Abstract  High performance films of phenyl substituted perylene diimide are obtained by heteroepitaxy growth through Weak Epitaxy Growth technique. As epitaxially grown on the para-sexiphenyl (p-6P) ordered layers, the N,N'-di-phenyl perylene tetracarboxylic diimide (PTCDI-Ph) grows to form continuous and highly oriented films with large grain size, which possess low density of grain boundary and smooth surface. This quality films bring about improvement of two orders of magnitude in mobility compare to the traditional films, and present relative good air stability. Ambipolar transport behavior was also observed as tuning the thickness of p-6P. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  A series of novel 1,8-naphthlimide derivatives containing a thiophene ring at the C-4 position was synthesized through Pd-catalyzed direct C-H bond arylation and characterized by H-1 NMR, C-13 NMR, MALDI-HRMS and elemental analysis. The crystal structure of N-hexyl-4-(benzo[b]thiophen-2-yl)-1,8-naphthalimide was found to be a kite structure. The moderate pi-pi stacking interaction between the two core planes (naphthalimide ring) and the van der Waals' forces between the flexible hexyl groups constructed a 3D structure. The UV-vis and fluorescence property of synthesized compounds in chloroform were investigated. All compounds can emit blue, green or yellow emission except for N-hexyl-4-(5-nitrothiophene-2-yl)-1,8-naphthalimide. The results show that the 1,8-naphthalimide derivatives with an electron-donating group on the thiophene ring or larger conjugated structure have enhanced fluorescence properties. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract  We investigated the effects of annealing on device performances of bulk heterojunction organic solar cells based on copper phthalocyanine (CuPc) and N,N'-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C6). Blended films of CuPc and PTCDI-C6 with annealing at elevated temperature were characterized by measuring optical absorption, photoluminescence, and X-ray diffraction. Enhanced molecular ordering and increments in domain sizes of donor and acceptor for the blended films were observed, and their influences on device performances were discussed. Annealing led to substantial improvements in photocurrent owing to enhanced molecular ordering and formation of percolation pathways. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  N,N'-diphenylbutyl-3,4,9, 10-perylenebiscarboximide (PTCDI-C4Ph) were characterized by optical and electrochemical methods. A device with an ITO/PTCDI-C4Ph (approximate to 2 mu m)/Al structure was fabricated to measure mobility by time-of-flight techniques. This vacuum deposited organic layer was an amorphous state. Electrons were observed faster than holes. The electron and hole mobilities were 1.8 x 10(-4) cm(2)/V s and 1.1 X 10(-4) cm(2)/Vs under the electric field of 500 (V/cm)(1/2), respectively. This result shows that this organic compound is a good candidate for an n-type conduction. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  Donor-sigma-acceptor molecules of HPBT-n(PDI) (n = 1, 2, and 4) containing perylene diimide (PDI) and pi-extended 1,2,4,5-tetrakis((E)-2-(5'-hexyl-2,2'-bithiophen-5-yl)vinyl)benzene (HPBT) have been successfully synthesized for studying the self-organization of each moiety and their applications in photovoltaic devices. Interesting features were found in these molecules: the aggregation-induced crystallization in the HPBT moieties enhanced the power conversion efficiency (PCE) in the photovoltaic cell. By incorporating HPBT as the donor and PDI as the acceptor moiety, we anticipated that their high degree of independent aggregation-induced crystallization would yield electron/hole transport channels and high mobility in the desired direction of charge transport. In a photovoltaic device, HPBT-1(PDI) gave a PCE of 0.22% with an open circuit voltage ranging from 0.62 to 0.63 V. When the HPBT moiety was more hindered by the PDI moiety, less PCE was observed in HPBT-2(PDI). Addition of methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) resulted in enhancement of the PCE due to enhanced visible absorption. The device bearing HPBT-1(PDI) and PCBM (1:4 mol ratio) demonstrate much higher PCE to be around 1.60%. (C) 2009 Elsevier B.V. All rights reserved.

Abstract  The synthesis of two, unsaturated 1,8-naphthalimide derivatives was studied; it was found that the synthesis of the two dyes was more efficient than previously reported. Quantitative thin-layer chromatography (tlc) was used to monitor the process and check the purity of the products. The dyes were copolymerized with methylmethacrylate (MMA) giving polymers with intense colour and fluorescence that were stable to solvent extraction. Wool and polyamide fibres were dyed and the colorimetric characteristics of the dyed fabrics were measured. (C) 2000 Elsevier Science Ltd. All rights reserved.

