluorescence of naphthalimide chromophore via photoinduced electron transfer pathway (PET). The fluorescence and photoisomerization in the triad system are well modulated with chemical-or electrochemical redox and light stimuli, which enables the specific gated photochromism and fluorescence switches work in multi-addressable states.

Abstract  Two new gelators containing bis-naphthalimides group were designed and synthesized. The gelator 1b could form gels in DMF and mixed solvent of DMSO/H2O (10/1, v/v). The self-assembly processes of 1b in two kinds of solvents were detailedly investigated by UV-vis, fluorescence, infrared spectroscopy, field emission scanning electron microscope (FE-SEM), X-ray diffraction and contact angle experiments. The experiment results showed the hydrogen bonding was the main force for the gel formation. The gel 1b formed in mixed solvent of DMSO/H2O (10/1, v/v) possessed of the ability of distinguishing of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine. At the same time, the gelator 1b could selectively and sensitively detect p-phenylenediamine in solution with the detection limit of 8.961×10(-8)ML(-1). The detection experiment was also confirmed by DFT theoretical calculations. This research would expand the supramolecular self-assembly materials application in sensor field and offer a new detection method for organic amines.