Abstract  Clusters of phthalocyanine and phthalocyanine-perylene diimide have been prepared and electrophoretically deposited on nanostructured SnO2 electrodes. The structure and photoelectrochemical properties of the clusters have been investigated by using UV-visible absorption, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and photoelectrochemical and photodynamical measurements. Enhancement of the photocurrent generation efficiency in the composite system has been achieved relative to that in the phthalocyanine reference system without the perylene diimide. Such information will be valuable for the design of molecular photoelectrochemical devices that exhibit efficient photocurrent generation.

Abstract  A bisthienylethene-functionalized perylene diimide (BTE-PDI) photochromic dyad was synthesized for self-assembly into 1-D nanotubes by a reprecipitation method. SEM and TEM observations showed that the nanotubes were formed from their 0-D precursors of hollow nanospheres. HR-TEM images revealed that both the nanospheres and the nanotubes have highly ordered lamellar structure, indicating the hierarchical process during assembly. The IR and XRD results revealed that DAE-PDI molecules were connected through intermolecular hydrogen bonds to form building blocks that self-assembled into nanostructures. Electronic absorption and fluorescence spectroscopic results indicated the H-aggregate nature of the self-assembled nanostructures. Competition and cooperation between the dipole-dipole interaction, intermolecular pi-pi stacking, and hydrophilic/hydrophobic interaction are suggested to result in nanostructures. Reconstruction was found to happen during the morphology transition progress from the 0-D nanospheres to the 1-D nanotubes, which was driven by donor-acceptor dipole-dipole interactions. Green emission at 520 nm originating from the DAE subunit was observed for the aggregates of vesicles and nanotubes, which could be regulated by photoirradiation with 365 nm light, suggesting the nanoaggregates to be photochromic switches.

Abstract  We demonstrate that thin films of metal-organic framework (MOF)-like materials, containing two perylenediimides (PDICl4, PDIOPh2) and a squaraine dye (S1), can be fabricated by layer-by-layer assembly (LbL). Interestingly, these LbL films absorb across the visible light region (400-750 nm) and facilitate directional energy transfer. Due to the high spectral overlap and oriented transition dipole moments of the donor (PDICl4 and PDIOPh2) and acceptor (S1) components, directional long-range energy transfer from the bluest to reddest absorber was successfully demonstrated in the multicomponent MOF-like films. These findings have significant implications for the development of solar energy conversion devices based on MOFs.

Abstract  We report a comparative study on the self-assembly from solution and electrical characterization of n-type semiconducting fibres obtained from five different perylenebis(dicarboximide) (PDI) derivatives. In particular we investigated the role of the nature of the alkyl chain covalently linked to the N,N' sites of the PDI in modulating the molecular solubility and aggregation capacity. We explored the morphologies of the self-assembled architectures physisorbed on dielectric surfaces and in particular how they can be modified by tuning the deposition and post-deposition procedures, i.e. by modulating the kinetics of the self-assembly process. To this end, alongside the conventional spin-coating, solvent vapour annealing (SVA) and solvent induced precipitation (SIP) have been employed. Both approaches led to fibres having widths of several hundred nanometres and lengths up to tens of micrometres. SVA formed isolated fibres which were tens of nanometres high, flat, and tapered at the ends. Conversely, SIP fibres exhibited nearly matching heights and widths, but organized into bundles. Despite these morphological differences, the same intermolecular packing is found by XRD in each type of structure, albeit with differing degrees of long-range order. The study of the electrical characteristics of the obtained low dimensional nano-assemblies has been accomplished by fabricating and characterizing organic field-effect transistors.