Abstract  An efficient, one-pot multicomponent synthesis of novel naphthalimide-based acridine-1,8-dione derivatives was achieved by condensation of dimedone, aromatic aldehydes, hydrazine hydrate, and 1,8-naphthanoic anhydride in the presence of a [bmim]HSO4 ionic liquid, which acts as a green solvent medium. Mild conditions with excellent conversions and a simple isolation procedure are noteworthy advantages of this method. The recovery and recydability of the ionic liquid make this protocol environmentally desirable.

Abstract  Graphene oxide/reduced perylene diimide radical anion hybrid (GO/rSFPDI) with high dispersibility in polar organic solvents has been flexibly developed using N,N'-diethylhexyl-1-bromo-7-pentafluorophenox-perylene diimide (SFPDI). The interaction of the GO with the SFPDI suggested the catalysis of perylene diimide (SFPDI) to reduced perylene diimide radical anion (rSFPDI). The successful preparation of GO/rSFPDI was confirmed via FT-IR, Raman, UV-Vis absorption spectrum, XRD, and SEM. Compared to the two neutral SFPDI and GO, GO/rSFPDI exhibited a novel lower energy electronic transition (max. at 700 nm) in addition to the solvatochromism and characteristics of spectral response to pH. Moreover, the fluorescence emission spectrum of GO/rSFPDI shows strong fluorescence quenching in dilute solution.

Abstract  Through cracking perylene diimide by inserting a single bond, small pi-conjugation unit thiophene and large ir-conjugation unit indaceno[1,2-b:5,6-b']dithiophene, three molecules were synthesized and used as electron acceptors for solution-processed polymer solar cells. These three compounds showed excellent thermal stability with decomposition temperatures over 370 degrees C. As the size of inserted conjugation units increased, the extinction coefficient increased from 2.9 x 10(4) to 6.5 x 10(4) M-1 cm(-1), the absorption wavelength maximum in thin film red shifted from 360 to 488 nm, the optical band gap decreased from 2.98 to 2.25 eV, the highest occupied molecular orbital energy level was upshifted from -6.18 to -5.67 eV, the lowest unoccupied molecular orbital energy level was downshifted from -3.59 to -3.68 eV, power conversion efficiencies of solar cells based on blends of poly(3-hexylthiophene) donor and these acceptors increased from 0.28% to 2.36%. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  A sugar functionalized naphthalimide derivative (H1) self-assembles into supramolecular nanotubes (25 nm pore diameter) by the reaction of 4-N-ethylaminenaphthalimide-N-propinyl and delta-gluconolactone in refluxed ethanol. The suspension of the tube assembly in water can directly form hydrogels when triggered by sonication, without change in morphology or molecular aggregates in the pH range of 5-8. Modified with aminocarproic acid, H2 with more hydrogen bonding sites can form pH tolerant hydrogels in the widest range of pH values from 1-14 accelerated by sonication. The gelation mechanism was studied in detail. To the best of our knowledge, this is the first paradigm wherein hydrogels were constructed from naphthalimide derivatives. Finally, the potential of the hydrogel as a drug delivery and release system for hydrophilic medicine was explored.

Abstract  A series of novel V-shaped naphthalimide derivatives are reported herein, designed through a strategy to achieve aggregation induced emission (AIE), giving rise to unexpected self-assembly properties. This includes an aggregation induced emission enhancement (AIEE) active small organic molecule viz. naphthalimide derivative functionalized with 8-hydroxyquinoline (alpha-NQ), that spontaneously forms highly fluorescent "nanoribbon'' like structures with < 100 nm diameter and hundreds of micron length in aqueous media irrespective of concentration and surface at room temperature. The classical head-to-tail p-p stacking, as revealed by the single crystal X-ray study, was found to be the main driving force for the J-type aggregation with unique self-aggregating behavior. A comparative mechanistic study confirms that the N-atom in the hydroxyquinoline moiety is responsible for directing the entire molecular behavior in solution as well as in its aggregated state. These alpha-NQ nanoribbons formed in aqueous media were found to be highly sensitive and selective towards the multi-functional nonheme protein ferritin (K-sv = 0.83 x 107 M-1) with a limit of detection 67.25 x 10(-11) M (0.33 ng mu L-1) under physiological conditions, which serves as a well-known inflammatory marker for various diseases. The fluorescent nanoribbons were also found to modify the a-helix content of ferritin, thereby inducing conformational changes in their secondary structure as confirmed through circular dichroism (CD) spectroscopy techniques. Collectively, these findings improve the fundamental understanding of the self-assembly of AIEE active molecules along with the photophysical properties of core substituted naphthalimide derivatives that report the highest sensitivity towards ferritin in the presence of a bright AIEEgen under physiological conditions.

