Series Of Naphthalene Diimide Research Articles

Lone-Pair-π Bond Strength Unveiled by a Combined Experimental and Computational Study.

A series of naphthalene-diimide (NDI) and perylene-diimide (PDI) connected bis-N-heterocyclic carbene complexes of iridium(III) have been prepared and fully characterized. The analysis of their NMR spectroscopic features, together with their molecular structures show that these species display lone-pair-π interactions between the chloride ligands of the Ir(III) complex and the heterocycles of the NDI/PDI moieties. The detection of this type of interaction in solution is due to the formation of two atropisomers, which are formed as a result of the restricted rotation about the Ir-Ccarbene bond imposed by the (Cl)lp⋅⋅⋅π interaction. Variable-temperature 1H NMR analysis allowed the determination of the strength of this non-covalent interaction, which lies between ΔH=6.6 and 10 kcal/mol. The computational studies performed fully support the experimental findings.

Asymmetric side-chain engineering of organic semiconductor for ultrasensitive gas sensing

Molecular structure of organic semiconductor plays a critical role in determining the performance and functionality of organic electronic devices, by optimizing the electrical, optical and physicochemical properties. Substituted alkyl chains are fundamental units in tailering the solubility and assemblability, among which the asymmetric properties have been reported as key element for controlling the packing motifs and intrinsic charge transport. Here, we expanded the scope of molecular asymmetry dependent sensing features based on a new series of naphthalene diimides (NDI)-based derivatives substituted with a same branching alkyl chain but various linear-shaped alkyl chains (Cn-). A clear molecular stacking change, from head-to-head bilayer to head-to-tail monolayer packing model, is observed based on the features of anisotropic molecular interactions with the change in the chain length. Most importantly, a unique LUMO level shift of 0.17 eV is validated for NDI-PhC4, providing a record sensitivity up to 150% to 0.01 ppb ammonia, due to the desired molecular reactivity and device amplification properties. These results indicate that asymmetric side-chain engineering opens a route for breath healthcare.

Modulation of red organic room-temperature phosphorescence in heavy atom-free phosphors

Red room temperature phosphorescence (RTP) was conventionally obtained by incorporating heavy metal ions or halogens. However, heavy metals are toxic and expensive while C-halogen bonds are usually prone to photobleaching. Meanwhile, heavy atoms often lead to much reduced RTP lifetimes, precluding their use in certain fields. Herein, a series of naphthalene diimides with various electron-donor substituents on the nitrogen atoms were used to achieve red RTP. It was found that a moderate intramolecular charge transfer (CT) state provides mediating intersystem crossing channels for promoting red RTP with quantum yields circa. 5%. However, much stronger donors can in fact inhibit all forms of luminescence emission including RTP via photo-induced electron transfer quenching at room temperature, in which case the red phosphorescence could be restored if the donor, such as an amine, is suppressed by protonation.

All-Small-Molecule Solar Cells Incorporating NDI-Based Acceptors: Synthesis and Full Characterization

A series of naphthalene diimide (NDI)-based small molecules were synthesized as nonfullerene acceptors and incorporated in all-small-molecule solar cells. Three NDI-based small molecules, NDICN-T, NDICN-BT, and NDICN-TVT, were designed with different linkers between two NDI units to induce the different conjugation length and modulate the geometric structures of the NDI dimers. The small NDI-based dimer electron acceptors with slip-stacked structures that facilitate π-π stacking interactions and/or hinder excessive aggregation exhibited different morphological behaviors, such as miscibility or crystallinity in bulk heterojunction blends with 7,7'-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(6-fluoro-4-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole) (DTS-F) electron donors. The photovoltaic devices prepared with NDICN-TVT gave the highest power conversion efficiency (PCE) of 3.01%, with an open-circuit voltage (Voc) of 0.75 V, a short-circuit current density (Jsc) of 7.10 mA cm-2, and a fill factor of 56.2%, whereas the DTS-F:NDICN-T and DTS-F:NDICN-BT devices provided PCEs of 1.81 and 0.13%, respectively. Studies of the charge-generation properties, charge-transfer dynamics, and charge-transport properties for understanding the structure-property relations revealed that DTS-F:NDICN-TVT blend films with well-developed domains and well-ordered crystalline structures performed well, whereas an excessive miscibility between DTS-F and NDICN-BT disrupted the crystallinity of the material and yielded a poor device performance.