Abstract  A facile approach for introducing photoactive poly(fluorene-perylene diimide) arrays (PFPDI) onto graphene sheets was accomplished. Noncovalent PFPDI/graphene ensembles formed via π-π stacking interactions between the two components and covalent PFPDI-graphene hybrids realized upon a Stille polycondensation reaction between an iodobenzyl-functionalized graphene, a 9,9-dialkyl substituted fluorene diboronic acid, and a 1,7-dibromo-PDI derivative were prepared. The morphology of PFPDI/graphene and PFPDI-graphene was evaluated by high-resolution transmission electron microscopy (HR-TEM), revealing the presence of even monolayered graphene sheets. Moreover, their photophysical and redox properties as assessed by electronic absorption spectroscopy and steady-state as well as time-resolved photoluminescence assays and electrochemistry, respectively, disclosed charge-transfer characteristics owing to the high photoluminescence quenching of PFPDI in the presence of graphene and the fast component attributed to the decay of the emission intensity of the singlet excited state of PFPDI in both PFPDI/graphene and PFPDI-graphene. Next, testing their ability to operate in energy conversion schemes, the PFPDI-graphene was successfully employed as catalyst for the reduction of 4-nitrophenol to 4-aminophenol. Notably, the kinetics for the reduction were enhanced by visible light photoirradiation as compared to dark conditions as well as the presence of PFPDI-graphene, contrasting the case where only PFPDI, in the absence of graphene, was employed. Finally, recycling of the catalyst PFPDI-graphene was achieved and reutilization in successive reduction reactions of 4-nitrophenol was found to proceed with the same efficiency.

Abstract  The self-organizing structures formed by a water-soluble perylene diimide dye (PDI) have been studied by several experimental techniques as potential templates for the preparation of hybrid nanomaterials. The dye forms chromonic-nematic and hexagonal liquid crystals in water. The aggregates in liquid crystals consist of one-molecule-wide stacks. From the changes in the solution proton NMR chemical shifts with concentration, it appears that adjacent molecules are twisted. There is significant broadening of the aromatic resonances at higher concentrations, arising from nonmotionally averaged dipole-dipole coupling between adjacent aromatic hydrogens. This is attributed to slow overall rotation of the aggregates in solution, suggesting that they grow up to several tens of nanometers. Dye aggregates serve as templates for the formation of silica tubules (1-5 μm length, average diameter ≈300 nm), with aligned and very thin (1-2 nm) dye nanostripes embedded in the walls. The silica tubes precipitated from solution are formed by the cooperative interaction between PDI and silica species during the sol-gel reaction. Upon calcination, silica nanotubules with supermicroporous walls are obtained. In comparison with conventional surfactant systems, the use of π-π stacked chromonic aggregates brings new possibilities for the templated fabrication of pores with sizes below the mesoporous range. Materials could find applications in photovoltaics as well as in shape selective catalysis and adsorption.

Abstract  A series of 4-amino-N-substituted-1,8-naphthalimide and 4-allylamino-N-substituted-1,8-naphthalimide derivatives were synthesized from intermediate 4-nitro-1,8-naphthalimide by imidation, reduction and allylation reactions. These compounds were characterized by thin layer chromatography (TLC), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), elemental analysis, H-1-nuclear magnetic resonance (1HNMR), C-13-NMR, liquid chromatography-mass spectroscopy, UV-Vis spectroscopy and fluorimetry. 1,8-Naphthalimide derivatives with amino and allylamino groups in the C-4 position exhibit fluorescent emission on irradiation. In addition, synthesized compounds had biological properties due to the presence of sulfonamide group (-SO2-N-) in their structure. The absorption maximum wavelength of synthesized dyes that are fluorescent is in the range of 427-439 nm while emitting in the range of 526-528.5 nm. The absorption spectra of synthesized dyes demonstrated that the type of substitutions in C-4 position and N-imide of naphthalimide ring had small effect on their colour. The photophysical characteristics of these dyes were assessed, and their Stokes shift values were determined in dimethylformamide solvent. The results demonstrated that Stokes shift values were between 3860 and 4469 cm(-1). Antibacterial and antifungal activities of the dyes were evaluated against gram positive and gram negative bacteria and Candida albicans fungi using cup plate, minimum inhibitory concentration and minimum bactericidal concentration methods. The results revealed that dye 10 had the most levels of antimicrobial activity against bacteria and fungi.