Abstract  Although being widely used in organic synthesis, thiophenol (Tp) is toxic to the human body. We report here the preparation of a ratiometric fluorescence probe for the selective, transient determination of Tp in full aqueous solution. The probe was synthesized by a click reaction coupling between an alkynyl naphthalimide-dansyl dyad and an azido galactoside which increases the water solubility. Fluorescence spectroscopic analyses showed that the probe had a specific ratiometric response to Tp transiently in a full aqueous solution, over a range of other species. The probe has also proven suitable for the quantification of Tp in environmental water samples, and possesses superior properties to previous Tp fluorescence probes in terms of water solubility and sensitivity. (C) 2015 Elsevier Ltd. All rights reserved.

Abstract  We describe a convenient approach to achieve fluorescence modulation based on self-assembled complexes between photochromic diarylethenes and solid-emissive Boron Fluorine dye. Photochromism of the self-assemblies results in slight modulation of the Boron Fluorine dye's fluorescence in dilute solution, but high-contrast ON/OFF fluorescence switching in nanoparticles and in the solid state. During this process, intermolecular hydrogen bonds between the carboxyl units on diarylethenes and the imidazole ring on Boron Fluorine dye play important role in the efficient fluorescence resonance energy transfer from Boron Fluorine dye to closed isomer of diarylethenes. The excitation wavelength (405 nm) of the self-assembled complexes hardly induces photochromism of diarylethene molecules, providing non-destructive readout ability. This system represents a simple and efficient alternative to the covalent system to achieve fluorescent switch in the solid state, and it may be potentially applied in rewritable high-density optical storage. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  Direct visualization evidence is important for understanding the microbial degradation mechanisms. To track the microbial degradation pathways of azo dyes with different polar characterizations, sensors based on the fluorescence resonance energy transfer (FRET) from 1,8-naphthalimide to azo dyes were synthesized, in which the quenched fluorescence will recover when the azo bond was cleaved. In living cells, the sensor-tracking experiment showed that the low polarity and hydrophobic azo dye can be taken up into the cells and reduced inside the cells, whereas the high polarity and hydrophilic azo dye can be reduced only outside the cells because of the selective permeability of the cell membranes. These results indicated that there were two different bacterial degradation pathways available for different polarity azo dyes. To our knowledge, no fluorescent sensor has yet been designed for illuminating the microbial degradation mechanisms of organic pollutants with different characteristics.

Abstract  A novel ratiometric fluorescent chemodosimeter REPN based on 1,8-naphthalimide-rhodamine was successfully synthesized. Two different strategies of fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET) for ratiometric detection of Hg2+/Fe3+ were designed into one sensing system. REPN exhibits typical FRET signal from pyridine-naphthalimide moiety to rhodamine moiety which was induced by Hg2+ with a detection limit of 2.72 x 10(-6) M in EtOH/PBS buffer (1:1, v/v, pH = 7.4) solution. However, the probe REPN performed ratiometric detection behavior via PET process combined with the classical ring-opening sensor system in the presence of Fe3+, the detection limit was 5.7 x 10(-7) M. REPN emitted bright yellow fluorescence in solid state and the maximum emission wavelength was 538 nm. Besides, the silica nanoparticles loaded AIE dye REPN maintained and further reinforced the AIE effect with higher water solubility. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  In this paper, the molecular structure of a 1,8-naphthalimide fluorophore modified sextuple H-bond self-assembly homodimer, comprising two linear oligoamide molecular strands bearing arrays on one edge with complementary hydrogen bond sequences of DDADAA and AADADD, is characterized via H-1 NMR, ESI-MS, C-13 NMR, and elementary analysis. The target duplex emits strong yellowish green light with emission peaks at 518 nm and 535 nm under UV photoexcitation in solution and solid film, respectively, and its photoluminescence quantum efficiency (solid state) has been enhanced greatly compared to its small molecular 1,8-naphthalimide counterpart (0.637 versus 0.324). Employing the duplex and the counterpart as emitting dopants, two yellowish green polymer light-emitting diodes (PLED) with the device configuration of ITO/PEDOT:PSS (50 nm)/PFO + dopant (5wt%) (80 nm)/CsF (3 nm)/Al (150 nm) have been fabricated. The results indicate that the PLED with the duplex as emitter has dramatically improved performance, for example, a much higher external electroluminescence quantum efficiency (QE(ext)) of 1.87% (ph/el), and a much lower turn-on voltage of 6.4 V, compared to the one with the counterpart as emitter (QE(ext): 0.12%; turn-on voltage: 15 V), suggesting that the incorporation of H-bond self-assembly motif with the light-emitting fluorophore is an effective way for the design of electroluminescent materials.

