Synthesis and optical properties of triphenylene-based dendritic donor perylene diimide acceptor systems

A donor-acceptor charge transfer system based on two discotic mesogens has been synthesized. The donor is either a triphenylene (POG0) or a triphenylene-based conjugated dendron (POG1), while the acceptor is a perylene diimide (PDI) core. The donors are covalently linked to the bay positions of the PDI core through an ether linkage. In chloroform, due to the short donor-acceptor distance and the matching frontier orbital levels, photoinduced charge transfer from either the donor excitation or the acceptor excitation are both thermodynamically and kinetically favored, resulting in efficient quenching of both donor and acceptor fluorescence. In a less polar solvent, hexane, while charge transfer is still the dominant mechanism for decay of the excited electronic state of POG1, photoinduced charge transfer is no longer energetically favorable for POG0 when the acceptor PDI core is excited, making the PDI core of POG0 weakly fluorescent in chloroform but strongly so in hexane. In solid film, POG0 is highly aggregated through both PDI-PDI and triphenylene-triphenylene homotopic stacking. POG1, on the other hand, aggregates through triphenylene dendrons with limited PDI-PDI core stacking, presumably due to the steric hindrance caused by bulky triphenylene moieties which block the access to the PDI core. The efficient photoinduced charge transfer, coupled with the homotopic stacking that forms separated electron-transporting PDI-stacked columns and hole transporting triphenylene-stacked columns, suggests that the reported donor-acceptor systems based on dual-discotic mesogens are potentially new efficient photovoltaic materials.     

Small molecular non-fullerene electron acceptors for P3HT-based bulk-heterojunction solar cells

Three small molecules with the same arms and different cores of perylene diimide(PDI)or indaceno[2,1-b:6,5-b']dithiophene(IDT)were designed and synthesized as the acceptor materials for P3HT-based bulk-heterojunction(BHJ)solar cells.The impacts of the different cores on the optical absorption,electrochemical properties,electron mobility,film morphology,photoluminescene characteristics,and solar cell performance were thoroughly studied.The three compounds possess a broad absorption covering the wavelength range of 400–700 nm and relatively low lowest unoccupied molecular orbital(LUMO)energy levels of?3.86,?3.81 and?3.99 eV.The highest power conversion efficiency of 0.82%was achieved for the BHJ solar cells based on SM3 as the acceptor material,the compound with a PDI core.     

Direct Evidence of Significantly Different Chemical Behavior and Excited‐State Dynamics of 1,7‐ and 1,6‐Regioisomers of Pyrrolidinyl‐Substituted Perylene Diimide

Novel bay‐functionalized perylene diimides with additional substitution sites close to the perylene core have been prepared by the reaction between 1,7(6)‐dibromoperylene diimide 6 (dibromo‐PDI) and 2‐(benzyloxymethyl)pyrrolidine 5 . Distinct differences in the chemical behaviors of the 1,7‐ and 1,6‐regioisomers have been discerned. While the 1,6‐dibromo‐PDI produced the corresponding 1,6‐bis‐substituted derivative more efficiently, the 1,7‐dibromo‐PDI underwent predominant mono‐debromination, yielding a mono‐substituted PDI along with a small amount of the corresponding 1,7‐bis‐substituted compound. By varying the reaction conditions, a controlled stepwise bis‐substitution of the bromo substituents was also achieved, allowing the direct synthesis of asymmetrical 1,6‐ and 1,7‐PDIs. The compounds were isolated as individual regioisomers. Fullerene (C₆₀) was then covalently linked at the bay region of the newly prepared PDIs. In this way, two separate sets of perylene diimide–fullerene dyads, namely single‐bridged (SB‐1,7‐PDI‐C₆₀ and SB‐1,6‐PDI‐C₆₀) and double‐bridged (DB‐1,7‐PDI‐C₆₀ and DB‐1,6‐PDI‐C₆₀), were synthesized. The fullerene was intentionally attached at the bay region of the PDI to achieve close proximity of the two chromophores and to ensure an efficient photoinduced electron transfer. A detailed study of the photodynamics has revealed that photoinduced electron transfer from the perylene diimide chromophore to the fullerene occurs in all four dyads in polar benzonitrile, and also occurs in the single‐bridged dyads in nonpolar toluene. The process was found to be substantially faster and more efficient in the dyads containing the 1,7‐regioisomer, both for the singly‐ and double‐bridged molecules. In the case of the single‐bridged dyads, SB‐1,7‐PDI‐C₆₀ and SB‐1,6‐PDI‐C₆₀, different relaxation pathways of their charge‐separated states have been discovered. To the best of our knowledge, this is the first observation of photoinduced electron transfer in PDI‐C₆₀ dyads in a nonpolar medium.     