Abstract  This OECD Emission Scenario Document (ESD) is intended to provide information on the sources, use patterns, and potential release pathways of non-volatile chemicals used in textile dyes. The document focuses primarily on the application of dyes to fibers, yarns and fabrics by batch or continuous processes. The document presents standard approaches for estimating the environmental releases of and occupational exposures to non-volatile chemicals used in dye formulations.

Abstract  Combined electronic structure and quantum dynamical calculations are employed to investigate charge separation in a novel class of covalently bound bisthiophene-perylene diimide type donor-acceptor (DA) co-oligomer aggregates. In an earlier spectroscopic study of this DA system in a smectic liquid crystalline (LC) film, efficient and ultrafast (subpicosecond) initial charge separation was found to be followed by rapid recombination. By comparison, the same DA system in solution exhibits ultrafast resonant energy transfer followed by slower (picosecond scale) charge separation. The present first-principles study explains these contrasting observations, highlighting the role of an efficient intermolecular charge-transfer pathway that results from the molecular packing in the LC phase. Despite the efficiency of this primary charge-transfer step, long-range charge separation is impeded by a comparatively high Coulomb barrier in conjunction with small electron- and hole-transfer integrals. Quantum dynamical calculations are carried out for a fragment-based model Hamiltonian, parametrized by ab initio second-order Algebraic Diagrammatic Construction (ADC(2)) and Time-Dependent Density Functional Theory (TDDFT) electronic structure calculations. Simulations of coherent vibronic quantum dynamics for up to 156 electronic states and 48 modes are performed using the Multi-Layer Multi-Configuration Time-Dependent Hartree (ML-MCTDH) method. Excellent agreement with experimentally determined charge separation time scales is obtained, and the spatially coherent nature of the dynamics is analyzed.

Abstract  The reactions of the lithium salt of (S)-2-(1,8-naphthalimido)-3-hydroxypropanoate (L-ser(-)), an enantiopure carboxylate ligand containing a 1,8-naphthalimide pi center dot center dot center dot pi stacking supramolecular tecton and an alcohol functional group, with La(NO3)(3), Ce (NO3)(3), SmCl3, Eu(NO3)(3), Gd(NO3)(3), Tb(NO3)(3), and Dy(NO3)(3) under solvothermal conditions (water/ethanol) produced single crystals (characterized by single-crystal X-ray crystallography) of [La-3(L-ser)(8)-(OH)(H2O)]center dot(H2O,EtOH)(x) (1), [Ce-3 (L-ser)(8)(OH)(H2O)]center dot(H2O,EtOH)(x) (2), [Sm-3(L-ser)(8)(OEt)]center dot(H2O,EtOH)(x) (3), [Eu-3(L-ser)(8) (OEt)]center dot(H2O,EtOH)(x) (4), [Gd-3(L-ser)(8)(OEt)]center dot(H2O,EtOH)(x) (5), [Tb-3 (L-ser)(8)(OEt)]center dot(H2O,EtOH)(x) (6), and [Dy-3(L-ser)(8)(OEt)]center dot(H2O,EtOH)(x) (7), respectively. Mixed-metal complexes [Ce2.3Tb0.7(L-ser)(8)(OH)]center dot(H2O,EtOH)(x) (8), [Gd0.4Tb2.6(L-ser)(8)(OEt)]center dot(H2O,EtOH)(x) (9), and [Ce1.4Gd0.3Tb1.3(L-ser)(8)(OH)]center dot(H2O,EtOH)(x) (10) were prepared by using two or more types of lanthanides in the solvothermal reactions (additional mixed-metal complexes were prepared and characterized by ICP-MS). Single crystals of compounds 1-10 are isostructural: trinuclear, carboxylate-bonded helicates organized by the non-covalent, pi center dot center dot center dot pi stacking interactions of the 1,8-naphthalimide groups into intertwined M helices, with a pitch of 56 angstrom, that are further arranged into a three-dimensional supramolecular framework by additional pi center dot center dot center dot pi stacking interactions. Magnetic measurements of several compounds were as expected for the metal(s) present, indicating no significant interactions between metals within the helicates. The Ce complex 2 showed weak antiferromagnetic ordering below 50 K. All of the complexes, with the exception of 2, showed luminescence based on the 1,8-naphthalimide group. Complex 2 has no emission, and complexes with mixed Ce/Tb ratios showed significant quenching of the naphthalimide-based luminescence, as quantitated with solid-state, absolute quantum yield measurements of these mixed-metal and the pure metal complexes. Lanthanide-based luminescence was only observed for the Eu complex 4.