Abstract  The absorption and emission spectra of a series of 4-carbazolyl/4-diphenylamino-N-(H-, methyl, cyclohexyl, phenyl)-1, 8-naphthalimide derivatives in gas-phase have been calculated using TD-B3LYP/6-31G* approaches. With different substituents on the N-imide group and naphthalimic group, their optical properties in solvent have also been studied by C-PCM model. Result show that there are three peaks in the absorption spectra. For absorption spectra, the third peak, similar to the luminescent peak emitted by diphenylamine or carbazoly, the second peak, similar to the luminescence emitted by the 1, 8-naphthalimide, and a considerable long-wavelength luminescent are observed. The extended conjugation comprising the carbazolyl and naphthalimide moieties, attributed to the coplanar geometry, endows the first peak excited state with charge transfer property.

Abstract  Pestemer's rule on the relationship between the difference in absorption in solution and fluorescence on fiber substrate and low frequency half-value component (H) was demonstrated and developed to study the relationship between the Stoke's shift in solution and the low frequency half-value component. The following equation was established: Stoke's shift = 2kH + b cm(-1) where k is greater than 2 and b is a constant. Examples are given on the experimental correlation between Stoke's shifts and the low frequency half-value components of naphthalimide dyes, DNA intercalative dyes and benzoxazole dyes. Copyright (C) 1996 Elsevier Science Ltd

Abstract  The current challenges for efficient bulk heterojunction (BHJ) organic photovoltaics (OPVs) based on organic/polymeric (non-fullerene) acceptors involve difficult control of neat phase separation in the nanoscale, severe geminate charge recombination, etc. Herein, a new molecular design concept, that is to construct donor-spacer-acceptor (D-S-A) co-oligomers with self-assembly properties, is proposed in order to realize ideal film morphology and manipulate the exciton dissociation and geminate charge recombination processes simultaneously. Three D-S-A co-oligomers, i.e. F5T8P-C2, F5T8P-C4 and F5T8P-C6 with oligo(fluorene-alt-bithiophene), perylene diimide (PDI) and alkyl as D-, A- and S-segments, respectively, were synthesized. All three D-S-A co-oligomers can form D-A alternating lamellar nanostructures with periods of similar to 15 nm, an ideal nanostructure for BHJ OPVs. Compared to D-A co-oligomer F5T8-epP in which the D- and A-segments are directly connected without the alkyl spacer, the D-S-A co-oligomers not only show higher electron mobilities due to closer packing of PDI moieties, but also exhibit longer lifetimes of the charge-transfer states that can potentially restrain the geminate charge recombination and improve the charge generation efficiency. Accordingly, the single-molecule photovoltaic cells based on the D-S-A co-oligomers exhibit an improved fill factor of 0.47 and a high open-circuit voltage of 1.04 V. In particular, an external quantum efficiency of similar to 65%, which is the highest for BHJ OPVs based on non-fullerene acceptor materials, has been demonstrated. By further extending the absorption onset of D-S-A co-oligomers to similar to 600 nm, a single-molecule photovoltaic device with a power conversion efficiency of 2.70% has been fabricated. These results prove that high-efficiency BHJ OPVs based on non-fullerene acceptors are achievable if both the film morphology of the D-A blend and D-A interfaces are suitably manipulated.