Unprecedented Charge‐Transfer Complex of Fused Diporphyrin as Near‐Infrared Absorption‐Induced High‐Aspect‐Ratio Nanorods

Charge‐transfer (CT) complexes of near‐infrared absorbing systems have been unknown until now. Consequently, structural similarities between donor and acceptor are rather important to achieve this phenomenon. Herein, we report electron donors such as non‐fused diporphyrin‐anthracene (DP), zinc diporphyrin‐anthracene (ZnDP) and fused zinc diporphyrin‐anthracene (FZnDP) in which FZnDP absorbs in NIR region and permits a CT complex with the electron acceptor, perylene diimide (PDI ) in CHCl₃ exclusively. UV/Vis‐NIR absorption, ¹H NMR, NOESY and powder X‐ray diffraction analysis demonstrated that the CT complex formation occurs by π–π stacking between perylene units in FZnDP and PDI upon mixing together in a 1:1 molar concentration in CHCl₃, unlike non‐fused ZnDP and DP. TEM and AFM images revealed that the CT complex initially forms nanospheres leading to nanorods by diffusion of CH₃OH vapors into the CHCl₃ solution of FZnDP/PDI (1:1 molar ratio). Therefore, these CT nanorods could lead to significant advances in optical, biological and ferroelectric applications.     

18-冠-6修饰苝酰亚胺衍生物的合成及离子识别行为

合成了一种18-冠-6修饰的苝酰亚胺衍生物(1), 研究了其作为主体对金属离子与阴离子的选择性识别行为. 结果表明, 主体1对Ba²⁺离子具有一定的选择性响应, 并可以通过Ba²⁺调控主体1的堆积行为; 主体1还对F^-离子有选择性响应, F^-与苝酰亚胺单元之间发生了阴离子-π相互作用.     

Supramolecular p-n-heterojunctions by co-self-organization of oligo(p-phenylene vinylene) and perylene bisimide dyes

Comparative studies on hydrogen-bonded versus covalently linked donor-acceptor-donor dye arrays obtained from oligo(p-phenylene vinylene)s (OPVs) as donor and bay-substituted perylene bisimides (PERYs) as acceptor dyes are presented. Both systems form well-ordered J-type aggregates in methylcyclohexane, but only hydrogen-bonded arrays afford hierarchically assembled chiral OPV-PERY dye superstructures consisting of left-handed helical pi-pi co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study). In the case of hydrogen-bonded arrays, the stability of the aggregates in solution increases with increasing conjugation length of the OPV unit. The well-defined co-aggregated dyes presented here exhibit photoinduced electron transfer on subpicosecond time scale, and thus, these supramolecular entities might serve as valuable nanoscopic functional units.     

Isomeric Effect on Optoelectronic Properties and Photovoltaic Performance of Anthraquinone-Core Perylene Diimide (PDI) and Helical PDI dimers

Isomerism heavily influences the optoelectronic properties and self-assembly behavior of compounds and subsequently affects their device performance. Herein, two pairs of isomeric perylene diimide (PDI) dimers, PDI and PDI2, were designed and synthesized. The electron-deficient 9,10-anthraquinone group was employed as the bridge, and thus, the resultant dimers exhibited an acceptor–acceptor–acceptor (A-A-A) structure. To determine the isomeric effects on the optoelectronic properties and photovoltaic performance of these dimers, their absorptivity, luminescence, and redox behavior were studied. Bulk heterojunction organic solar cells based on these four dimers were fabricated and measured. The two PDI dimers exhibited clear differences in photovoltaic performance, whereas the two PDI2 analogues showed similar power conversion efficiencies (PCEs). The PCEs of the two PDI2 dimers are much higher than those of the PDI dimers. These results illustrate that the isomeric effect of PDI dimers is much larger than that of PDI2 dimers on the device performance, and proper expansion of conjugation could improve the device performance.     