Abstract  Due to their high electron affinities, chemical and thermal stabilities, π-conjugated molecules with imide/amide frameworks have received considerable attentions as promising candidates for high-performance optoelectronic materials, particularly for organic semiconductors with high carrier mobilities. The purpose of this Research News is to give an overview of recent advances in development of high performance imide/amide based organic semiconductors for field-effect transistors. It covers naphthalene diimide-, perylene diimide- and amide-based conjugated molecules and polymers for organic semiconductors.

Abstract  The molecular packing of a new class of perylene diimide-based acceptor-donor (A-D) co-oligomers has been investigated by combining electron diffraction and X-ray scattering methods for AD dyads and an ADA triad structure. The AD and ADA compounds form highly ordered lamellar mesophases with well-defined donor and acceptor domains. To determine the structure of the co-oligomers, highly oriented films with different orientations were prepared. Both flat-on and edge-on orientations of the lamellae were obtained by using two different alignment methods. High temperature rubbing leads to edge-on oriented lamellae with the long molecular axis of the co-oligomer oriented almost parallel to the rubbing direction. Instead, on oriented substrates of poly(tetrafluoroethylene) (PTFE), flat-on lying lamellae with the pi-stacking direction oriented parallel to the PTFE chains are obtained. The structural data gathered by low dose selected area electron diffraction and high resolution transmission electron microscopy are used to establish a structural model of an AD dyad. Driven by the strong pi-stacking of the PDI core, both AD and ADA co-oligomers form two similar self-assembled lamellar structures with an original zipper-like organization of the PDI blocks.

Abstract  Perovskite hybrid solar cells (pero-HSCs) were demonstrated to be among the most promising candidates within the emerging photovoltaic materials with respect to their power conversion efficiency (PCE) and inexpensive fabrication. Further PCE enhancement mainly relies on minimizing the interface losses via interface engineering and the quality of the perovskite film. Here, we demonstrate that the PCEs of pero-HSCs are significantly increased to 14.0% by incorporation of a solution-processed perylene-diimide (PDINO) as cathode interface layer between the [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) layer and the top Ag electrode. Notably, for PDINO-based devices, prominent PCEs over 13% are achieved within a wide range of the PDINO thicknesses (5-24 nm). Without the PDINO layer, the best PCE of the reference PCBM/Ag device was only 10.0%. The PCBM/PDINO/Ag devices also outperformed the PCBM/ZnO/Ag devices (11.3%) with the well-established zinc oxide (ZnO) cathode interface layer. This enhanced performance is due to the formation of a highly qualitative contact between PDINO and the top Ag electrode, leading to reduced series resistance (R-s) and enhanced shunt resistance (R-sh) values. This study opens the door for the integration of a new class of easily-accessible, solution-processed high-performance interfacial materials for pero-HSCs.