Naphthalene Diimide Based n-Type Conjugated Polymers as Efficient Cathode Interfacial Materials for Polymer and Perovskite Solar Cells.

A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure-performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.

A DNA-NDI Hybrid to Efficiently Detect Histone in Parts per Trillion (ppt) Level

To develop a new sensor for histone, a series of Naphthalenediimide (NDI) derivatieves were subjected to DNA binding studies and the NDI derivative with strongest affinity for DNA was selected. This NDI-DNA hybrid is used for highly selective and sensitive detection of a DNA binding protein, histone which dislodges the intercalated NDI groups and thus “turn-on” the emission.

Naphthalene diimide-based random terpolymer for efficient all-polymer solar cells with high open circuit voltage

A series of naphthalene diimide (NDI)-based random terpolymers x-NDI as polymer acceptors were synthesized with variation of T-NDI/Se-NDI ratios in polymers, which x-NDI were composed of naphthalene diimide with an octyldodecyl branched chain acceptor units and randomly distributed thiophene (T) and selenophene (Se) donor units. Meanwhile, the reference alternating copolymers (P(NDI2OD-T) and P(NDI2OD-Se)) were synthesized. The structure-property relationships of the random terpolymers were systematically studied. The effects of T-NDI/Se-NDI ratios on the absorption, energy levels, crystallinity, film morphology, charge transport and photovoltaic performance of the fabricated polymer solar cells were investigated. The acceptor 0.5-NDI with proper crystallinity was fully miscible with the chosen donor polymer PBDT(T)TPD, and formed the nanostructured blend. Compared to that of PBDT(T)TPD/P(NDI2OD-T) or PBDT(T)TPD/P(NDI2OD-Se) solar cells, the PBDT(T)TPD/0.5-NDI solar cells exhibited an improved short-circuit current density (Jsc) of 9.1 mA/cm2, a high open circuit voltage (Voc) of 1.05 V and enhanced power conversion efficiency (PCE) of 5.4%. Our work demonstrates that the development of random terpolymers is a simple and effective method to obtain polymer acceptor matching with the chosen polymer donor leading to efficient PSCs.

Importance of Electron Transport Ability in Naphthalene Diimide-Based Polymer Acceptors for High-Performance, Additive-Free, All-Polymer Solar Cells

We report a systematic investigation of the correlations between the electron mobility of polymer acceptors and the photovoltaic performances of all-polymer solar cells (all-PSCs) by using a series of naphthalene diimide (NDI)-based polymer acceptors. Polymer acceptors typically have much lower electron mobility than fullerenes, which is one of the main factors in limiting the performance of all-PSCs. In addition, the anisotropic charge transport properties of the polymers require careful control of their packing structure and orientation suitable for their use in all-PSCs. To control the planarity of the polymer backbone and enhance electron mobility, we introduce three different electron-rich units (i.e., thiophene (T), bithiophene (T2), and thienylene–vinylene–thienylene (TVT)) into the NDI-based polymers. Particularly, P(NDI2OD–TVT) polymers exhibit the highest electron mobility (2.31 cm2 V–1 s–1) in organic field-effect transistors owing to various factors including enhanced degree of coplanarity, st...

Synthesis and Anticancer Properties of a Novel Bis-intercalator

A series of naphthalene diimide (ND)-based mono-, bis-, and tris-intercalators are synthesized and evaluated for their anticancer activities. All compounds show anticancer activities in the micromolar range. Among them the bis-intercalator is the most promising. Experimental results indicate that (i) target compounds intercalate DNA and (ii) the bis-intercalator with the optimal linker shows considerably more affinity to DNA than corresponding mono-and tris-intercalators. Spectroscopic measurements indicate that the ND groups bind to the double-stranded DNA (ds-DNA) in a classical threading intercalation mode, while the cationic linker reinforces the intercalation via electrostatic interaction with ds-DNA. In vitro cytotoxicity of the bis-intercalator towards a number of cancer cells, such as C6, HeLa, and MDA-435S, is tested and compared to that of normal cells. Attractive anticancer activity is observed with the bisintercalator, which provides a new lead in the anticancer drug design strategy.