Influence of intermolecular orientation on the photoinduced charge transfer kinetics in self-assembled aggregates of donor-acceptor arrays

The kinetics of photoinduced charge transfer reactions in covalently linked donor-acceptor molecules often undergoes dramatic changes when these molecules self-assemble from a molecular dissolved state into a nanoaggregate. Frequently, the origin of these changes is only partially understood. In this paper, we describe the intermolecular spatial organization of three homologous arrays, consisting of a central perylene bisimide (PERY) acceptor moiety and two oligo(p-phenylene vinylene) (OPV) donor units, in nanoaggregates and identify both face-to-face (H-type) and slipped (J-type) stacking of the OPV and PERY chromophores. For the J-type aggregates, short intermolecular OPV-PERY distances are created that give rise to a charge-transfer absorption band. The proximity of the donor and acceptor groups in the J-type aggregates enables a highly efficient photoinduced charge separation with a rate (k(cs) > 10(12) s(-1)) that significantly exceeds the rate of the intramolecular charge transfer of the same compounds when molecularly dissolved, even in the most polar media. In the H-type aggregates, on the other hand, the intermolecular OPV-PERY distance is not reduced compared to the intramolecular separation, and hence, the rates of the electron transfer reactions are not significantly affected compared to the molecular dissolved state. Similar to the forward electron transfer, the kinetics of the charge recombination in the aggregated state can be understood by considering the different interchromophoric distances that occur in the H- and J-type aggregates. These results provide the first consistent rationalization of the remarkable differences that are observed for photoinduced charge-transfer reactions of donor-acceptor compounds in molecularly dissolved versus aggregated states.     

Synthesis and controlled self-assembly of covalently linked hexa-peri-hexabenzocoronene/perylene diimide dyads as models to study fundamental energy and electron transfer processes

We report the synthesis and photophysical characterization of a series of hexa-peri-hexabenzocoronene (HBC)/perylenetetracarboxy diimide (PDI) dyads that are covalently linked with a rigid bridge. Both the ratio of the two components and the conjugation of the bridging element are systematically modified to study the influence on self-assembly and energy and electron transfer between electron donor HBC and acceptor PDI. STM and 2D-WAXS experiments reveal that both in solution and in bulk solid state the dyads assemble into well-ordered two-dimensional supramolecular structures with controllable mutual orientations and distances between donor and acceptor at a nanoscopic scale. Depending on the symmetry of the dyads, either columns with nanosegregated stacks of HBC and PDI or interdigitating networks with alternating HBC and PDI moieties are observed. UV-vis, photoluminescence, transient photoluminescence, and transient absorption spectroscopy confirm that after photoexcitation of the donor HBC a photoinduced electron transfer between HBC and PDI can only compete with the dominant F?rster resonance energy transfer, if facilitated by an intimate stacking of HBC and PDI with sufficient orbital overlap. However, while the alternating stacks allow efficient electron transfer, only the nanosegregated stacks provide charge transport channels in bulk state that are a prerequisite for application as active components in thin film electronic devices. These results have important implications for the further design of functional donor-acceptor dyads, being promising materials for organic bulk heterojunction solar cells and field-effect transistors.     

Multivariate Fluorimetric Determination of Mixture of Pyrene,Perylene and Triphenylene in Water Sample

ABSTRACT

Micellization is described as a successful media for simultaneous fluorimetric determination of perylene, pyrene and triphenylene in water samples by reducing interference between them. A multivariate method based on synchronous fluorescence scan to estimate perylene, pyrene and triphenylene in their mixture solution has been proposed. The method does not require solving of large amounts of data obtained from the whole spectrum of the samples, thus making the analysis simple and fast. The method gives the best result for perylene and satisfactory results for pyrene and triphenylene. Analysis of water samples of two different origins spiked with known amount of perylene, pyrene and triphenylene also gives satisfactory result. Presence of fluoranthene up to 1 μM does not interfere in the analysis.     