Abstract  A triple bond-linked perylene diimide (PDI) conjugated polymer, poly{[N,N'-dioctylperylene-3,4,9,10-bis(dicarboximide)-1,7(6)-diyll-alt-[(2,5-bis(2-ethylhexyl)-1,4- phenylene)bis(ethyn-2,1-diyl]} (PDIC8-EB), was examined as an electron-accepting component in all-polymer solar cells. As an electron-donating component, poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyllthieno[3,4-b]-thiophenediyl] (PTB7) and poly[4,8-bis(5-(2-ethylhexyp thiophen-2-yl)benzo[1,2-b:4,5-b'] dithiophene-alt-3-fluorothieno [3,4-b]thiophene-2-carboxylate] (PTB7-Th) were introduced in order to investigate the feasibility of PDIC8-EB because of their similarity. Results showed that the power conversion efficiency (PCE) was higher for the PTB7-Th:PDIC8-EB solar cells (PCE = 3.58%) than the PTB7:PDIC8-EB solar cells (PCE = 2.81%). The better performance of the PTB7-Th:PDIC8-EB solar cells has been attributed to the formation of a well-defined nanodomain morphology in the PTB7Th:PDIC8-EB bulk heterojunction layer, as measured with transmission electron microscopy (TEM), atomic force microscopy (AFM), and synchrotron radiation grazing incidence X-ray diffraction (GIXD).

Abstract  A nonfullerene electron acceptor (IEIC) based on indaceno[1,2-b:5,6-b']dithiophene and 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile was designed and synthesized. IEIC exhibited good thermal stability, strong absorption in the 500-750 nm region with an extinction coefficient of 1.1 x 10(5) M-1 cm(-1) at 672 nm, deep LUMO energy level (-3.82 eV) close to those of fullerenes, and a relatively high electron mobility of 2.1 x 10(-4) cm(2) V-1 s(-1). Fullerene-free polymer solar cells (PSCs) based on the blends of the IEIC acceptor and a low-bandgap polymer donor PTB7-TH, using a perylene diimide derivative as a cathode interlayer, showed power conversion efficiencies (PCEs) of up to 6.31%, which is among the best PCEs reported for fullerene-free PSCs.

Abstract  We report on the straightforward preparation and photophysical characterization of four symmetrically substituted water soluble perylene diimides, obtained by functionalizing the imide positions with L-threonine, L-aspartic acid, L-cysteine and L-methionine. The presence of carboxylic groups on the two sides of the aromatic structure conveys a pH-dependent water solubility to all the molecules. The combined effect of the hydrophobic perylene core with the specific aminoacidic functionalities leads to different aggregation behaviors in both aqueous and organic media affecting the optical absorption and emission of the aromatic chromophore. By a comparative study of the optical properties we shed light on the main characteristics of these perylene derivatives in organic and aqueous diluted solution. These aminoacid perylene diimide molecules have the potential to be exploited in new sensing applications based on assembly/disassembly-driven fluorescence switching off-on in aqueous media. (C) 2015 Published by Elsevier Ltd.

Abstract  The development of methods to grow well-ordered chromophore thin films on solid substrates is of importance because such surface-associated arrays have potential applications in the generation of functional electronic and optical materials and devices. In this article, we demonstrate a straightforward layer-by-layer (LBL) supramolecular deposition strategy to prepare numerous layers (up to 19) of functionalized perylene diimide (PDI) chromophores built upon a covalent scaffolding multivalent porphyrin monolayer. Our thin film formation strategy employs water as the immersion solvent and exploits the β-cyclodextrin-adamantane host-guest couple in addition to PDI based aromatic stacking. Within the resultant film the porphyrin scaffold is oriented close to parallel to the glass substrate while the PDI chromophores are aligned closer to the surface normal. Together, the porphyrin monolayer and the multi-PDI layers exhibit a large absorption bandwidth in the visible spectrum. Importantly, because a self-assembly strategy was utilized, when a single monolayer of PDI is deposited on the porphyrin scaffolding layer, this PDI monolayer can be readily disassembled by washing with DMF leading to the regeneration of the porphyrin monolayer. The PDI thin film can subsequently be regrown from the regenerated porphyrin surface. The reported LBL strategy will be of broad interest for researchers developing well-organized chromophoric films and materials due to its simplicity as well as the added advantage of being performed in sustainable and cost-effective aqueous media.