Abstract  A new hetero-bifunctional ligand designed to form supramolecular structures with a combination of covalent and noncovalent forces has been prepared. The ligand, (1,8-naphthalimide)CH2C6H4CH2OCH2C(pz)(3) (L-tris, pz = pyrazolyl ring), contains both a tris(pyrazolyl)methane coordination unit and a 1,8-naphthalimide strong pi center dot center dot center dot pi stacking unit. The reactions of iron (II), copper(II), and cadmium(II) tetrafluoroborate salts with 2 equiv of L-tris yield [Fe(L-tris)(2)](BF4)(2) (1), [Cd(L-tris)(2)](BF4)(2) (2), and [Cu(L-tris)(2)](BF4)(2) (3), respectively. Vapor diffusion crystallization yielded two pseudopolymorphs for 1. In the solid-state structures of both forms, the iron is in an octahedral environment with bond distances expected for low-spin iron(II); both tris(pyrazolyl)methane donor sets are in a kappa(3)-coordination mode with each L-tris ligand in a U-shaped, syn arrangement. In one pseudopolymorph, the 1,8-naphthalimide side chains are on the same side of the molecule when viewed down the metal axis (syn-1), twisted only 30 degrees with respect to each other. In the second pseudopolymorph, the side chains are oriented in opposite directions at 180 degrees (anti-1). Both structures are one-dimensional, organized by intermolecular pi center dot center dot center dot pi stacking interactions of the 1,8-naphthalimide units. Each naphthalimide unit reaches past the naphthalimide unit on the adjacent cation leading to a pi center dot center dot center dot pi stack using the face of the naphthalimide unit directed toward its metal complex, interlocking the U-shaped groups. The interaction of the two naphthalimide groups is directionally specific; they are oriented head to tail with substantial overlap of the parallel rings. The twisting of the side chains at 30 degrees for syn-1 leads to a helical structure, whereas the 180 degrees orientation of the side chains in anti-1 leads to a linear structure. The cadmium(II) complex is isostructural to syn-1 and the copper(II) is isostructural to anti-1. Although the supramolecular structures of these two compounds are similar to the matched iron(II) complexes because of the similar orientations of the side-chains and the consistent noncovalent interactions of the naphthalimide synthon, the larger size of cadmium(II) leads to a highly distorted structure about the metal. The copper(II) structure is also distorted, as expected for a d(9) complex.

Abstract  A colorimetric chemosensor TBS-NA, 4-(tert-butyldimethylsilyloxy)-N-butyl-naphthalimide was designed and synthesized. Addition of fluoride ion to a CH(3)CN solution of TBS-NA can result in an obvious color change (from colorless to yellow) and UV-Vis absorption spectral change in a short time. This indicated that TBS-NA had highly selectivity for fluoride detection over other anions, such as Cl(-), Br(-), I(-), HSO(4)(-), ClO(4)(-) and AcO(-) in CH(3)CN solutions, and the selectively detection was due to the selective cleavage of Si-O bond in TBS-NA by fluoride. The detection limit was calculated to be 0.59 mu M. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract  A solvent-exchange process was applied to three fluorescent dyes belonging to the 2-benzimidazolyl-7-diethylaminocoumarin series (namely Coumarin 7 (1), Coumarin 30 (2), and one of their derivatives bearing a butyl chain (3)). The three compounds only differ by the substitution of the nitrogen atom of the benzimidazolyl group. They were first dissolved in acetone and then suddenly placed in an aqueous environment where they generated molecular assemblies. The size and shape of the latter were studied by fluorescence microscopy and transmission and scanning electron microscopy. It appeared that 1 gave aggregates and flat microcrystals that evolved toward elongated structures. 2 formed straight nanofibers that are 10-20 microm long and exhibit a crystal structure. 3 gave short fibers (1 micromx25 nm), which finally arrange into entangled solid nanofibers. The formation of fibers arising from low-molecular-weight molecules was particularly interesting. The optical properties of the free-standing particles in suspension were analyzed and compared to those of highly dilute dyes, with the aim to get additional information about the dye arrangement in the nanostructures.