Atropisomer-based construction of a new perylene diimide macrocycle as visible-light photocatalyst for selective sulfide oxidation

By using a perylene diimine (PDI) syn-atropisomer as highly preorganized precursor, we successfully constructed a visible-light-active organic macrocycle PDI-M. The formation of macrocyclic structure effectively avoids self-aggregation of PDI cores and enhances the absorption in visible region. As a photocatalyst, PDI-M exhibits excellent activity on aerobic selective oxidation of sulfide into sulfoxide under visible light irradiation at room temperature. Mechanism studies show that both superoxide and singlet oxygen act as reactive oxygen species. This work provides a typical case toward the maximum utilization of photosensitive groups under mild conditions.     

Ethynyl-linked perylene bisimide based electron acceptors for non-fullerene organic solar cells

Star-shaped electron acceptors based on perylene bisimide as end groups and spiro-aromatic core linked with ethynyl units were developed for nonfullerene solar cells. Ethynyl linkers are able to improve the planarity of conjugated backbone, resulting in enhanced electron mobility and power conversion efficiency in solar cells.     

Synthesis, electrochemical, and spectroscopic properties of soluble perylene monoimide diesters

Perylene derivatives are an important class of n-type semiconductors. With the exceptions of bay-substituted and N-swallow-tail alkyl/tert-butyl substituted derivatives, most perylene diimides are insoluble. The recently reported perylene tetraesters are highly soluble, but are less electron-deficient. In this paper, a series of perylene monoimide diesters have been synthesized, which have good solubility and acceptable electron-accepting property due to the introducing of imide and ester groups in one perylene molecule. Their electrochemical properties and structural ordering were examined by cyclovoltammetry and X-ray diffraction technique, respectively. Their absorption and emission spectra are reported and discussed.     

Photophysical and electrochemical properties of 1,7-diaryl-substituted perylene diimides

Substituent effects on the photophysical and electrochemical properties of 1,7-diaryl-substituted perylene diimides (1,7-Ar(2)PDIs) have been carefully explored. Progressive red-shifts of the absorption and emission maxima were observed when the electron-donating ability of these substituents was increased. Linear Hammett correlations of 1/lambda(max) versus sigma(+) were observed in both spectral analyses. The positive slopes of the Hammett plots suggested that the electronic transitions carry certain amounts of photoinduced intramolecular charge-transfer (PICT) character from the aryl substituents to the perylene diimide core which leads to the reduction of the electron density on the substituents. The substituent electronic effects originated mainly from the perturbation of the core PDI HOMO energy level by the substituents. This conclusion was supported by PM3 analyses and confirmed by cyclic voltammetry experiments. More interestingly, the Ph(2)NC(6)H(4)-substituted PDI, 4i, showed an unusual dual-band absorption that spans from 450 to 750 nm. We tentatively assigned these two bands as the charge-transfer band and the PDI core absorption, respectively.     

Time‐Dependent Aggregation‐Induced Enhanced Emission,Absorption Spectral Broadening,and Aggregation Morphology of a Novel Perylene Derivative with a Large D–π–A Structure

Strong aggregation‐caused quenching of perylene diimides (PDI) is changed successfully by simple chemical modification with two quinoline moieties through C?C at the bay positions to obtain aggregation‐induced enhanced emission (AIEE) of a perylene derivative ( Cya‐PDI ) with a large π‐conjugation system. Cya‐PDI is weakly luminescent in the well‐dispersed CH₃CN or THF solutions and exhibits an evident time‐dependent AIEE and absorption spectra broadening in the aggregated state. In addition, morphological inspection demonstrates that the morphology of the aggregated form of Cya‐PDI molecules changed from plate‐shaped to rod‐like aggregates under the co‐effects of time and water. An edge‐to‐face arrangement of aggregation was proposed and discussed. The fact that the Cya‐PDI aggregates show a broad absorption covering the whole visible‐light range and strong intermolecular interaction through π–π stacking in the solid state makes them promising materials for optoelectric applications.     

V形咔唑衍生物的合成及荧光性质

以N-烷基咔唑作为电子给体和共轭桥中心, 二米基硼作为端基电子受体, 合成了两个V形A-π-D-π-A型新化合物: 3,6-二{[(E)-2-(5-二米基硼)噻吩]乙烯基}-N-丁基-咔唑 {N-butyl-3,6-bis{(E)-2-[5-(dimesitylboryl)thiophen-2-yl]-vinyl}-carbazole, BBTC}和3,6-二[(E)-(4-二米基硼)苯乙烯基]-N-己基-咔唑, {N-hexyl-3,6-bis[(E)-4-(dimesitylboryl)-styryl]-carbazole, BBSC}. 这两个化合物在蓝绿光波段都有较强的荧光发射. 光谱数据表明, 扩大共轭体系并在端基引入含硼基团导致吸收谱和发射谱显著红移, 并增大分子内电荷转移.     

Synthesis and photochromic reactivity of diarylethene trimers bridged by ethenyl and ethynyl unit

Two diarylethene trimers bridged by ethenyl and ethynyl groups were synthesized and their photochromic behaviors were examined. Upon irradiation of the trimers 2 and 4 with UV light, one-three photoinduced cyclization reactions occur. Each isomer was isolated and analyzed by ¹H NMR spectrum. The quantum yield of 2 and 4 is 0.52 and 0.311, respectively.     

One donor–two acceptor (D–A1)‐(D–A2) random terpolymers containing perylene diimide,naphthalene diimide,and carbazole units

A series of one donor–two acceptor (D–A₁)‐(D–A₂) random terpolymers containing a 2,7‐carbazole donor and varying compositions of perylene diimide (PDI) and naphthalene diimide (NDI) acceptors was synthesized via Suzuki coupling polymerization. The optical properties of the terpolymers are weighted sums of the constituent parent copolymers and all show strong absorption over the 400 to 700 nm range with optical bandgaps ranging from 1.77 to 1.87 eV, depending on acceptor composition. The copolymers were tested as acceptor materials in bulk heterojunction all‐polymer solar cells using poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo[1,2‐b;4,5‐b′]dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene)‐2,6‐diyl] (PBDTTT‐C) as the donor material. In contrast to the optoelectronic properties, the measured device parameters are not composition dependent, and rather depend solely on the presence of the NDI unit, where the devices containing any amount of NDI perform half as well as those using the parent polymer containing only carbazole and PDI. Overall this is the first example of a one donor–two acceptor random terpolymer system containing perylene diimide (PDI) and naphthalene diimide (NDI) acceptor units, and demonstrates a facile method of tuning polymer optoelectronic properties while minimizing the need for complicated synthetic and purification steps. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3337–3345     

Chemisorption,Morphology, and Structure of a n‐Type Perylene Diimide Derivative at the Interface with Gold: Influence on Devices from Thin Films to Single Molecules

We have investigated thin films of a perylene diimide derivative with a cyano‐functionalized core (PDI‐8CN₂) deposited on Au(111) single crystals from the monolayer to the multilayer regime. We found that PDI‐8CN₂ is chemisorbed on gold. The molecules experience a thickness‐dependent reorientation, and a 2D growth mode with molecular stepped terraces is achieved adopting low deposition rates. The obtained results are discussed in terms of their impact on field effect devices, also clarifying why the use of substrate/contact treatments, decoupling PDI‐8CN₂ molecules from the substrate/contacts, is beneficial for such devices. Our results also suggest that perylene diimide derivatives with CN bay‐functionalization are very promising candidates for single‐molecule electronic devices.     

Controllable Electronic Structures and Photoinduced Processes of Bay‐Linked Perylenediimide Dimers and a Ferrocene‐Linked Triad

A series of perylene‐3,4,9,10‐bis(dicarboximide) (PDI) dimers linked through the bay regions was systematically synthesized to examine the electronic structures and photophysical properties in dependence on the distance and orientation between the two PDI units. The spectroscopic and electrochemical measurements suggested that the coupling value of a directly linked PDI dimer (PDI)₂ is much larger than those of para‐ and meta‐phenylene‐bridged PDI dimers p‐(PDI)₂ and m‐(PDI)₂. The width of Davydov splitting was quantitatively evaluated to compare the coupling values between the two PDI units in these dimers by absorption spectroscopy in frozen 2‐methyl‐THF. Excimer formation of PDI dimers induced the strong fluorescence quenching and large red‐shifts. Femtosecond transient absorption revealed a broad absorption derived from an excimer in the range from about 600 nm to the near‐IR region. The rate constants of formation and decay of the excimer are strongly dependent on the coupling values. Time‐resolved measurements on ferrocene‐linked p‐(PDI)₂ revealed a competition between the photoinduced processes of electron transfer and excimer formation in PhCN, which is in sharp contrast with the sole electron‐transfer process in toluene.