Abstract  We have studied the initial stages of the adsorption of N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxdiimide (EP-PTCDI) on Cu(100) using scanning tunnelling microscopy (STM), X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and density functional theory (DFT) calculations. STM images show that the EP-PTCDI molecules initially absorb on the surface, forming ordered islands, without preferential nucleation at the step-edges of the terraces as is the case for adsorption of the same molecule on Ag(111). The 2D islands grow upon the completion of the surface with a single-molecular layer. The experimental and simulated LEED patterns show that the molecular arrangement within the islands can be explained by a commensurate superstructure and its four rotational equivalents. The electron spectroscopies show net charge transfer from the surface to the molecule and a decrease of about 0.7 eV in the work function (from 4.59 to 3.9 eV) after a single-layer adsorption. The DFT calculations for the adsorption of a single layer qualitatively reproduce the features observed in STM images and allow us to explain the observed charge exchange behavior together with the work function change.

Abstract  Supramolecular interactions of N-(4-pyridylmethyl)-1,8-naphthalimide (L) and flexibility of intervening units of dicarboxylate ligands contribute to formation of different types of coordination polymers such as [MnL2(Adp)(H2O)(2)](n)center dot 2nH(2)O (1), [CoL2(Fum)(H2O)(2)]n center dot-2nH(2)O (2), [CoL2(Adp)(H2O)(2)](n)center dot 2nH(2)O (3), [NiL(Fum)(H2O)(3)](n)center dot H2O (4), [CuL2(Fum)](n)center dot nH(2)O (5), [CuL(Mal)](n) (6), and [Cu3L6(Adp)(3)(H2O)(3)] (7) (where Adp = adipate, Fum = fumarate, and Mal = malonate). These coordination polymers are structurally characterized. Coordination polymers 1 and 3 are isostructural having three-dimensional (3D) supramolecular layer-like structures. Coordination polymer 2 forms a two-dimensional (2D) supramolecular network through C-H center dot center dot center dot pi and O center dot center dot center dot pi interactions. Coordination polymer 4 forms H-bonded 3D chainlike supramolecular architecture. Coordination polymer 5 forms a 3D supramolecular sheet-like structure, whereas coordination polymer 6 and coordination polymer 7 forms a 2D lamellar structure through pi center dot center dot center dot pi and C-H center dot center dot center dot pi interactions. Manganese coordination polymer 1 shows weak antiferromagnetic interactions between chains at low temperature and also exhibits single chain magnetic behavior. Coordination polymers 2 and 3 show saturation value of magnetic moment at 2 K and 7 T, which are lower than the spin-only Co(II) ion. Coordination polymer 4 show spin-only values for NO) ion. The room-temperature chi T-M value for coordination polymer 5 is dose to the spin-only value for two Cu(II) ions. With lowering of the temperature, the chi T-M value remains constant to 35 K, from where the value begins to decrease to a minimum at 2 K. For copper coordination polymer 6 value of chi T-M smoothly decreases with lowering of the temperature to attain a quasi plateau between 80 K and 35 K, and it further sharply increases at 2 K. Coordination polymer 7 shows spin-only Cu(II) ion. These coordination polymers in solid state show quenching of fluorescence emission of ligand L, as well as a shift of emission toward a shorter wavelength.

Abstract  Novel 4-amino- and 4-(acetyl)amino-N-aryl-1,8-naphthalimides containing aza-15-crown-5 ether receptor unit in the N-aryl fragment and at C-4 of the naphthalimide residue were designed and prepared. Significant internal charge transfer from electron donating amino or amido group at C-4 of the naphthalene ring to the acceptor carboxyimide moiety as well as photoinduced electron transfer between N-aryl receptor and the naphthalimide fragment was revealed by the UV/Vis absorption spectroscopy and considerable fluorescence quenching. The addition of calcium perchlorate to an acetonitrile solution of naphthalimides with the receptor at imide nitrogen hindered the photoinduced electron transfer process and accordingly restored the quenched fluorescence of the free ligands. In the case of the compound in which the aza-15-crown-5 receptor is located at C-4, the coordination with Ca2+ reduced the internal charge transfer interaction in the chromophore and caused a significant blue-shift of the absorption and emission peak. The observed spectral effects were analyzed using PM6 semiempirical calculations. Formation of complexes was also confirmed by H-1 NMR spectroscopy. (c) 2013 Elsevier Ltd. All rights reserved.